baywide water quality monitoring program milestone...

BAYWIDE WATER QUALITY MONITORING PROGRAM

MILESTONE REPORT NO.6

SEPTEMBER 2010

BAYWIDE WATER QUALITY MONITORING PROGRAM — MILESTONE REPORT NO. 6

2

EXECUTIVE SUMMARY

Port Phillip Bay (PPB) is a large, shallow, almost landlocked bay under the influence of substantial

urbanisation. Maintaining the key environmental processes of PPB is essential for sustainability.

Water quality is important to a variety of assets, values and uses of PPB. There are several factors that can

influence water quality in PPB, including:

• Exchanges between the water column, sediment and atmosphere

• Tidal flushing from Bass Strait

• Sediment, nutrient and toxicant loads in freshwater inflows, particularly from the Yarra River

• Discharges from industry and other users.

These influences are reflected in the spatial and temporal variability of water quality parameters such as

toxicants, nutrients and turbidity. This is the context for the Water Quality Baywide Monitoring Program

(WQBMP) associated with the Channel Deepening Project (CDP).

The WQBMP has been monitoring water quality in PPB on a monthly basis since November 2007, three

months prior to the commencement of dredging activities for the CDP. Generally, the results of water quality

monitoring in PPB over this period are within natural variability and the expected effects of the CDP, as

determined by historical range and associated statistical analyses. For the most part, water quality was

within accepted guidelines.

EPA identified no major areas of concern from assessment of the six month reporting period, January – June

2010. The results reported here are consistent with an understanding of water quality in PPB derived from

earlier studies and other monitoring programs. Water quality in PPB continues to be influenced by rainfall

and associated catchment inputs. In particular, the large rainfall event in March 2010 resulted in an inflow of

nutrients, particularly nitrogen from the catchments. Phytoplankton biomass was highest along the western

shores and north of the Bay refecting this distribution of available nutrients.

The results from this and other programs designed to monitor the health of PPB have indicated that changes

in key environmental processes and assets are within the natural variability expected for PPB. Water quality

throughout PPB remains as high as it has been for at least the past 20 years and is sufficient for maintaining

assets and beneficial uses.

3

Table of Contents

Baywide water Quality monitoring Program.........................................................................1 Milestone REport No.6.........................................................................................................1 September 2010 ..................................................................................................................1 Executive Summary.............................................................................................................2 1. Introduction...................................................................................................................9 2. Discussion ..................................................................................................................12 3. Conclusions ................................................................................................................23 4. References .................................................................................................................25 Appendix 1 - Background...................................................................................................30 Appendix 2 - Methods........................................................................................................33 Appendix 3 - Results..........................................................................................................44 Appendix 4 - QA/QC data and discussion........................................................................101 Appendix 5 - Results outside of natural/expected variability ............................................104 Appendix 6. - Summary Statistics (July 2009 – June 2010).............................................108

List of Tables

Table A1.1 SEPP (WoV) objectives and ANZECC trigger values......................................32 Table A2.1 Locations and corresponding SEPP (WoV) segments ....................................33 Table A2.2 EWMA control limits for listed water quality parameters..................................37 Table A2.3 Shewhart control limits for listed water quality parameters..............................38 Table A3.1 Field sampling dates and weather conditions (January – June 2010) .............44 Table A3.2 Summary of Exception Reports (January – June 2010) ..................................45 Table A3.3 Summary of exceedence of control limits for physico-chemical data and nutrients (January – June 2010) ........................................................................................53 Table A3.4 Temperature Stratification in PPB (January – June 2010)...............................59

Table A5.1 PoMC/EPA Assessment (January – June 2010) ...........................................105 Table A6.1 Yarra River at Newport summary statistics – Schedule F7 Yarra Port Segment Objectives ........................................................................................................................108 Table A6.2 Yarra River at Newport summary statistics – Schedule F6 Hobsons Segment objectives.........................................................................................................................109 Table A6.3 Hobsons Bay summary statistics...................................................................110 Table A6.4 Corio Bay summary statistics ........................................................................111 Table A6.5 Long Reef summary statistics........................................................................112 Table A6.6 Central Bay summary statistics .....................................................................113 Table A6.7 POM DMG summary statistics.......................................................................114 Table A6.8 Patterson River summary statistics ...............................................................115 Table A6.9 Dromana summary statistics .........................................................................116 Table A6.10 Middle Ground Shelf summary statistics .....................................................117 Table A6.11 Sorrento Bank summary statistics ...............................................................118 Table A6.12 Popes Eye summary statistics.....................................................................119


4

List of Figures

Figure 1 Water Quality Monitoring Program sampling sites in PPB ...................................11 Figure A2.1 DPI Nutrient cycling continuous in-situ monitoring sites .................................40 Figure A2.2 Examples of IMOS shipborne data sampled from the Spirit of Tasmania. .....41 Figure A2.3 EPA and PoMC Beach monitoring sites .........................................................42 Figure A3.1 Victorian rainfall deciles Jan – June 2010 ......................................................47 Figure A3.2 Victorian rainfall deciles July – Dec 2009 .......................................................47 Figure A3.3 Victorian rainfall deciles Jan - June 2009 .......................................................48 Figure A3.4 Yarra River rainfall, river flow and storm events (January – June 2010) ........49 Figure A3.5 Patterson River rainfall and storm events (January – June 2010)..................49 Figure A3.6 IMOS shipborne track data (March 7 - 10 2010) ............................................50 Figure A3.7 Victorian temperature deciles (January – June 2010) ....................................51 Figure A3.8 Map of WQBMP exceedences (January – June 2010)...................................52 Figure A3.9 Two Bays continuous water quality monitoring measurements (10-23 January 2010)..................................................................................................................................54 Figure A3.10 Surface water temperature at Central Bay (January – June 2010)...............55 Figure A3.11 February surface water temperature across PPB and the Yarra River (2008 – 2010)..................................................................................................................................55 Figure A3.12 IMOS shipborne water temperature measurements for PPB (August 2008 – July 2009 and September 2009 – June 2010) ...................................................................56 Figure A3.13 Average salinity for PPB (January 2008 – June 2010) .................................56 Figure A3.14 Hobsons Bay surface and bottom salinity measurements (December 2009 – June 2010).........................................................................................................................57 Figure A3.15 Yarra River at Newport CTD salinity profiles (January – June 2010) ...........57 Figure A3.16 Popes Eye CTD salinity profiles (January – June 2010) ..............................58 Figure A3.17 IMOS shipborne salinity measurements for PPB (August 2008 – July 2009 and September 2009 – June 2010) ...................................................................................58 Figure A3.18 Hobsons Bay surface salinity and chlorophyll-a measurements (December 2009 – June 2010).............................................................................................................59 Figure A3.19 Yarra River at Newport stratification (February 2010) ..................................60 Figure A3.20 CTD profile of salinity, DO and fluorescence at Yarra River Newport (March 2010)..................................................................................................................................60 Figure A3.21 CTD profile of salinity, DO and fluorescence at Long Reef (March 2010) ....61 Figure A3.22 Hobsons Bay surface DO measurements (January – June 2010)................61 Figure A3.23 CTD profile of DO and chlorophyll fluorescence at Central Bay (April 2010)62 Figure A3.24 CTD profile of DO and chlorophyll fluorescence at PoM DMG (April 2010) .62 Figure A3.25 CTD profile of salinity, temperature and DO at Central Bay (April 2010)......63 Figure A3.26 CTD profile of salinity, temperature and DO at PoM DMG (April 2010)........63 Figure A3.27 Water clarity (Secchi depth) at Yarra River at Newport (November 2007– June 2010).........................................................................................................................64 Figure A3.28 Water clarity (Secchi depth) at Corio Bay (November 2007– June 2010) ....64 Figure A3.29 Yarra River at Newport CTD turbidity profile (January - June 2009; January - June 2010).........................................................................................................................65 Figure A3.30 Ammonium Shewhart control chart for PoM DMG (November 2007 – June 2010)..................................................................................................................................66

5

Figure A3.31 Ammonium EWMA control chart for Dromana (November 2007 - June 2010)...........................................................................................................................................67 Figure A3.32 Ammonium EWMA control chart for Central Bay (November 2007 - June 2010)..................................................................................................................................67 Figure A3.33 Ammonium EWMA control chart for Yarra River at Newport (November 2007 - June 2010).......................................................................................................................68 Figure A3.34 NOx Shewhart control chart for Central Bay (November 2007 - June 2010)68 Figure A3.35 NOx EWMA control chart for Yarra River at Newport (November 2007 - June 2010)..................................................................................................................................69 Figure A3.36 River flow and NOx measurements for Yarra River at Newport (May 2006 - June 2010).........................................................................................................................69 Figure A3.37 Melbourne Water and EPA NOx data (January – June 2010) ......................70 Figure A3.38 NOx Shewhart control chart for Popes Eye (November 2007 - June 2010) .70 Figure A3.39 Total nitrogen Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)..............................................................................................................71 Figure A3.40 Total nitrogen EWMA control chart for Yarra River at Newport (November 2007 - June 2010)..............................................................................................................71 Figure A3.41 Total nitrogen Shewhart control chart for Corio Bay (November 2007 - June 2010)..................................................................................................................................72 Figure A3.42 Total nitrogen EWMA control chart for Corio Bay (November 2007 - June 2010)..................................................................................................................................72 Figure A3.43 Phosphate Shewhart control chart for Corio Bay (November 2007 - June 2010)..................................................................................................................................73 Figure A3.44 Phosphate EWMA control chart for Corio Bay (November 2007 - June 2010)...........................................................................................................................................73 Figure A3.45 Phosphate Shewhart control chart for Central Bay (November 2007 - June 2010)..................................................................................................................................74 Figure A3.46 Phosphate EWMA control chart for Central Bay (November 2007 - June 2010)..................................................................................................................................74 Figure A3.47 WTP nutrient loads (January – June 2010) ..................................................75 Figure A3.48 WTP phosphate loads (May 2008 – June 2010) ..........................................75 Figure A3.49 Long Reef salinity and phosphate measurements (November 2007 – June 2010)..................................................................................................................................76 Figure A3.50 Melbourne Water and EPA phosphate water quality data (January – June 2010)..................................................................................................................................76 Figure A3.51 Phosphate Shewhart control chart for Dromana (November 2007 - June 2010)..................................................................................................................................77 Figure A3.52 Phosphate EWMA control chart for Dromana (November 2007 - June 2010)...........................................................................................................................................77 Figure A3.53 PPB salinity and phosphate concentrations (November 2007 - June 2010).78 Figure A3.54 Total Phosphorus Shewhart control chart for Hobsons Bay (November 2007 - June 2010).........................................................................................................................78 Figure A3.55 Total Phosphorus EWMA control chart for Hobsons Bay (November 2007 - June 2010).........................................................................................................................79 Figure A3.56 Total Phosphorus Shewhart control chart for PoM DMG (November 2007 - June 2010).........................................................................................................................79


6

Figure A3.57 Total Phosphorus EWMA control chart for PoM DMG (November 2007 - June 2010).........................................................................................................................80 Figure A3.58 Total Phosphorus Shewhart control chart for Dromana (November 2007 - June 2010).........................................................................................................................80 Figure A3.59 Total Phosphorus EWMA control chart for Dromana (November 2007 - June 2010)..................................................................................................................................81 Figure A3.60 Melbourne Water and EPA total phosphorus water quality data (January – June 2010).........................................................................................................................81 Figure A3.61 Silicate control chart for Yarra River at Newport (November 2007 - June 2010)..................................................................................................................................82 Figure A3.62 Silicate control chart for Corio Bay (November 2007 - June 2010)...............82 Figure A3.63 Silicate control chart for Patterson River (November 2007 - June 2010)......83 Figure A3.64 Silicate control chart for Popes Eye (November 2007 - June 2010) .............83 Figure A3.65 Total phytoplankton cell numbers across PPB (February 2008 – June 2010)...........................................................................................................................................84 Figure A3.66 Average Pseudo-nitzschia species cell counts from PPB (1998 – 1996; 2008 -2010) ................................................................................................................................85 Figure A3.67 Pseudo-nitzschia species cell counts across PPB (1991) ............................85 Figure A3.68 Pseudo-nitzschia species cell counts in PPB (1988-1996; 2008-2010)........86 Figure A3.69 Hobsons Bay interpolated water quality data (January – June 2010)...........88 Figure A3.70 Corio Bay interpolated water quality data (January – June 2010) ................89 Figure A3.71 Yarra River at Newport and Corio Bay phytoplankton species composition (January – March 2010).....................................................................................................90 Figure A3.72 IMOS shipborne in-situ chlorophyll fluorescence measurements for PPB (August 2008 – July 2009 and September 2009 – June2010)...........................................91 Figure A3.73 Chlorophyll a control chart for Yarra River at Newport (November 2007 - June 2010).........................................................................................................................92 Figure A3.74 Chlorophyll a EWMA control chart for Yarra River at Newport (November 2007 - June 2010)..............................................................................................................92 Figure A3.75 Chlorophyll a control chart for Corio Bay (November 2007 - June 2010) .....93 Figure A3.76 Chlorophyll a EWMA control chart for Corio Bay (November 2007 - June 2010)..................................................................................................................................93 Figure A3.77 Chlorophyll a EWMA control chart for Sorrento Bank (November 2007 - June 2010)..................................................................................................................................94 Figure A3.78 Yarra River Melbourne Water metals data (January – June 2010)...............94 Figure A3.79 St Kilda Beach monitoring metals data (January – June 2010)....................95 Figure A3.80 Arsenic control chart for Dromana (November 2007 - June 2010) ...............96 Figure A3.81 Arsenic EWMA control chart for Dromana (November 2007 - June 2010) ...96 Figure A3.82 Arsenic control chart for Central Bay (November 2007 - June 2010) ...........97 Figure A3.83 Arsenic EWMA control chart for Central Bay (November 2007 - June 2010)...........................................................................................................................................97 Figure A3.84 Total chromium control chart for Yarra River at Newport (November 2007 - June 2010).........................................................................................................................98 Figure A3.85 Total copper Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)..............................................................................................................98 Figure A3.86 Dissolved copper control chart for Yarra River at Newport (November 2007 - June 2010).........................................................................................................................99

7

Figure A3.87 Total lead Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)..............................................................................................................99 Figure A3.88 Dissolved lead control chart for Yarra River at Newport (November 2007 - June 2010).......................................................................................................................100


8

List of Abbreviations

ANZECC Australian & New Zealand Environment Conservation Council

Guidelines for Fresh and Marine Water Quality (2000)

BMP Baywide Monitoring Program

CDBMP Channel Deepening Baywide Monitoring Programs

CDP Channel Deepening Project

CTD Conductivity, Temperature and Depth profiler

DIN Dissolved Inorganic Nitrogen

DO Dissolved Oxygen

DPI Department of Primary Industries (Victoria)

EES Environment Effects Statement

EPA Environment Protection Authority

EWMA Exponentially Weighted Moving Average

IMOS Integrated Marine Observing System

LOR Limit of Reporting

MU Measurement Uncertainty

NATA National Association of Testing Authorities

NCBMP Nutrient Cycling Baywide Monitoring Program

PAR Photosynthetic Active Radiation

PoM DMG Port of Melbourne Dredge Material Ground

PoMC Port of Melbourne Corporation

PPB Port Phillip Bay

PPBES Port Phillip Bay Environmental Study

PR Progress Report

QA Quality Assurance

QC Quality Control

SEES Supplementary Environment Effects Statement

SEPP (WoV) State environment protection policy (Waters of Victoria)

SOP Standard Operating Procedure

TBT Tributyl tin

TSHD Trailing Suction Hopper Dredger

VSOM Victorian Shellfish Operations Manual

WQBMP Water Quality Baywide Monitoring Program

WTP Western Treatment Plant

9

1. INTRODUCTION

1.1 Water Quality Baywide Monitoring Program

Water quality is important to a variety of assets, values and uses of Port Phillip Bay (PPB). There are several

factors that influence water quality in PPB such as tidal flushing from Bass Strait, freshwater inflows,

particularly from the Yarra River, and discharges from industry. Exchanges between the atmosphere, water

column, aquatic plants and animals and sediment are also important. The combination of these factors

affects a range of water quality parameters, including contaminants, nutrients and turbidity, which can be

variable in space and time.

For interpreting PPB water quality, important considerations include:

• PPB is relatively enclosed and has limited tidal exchange

• PPB is under the influence of substantial urbanisation within the catchment

• Growth of plants in PPB is considered to be nitrogen limited

• Historically, nitrogen fixing blue-green algae have been very limited in their extent and significance in

PPB

• With respect to eutrophication, the ‘health’ of PPB is highly dependent upon sediment metabolic

processes involving benthic infauna and areas of adjacent oxic and anoxic sediment. This favours

nitrification / denitrification processes which allow nitrogen to be lost from PPB more rapidly than

tidal exchange would achieve (Harris et al. 1996).

The Water Quality Baywide Monitoring Program (WQBMP) undertakes monthly monitoring of selected water

quality parameters at 11 fixed sites in PPB (Figure 1) as part of the Channel Deepening Baywide Monitoring

Programs (CDBMP) of the Channel Deepening project (CDP). Background to the WQBMP, including details

of the EPA role in monitoring water quality in PPB, is provided in Appendix 1. Further information about the

selection of all 11 sites is outlined in Appendix 2, Table A2.1.

The parameters monitored and associated limits of reporting for the WQBMP are listed in section 4.1.2 and

4.1.3 of the Detailed Design Water Quality – Detailed Design CDP_ENV_MD_023 Rev 5.0 (PoMC 2010a).

Algal indicators to be measured are listed in section 4.1.1 of the Algal Blooms-Detailed Design

CDP_ENV_MD_012_Rev 3.0 (PoMC 2009a).

The objective of the WQBMP is to:

‘Detect changes in water quality outside expected variability’.

‘Expected variability’ refers to changes in the monitored indicator/s that are expected due to ‘natural

variability’ (i.e. background based on historical data) and the anticipated CDP - related changes as predicted

by the Supplementary Environment Effects Statement (SEES).

1.2 Port Phillip Bay Dynamics

Port Phillip Bay (PPB) is shallow (<25 m deep) and large (2,000 km2) in relation to its catchment (about

10,000 km2). It is almost land-locked, with the narrow entrance to Bass Strait and associated sand banks

(the Sands) greatly restricting exchange of water between PPB and Bass Strait.

The Western Treatment Plant (WTP) supplies about half of the nutrients entering PPB, a smaller proportion

of toxicants, and discharges treated water to PPB on a year-round basis, with highest flows in winter. Other

nutrient and toxicant sources include rivers (principally the Yarra and Maribyrnong Rivers), streams and


10

drains, with minor inputs from the atmosphere. Most of the riverine delivery of nutrients and toxicants to PPB

occurs during storms (Harris et al. 1996; Parslow et al. 1999; Sokolov and Black 1999). Storm wash-off rate

depends on the intensity of the surface run-off and on the mass of transportable chemical available within

the catchment that builds up between storm events. Maximum concentrations of chemicals in catchment

flows occur early in the first storm after prolonged dry periods.

Nutrients and toxicants are subject to a range of physical processes once they enter PPB. These include:

• Water circulation: wind and tides drive the movement of water in PPB with tidal currents dominating

on and south of the Sands;

• Evaporation and stream flow: generally water loss from evaporation is nearly equal to freshwater

inflows in PPB, so that except near discharges, salinity is similar to oceanic levels. Prevailing drought

conditions can result in higher salinity in PPB as stream flows are reduced and evaporation is

enhanced;

• Residence times: the theoretical residence time for water in the centre of PPB is about one year,

which is long enough for nutrients entering PPB to be taken up and recycled through the plankton

many times before they could be flushed to Bass Strait. Flushing times are much shorter on and

south of the Sands.

The WTP discharge is predominantly wind-driven once it enters PPB, and may move toward Hobsons Bay

under south and westerly winds or toward Corio Bay under north and easterly winds. The Yarra/Maribyrnong

Rivers typically flow down the eastern coast of PPB. Past studies indicate that the increased plankton growth

arising from these nutrient inputs might reflect these spatial patterns. Depending on the strength of the

circulation, the impacts of nutrient inputs may occur some distance from the location of the input (Longmore

2006).

The food supply of all animals in PPB depends on the production of plants, and associated nutrient supply.

Too little nutrient may lead to restricted growth, while too much may lead to undesirable impacts from

explosive growth, including aesthetic, ecosystem and human health impacts. Nitrogen has been identified as

the key nutrient limiting plant growth in PPB. The Werribee and Hobsons Bay areas receive the largest

nitrogen loads from land-based sources, and are thus two of the most highly productive areas of PPB as

indicated by phytoplankton biomass (Longmore 2006).

Ultimately almost all of the annual nitrogen input to PPB is thought to be lost from the system as N2 gas. The

process leading to this loss takes place in the sediment, and arises from the coupling of two microbial

processes, called nitrification and denitrification. Maintenance of high efficiency for these processes is

essential for maintaining high water quality in PPB (Harris et al.1996).

1.3 Methods and Results

Details of the water quality sampling and data assessment methods and results are presented in Appendices

2 and 3, respectively. To identify changes outside of natural variability, results are compared against derived

exponentially-weighted moving-average (EWMA) and Shewhart control limits and, where applicable, to

SEPP/ANZECC objectives. A discussion on quality assurance and quality control (QAQC) is provided in

Appendix 4. An assessment of the results identified as outside expected variability is available as Appendix

5. Previous results for the WQBMP have been reported by EPA (EPA 2008l, m; EPA 2009m, n; 2010h).

11

Figure 1 Water Quality Monitoring Program sampling sites in PPB

1.4 Purpose of this Report

Milestone Report # 6 (this report) is required under the Water Quality Detailed Design (PoMC 2010a) and

describes the water quality monitoring component of the Baywide Monitoring Program (BMP) for the six

month reporting period from January – June 2010 inclusive, while also reflecting on the program to date

(November 2007 – June 2010).

Its function is to provide an overall appreciation of the status of water quality in PPB for the stated reporting

period. The report summarises and interprets the information gained during the field sampling events and

documented in the monthly progress reports (EPA 2008a-k; EPA 2009a-l; EPA 2010a-g) and consolidates

results in the context of longer-term trends, background conditions, SEPP (WoV) objectives and control chart

limits, concurrent external influences (i.e. rainfall/ river flow) and other relevant studies (including other

CDBMP).


12

2. DISCUSSION

Physico-chemical Parameters

Physico-chemical parameters of interest in PPB include salinity, temperature, dissolved oxygen (DO), water

clarity (Secchi disc depth and turbidity), total suspended solids (TSS) and light (Photosynthetic Active

Radiation (PAR)). Salinity data are useful as they may give information about the size and amount of fresh

water inputs, stratification, circulation within PPB and exchange with Bass Strait. Temperature is important

for control of plant growth and microbial processes, and as a contributing factor to stratification of the water

column. Dissolved oxygen is essential for respiration for all living plants and animals. It also plays a key role

at the sediment surface in supporting nitrification and suppressing denitrification. Water clarity and TSS are

related and measured because of their impact on light availability for plants, as well as aesthetics.

Salinity, temperature, dissolved oxygen

Temperature and salinity followed expected seasonal patterns. Water temperatures across the Bay were

generally warmer and extended for a longer period in late 2009 / early 2010 compared to the previous year.

February 2010 temperatures were the highest recorded for the WQBMP in response to above average air

temperatures. Increased catchment inputs have caused a decline in average salinity with the expected

autumn peak at the lowest level for the WQBMP. Salinity within PPB is still greater than Bass Strait. DO

concentrations continue to show temporal and spatial variation but remain high enough to support the

ecology of PPB.

Salinity, temperature and DO are water quality parameters that are strongly inter-related. Changes in

temperature and salinity can both affect the concentrations of DO. This can occur via two mechanisms:

• Increased temperature and salinity directly affect the oxygen carrying capacity of water, which is

reduced as temperature and salinity increase.

• Temperature and salinity can affect the density of water, and under certain circumstances can lead

to stratification with cooler and / or more saline water (with a consequently higher density)

underlying a layer of less dense, warmer and / or fresher water. The lower layer of water is

effectively isolated from the atmosphere for the period that the stratification lasts, and oxygen

becomes depleted as it is consumed in respiratory processes of aquatic biota.

Temperature throughout the reporting period followed expected patterns with a variation of 10 - 12 °C from

summer to winter months (Figure A3.10). Air temperatures in January and February 2010 were above

average for Melbourne, and sampling in both these months followed a period of consecutive days with

maximum temperatures over 30°C. There is a direct relationship between mean air temperature and mean

surface water temperature when averaged over a few days (Black and Mourtikas 1992). Air temperatures in

summer, warmer than usual by 1.9–2.4°C, translated to warmer water temperatures recorded for the

WQBMP. February surface water temperatures in 2010 were the warmest recorded since commencement of

the WQBMP, with temperatures at some sites 2–4 °C hotter than in 2008 or 2009 (Figure A3.11). This was

confirmed by the IMOS shipborne data which show temperatures were generally warmer across the Bay for

a longer period of time in 2009/2010 compared to 2008/2009 (Figure A3.12). The continuous measurements

carried out by DPI since 2002 show higher temperatures in 2007 and 2009, however the DPI instruments

were out of the water for service in the period 5–16 February 2010 (Figure A3.10) and may have missed the

period of peak temperature. The implications of increased temperature include: increased biological

metabolic rate (by 10-30%; Mickelson 1990), lower capacity of the water to hold oxygen (by 4–6% at a

13

salinity of 37 psu; Parsons et al. 1984), and a likelihood of increased stratification (since surface heating is

the source of the increased temperature). Temperature stratification occurred at a number of sites (Table

A3.4), particularly in February 2010. The CTD profile data indicate that most of the temperature stratification

events show a gradual decline in temperature with depth rather than a marked thermocline. The strongest

thermal stratification occurred at the Yarra River at Newport site, where changes in temperature coincided

with changes in salinity at depth, indicating colder freshwater inflows at the surface (Figure A3.19).

Salinity in PPB is influenced by freshwater inflows, patterns of circulation and exchange with Bass Strait.

Prior to 1997, highest salinity was usually found at the Heads (from Bass Strait), but the domination of

evaporation over river flow since then has led to higher salinity in PPB than in Bass Strait. Average rainfall in

the latter half of 2009 reduced average salinity in the Bay to less than 36 psu in December 2009 (Figure

A3.13). Due to the continuation of average rainfall in the catchment into summer and autumn of 2010, the

seasonal increase in salinity which is observed each autumn was at a lower level (<37 psu) than observed

during 2008 or 2009 (Figure A3.13). Rainfall in PPB and its catchment since spring 2009 has not been

sufficient to reduce salinity throughout the Bay to oceanic levels.

Strong spatial variability in salinity across PPB remains. Salinity, particularly in surface waters close to

significant freshwater inflows, such as Hobsons Bay near the Yarra River and to a lesser extent Patterson

River and the WTP, dropped substantially following periods of rainfall (Figure A3.14). Sites closer to the

Heads were generally between 35 and 36 psu, reflecting exchange with water in Bass Strait (Figure A3.16).

The Corio Bay site in the Geelong Arm of the Bay, where circulation with the rest of the Bay and Bass Strait

is limited and there are fewer freshwater discharges, remained above 37.5 psu throughout the summer,

autumn and early winter period (Figure A3.70). The spatial variability in salinity across PPB is illustrated

somewhat by the IMOS shipborne track data (Figure A3.17) and clearly by the Two Bays water quality

monitoring in January 2010 (Figure A3.9).

By definition (PoMC 2010), salinity stratification (greater than 10 psu difference between surface and bottom

waters) did not occur during the period January to June 2010, although there was an evident halocline at the

Yarra River at Newport site in both March and April 2010 following periods of high rainfall and consequent

river flow (Table A3.4). In March this resulted in an unusual pattern of DO stratification at the Yarra River at

Newport, with a decline of over 20% in DO from the surface to the halocline and then a subsequent increase

in DO at depth in the lower saline water layer (Figure A3.20). A similar pattern for DO was observed at Long

Reef in March 2010 (Figure A3.21).

This unusual pattern of DO variation with depth was mimicked by the fluorescence measurements of

chlorophyll at both these sites (Figure A3.20 and Figure A3.21). These indicate higher chlorophyll (and

phytoplankton) at the surface that decline through the freshwater layer, with a subsequent increase in

chlorophyll in the deeper saline water layers. As the samples were collected in the middle of the day, it is

hypothesised that DO concentrations reflect oxygen production by phytoplankton at different abundances

within the water column.

A similarly interesting pattern of DO and chlorophyll fluorescence occurred in the centre of PPB during

February 2010 at both the Central Bay and Port of Melbourne Dredge Material Ground (PoM DMG) sites. At

these sites there was a decline in DO at depth and a corresponding increase in chlorophyll fluorescence

(Figure A3.23 and Figure A3.24). This may indicate the breakdown of phytoplankton in bottom waters,

consuming oxygen and releasing chlorophyll, or the net respiration of phytoplankton in deep water where

light is limiting.

Stratification hinders the transfer of oxygen from the upper layers to the sediment, where most oxygen

consumption occurs. Although declines in DO were observed in the bottom 3m at PoM DMG and bottom 2m


14

at Central Bay in April 2010, coincident with colder temperatures and higher salinity (Figure A3.25 and

Figure A3.26), the DO concentrations were still high enough (>85%) to be of no ecological concern. Similar

observations were made in the centre of PPB 25 years ago (Mickelson 1990). As PPB is relatively shallow

and open, stratification events are usually short and quickly broken down by wind mixing of the water

column. Unless stratification increases (e.g. by increased river flow, further temperature increases or a

decline in winds), and/or the supply of organic matter to the sediment increases (from increased primary

production), there is the expectation that DO will remain at levels sufficient to support the ecology of PPB.

Water clarity, total suspended solids and light attenuation

Water clarity across PPB was generally good. SEPP (WoV) objectives for Secchi disc depth and light

attenuation were not met at the Yarra River at Newport, which remains the most turbid of all sites due to the

influence of the Yarra River. Turbidity levels were considerably lower than recorded in 2009 with no evident

impact from the maintenance dredging. Light attenuation during the current reporting period was high at this

site due to phytoplankton activity and the influence of the Yarra River.

Water clarity may affect light availability for primary productivity and is also important for aesthetic purposes.

In addition, the amount of suspended particulate matter in the water column (as indicated by total suspended

solid concentrations) can influence the health of aquatic fauna by physical action on gills (Jenkins and

McKinnon 2006).

Turbidity, light, Secchi depth and total suspended solids are all measures that are related to water clarity.

However, the relationship between each measure is not necessarily direct or linear (Davies-Colley and Smith

2001). For example, while an increase in suspended solids will result in an increase in light attenuation and

decrease in Secchi depth, properties of the particles in the water such as shape, size, and reflective nature

of the surfaces will influence the degree to which light is attenuated (Davies-Colley and Smith 2001).

Therefore, it is pertinent to consider at least one direct measure of water clarity and also suspended

sediments due to their different biological effects.

Water clarity, as indicated by Secchi disc depth was, for the most part, within historical measures and

SEPP (WoV) water quality objectives. The Yarra River at Newport site is generally the most turbid area

due to the large amounts of sediment transported from urban and rural catchments in the Yarra River.

The central sites of PPB show little variability and are generally clear, while the water clarity at other sites

is often influenced by natural and site specific processes including wind, storms, local currents and tides

and phytoplankton growth.

Despite maintenance dredging in the Yarra River and Hobsons Bay from November 2009 to June 2010,

turbidity levels remained low (Figure A3.29) and the SEPP (WoV) Secchi depth objectives were met in May

and June 2010 (Figure A3.27). Previous investigations of maintenance dredging activities have indicated that

increased turbidity was not detected more than 200 metres from the active dredge, and persisted for a period

of less than two hours after dredging ceased (Hale 2006a).

Despite turbidity and suspended solids remaining within SEPP (WoV) objectives, the annual 90th percentile

objective for light attenuation was exceeded for the Yarra River at Newport and Sorrento Bank sites

(Appendix 6). At Sorrento Bank the exceedence of the SEPP (WoV) light attenuation objective was by a

very small margin (Table A6.11). This may be due to tidal or wave-driven resuspension of sediments, but

might also reflect the difficulty of measuring light attenuation (an integrated measure calculated over depth)

at a shallow site. At the Yarra River at Newport site, the exceedence of the guideline was substantial (Table

A6.2). An examination of the raw data indicates that light attenuation was very high on two occasions, in

15

July 2009 and February 2010. The first of these occurred during CDP dredging, when turbidity levels were

high, while the second occurred during a phytoplankton “bloom”. Light attenuation at this site was above the

90th percentile objective for nine of the last 12 sampling occasions. This perhaps reflects the position of the

site (in a river rather than PPB), and the freshwater influences of the site, which make it difficult for PPB

SEPP (WoV) objectives to be met for some parameters.

Nutrients

Nutrients in aquatic ecosystems are significant for the role they play in primary production. Deciphering

patterns and trends in nutrients in aquatic systems is difficult as they cycle through various forms within the

water column and sediments. Aquatic plants and phytoplankton take up nutrients in dissolved inorganic

forms (e.g. NOx, ammonium, phosphate) and dissolved organic forms (e.g. urea). Measures of total nitrogen

and phosphorus include inorganic particulate forms as well as nutrients within the cells of phytoplankton and

zooplankton. In the sediment, particulate forms of nitrogen and phosphorus can be remineralised into

dissolved forms by micro-organisms. The processes of deamination, nitrification and denitrification can

result in the release of ammonium into the water column or nitrogen gas lost to the atmosphere. Sediment

nutrient cycling is strongly influenced by the oxygen regime at the sediment water interface (Murray and

Parslow 1997).

Plant growth in PPB is nitrogen-limited (Harris et al. 1996) and there is a hierarchy of interest in considering

the various nitrogen forms. Of particular interest are the dissolved inorganic nitrogen forms, ammonium,

nitrite and nitrate (NOx), because they are the most readily taken up by plants. Silicate is also of interest

because historically, under certain conditions (off the Werribee coast), it may limit growth of the most

abundant plankton type (diatoms) (Longmore et al. 1996). Phosphate, although in a form readily taken up by

plants, is of lower interest because it is present in excess in PPB compared to inorganic nitrogen. The

organic and particulate forms of nitrogen and phosphorus are also of lesser interest, as they are generally

not readily available for uptake by plants. Other important factors that influence nutrient concentrations in the

Bay include freshwater inflows (rivers and WTP), which discharge nutrients into the Bay; seasonal cycles in

underwater light climate, which influence rates of primary productivity; and exchange rates with Bass Strait

(Harris et al. 1996).

Set against this complex backdrop is the monthly instantaneous sampling of nutrient concentrations from 11

sites around PPB. The difficulty in assessing the significance of nutrient concentrations in the Bay is

recognised in the SEPP (WoV) Schedule F6, which does not have objectives for nutrient concentrations.

The effects of increased nutrients are assessed through their primary production response (increased

phytoplankton production), with SEPP (WoV) objectives for chlorophyll-a concentrations. Assessment of

nutrient concentrations for the WQBMP is via EWMA and Shewhart control limits.

Nitrogenous compounds

Total nitrogen and NOx concentrations are highest at sites close to freshwater inputs. Continued

exceedences during the reporting period have occurred at the Yarra River at Newport site due to increased

inflows from the catchment compared to the historical period. Winter increases in NOx, associated with Bass

Strait waters, were again observed in southern PPB. A small increase in ammonium concentrations

coincident with small increases in chlorophyll-a was observed across the Bay, suggesting increased grazing

by zooplankton.


16

Total nitrogen is the sum of dissolved inorganic nitrogen, organic nitrogen and particulate nitrogen. The

latter two groups include a wide range of compounds from terrestrial and aquatic plant production, such

as phytoplankton cells. They are present throughout PPB in much higher concentrations than the

dissolved inorganic (readily available) forms, but are thought to be resistant to decomposition to forms

readily available for plant growth.

In general, nutrient concentrations during the reporting period followed expected patterns with higher

concentrations recorded in the north of the Bay and at sites adjacent to known nutrient sources (e.g. Long

Reef near the WTP, and Yarra River at Newport and Hobsons Bay under the influence of the Yarra River). In

particular, the large rainfall event in March 2010 resulted in an inflow of nutrients, particularly nitrogen, from

the catchments. This is illustrated in the Melbourne Water data collected from the Yarra River, which saw

peaks of total nitrogen (4745 µg/L) and NOx (920 µg/L) in the Yarra River (Figure A3.37). This was also

reflected in high NOx and total nitrogen concentrations at the Yarra River at Newport site (Figure A3.36 and

Figure A3.39).

During the past year, control limits for NOx and total nitrogen have continually been exceeded at the Yarra

River at Newport site. These exceedences are a response to the increased rainfall and associated

catchment flows since late 2009. The control limits for this site were calculated from 12 data points collected

during prevailing drought conditions in 2006/2007 when catchment flows rarely exceeded 1500ML/day and

NOx concentrations were typically <50µg/L. With a resumption of normal rainfall patterns, flows from late

2009 have been considerably greater than for the background period, reaching as high as 5000ML/day in

March 2010 with NOx concentrations consistently exceeding 100µg/L (Figure A3.36). The same pattern is

also evident for total nitrogen.

The most southern sites (Sorrento Bank and Popes Eye, and to a lesser extent Middle Ground Shelf (MGS)

and Dromana) saw increases in NOx concentrations during April-June 2010. This is consistent with the

intrusion of Bass Strait water as a source of NOx to southern PPB in winter (Figure A3.38; EPA 2010h).

A trend of increasing ammonium concentration between January and April–May 2010 was observed in both

the raw data and EWMA transformed data at most sites, excluding Hobsons Bay, Corio Bay and Long Reef.

The increase was greatest at the Yarra River at Newport and smallest at Popes Eye and Sorrento (about 50,

2 and 2 µg/L respectively), with the increase at the Yarra River at Newport due mostly to the March 2010

high flow event (Figure A3.33). The Baywide increase is unlikely to have been caused by increased Yarra

discharge because no such change was observed at Hobsons Bay. Increasing discharge of ammonium

from the WTP in May–June 2010 (Figure A3.47) was matched by an increase at Long Reef in June, but

WTP is unlikely to have caused the increasing trend in ammonium concentrations in the rest of PPB because

it began before the WTP discharge increased.

This pattern of increasing ammonium concentrations can be indicative of nutrient cycling within the Bay.

Data from the Nutrient Cycling Baywide Monitoring Program (NCBMP) indicates that changes to benthic

nutrient recycling rates are unlikely to be the cause of the observed increases in ammonium concentration,

as benthic inorganic nitrogen (ammonium plus NOx) fluxes declined by 66% at Hobsons Bay and by 19% at

Central PPB between February and May 2010 (Longmore and Nicholson 2010a, b). The most likely cause of

increased ammonium concentrations is zooplankton grazing. When zooplankton consume phytoplankton,

nitrogen is released to the water column, either by leakage of cell contents when cells are ruptured or by

excretion as ammonium from the zooplankton. More than 60% of primary production is recycled in the water

column, principally by grazing (Murray and Parslow 1999). An increase in ammonium concentration

coincident with an increase in chlorophyll-a concentration (0.5–1.0 µg/L between January and June 2010 at

most sites) is consistent with these processes.

17

Denitrification (the process which removes most of the nitrogen from PPB) increases with increasing water

residence time (Seitzinger et al. 2006). Under drought conditions, residence time of water in PPB would be

expected to increase, along with rates of denitrification. With a return to normal rainfall patterns in the past

six months, residence time in PPB would be expected to decrease as rainfall on the Bay and freshwater

flows from the catchment increased. The relatively small changes in salinity observed during the reporting

period suggest residence time did not change greatly, and denitrification efficiency during this reporting

period (in February and May 2010; Longmore and Nicholson 2010a, b) was not significantly different to that

estimated in 2008 or 2009.

Ammonium concentrations at Dromana continued to exceed EWMA control limits (Figure A3.31). The

control limit set for this site was based on limited data (30 records from 1994-2006) and is low compared

to other sites in the Bay. In comparison, the ammonium EWMA control limit for the Central Bay site

(based on over 100 records from 1994 to 2007) is 9.9µg/L, nearly double that of Dromana. The

ammonium concentrations in the centre of PPB are theoretically expected to be lower than those that are

inshore, which are subject to more direct influences of nutrient rich, freshwater inflows from rivers and

storm water drains (Murray and Parslow 1997; PoMC 2008).

Phosphorous compounds and silicate

WTP continues to be the principal source of phosphate into PPB. The decline in concentration seen during

2008-2009 and partial recovery in 2010 is almost certainly due to changes in the discharge from WTP. The

key process affecting phosphate concentrations over most of PPB remains dilution. Silicate concentrations

were again highest at the Yarra River and lowest in the south of the Bay. There is some evidence to suggest

recycling of silicate from the sediment is a key source for phytoplankton growth independent of external

inputs.

The WTP is the principal source of phosphorus to the bay (800-1,500 t y-1

between 1996 and 2008;

Melbourne Water WTP monitoring data), with the Yarra River and other streams of secondary importance

(200-600 t y-1

; Harris et al. 1996). About as much phosphorus (1,000-1,900 t; Harris et al. 1996) is held in

PPB waters as enters each year from the catchment. Because phosphate is far in excess of that needed for

plankton growth, its distribution is governed by dilution, and the primary loss is via flushing to Bass Strait.

The historical spatial distribution for phosphate shows concentrations decreasing in the following order: Long

Reef, Corio Bay, Yarra River at Newport and Hobsons Bay, Central Bay and near shore PPB, and south of

the Sands.

Over the past two years (since May 2008), there has been a substantial (30-50%) downward trend in

phosphate concentration at most sites in PPB, with a partial recovery at some sites since January 2010

(Figure A3.48). Assuming that WTP remains the most significant source of phosphate to PPB, the decline

could indicate either:

• A decline and subsequent partial increase in the input (from WTP) or

• An increase and decrease in dilution (exchange with Bass Strait)

As soils dry, the bonds attaching phosphate to soil particles weaken (Kerr et al. 2010). When soils are

subsequently wetted, phosphate is released to the runoff. Phosphate concentrations are therefore high in

high flows following dry periods (Sokolov and Black 1999) and the Yarra River may have contributed

significant amounts of phosphate to the Bay during the high-flow events in spring 2009. However, it is clear

from the Melbourne water data (Figure A3.50) that there was no correlation between river flow and


18

phosphate concentration in the Yarra River during January to June 2010, and the increase in phosphate

concentration at the Yarra River at Newport over the same period reflected increases in the rest of the Bay.

This confirms that even in the mouth of the Yarra, the main source of phosphate is the WTP, and not the

Yarra River catchment. Alternative terrestrial sources of phosphate are therefore discounted as a reason for

increased phosphate concentrations over the reporting period.

Mixing diagrams (Boyle et al. 1974; Cifuentes et al. 1990; Longmore et al. 1999) may be used to infer the

number of sources of nutrients to a water body, and also whether any process other than dilution (e.g. algal

uptake, loss to sediment) is occurring. Mixing diagrams are based on the premise that if a nutrient is neither

consumed nor regenerated during its residence in a bay or estuary, its concentration should vary linearly

with salinity. This is because the only important process occurring is dilution of the discharge with bay water,

and ultimately with the open ocean. Conversely, non-linear variations may indicate the importance of other

processes, such as uptake by plants. Mixing diagrams are used here to indicate if there has been a change

in the key process (dilution) that has been assigned to phosphate in both major studies of PPB (MMBW/FWD

1973; Harris et al. 1996).

When applied to samples from Long Reef (the site closest to WTP) collected since November 2007, data

below a salinity of about 37.5 psu fits to a straight line on a plot of phosphate concentration versus salinity

(Figure 3.52). The data indicates linear mixing of WTP water at an initial phosphate concentration of 7,000

µg/L with Central PPB water. In this case, phosphate concentration decreases as salinity increases, as the

nutrient-rich freshwater mixes with Bay water. When applied to all the southern sites (Figure 3.53) two

straight lines are apparent. The first applies to all of the sites south of and including Central PPB, and in this

case phosphate concentration decreases as salinity decreases. This implies the key process is dilution of

PPB water with less saline (and phosphate-poor) Bass Strait water. The second straight line applies to

samples from Corio Bay. Phosphate again decreases as salinity decreases but at a lower slope than the

other sites, indicating evaporation is an important process in Corio Bay. The lower slope indicates there is

also another process, presumably algal uptake, that accounts for a small proportion of phosphate in Corio

Bay. Mixing diagrams for sites to the north of Central PPB indicate that WTP is still the only significant

phosphate source in PPB. Throughout the monitoring period, benthic flux measurements (Longmore and

Nicholson 2010b) have indicated that about 55–70% of the phosphate from recycling of organic matter is

trapped in the sediment, and there has been no change between May 2008 and May 2010 to indicate

increased burial in the sediment. There is no evidence from this analysis that the processes affecting

phosphate concentration have changed during the WQBMP, despite apparent trends, both up and down, in

concentration.

The phosphate load discharged from the WTP declined from July to December 2008, increased from

February to June 2009, declined from June to December 2009 and increased from January to June 2010

(Figure A3.48). These changes match the observations in PPB, with the increase in load in February to June

2010 shown as a “flattening” of the downward trend in the observations in PPB. This most likely reflects the

time it takes for the WTP discharge to mix into the deeper central water mass.

In summary, there is no evidence during the WQBMP of a change in the number of phosphate sources to the

Bay or the amount buried in the sediments, and the key process affecting phosphate concentration over

most of PPB remains dilution. The decline in Baywide phosphate concentrations through 2008-09 and

subsequent recovery in 2010 was almost certainly caused by changes to the discharge from the WTP.

Nitrogen remains the limiting nutrient for plant growth, and the phosphate decline and subsequent increase

at some sites has no consequence for the health of PPB.

19

Silicate concentrations varied throughout the Bay, with highest concentrations (up to 900 µg/L) at the Yarra

River at Newport following the high-flow event in March 2010 (Figure A3.61), and lowest concentrations at

the sites nearest Bass Strait (about 40 µg/L at Sorrento Bank and Popes Eye (Figure A3.64)). The available

evidence indicates that the main catchment source of silicate to PPB during the reporting period was the

Yarra River. This is consistent with earlier measurements (Sokolov 1996; Harris et al. 1996; Longmore et al.

1996). The Yarra River silicate load estimate of 3,900 t y-1

in 1995 was based on higher river flows than has

occurred since the WQBMP began, and the estimated annual load from the WTP (about 800t in 1995) may

form a more significant proportion of the total load now than it did during the Port Phillip Bay Environmental

Study (PPBES). Benthic flux measurements (DPI unpublished data) suggest that recycling of silicate from

the sediment in 2002-10 could have supplied about 12,000 t y-1

; well in excess of known terrestrial inputs.

Recycling from the sediment may be a key source of silicate for plankton growth throughout the Bay,

independent of external inputs.

Comparisons of inorganic nitrogen, phosphate and silicate concentrations indicated that at all sites the

inorganic nitrogen to phosphate ratio was about one-tenth of that needed for plankton growth, indicating

nitrogen is still the growth limiting nutrient. The inorganic nitrogen to silicate ratio also indicated strong

nitrogen limitation at all sites, except at Long Reef in March and Popes Eye in June 2010. In both these

cases, nitrogen and silicate concentrations were nearly in balance with demand.

Phytoplankton and chlorophyll-a

While phytoplankton populations were considerably lower than blooms recorded during late 2009, potentially

harmful phytoplankton species (diatoms and dinoflagellates) were detected in substantial numbers. Pseudo-

nitzschia species, Alexandrium catenella and Karlodinium species were all detected above Victorian

Shellfish Operations Manual (VSOM) warning levels for the first time during the WQBMP. The SEPP (WoV)

annual objectives for chlorophyll-a were not met at the Corio Bay, Yarra River at Newport and Patterson

River sites due to the peaks in phytoplankton biomass over the past year.

Phytoplankton is the most significant primary producer in PPB, accounting for the majority of net primary

production (Beardall and Light 1997). Despite this, biomass is generally low compared to similar estuaries

and bays within Australia and internationally (Harris et al. 1996). It was suggested by Beattie et al. (1997)

that the phytoplankton biomass within PPB is maintained at these low levels by zooplankton grazing, thereby

providing a rapid flow of the products of photosynthesis into the food chain.

Although low, phytoplankton biomass within PPB is highly variable across space and time. Available

nutrients, light and temperature are considered the most important factors influencing phytoplankton growth

in PPB (Wood and Beardall 1992). Greater biomass generally occurs within Hobsons Bay and the Yarra

River, and lower biomass is generally recorded in the south of PPB reflecting the distribution of available

nutrients. Temporal trends in phytoplankton biomass are more difficult to characterise, but biomass is

generally higher during summer / autumn months than over winter, reflecting seasonal patterns of light and

temperature (Beardall et al. 1997).

The pattern of phytoplankton biomass (as reflected by chlorophyll-a concentrations) over the period January

to June 2010, was consistent with these historical trends of spatial and temporal variability. The IMOS

shipborne data shows both spatial and temporal variability in chlorophyll fluorescence (Figure A3.72). Along

the route followed by the ship from Hobsons Bay, through central PPB to Bass Strait, chlorophyll

fluorescence was always highest in Hobsons Bay and lowest at the Heads. Chlorophyll fluorescence

measurements from the Two Bays monitoring program in January 2010 also provide a spatial snapshot of


20

coastal plankton patterns in the Bay (Figure A3.9). Highest chlorophyll concentrations were seen along the

western shores and north of the Bay associated with nutrients from nearby sources (Figure A3.9).

SEPP (WoV) water quality objectives for chlorophyll-a are based on annual medians and 90th percentiles to

integrate seasonal variability. Annual medians and 90th percentiles for chlorophyll-a calculated over the

period July 2009 to June 2010 were within SEPP (WoV) objectives at most sites. The exceptions were

exceedences of the 90th percentile objectives at the Yarra River at Newport, Corio Bay and Patterson River

(Appendix 6). EWMA control limits were also exceeded at the Yarra River (Figure A3.74) and Corio Bay

sites (Figure A3.76), driven by peaks in phytoplankton biomass in February 2010 at both sites and May 2010

in Corio Bay (Figure A3.73and Figure A3.75).

High cell counts from both the Yarra River at Newport and Corio Bay sites once again did not correspond

with the chlorophyll-a data. There are a number of possible explanations for the inconsistency in cell counts

and chlorophyll-a concentrations. Different species of phytoplankton can contain different amounts of

chlorophyll-a depending on their size, dominant pigments and responses to environmental variables such as

light and temperature. During this reporting period, there were significant shifts in phytoplankton community

composition that may account for the disparity between cell counts and chlorophyll-a concentrations.

The phytoplankton community at the Yarra River at Newport site, although dominated by diatoms, had a shift

in species composition from January to February and again in March 2010. In January a potentially harmful

species from the Pseudo-nitzschia delicatissma group and Skeletonema costatum were the most dominant

species. In February, the diatom S. costatum was dominant, while in March, when cells numbers plummeted

but chlorophyll-a concentrations did not, there was a mixture of species present but no clear dominant

species (Figure A3.71).

There was also a shift in dominant species at Corio Bay over this time period. In January 2010,

Skeletonema japonicum/pseudocostatum was the dominant species. In February, when cell counts

decreased, but chlorophyll-a increased, cryptopytes and dinoflagellates where the most numerous

phytoplankton groups. In March, where cell numbers increased, but chlorophyll-a concentrations decreased,

diatoms were once again the dominant group in the phytoplankton community (Figure A3.71).

Peaks in phytoplankton populations (total cells) observed during this reporting period were considerably

lower than blooms recorded earlier in the WQBMP, such as those seen at the Yarra River at Newport and

Hobsons Bay in November and December 2009 and in Corio Bay in April 2009 (Figure A3.65). The

presence of potentially harmful species (Pseudo-nitzschia species, Alexandrium catanella and Karlodinuium

species) in substantial numbers, have not previously been recorded during the WQBMP. Notification was

provided to the Department of Sustainability and Environment (DSE) on each occasion that identified

potentially harmful species detected above VSOM warning levels.

The P. delicatissma group contains two species that are difficult to distinguish (P. delicatissma and P.

pseudodelicatissma), and for the purposes of the WQBMP are counted together. Although this group of

species has the potential to produce domoic acid which causes amnesic shellfish poisoning, they are not

known to produce the toxin in Australia (Hallegraeff 1994). Adopting a precautionary approach, the

Victorian Marine Biotoxin Management Plan (VMBMP) sets a threshold for warnings to shellfish farmers in

PPB at 100,000 cells/ L and suspension of shellfish harvesting at 500,000 cells / L (Walker 2009). Numbers

of P.delicatissma group above the warning and suspension thresholds were recorded in the Yarra River at

Newport (987,000 cells/L) and Hobsons Bay (3,650,000 cells/L) in January 2010 (Figure A3.68) and in Corio

Bay (535,000 cells/L) in April 2010. These sites are remote from existing shellfish farming areas in PPB and

no closures to shellfish harvesting occurred in PPB due to these threshold exceedences during the period

April 2009-April 2010 (A. Clarke, DPI, pers. comm.).

21

The 2010 Pseudo-nitzschia blooms were short lived, localised and followed a peak and decline of other

diatom species. The January Pseudo-nitzschia bloom in the north of the Bay followed a peak and decline of

S. japonicum/pseudocostatum in December 2009, while the April Pseudo-nitzschia bloom in Corio Bay

followed a peak and decline of Cylindrotheca closterium in Corio Bay in March 2010. The growth of P.

delicatissma group is reportedly linked to NOx concentrations and potentially nitrate to silicate ratios

(Parsons and Dortch 2002). It is possible that following the decline in blooms of other diatoms, nitrate and

silicate were released into the water column making conditions suitable for growth of Pseudo-nitzschia. In

the Yarra River, the decline of S. japonicum/pseudocostatum occurred following heavy rains in late

December/early January. This is consistent with reports of the ecology of Skeletonema spp. from elsewhere,

where decreases in salinity following heavy rain led to a decline in the species and subsequent rise of an

opportunistic species (Han et al. 2002).

These species have a relatively constant low level presence in PPB, and previously blooms of this species in

PPB and other southern Australian waters were considered common (Hallegraeff 1994). The species

bloomed in PPB in 1991/1992 with a peak of 4,200,000 cells/L in December 1991, and again in September

1996 with a peak of 2,800,000 cells/L (Longmore 2010; Figure A3.68). On several occasions in the past

(most notably 1991), the bloom extended across many areas of the Bay including Grassy Point in the East,

through Hobsons Bay to Dromana in the south (Longmore 2010; Figure A3.67).

Alexandrium spp. are potentially harmful dinoflagellates that have been known to result in the presence of

toxins in mussels in PPB in the past, with paralytic shellfish poisons detected in tissue samples from a

number of locations in the Bay (Arnott et al. 1997). Alexandrium catenella was detected in the Yarra River at

Newport in February 2010 at 4,100 cells/L. The VSOM levels for A. catenella are 200 cells/L for a warning

issued to growers and 500 cells/L for suspension of harvest (Walker 2009). Alexandrium spp. are cyst

forming species. Cysts were abundant in the sediments of the Yarra River and Hobsons Bay in 1994 (Arnott

et al, 1994), although not detected in more recent surveys (Hale 2006b). Release of the cysts from the

sediment is thought to be controlled by increasing day length, increased temperatures and nutrient

concentrations (Sgrosso 2006). Past blooms in Hobsons Bay have all been preceded by heavy rainfall or

storm events. It is likely that the prolonged drought over the past decade resulted in a lack of opportunities

for germination of cysts in the sediments of Hobsons Bay. The return of average rainfall, increased

catchment inputs and the summer storm events that resulted in a combination of warm water temperatures

and increased nutrients provided suitable conditions for germination and growth.

Karlodinium spp. are small unarmoured dinoflagellates usually considered together with members of the

Karenia genus. Members of the group are known to cause fish deaths, but the mechanism is unknown

(Walker 2009). VSOM warning levels for Karlodinium spp. start at 100,000 cells/L, however it is widely

thought that Karlodinium spp. in general and Karlodinium australe in particular are not toxic (Mooney et al.

2009). The ecology of Karlodinium is not well documented, but it is thought to be inhibited by low salinity

and this may be why conditions in Corio Bay were suitable for growth in March and April 2010, when salinity

was greater than 38.2 psu.

As previously stated, WQBMP monitoring sites where elevated levels of potentially harmful phytoplankton

were detected during the reporting period are remote from existing shellfish farming areas in PPB and no

closures to shellfish harvesting occurred in PPB due to exceedence of phytoplankton threshold levels during

the period April 2009-April 2010 (A. Clarke, DPI, pers. comm.).


22

Metals

Concentrations of heavy metals in the waters of PPB remain low. Most metals are transported to PPB

through the catchment inflows following heavy rain, as evident in the Melbourne Water and Beach monitoring

program data.

Heavy metals in the waters of PPB, with the exception of arsenic, are low compared to ranges found in

estuaries and close to values for coastal waters (Fabris and Monahan 1995). Metals from the catchment are

transported through the rivers, streams and drains that discharge into PPB, with the greatest loads received

in the first few hours following heavy rain. The majority of metals occur in particulate form, and sedimentation

removes a significant proportion of the incoming load from the water column (Fabris and Monahan 1995).

The results from the sampling period January to June 2010 are consistent with this understanding of heavy

metals in PPB. This is evident mostly in peaks in metal concentrations following heavy rain and peak river

flow in March 2010 from the Melbourne Water and Beach monitoring data (Figure A3.78 and Figure A3.79).

The majority of samples from the WQBMP contained very low concentrations of metals. There was only one

occasion where a metal concentration exceeded the control limit i.e. chromium at the Yarra River at Newport,

predominantly in particulate form. In the particulate state, metals pose a lower ecological risk as they cannot

be taken up directly by organisms, and toxicity is therefore reduced (Goossens and Zwolsman 1996).

23

3. CONCLUSIONS

The WQBMP has been monitoring water quality in PPB on a monthly basis since November 2007, three

months prior to the commencement of dredging activities for the CDP. Generally, the results of water quality

monitoring in PPB over this period are within natural variability and the expected effects of the CDP, as

determined by historical range and associated statistical analyses. For the most part, water quality was

within accepted guidelines.

A summary of results from the current reporting period January – June 2010 are presented below:

• Temperature throughout the reporting period varied by 10 - 12°C from summer to winter months,

with an extended period of elevated water temperatures from late 2009 to early 2010.

• February surface water temperatures were the highest recorded at most sites for the WQBMP

following above average summer air temperatures.

• Salinity in PPB is still higher than Bass Strait. Average salinity has declined in PPB with historical

autumn peaks at their lowest level since commencement of the WQBMP.

• DO concentrations continue to show temporal and spatial variation but remain high enough to be of

no ecological concern.

• Water clarity across PPB was generally good. The Yarra River at Newport remains the most turbid

site due to the influence of the Yarra River.

• SEPP (WoV) objectives for light attenuation were met at most sites. The influence of the Yarra River

and increased phytoplankton activity were the causes of poor light attenuation at the Yarra River at

site.

• Total nitrogen and NOx concentrations were highest close to freshwater inputs. Increased catchment

flows have resulted in continued exceedences at the Yarra River at Newport.

• Winter increases in NOx associated with water from Bass Strait were again observed in southern

PPB.

• Small increases in ammonium and chlorophyll-a were observed across many areas of PPB

suggesting grazing by zooplankton.

• WTP continues to be the main source of phosphate into PPB with changes in concentrations

reflecting changes in discharges.

• Recycling of silicate from the sediments may be a key source for phytoplankton (diatoms)

independent of external sources.

• Potentially harmful phytoplankton species (diatoms and dinoflagellates) were detected in substantial

numbers for the first time during the WQBMP, but the relevant sites were remote from shellfish

farming areas in PPB and no closures to harvesting occurred.

• SEPP (WoV) chlorophyll-a objectives were not met at the Yarra River at Newport, Corio Bay and

Patterson River sites due to peaks in phytoplankton biomass over the past year.

• Metal concentrations remained low and consistent with historical studies.

EPA identified no major areas of concern from assessment of the current reporting period. The results

reported here are consistent with an understanding of water quality in PPB derived from earlier studies and

other monitoring programs.


24

The results from this and other programs designed to monitor the health of PPB have indicated that changes

in key environmental processes and assets are within the natural variability expected for PPB. Water quality

throughout PPB remains as high as it has been for at least the past 20 years and is sufficient for maintaining

assets and beneficial uses.

25

4. REFERENCES

ANZECC 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000),

Australian and New Zealand Environment Conservation Council.

Arnott, G., Conron, S., Reilly, D., Hill, D. and Sonneman, J., 1994, Effects of channel maintenance dredging

on the mobilization and translocation of toxic algal cysts in Port Phillip Bay, Report to Port of Melbourne

Authority, Victorian Fisheries Research Institute, Queenscliff, Victoria

Arnott, G., Gason, A., Hill, D., Margo, K., Reilly, D. and Coots, A., 1997, Phytoplankton composition,

distribution and abundance in Port Phillip Bay from March 1990 to February 1995, Port Phillip Bay

Environmental Study, Technical Report No.40, CSIRO, Melbourne.

Beardall, J. and Light, B., 1997, Microphytobenthos in Port Phillip Bay: Distribution and primary productivity,

Port Phillip Bay Environmental Study, Technical Report No.30, CSIRO, Melbourne.

Beardall J., Roberts S. and Royle, R., 1997. Phytoplankton productivity in Port Phillip Bay: seasonal and

spatial distributions. Technical Report No. 35, CSIRO Port Phillip Bay Environmental Study, ACT.

Black, K.P and Mourtikas, S 1992. Literature review of the physics of Port Phillip Bay, Port Phillip Bay

Environmental Study Technical Report No.3

Boyle, E.A., Collier, E.R., Dengler, A.T., Edmond, J., Ng, A.C. and Stallard, R.F. 1974. On the chemical

mass balance in estuaries. Geochim. Cosmochim. Acta 38, 1719-1728.

Cifuentes, L.A., Schemel, L.E. and Sharp, J.H. 1990. Qualitative and numerical analyses of the effects of

river inflow variations on mixing diagrams in estuaries. Estuarine, Coastal and Shelf Science 30, 411-427.

Davies-Colley, R. J. and Smith D.G, 2001. Turbidity, Suspended Sediment, and Water Clarity: A Review.

Journal of the American Water Resources Association 37: 1085–1101.

EPA 1999 Variation of the state environment protection policy (Waters of Victoria) - insertion of schedule F7.

Waters of the Yarra catchment. Victorian Government Gazette S 89.

EPA 2003 Variation of the state environment protection policy (Waters of Victoria) – Schedule to the order in

council. Victorian Government Gazette S 107.

EPA 2008a. Baywide Water Quality Monitoring Program Progress Report No 1. (November 2007 – January

2008), March 2008, EPA.

EPA 2008b. Baywide Water Quality Monitoring Program Progress Report No 2. (February 2008), April 2008,

EPA.

EPA 2008c. Baywide Water Quality Monitoring Program Progress Report No 3. (March 2008), May 2008,

EPA.

EPA 2008d. Baywide Water Quality Monitoring Program Progress Report No 4. (April 2008), May 2008,

EPA.

EPA 2008e. Baywide Water Quality Monitoring Program Progress Report No 5. (May 2008), June 2008,

EPA.

EPA 2008f. Baywide Water Quality Monitoring Program Progress Report No 6. (June 2008), July 2008, EPA.

EPA 2008g. Baywide Water Quality Monitoring Program Progress Report No 7. (July 2008), August 2008,

EPA.


26

EPA 2008h. Baywide Water Quality Monitoring Program Progress Report No 8. (August 2008), September

2008, EPA.

EPA 2008i. Baywide Water Quality Monitoring Program Progress Report No 9. (September 2008), October

2008, EPA.

EPA 2008j. Baywide Water Quality Monitoring Program Progress Report No 10. (October 2008), November

2008, EPA.

EPA 2008k. Baywide Water Quality Monitoring Program Progress Report No 11. (November 2008),

December 2008, EPA.

EPA 2008l. Baywide Water Quality Monitoring Program Milestone Report No 1. July 2008, EPA.

EPA 2008m. Baywide Water Quality Monitoring Program Milestone Report No 2. November 2008, EPA.

EPA 2009a. Baywide Water Quality Monitoring Program Progress Report No 12. (December 2008), January

2009, EPA.

EPA 2009b. Baywide Water Quality Monitoring Program Progress Report No 13. (January 2009), February

2009, EPA.

EPA 2009c. Baywide Water Quality Monitoring Program Progress Report No 14. (February 2009), March

2009, EPA.

EPA 2009d. Baywide Water Quality Monitoring Program Progress Report No 15. (March 2009), April 2009,

EPA.

EPA 2009e. Baywide Water Quality Monitoring Program Progress Report No 16. (April 2009), May 2009,

EPA.

EPA 2009f. Baywide Water Quality Monitoring Program Progress Report No 17. (May 2009), June 2009,

EPA.

EPA 2009g. Baywide Water Quality Monitoring Program Progress Report No 18. (June 2009), July 2009,

EPA.

EPA 2009h. Baywide Water Quality Monitoring Program Progress Report No 19. (July 2009), August 2009,

EPA.

EPA 2009i. Baywide Water Quality Monitoring Program Progress Report No 20. (August 2009), September

2009, EPA.

EPA 2009j. Baywide Water Quality Monitoring Program Progress Report No 21. (September 2009), October

2009, EPA.

EPA 2009k. Baywide Water Quality Monitoring Program Progress Report No 22. (October 2009), November

2009, EPA.

EPA 2009l. Baywide Water Quality Monitoring Program Progress Report No 23. (November 2009),

December 2009, EPA.

EPA 2009m. Baywide Water Quality Monitoring Program Report No 3. May 2009, EPA.

EPA 2009n. Baywide Water Quality Monitoring Program Report No 4. October 2009, EPA.

EPA 2010a. Baywide Water Quality Monitoring Program Progress Report No 24. (December 2009), January

2010, EPA.

27

EPA 2010b. Baywide Water Quality Monitoring Program Progress Report No 25. (January 2010), February

2010, EPA.

EPA 2010c. Baywide Water Quality Monitoring Program Progress Report No 26. (February 2010), March

2010, EPA.

EPA 2010d. Baywide Water Quality Monitoring Program Progress Report No 27. (March 2010), April 2010,

EPA.

EPA 2010e. Baywide Water Quality Monitoring Program Progress Report No 28. (April 2010), May 2010,

EPA.

EPA 2010f. Baywide Water Quality Monitoring Program Progress Report No 29. (May 2010), June 2010,

EPA.

EPA 2010g. Baywide Water Quality Monitoring Program Progress Report No 30. (June 2010), July 2010,

EPA

EPA 2010h. Baywide Water Quality Monitoring Program Report No 5. March 2010, EPA.

Fabris, G.J. and Monahan, C.A., 1995. Characterisation of Toxicants in Waters from Port Phillip Bay: Metals.

CSIRO INRE Port Phillip Bay Environmental Study Technical Report No. 18. ISSN 1039-3218. CSIRO.

Fabris, G.J., Monahan, C.A., Werner, G.F. and Theodoropoulos, T., 1995. Impact of Shipping and Dredging

on Toxicants in Port Phillip Bay, Port Phillip Bay Environmental Study Technical Report No. 20, CSIRO.

Goossens, H. and Zwolsman, J., 1996, An Evaluation of the Behaviour of Pollutants During Dredging

Activities, Terra et Aqua 62: 20-28.

Hale, J., 2006a, Maintenance Dredging Campaign: Water Quality Monitoring In The Dredge And Disposal

Plumes, Report to PoMC, Melbourne.

Hale, J., 2006b, Appendix 1, Phytoplankton Blooms in Longmore AR (2006), Channel Deepening Project

Supplementary Environmental Effects Statement Head Technical Report: Nutrient Cycling. Marine and

Freshwater Systems l Report Series No.17. Primary Industries Research Victoria: Queenscliff.

Hallegraeff, G.M., 1994, Species of the Diatom Genus Psuedo-nitzschia in Australian Waters. Botanica

Marina, 37: 397 - 411.

Han, M-S., Furuya, K. and Nemoto, T., 1992, Species specific productivity of Skeletonema costatum in the

inner part of Tokyo Bay, Marine Ecology Progress Series 79: 267-273.

Harris, G., Batley, G., Fox, G., Hall, D., Jernakoff, P., Molloy, R., Murray, A., Newell, B., Parslow, J., Skyring,

G. and Walker, S. 1996. Port Phillip Bay Environmental Study Final Report. CSIRO, ACT.

Jenkins, G.P. and McKinnon, L., 2006, Channel Deepening Supplementary Environment Effects Statement –

Aquaculture and Fisheries. Internal Report No. 77, Primary Industries Research Victoria, Queenscliff.

Kerr, J.G., Burford, M., Olley, I. and Udy, J. (2010). The effects of drying on phosphorus sorption and

speciation in subtropical river sediments. Marine and freshwater research 61, 928-935.

Longmore, A.R., 2006. Supplementary Environment Effects Statement, Head Technical Report: Nutrient

cycling- current conditions and impact assessment. Marine and Freshwater Systems Report Series No. 17.

Primary Industries Research Victoria, Queenscliff.

Longmore, 2010. DPI Phytoplankton Data 1987 – 1996


28

Longmore, A.R., Cowdell, R.A. and Flint, R. 1996. Nutrient Status of the Water in Port Phillip Bay. Technical

Report No. 24. Port Phillip Bay Environmental Study. CSIRO. Yarralumba, ACT. August.

Longmore, A. and Nicholson, G. 2010a. Baywide Nutrient Cycling (Denitrification) Monitoring Program-

Milestone Report No. 8 (Oct.-Dec. 2009). Fisheries Victoria Technical Report Series No. 88, February 2010.

Department of Primary Industries, Queenscliff, Victoria, Australia. 52 pp.

Longmore, A. and Nicholson, G. 2010b. Baywide Nutrient Cycling (Denitrification) Monitoring Program-

Milestone Report No. 10 (February–June 2010). Fisheries Victoria Technical Report Series No. 109, August

2010. Department of Primary Industries, Queenscliff, Victoria, Australia. 47 pp.

Magro, K., Arnott, G. and Hill, D., 1997, Algal blooms in Port Phillip Bay from March 1990 to February 1995:

Temporal and spatial distribution and dominant species, Port Phillip Bay Environmental Study, Technical

Report No.27, CSIRO, Melbourne.

Mickelson, M. 1990. Dissolved oxygen in bottom waters of Port Phillip Bay. Environmental Services Series

No. 90/010, Melbourne and Metropolitan Board of Works, Melbourne.

MMBW/FWD 1973. Environmental study of Port Phillip Bay. Report on phase 1, 1968-1971. Melbourne and

metropolitan Board of Works and Fisheries and Wildlife Department of Victoria, Melbourne. 372 pp.

Mooney, B and de Salas, MF and Hallegraeff, GM and Place, AR, 2009, Survey for karlotoxin production in

15 species of gymnodinioid dinoflagellates (Kareniaceae, Dinophyta), Journal of Phycology, 45, (1): 164-175.

Murray, A. and Parslow, J., 1997, Port Phillip Bay Integrated Model: final report. Technical Report No. 44,

CSIRO Port Phillip Bay Environmental Study, ACT.

Parsons, TR, Maita, Y. and Lalli, CM 1984. A manual of chemical and biological methods for seawater

analysis. Pergamon, Oxford, UK. 173 pp.

Parsons, M. and Dortch, Q., 2002, Sedimentological evidence of an increase in Pseudo-nitzschia

(Bacillariophyceae) abundance in response to coastal eutrophication. Limnol. Oceanogr., 47(2): 2002, 551–

558

PoMC 2008. Water Quality Progress Report #1- 6 – Zinc and Ammonium Assessment, 15 July 2008, Port of

Melbourne Corporation.

PoMC 2009a. Algal Blooms-Detailed Design CDP_ENV_MD_012_Rev 3.0, Port of Melbourne Corporation.

PoMC 2010a. Water Quality – Detailed Design CDP_ENV_MD_023 Rev 5.0, Port of Melbourne Corporation.

Post, A.F., Dubinsky, Z., Wyman, K. and Falkowski, P. G., 1984, Kinetics Of light-intensity adaptation In a

marine planktonic diatom, Marine Biology, 83: 231–238.

Seitzinger, S., Harrison, J.A., Bohlke, J.K., Bouwman, A.F., Lowrance, R., Peterson, B., Tobias, C., van

Drecht, G. 2006. Denitrification across landscapes and waterscapes: a synthesis. Ecological Applications 16,

2064-2090.

Sgrossa, S., Esposito, F. and Montresor, M., 2001, Temperature and daylength regulate encystment in

calcareous cyst- forming dinoflagellates, Marine Ecology Process Series 211: 77 – 87.

Sokolov, S. 1996, Inputs from the Yarra River and the Patterson River/Mordialloc Main Drain into Port Phillip

Bay, Port Phillip Bay Environmental Study, Technical Report No. 33, CSIRO, Melbourne.

Sokolov, S. and Black, K.P. 1999. Long-term prediction of water quality for three types of catchment. Marine

and freshwater Research 50, 493-502.

29

Walker, 2009, Victorian Marine Biotoxin Management Plan, Third Edition, Fisheries Victoria.

Wood, M. and Beardall, J., 1992, Phytoplankton Ecology of Port Phillip Bay, Victoria, Port Phillip Bay

Environmental Study, Technical Report No.8, CSIRO, Melbourne.


30

APPENDIX 1 - BACKGROUND

EPA’s Role in Monitoring Water Quality in Port Phillip Bay

EPA Victoria has been monitoring the water quality of Port Phillip Bay (PPB) since 1975 with the Marine

Fixed Sites Program commencing in 1984. The aims of this monitoring are to:

• Identify any long term trends in water quality

• Assess the general condition of PPB

• Assess the success of management actions through the compliance with environmental objectives.

This program has been extensively reported; most recently including an assessment of the long-term trends

in nutrient status and water clarity from 1984 to 1999.1

Inputs or loads of freshwater, nutrient and sediment to PPB are reasonably well understood. These inputs

enter primarily from several rivers, most notably the Yarra, smaller streams, about 350 storm water drains

and two sewage treatment plants (STPs) — Western Treatment Plant (WTP) at Werribee and at Altona.

Groundwater discharge into PPB is considered insignificant. Within PPB, nutrient and sediment

concentrations can vary greatly. Spatially, concentrations are usually greater inshore or adjacent to major

inputs.1

State environment protection policy (Waters of Victoria) (SEPP (WoV)) Schedule F6 Waters of Port Phillip

Bay, declared in 1997 is a comprehensive policy framework for the protection of water quality in PPB.2 A key

component of SEPP (WoV) is the identification of beneficial uses that the community want to protect and

which are used as the basis for maintaining environmental quality. The beneficial uses identified for marine

waters including the waters of PPB are:

• Maintenance of natural aquatic ecosystems

• Water based recreation

• Production of molluscs for human consumption

• Commercial and recreational use of edible fish and crustacea

• Industrial water use

• Navigation and shipping.

Within PPB, six (regional) segments are recognised. These are:

• Hobsons Segment: includes the mouth of the Yarra River and the City of Melbourne and its port

facilities

• Werribee Segment: the part of PPB adjacent to the WTP outfalls

• Corio Segment: All waters in Corio Bay

• Inshore Segment: covering all waters within 600m of low tide

• Aquatic reserves: those parts of the Bay afforded statutory protection as ‘protected areas’

• General Segment: all other waters in PPB.

1 EPA 2002. Port Phillip Bay Water Quality. Long-term Trends in Nutrient Status and Clarity 1984–1999. EPA Publication

806. 2 EPA Victoria 1997, Variation of the State environment protection policy (Waters of Victoria) - insertion of schedule F6.

Waters of Port Phillip Bay. Victorian Government Gazette S 101.

31

These segments reflect the different types and conditions of environments, surrounding land uses and major

inputs, and therefore have different beneficial uses requiring protection. A separate SEPP (WoV) Schedule

F7 Waters of the Yarra Catchment provides the policy framework for the protection of water quality in the

Yarra River.3

Environmental quality objectives are set for each segment to ensure the protection of designated beneficial

uses. The objectives provide targets for particular indicators of the condition of the environment in PPB.

Specific objectives are set for each segment and are shown in Table A1.1. As not all toxicant objectives are

set in the SEPP, the Australian and New Zealand Environment Conservation Council (ANZECC) trigger

values are used as the default SEPP (WOV) objectives (Table A1.1).4

EPA has historically sampled water quality approximately monthly at six fixed sites in PPB (see Appendix 2,

Table A2.1 for details):

• Hobsons Bay

• Central Bay

• Long Reef

• Corio Bay

• Dromana

• Patterson River.

Historically, Central Bay and Dromana were considered reference sites for the purpose of calculating nutrient

and suspended sediment trigger values. Information relating to coastal land use developments adjacent to

Dromana indicates that this site is also likely to be influenced by various human activities similar to the other

four sampling sites:

• Hobsons Bay site is approximately 800m from shore and is primarily influenced by discharge from

the Yarra River

• Long Reef site is located approximately 1km from the WTP

• Patterson River site is located about 300m from shore and to the south of Patterson River

• Corio Bay site is close to domestic and industrial inputs to Corio Bay.

As part of the establishment of the Water Quality component of the Channel Deepening Baywide Monitoring

Programs (CDBMP) for the CDP, five additional sites to improve the spatial coverage across key areas of

PPB augmented EPA’s water quality monitoring program. These additional sites are:

• Yarra River at Newport

• PoM DMG

• Middle Ground Shelf

• Sorrento Bank,

• Popes Eye.

The location of all 11 sampling sites for the Water Quality Baywide Monitoring Program (WQBMP) is

provided in Figure 1.

3 EPA Victoria 1999. Variation of the state environment protection policy (Waters of Victoria) - insertion of schedule F7. Waters of the Yarra catchment. Victorian Government Gazette S 89. 4 ANZECC 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000), Australian and

New Zealand Environment Conservation Council.


32

Table A1.1 SEPP (WoV) objectives and ANZECC trigger values

Attenuation

of PAR

Sampling Site

SEPP (WoV)

schedule &

segment

ANZECC

Level of

Protection

Min

fo

r 1m

be

low

su

rfa

ce

Min

1m

abo

ve b

ott

om

Lo

we

r lim

it f

or

90

th p

erc

entile

Min

perc

en

tag

e c

on

ce

ntr

ation

Sa

linity v

ari

atio

n

Te

mp

era

ture

( o

C)

Se

cch

i d

isc d

ep

th (

m)

An

nu

al 9

0th

pe

rce

ntile

An

nu

al 5

0th

pe

rce

ntile

An

nu

al 9

0th

pe

rce

ntile

An

nu

al 5

0th

pe

rce

ntile

An

nu

al 9

0th

pe

rce

ntile

An

nu

al m

edia

n

An

nu

al 9

0th

pe

rce

ntile

Ars

en

ic (µ

g/L

)

Cad

miu

m (µ

g/L

)

Chro

miu

m (µ

g/L

)

Cop

pe

r (µ

g/L

)

Le

ad

(µ

g/L

)

Merc

ury

(µ

g/L

)

Nic

ke

l (µ

g/L

)

Zin

c (µ

g/L

)

TB

T (µ

g/L

)

F6 Hobsons>90% >90% N ± 5% N ± 1 >2 0.5 2.5 4.0 <3 <5.5 <5 <1.3 <4.4 <0.4 <70 <10 <0.006

F7 Yarra Port>60% N + 2 <20 <50 <25 <60 <13 <0.2 <1 <1.3 <3.4 <0.05 <11 <8 <0.006

Hobsons Bay F6 Hobsons>90% >90% N ± 5% N ± 1 >2 0.5 2.5 4.0 <3 <5.5 <5 <1.3 <4.4 <0.4 <70 <10 <0.006

Corio Bay F6 Corio>90% >90% N ± 5% N ± 1 >3 0.45 1.5 2.5 <3 <5.5 <5 <1.3 <4.4 <0.4 <70 <5 <0.006

Long Reef F6 Werribee>90% >90% N ± 5% N ± 1 >3 0.45 2.5 4.0 <3 <5.5 <5 <1.3 <4.4 <0.4 <70 <5 <0.006

Central Bay F6 General>90% >90% N ± 5% N ± 1 >4 0.35 1.0 2.0 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

PoM DMG F6 General>90% >90% N ± 5% N ± 1 >4 0.35 1.0 2.0 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

Patterson River F6 Inshore>90% >90% N ± 5% N ± 1 >3 0.45 1.5 2.5 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

Dromana F6 Inshore>90% >90% N ± 5% N ± 1 >3 0.45 1.5 2.5 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

Middle Ground

Shelf F6 General>90% >90% N ± 5% N ± 1 >4 0.35 1.0 2.0 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

Sorrento Bank F6 General>90% >90% N ± 5% N ± 1 >4 0.35 1.0 2.0 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

Popes Eye F6 General>90% >90% N ± 5% N ± 1 >4 0.35 1.0 2.0 <3 <0.15 <5 <0.3 <2.2 <0.1 <7 <5 <0.0004

SEPP Waters of VictoriaSEPP Schedule F6 - Waters of Port Phillip Bay, and

SEPP Schedule F7 - Waters of the Yarra Catchment objectivesLimit of reporting above SEPP objective

N=natural background ANZECC trigger values not highlighted Limit of reporting above ANZECC trigger value

Chlorophyll-a

(ug/L)

Yarra River at

Newport

95%

99%

Policy Categories

Dissolved Oxygen

(% saturation)

Turbidity

(NTU)

Suspended

Solids (mg/L)

Notes

Schedule F7 (Waters of the Yarra Catchment) is included for comparison of water quality objectives at the Yarra River at Newport site, as this site has been determined to be in a crossover area between schedules F6 and F7. Both schedule segments can be applicable to the site dependent on tide cycle and flow conditions in the Yarra mouth

33

APPENDIX 2 - METHODS

Sampling Locations

The Water Quality Monitoring Program sampling schedule is monthly, at 11 fixed sampling sites across PPB

(Figure 1). Table A2.1 provides further information relating to the selection of the sites and corresponding

SEPP (WoV) segments.

Table A2.1 Locations and corresponding SEPP (WoV) segments

Site name

Site no. (PoMC)

Segment Historical

Data Purpose

Yarra River at Newport

8005

Yarra Port

segment of

Schedule F6/F7*

PoMC data 2004-2005 and 2006-

2007

This samples Yarra River water prior to entering PPB. Sediments here contain contaminants that may be mobilised by storms, shipping and dredging. It is near a popular fishing area known as the ‘Warmies’.

Hobsons Bay

7007

Hobsons segment

of Schedule

F6

PoMC 2004-5 and 2006-

7. ; EPA 1994 to present

Hobsons Bay is a recreational area and home to a Little Penguin colony. It is the interface between the Yarra River and PPB.

Corio Bay 4321 Corio (F6)

EPA 1994 - present

This is a recreational area and supports seagrass beds.

Long Reef

4310 Werribee

(F6) EPA 1994 -

present

This area is influenced by the WTP. Links to other Baywide Monitoring programs in same area.

Dromana 2808

General, bordering ‘Inshore’

(F6)

EPA 1994-1996

and2005 - present

This is an important recreational area.

Patterson River

4604

General, bordering ‘Inshore’

(F6)

EPA 1994-1996 and

2005-present

This site is near Patterson River which is a significant input to PPB.

PoM DMG

4503 General

This is at the centre of the PoM Dredged Material Ground, to confirm that placement and storage of contaminated material does not result in significant impacts to water quality.

Central Bay

4514 General

EPA 1994 – present.

PoMC nearby

(4519) 2004-2005 and

2006-2007

This site is indicative of water quality across large central area of PPB. Links to other Baywide Monitoring programs in same area.

Middle Ground Shelf

2719 General

Nearby (2710) PoMC

2004-2005 and 2006-

2007

This is on the edge of the Great Sands area. Links to other Baywide Monitoring programs in same area.

Sorrento Bank

2006 General PoMC 2004-

2005 and 2006-2007

Key recreational area and seagrass beds. Links to other Baywide Monitoring programs in same area.

Popes Eye

2301 General PoMC 2004-

2005 and 2006-2007

This is near the boundary of a marine national park, and is strongly influenced by tidal exchange with Bass Strait.


34

*There is an anomaly within the northern boundary of SEPP (WoV) Schedule F6 such that the latitude/longitude puts the

‘Yarra River at Newport’ site in the Hobsons segment, whereas ‘Eastings and Northings’ put this site in Schedule F7

Yarra Port segment. For the purpose of this report, objectives for both Schedules F6 and F7 values are considered for

the Yarra site, although for Progress Reports # 1 & 2, only Schedule F6 values were considered.

Field Sampling

EPA personnel or contractors, who are trained in the sampling methodology, conduct all field sampling.

Fieldwork involves both in-situ monitoring and the collection of water samples for laboratory analysis.

A summary of the methods for in-situ monitoring and the collection of water quality and algal samples are

provided below. Descriptions of the methods are provided in the following EPA Standard Operating

Procedures (SOPs):

• In-situ Monitoring

• Water Quality Sampling

• Algal Sampling

• Sample Handling and Custody.

Detail on sample and equipment preparation is also contained in the SOPs. This includes sourcing sample

containers from laboratories, marking up sample containers, checklists for equipment and supplies and

equipment maintenance and inspection. The SOPs are incorporated into the Quality System for delivery of

the WQBMP.

Field sampling is undertaken monthly within a 2-week window starting from the second week of the month.

This is preferably conducted over three consecutive days, however flexibility in timing is required due to

logistical and OH&S constraints.

In-situ Monitoring

A CTD Profiler is used to measure the in-situ parameters at each site including conductivity, depth,

temperature, dissolved oxygen (% saturation), photosynthetic active radiation (PAR), fluorescence and

turbidity. A Secchi disc and measured line is used to measure Secchi disc depth. Further detail on operation,

calibration and QC checks for the CTD profiler are provided in the ‘In-situ Monitoring’ SOP.

Water Quality

Water samples are collected using a peristaltic pump with medical grade silicone tubing. Samples are

collected at the near surface (~0.5 m) of the water column and sub-samples withdrawn for total nutrients,

total metals, TBT and suspended solids. Sub-samples are filtered through 0.45µm membrane filters and

stored for dissolved nutrient and dissolved metal analysis. Chlorophyll-a samples are collected by gravity

filtration of seawater through a glass fibre filter, and stored on ice.

The need for a bottom water sample is determined based on whether salinity stratification (a change with

depth of more than 10psu) is identified by the CTD profiler.

Sample containers, sampling and preservation methodologies, and sample handling and storage are

provided in the ‘Water Quality Sampling’ SOP.

35

Algal Sampling

At each site an integrated water sample is taken for algal enumeration and a net tow sample is collected for

algal identification. Full detail including sample containers, sampling and preservation methodologies and

sample handling and storage is provided in the ‘Algal Sampling’ SOP.

Sample blanks and replicates

Field sampling quality control measures include the collection of field blanks and replicates. This includes:

• Two freshwater field blanks per cruise to test for contamination during sample collection/ treatment/

storage.

• Two field replicates to test for contamination during sample collection/treatment/storage, site

heterogeneity and laboratory precision. These are two randomly selected sites per monthly

sampling cycle in each of the north and south of PPB, and are analysed for each of the parameters

normally tested for each location. Replicate sample sites are selected in advance on a random

basis so they will remain blind as far as the laboratories are concerned. Where a replicate is taken,

a filtered replicate is also collected for required parameters.

Sample handling and custody

Sample storage requirements and holding times are provided in the ‘Sample Handling and Custody’ SOP.

Chain of Custody forms accompany all samples.

Quality Assurance for field sampling

The EPA Quality Plan5 is the key document that outlines all relevant QAQC specifications for the EPA

WQBMP. This includes the QAQC requirements for the fieldwork as outlined below.

QA/QC for fieldwork includes:

• Sampling for metals, nutrients and TBT is carried out using powder-free, plastic disposable gloves to

minimise contamination

• Sampling equipment is left open to the water column for approximately five minutes allowing it to

sufficiently rinse prior to taking a sample

• All samples are stored on ice and transported to the laboratories within 24 hours of sample collection

• Collection of field blanks and replicates as described in Section 2.1.4

• The EPA Field Scientist provides field records for the CTD profiler to the EPA Project Manager for

the QA file including serial number, when new equipment is used, where used and details of

calibration checks. These records will show if any clear ‘steps’ in the data can be tracked and

attributed to changes in instrumentation,

• Chain of Custody forms are created and forwarded with the samples to the laboratories.

5 EPA 2010, EPA Victoria Baywide Water Quality Monitoring Program Quality Plan


36

Laboratory Analysis

The laboratory analysis of samples is contracted to Ecowise Australia for metals and TBT analysis,

Department of Primary Industries (DPI) Queenscliff for nutrients (and some physico-chemical parameters)

and MicroAlgal Services for algal analysis. DPI Queenscliff analyses samples for physico-chemical

parameters such as suspended solids, dissolved oxygen, salinity, dissolved nutrients, total N and P,

particulate N (and dissolved organic N), silicate and algal pigments (chlorophyll-a and phaeophytin-a).

Reports are provided by the laboratories detailing their QAQC programs while the EPA also undertakes

internal QAQC to ensure quality control for laboratory results.6

Data Assessment Methods

In order to detect changes in water quality outside expected variability in PPB, two control charting

techniques (CSIRO/Emphron 2007)7 have been employed in the analysis of the WQBMP results:

• An Exponentially Weighted Moving Average (EWMA) control chart is used for assessment of

longer-term changes in baseline results for nutrients, total metals and chlorophyll-a. The EWMA is

a statistic that averages the data in a way that gives less weight to data as they are further

removed in time. To do this EWMA applies weighting factors which decrease exponentially over

time. This gives relatively greater importance to recent observations while still not discarding older

observations entirely. EWMA is being used in this context to detect persistent changes from a

baseline ‘target’ concentration, usually the historical mean of the data, which may reflect long term

changes in water quality. An upper control limit for the EWMA has been calculated to assist in

deciding whether a persistent change from the target value may have occurred (Table A2.2).

• A Shewhart control chart is used to detect changes in the number or size of peak events for

nutrients, total metals and TBT. These changes will reflect short-term changes in water quality

(Table A2.3).

6 EPA 2010, EPA Victoria Baywide Water Quality Monitoring Program Quality Plan

7 CSIRO/Emphron 2007. Channel Deepening Project Bay-Wide Monitoring Programme Water Quality, Emphron

Informatics Pty Ltd, December 2007.

37

Table A2.2 EWMA control limits for listed water quality parameters

Ammonium Nitrate plus

Nitrite Total Nitrogen Phosphate

Total Phosphorus

Chlorophyll-a

Arsenic Sampling site

µg/L µg/L µg/L µg/L µg/L µg/L µg/L

Yarra River at Newport 32.42 39.52 278.39 86.19 108.01 2.0 3.23

Hobsons Bay 19.45 39.53 266.22 85.72 105.32 3.9 2.98

Central Bay 9.90 3.61 168.10 72.32 84.08 1.1 2.86

PoM DMG 6.16 9.92 176.47 66.31 83.99 1.0 3.10

Corio Bay 10.70 2.31 224.48 100.12 115.66 1.4 3.66

Long Reef 219.05 83.74 629.12 238.83 305.50 6.8 3.20

Patterson River 13.65 42.75 243.10 69.75 89.34 2.2 2.59

Dromana 5.00 4.29 170.20 56.93 70.12 1.6 2.52

Middle Ground Shelf 7.02 2.29 156.09 50.94 63.85 0.8 N/A

Sorrento Bank 8.16 4.93 143.10 36.40 45.74 0.8 N/A

Popes Eye 8.20 12.73 145.12 36.75 120.94 0.8 N/A

Notes

NA – Not available due to lack of historical data.

Source: Table 4 CDP_ENV_MD_023 Rev 5.0 (available on the CDP website www.channelproject.com).


38

Table A2.3 Shewhart control limits for listed water quality parameters

Sampling site

Total

Nitrogen

µg/L

Ammonium

µg/L

Nitrate plus

Nitrite µg/L

Total Phosphorus

µg/L

Phosphate

µg/L

Arsenic

µg/L

Cadmium

µg/L

Chromium

µg/L

Copper

µg/L

Lead

µg/L

Mercury

µg/L

Nickel

µg/L

Zinc

µg/L

TBT

µg/L

Yarra River at Newport 383.31 88.78 182.90 138.91 107.54 4.75 0.20 0.58 3.08 2.79 0.10 4.29 12.77 0.02

Hobsons Bay 382.82 50.61 257.50 135.51 129.08 4.43 0.25 1.17 1.70 0.95 0.13 2.28 9.13 0.01

Central Bay 206.91 21.50 7.43 106.48 112.50 4.66 * * * * * 1.95 * *

PoM DMG 217.07 7.81 28.33 107.98 76.61 4.73 * * * * * 2.82 * 0.02

Corio Bay 275.74 25.37 5.00 140.27 127.68 5.57 * NA * * * 1.90 * NA

Long Reef 1035.88 999.28 512.03 536.16 445.31 4.56 * NA * * * 2.17 * NA

Patterson River 367.57 30.57 366.52 111.81 87.58 3.56 * NA * * * 1.14 * NA

Dromana 222.84 11.03 5.71 89.64 75.42 3.58 * NA * * * 1.06 * NA

Middle Ground Shelf 185.93 10.66 2.71 96.82 65.33 NA NA NA NA NA NA NA NA NA

Sorrento Bank 168.74 11.54 9.50 63.20 48.44 NA NA NA NA NA NA NA NA NA

Popes Eye 209.84 14.74 42.71 471.38 148.04 NA NA NA NA NA NA NA NA NA

Notes

NA – Not available due to lack of historical data. * - No limit, as more than half historical data is below limits of reporting.

Source: Table 5 CDP_ENV_MD_023 Rev 5.0, (available on the CDP website www.channelproject.com)

39

EWMA and Shewhart charts have been generated for all parameters with chart-based limits specified in

Tables A2.2 and A2.3 respectively. Exceedence of these limits flag results as being outside of normal

background variability based on historical data. The next question is to determine whether results are also

outside of ’expected variability’, based on the predicted effects of the CDP as defined in the SEES. Where

results are considered to be outside expected variability, EPA/PoMC leads an assessment of the

significance of the result to the environment. If results are significant, this initiates further risk-based

assessments by PoMC in accordance with the Water Quality Detailed Design CDP_ENV_MD_023_Rev 5.0,

Decision Framework for Management. 8

In cases where no Shewhart limits exist (asterisks in Table A2.3), SEPP (WoV) objectives, or ANZECC

‘trigger values’ where no SEPP (WoV) objectives exist (Table A1.1), are used for comparison. Monthly

progress reports and six monthly milestone reports also include a discussion of all applicable results

compared to SEPP (WoV) as a general observation of water quality at the program’s monitoring sites.

In some cases, for example nutrients, SEPP (WoV) objectives do not exist but EWMA and Shewhart limits

have been derived. In other cases (e.g. some metals), either SEPP (WoV) objectives are explicit or, by

default, ANZECC trigger values are used. For most metals and sites there is insufficient historical data to

derive Shewhart or EWMA limits.

Interpretation of the algal analysis (species composition and enumeration) is defined in the Algal Blooms

Detailed Design CDP_ENV_MD_012_Rev 3.0.9 Algal results are compared against a threshold as a tool to

identify change outside of expected variability. The minimum warning levels used in the Victorian Shellfish

Operations Manual (VSOM) for toxic and nuisance species have been adopted as the threshold

concentrations. These are listed in Section 4.2.1 of the Algal Blooms Detailed Design. The Algal Blooms

Detailed Design also defines the method for interpreting chlorophyll-a results using an EWMA and

associated limits.

Another requirement of the Water Quality Detailed Design is the inclusion of summary statistics, particularly

as they relate to some SEPP (WoV) water quality parameter requirements for comparison with annual

statistical derivations such as median and percentiles. When calculating summary statistics, if a value is less

than the limit of reporting (LOR) then it is not possible to calculate a mean. When calculating percentiles,

including the median, values less than LOR are temporarily replaced with a number that is marginally less

than the LOR so as to make it distinguishable from the LOR itself (e.g. replace <0.2 with 0.199). The

percentiles and median are then calculated and any estimates that are smaller than the LOR are replaced

with '<LOR'.

External Data Sources

This report also includes data from concurrent water quality monitoring activities undertaken in PPB and the

surrounding catchments, in addition to historical datasets. The water quality monitoring program provides

monthly snapshots of the bay conditions, while the in-situ continuous measurements help fill the gaps to

understand prevailing dynamics affecting water quality. Historical and other data sets assist with

understanding the external influences and historical conditions.

As part of the Port Phillip Bay Environmental Management Plan (PPB EMP) continuous instrumental

measures of temperature, salinity dissolved oxygen and chlorophyll fluorescence have been maintained by

DPI at three mooring locations in PPB since 2002. These are located at:

8 PoMC 2010. Water Quality – Detailed Design CDP_ENV_MD_023 Rev 5.0, Port of Melbourne Corporation.

9 PoMC 2009. Algal Blooms – Detailed Design CDP_ENV_MD_012 Rev 3.0, Port of Melbourne Corporation.


40

• Hobsons Bay

• Central Bay

• Long Reef

A fourth site located in the south at Middle Ground Shelf was added in 2007 to augment this network for the

CDP nutrient cycling monitoring program. At each of these four monitoring sites, instruments collecting

hourly data are located at near surface (~3m) and near bottom. Site locations are shown in Figure A2.1 and

further details of their configuration and data capture are provided in PoMC (2010).10

The near-surface (3m)

sensor data is presented in the following results section with comparative results from the monthly water

quality monitoring program data.

Figure A2.1 DPI Nutrient cycling continuous in-situ monitoring sites

Source: PoMC 2010 Nutrient Cycling Detailed Design CDP_ENV_MD_019 Rev 5.0, Port of Melbourne Corporation.

To improve both spatial and temporal coverage of water quality conditions, EPA installed a marine

monitoring system on the ‘Spirit of Tasmania 1’ in 2008. This monitoring system measures water quality in

PPB and the background oceanic influences of Bass Strait. The system became operational in September

2008 and provided an unbroken record through to July 2009, when the vessel was taken out of service. The

10

PoMC 2010. Nutrient Cycling Detailed Design CDP_ENV_MD_019 Rev 5.0, Port of Melbourne Corporation.

41

system was back in service in September 2009 and has been operational to the end of the current reporting

period.

The Spirit of Tasmania 1 travels from Melbourne to Devonport daily. On each daily crossing the in-situ

monitoring system samples surface waters (0-6m deep) as ten second averages of salinity, temperature,

chlorophyll-a fluorescence, turbidity, and position. Travelling at approximately 20 knots this corresponds to

sample “grabs” at every 100m along the ship track. Sampling at high frequency significantly improves the

capability to resolve ecosystem dynamics in PPB. An example of daily shiptrack and sensor data is shown in

Figure A2.2.

Figure A2.2 Examples of IMOS shipborne data sampled from the Spirit of Tasmania.

This marine monitoring system is part of the “Ships of Opportunity” facility incorporated within the national

Integrated Marine Observing System (IMOS).11

Data (and associated metadata) for all IMOS observations is

available to support other researchers and end-users at IMOS (2010).12

11 IMOS 2010. Integrated Marine Observing System, http://www.imos.org.au.

12 IMOS 2010. Integrated Marine Observing System, Available Spirit of Tasmania 1 data from the IMOS data server, http://opendap-tpac.arcs.org.au/thredds/catalog/IMOS/SOOP/SOOP-TMV/VLST_Spirit-of-Tasmania-1/transect/catalog.html.


42

The data sampled from the Spirit of Tasmania 1, is referred to in this report as IMOS shipborne data.

Contoured sensor data is presented in the following results section as shiptrack distance in PPB (from Port

Melbourne Pier) against date. Each plot represents data from approximately 100 Bass Strait crossings.

Additional data on trace heavy metals is also sourced from the EPA extended beach monitoring program, the

PoMC maintenance dredging beach monitoring program, and the Melbourne Water, water quality monitoring

program.

EPA has been monitoring beach water quality for many years as part of the summer Beach Report program.

In March 2008, responding to increased community interest, the beach water quality monitoring program was

extended to operate for a full year and include a wider range of water quality indicators. The program

monitored 36 beaches around the Bay (Figure A2.3).The program monitored enterococci, algae, heavy

metals and organic chemicals on a weekly basis from March 2008 to September 2009 at 36 beaches around

the Bay (Figure A2.3).13

As part of the PoMC routine maintenance dredging program, water from six northern PPB beaches was

monitored for heavy metals (Figure A2.3). The monitoring program commenced on 17th November 2009 with

weekly testing concluding in June 2010.14

Melbourne Water conducts water quality monitoring at 136 sites along rivers and creeks in the Port Phillip

and Western Port region. The program monitors a range of water quality indicators including heavy metals

and nutrients. The program is designed to assess broad-scale, long-term trends in water quality (typically

over eight to 10 years) and to assess progress against SEPP objectives.15

Figure A2.3 EPA and PoMC Beach monitoring sites

13

EPA 2009. Extended Monitoring of Beach Water Quality in Port Philip Bay – March 2008 – September 2009. 14

OEM 2010. www.oem.vic.gov.au/Maintenancedredging. 15

MW 2010. www.melbournewater.com.au/content/rivers_and_creeks/river_health/water_quality_monitoring.

43

Further data sets that have been included in this report include the data collected from the annual Two Bays

monitoring program16

and historical phytoplankton data collected by DPI from 1987-199617

. The Two Bays

monitoring program undertaken in January 2010, survey along the coast of PPB using continuous loggers.

The water quality parameters monitored include nutrients (total nitrogen and total phosphorous) and physico

chemical parameters (salinity, temperature, turbidity and fluorescence). Historical phytoplankton data

collected by DPI includes all phytoplankton species identified and counted on a fortnightly basis from 1987-

1996 at numerous sites across PPB.

16

Two Bays 2010 http://www.svpelican.com.au/brain/twobays/2010/index.html 17

DPI phytoplankton data was made available through Andy Longmore.


44

APPENDIX 3 - RESULTS

This Milestone Report (#6) incorporates all data collected since the inception of the program in November

2007 with the focus primarily on this reporting period extending from January – June 2010.

Field Sampling

Field sampling was conducted monthly as outlined in Table A3.1. The maintenance dredging program, using

a backhoe/grab dredge, commenced on the 17th November 2009 in the Yarra River and Hobsons Bay and

was completed mid 2010.

Table A3.1 Field sampling dates and weather conditions (January – June 2010)

Progress Report Sampling Dates Weather Observations

13th January Moderate to strong 15-20kt winds increasing to 20-25kts; waves 0.7-1.2m

14th January Light 5-10kt winds increasing to 20-25kts; waves 0.2-1.5m

15th JanuaryModerate 10-15kt winds; waves 0.5m

Hobsons Bay very turbid

10th February

Light 0-5kt winds increasing to 10-15kts; waves 0.1-0.3m

Yarra River turbid

Light rain

11th FebruaryLight 0-5kt winds increasing to 15-20kts; waves 0-1.5m

Heavy rain

12th February

Moderate 10-15kt winds increasing to 20-25kts; waves 0.4-1.0m

Light rain

Slack water at Sorrento and strong ebb tide at Popes Eye

12th MarchLight 0-5kt winds increasing to 5-10kts; waves 0.1-0.4m

Strong ebb tide in south of PPB

14th March Light 5-10kt winds; waves 0.2m

15th March Light 5-10kt winds decreasing to 0-5kts; waves 0.3m

14th AprilModerate to strong 10-20kt winds decreasing to 5-10kts; waves 0.5-0.8m

Moderate to strong flood tide at Popes Eye and Sorrento

15th April Moderate 10-15kt winds; waves 0.5m

16th April Light 5-10kt winds; waves 0.2m

13th MayModerate 10-15kt winds; waves 0.3-0.4m

End of flood tide at Sorrento and slack water at Popes Eye

14th May Light 5-10kt winds; waves 0.4m

17th May Calm

18th May Light 0-5kt winds; waves 0-0.2m

21st JuneLight 0-5kt winds; waves 0.2m

Flood tide at MGS

22nd JuneLight 0-5kt winds; waves 0.3m

Slack water at Sorrento and 1st half of ebb tide at Popes Eye

23rd June Light 0-5kt winds increasing to 10-15kts; waves 0.2-0.4m

No.29

No.30

No.25

No.26

No.27

No.28

45

Quality Assurance/Control (QA/QC)

Field and laboratory QA/QC data and discussion relevant to this reporting period are provided in Appendix 4.

Exception reports

A number of deviations from the Detailed Design occurred during the reporting period. Formal exception

reports were provided with progress reports as a means of documenting events on each occasion. These

exception reports are referenced in relevant progress reports and help ensure that learning’s are captured

and improvements incorporated back into the program. All exception reports from this reporting period are

summarised in Table A3.2.

Table A3.2 Summary of Exception Reports (January – June 2010)

Report Number Exception

ER100101

A number of errors were identified in the reporting of phytoplankton data including:

- Total phytoplankton cell counts were incorrectly reported in Tables 4 and 8 of Progress

Report #19 (July 2009).

- The Long Reef dinoflagellate cell count was incorrectly reported in Tables 4 and 8 of Progress

Report #16 (April 2009).

- Progress Report #11 (November 2008) and #20 (August 2009) are missing data for Popes Eye

in Table 8.

ER100102EWMA NOx values for Long Reef and Corio Bay were incorrectly reported in Progress Reports

#23 (November 2009) and #24 (December 2009).

ER100103 No reliable lead data for Hobsons Bay is available for January 2010.

ER100301 No reliable data is available for filtered chromium, nickel and zinc at Central Bay in March 2010.

ER100401The summary statistics in Milestone Reports No 4 and 5 did not include the 10

th and 95

th

percentile values.

Results from Progress Reports

This subsection presents and discusses the data collected from field sampling events carried out from

January – June 2010, as outlined in Progress Reports # 25 -3018

, meteorological data and additional external

data sources.

The information in this subsection highlights exceedences of the program’s control limits (EWMA and

Shewhart), the criteria used to flag possible variation from historical water quality data.

Secondary comparison with SEPP (WoV) F6 and F7 objectives, or ANZECC trigger values as applicable, are

also made to assist broader interpretation of the results.

This section is presented according to the water quality parameter categories:

• Physico-chemical data

• Phytoplankton and Algal Pigments

• Nutrients

• Metals.

18

EPA 2010. Baywide Water Quality Monitoring Program Progress Reports No 25-30, January – June 2010.


46

Where appropriate, results are also charted in the context of the Shewhart and EWMA control limits,

SEPP/ANZECC values and historical means.

Tables A3.3 summarises all exceedences of EWMA and Shewhart control limits observed during the

reporting period for physico-chemical data/nutrients and metals, respectively. These tables also include

exceedences of SEPP/ANZECC objectives where no Shewhart limit is available.

Assessment by the PoMC of these exceedences in terms of any implications for the ecological health of PPB

and subsequently the management of this project are presented in Appendix 5, Results outside of natural/

expected variability.

Summary statistics are provided for relevant metals, nutrients and physico-chemical parameters for

comparison against SEPP (WoV) F6 and F7 objectives, or ANZECC trigger values (see Appendix 6). A

minimum of 11 (monthly) data points are required to gain a true comparison with SEPP objectives against an

annual statistic.

Control charts for a number of parameters are presented throughout the results section. The following notes

are provided to assist with interpretation:

• Where the historical mean is plotted below the limit of reporting (LOR), data without imposed reporting limits was used in calculations.

• Legends on control charts. Curr </> LOR: For all parameters (except Secchi disc depth) the result is below the LOR. For Secchi disc depth the Secchi disc was visible on the bottom. Hist mean: EPA historical mean Hist*mean: Historical mean value was obtained from Emphron (2007)

19

19

Emphron Informatics Pty Ltd 2008 Channel Deepening Project Bay-wide Monitoring Programme Water Quality (Report 2007/172)

47

Meteorological conditions

Rainfall

Total rainfall during summer and autumn was close to the long term average across the Melbourne region

while rainfall for June was slightly higher than usual (Figure A3.1).This continues the trend seen in the

previous reporting period (Figure A3.2) and is in contrast to the below average rainfall seen during the same

period in 2009 (Figure A3.3). Autumn 2010 was the wettest autumn Victoria has experienced since 2000.20

Figure A3.1 Victorian rainfall deciles Jan – June 2010

Figure A3.2 Victorian rainfall deciles July – Dec 2009

20

Bureau of Meteorology <www.bom.gov.au>


48

Figure A3.3 Victorian rainfall deciles Jan - June 2009

Water quality in PPB continues to be influenced by rainfall and associated catchment inputs. The majority of

nutrients and toxicants supplied by rivers to PPB are discharged during storms.21

The only storm event,

using storm event criteria outlined in Gibbs et al (2007)22

, identified for the Yarra River in the last six months

occurred on 8th March 2010 (Figure A3.4). The storm event on the 8

th March 2010 was a response to the

severe thunderstorms associated with large hail and heavy rain on the 6th March 2010. This heavy rainfall

(35.8mm) resulted in high mean river flows (1300 – 4940ML/day) for a number of days following the event.

Water quality sampling was conducted in the week after this event. The storm event criteria for the Yarra

River are that 24-hour rainfall must exceed 20 mm with rainfall continuing and Yarra River flow exceeds 15

m3.s-1 (~ 1,300 ML/day) and is rising. The storm event criterion of 24-hour rainfall exceeding 16mm for

Patterson River was exceeded on several occasions during the last six months (Figure A3.5). The storm

event on the 12th February coincided with sampling, while the storm event on the 6

th March occurred several

days prior to the water quality sampling event. The influence of the increased catchment inputs into PPB was

detected to some degree by the monthly sampling, with the continuous DPI nutrient cycling and Integrated

Marine Observing System (IMOS) data also capturing the changes in water quality (Figure A3.6).

Fairfield (river flow) and Viewbank (rainfall) were identified in Gibbs et al (2007) as the most relevant

Melbourne Water (MW)23

and Bureau of Meteorology (BoM)24

sites for the Yarra River, while Moorabbin was

identified as the most relevant BoM rainfall site for Patterson River.

21

Harris et al 1996, Port Phillip Bay Environmental Study Final Report 22

Gibbs et al 2007 Port of Melbourne Corporation Channel Deepening Project Baseline Water Quality Monitoring 2006-2007 Marine and Freshwater Systems Report Series No. 22, Primary Industries Research Victoria, Queenscliff. 23

All river flow data obtained from Melbourne Water < www.melbournewater.com.au> 24

All rainfall data obtained from the Bureau of Meteorology <www.bom.gov.au>

49

Figure A3.4 Yarra River rainfall, river flow and storm events (January – June 2010)

Figure A3.5 Patterson River rainfall and storm events (January – June 2010)


50

Figure A3.6 IMOS shipborne track data (March 7 - 10 2010)

51

Air Temperature

Minimum and maximum air temperatures for the Melbourne region over the last six months were warmer

than usual (Figure A3.7). During summer, minimum and maximum temperatures were on average 1.9-2.4°C

warmer than usually experienced, while autumn temperatures were around 1°C warmer and June

temperatures were 0.6°C warmer than usual.25

Figure A3.7 Victorian temperature deciles (January – June 2010)

25

Bureau of Meteorology <www.bom.gov.au>


52

Figure A3.8 Map of WQBMP exceedences (January – June 2010)

Ammonium: Ammonium is present in all natural waters. The exceedences at Dromana are considered to be associated with stepwise increases since the 1990’s and the relatively low control limit at this site

Chromium: Toxicants are known to be discharged from rivers following increases in catchment flows Secchi disk depth: Water clarity can be influenced by a range of natural high river flows, increased phytoplankton biomass and adverse weather conditions

NOx: Concentrations of NOx increase at sites close to rivers following rainfall as nutrients are washed from the rivers into PPB

Dissolved Oxygen: DO concentrations can vary greatly over a daily period depending on water temperature, salinity, photosynthetic and microbial activity

Total Nitrogen: Concentrations of Total Nitrogen increase following rainfall over the catchment with increases in river flow, surface runoff and nutrient input into PPB

Chlorophyll-a: Chlorophyll-a (as an indicator of phytoplankton biomass) is influenced by temperature, light and nutrients. High levels of chlorophyll-a are associated with increased catchment inputs at sites close to nutrient discharges in the north and west. Seasonal winter increases are observed in the south Harmful phytoplankton species The distribution of marine phytoplankton is regulated by chemical, physical and biological conditions. There have been a number of toxic or nuisance algal blooms in PPB since 1986, including A.catenella and Pseudo-nitzschia spp.

� Water Quality Monitoring Sites

Dredged Material Ground

Shipping Channel

53

Table A3.3 Summary of exceedence of control limits for physico-chemical data and nutrients (January – June 2010)

Date Site Depth

Secchi

disc depth

Dissolved

Oxygen

Total

Chromium

(m) (m) % sat. (μg/L)

Value EWMA Value EWMA Value EWMA Value1

EWMA

15/01/2010 Yarra River at Newport 0.5 1.8 80.7 343 4.77 3.44

15/01/2010 Hobsons Bay 0.5 1.1

15/01/2010 Long Reef 0.5 2.7

10/02/2010 Yarra River at Newport 0.5 1.3 65.0 322 8.87 4.53

11/02/2010 Corio Bay 0.5 291 3.50 1.48

15/03/2010 Yarra River at Newport 0.5 1.3 84.6 534 364 7.44 5.11 0.6

12/03/2010 Dromana 0.5 5.3

15/03/2010 Corio Bay 0.5 1.64

15/03/2010 Long Reef 0.5 4.92

16/04/2010 Yarra River at Newport 0.5 1.9 86 93.3 442 380 4.41

14/04/2010 Dromana 0.5 5.6

16/04/2010 Corio Bay 0.5 1.53

18/05/2010 Yarra River at Newport 0.5 87 83.5 355 3.89

17/05/2010 Corio Bay 0.5 2.9 225 3.47 1.92

14/05/2010 PoM DMG 0.5 8.5

13/05/2010 Dromana 0.5 6.0

14/05/2010 Patterson River 0.5 2.54

23/06/2010 Yarra River at Newport 0.5 77.4 331 3.66

21/06/2010 Dromana 0.5 5.9

22/06/2010 Corio Bay 0.5 1.77

23/06/2010 Patterson River 0.5 4.94

21/06/2010 Middle Ground Shelf 0.5 0.86

22/06/2010 Sorrento Bank 0.5 0.83

Chlorophyll-a

(μg/L) (μg/L) (μg/L)

Total Nitrogen

μg/L

Ammonium Nitrate plus Nitrite

Notes

1. The chlorophyll a value is above the 90th percentile objective in SEPP (WoV) Schedule F6.

Yellow coloured cells indicate measured results above the Shewhart control limit (for ‘total’ fraction). See Table A2.3 for detail.

Orange coloured cells indicate EWMA calculated results above EWMA control limits. See Table A2.2 for detail.

Blue coloured cells indicate results outside SEPP (WoV) objectives where a Shewhart limit is not available. See Table A1.1 for detail.


54

Water quality in PPB is highly variable as seen by both the WQBMP (Figure A3.8) and the continuous water

quality monitoring data collected by the Two Bays program in January (Figure A3.9). Turbidity is highest in

Hobson Bay close to the Yarra River while elevated nutrients and chlorophyll fluorescence are found close to

coastal discharges including the WTP near Werribee and the Yarra River.

During the current reporting period (January – June 2010) the most variable water quality was seen in the

north and west of PPB. The greatest number of control limit and SEPP (WoV) exceedences were reported

from the Yarra River at Newport while a number of nutrient and phytoplankton exceedences were recorded

at Corio Bay. Other sites typically had few or no exceedences.

Figure A3.9 Two Bays continuous water quality monitoring measurements (10-23 January 2010)

Physico-chemical data

Salinity and Temperature

Salinity and temperature readings from both the EPA water quality (WQBMP) and DPI nutrient cycling

(NCBMP) monitoring programs show similar patterns at each of the common sampling sites (Central Bay,

Long Reef, Hobsons Bay and Middle Ground Shelf).

Water temperature followed predictable seasonal patterns with highest temperatures recorded in February

2010 (Figure A3.10). Water temperatures have since cooled to around 13°C in June, in parallel with

decreasing air temperatures.

55

Figure A3.10 Surface water temperature at Central Bay (January – June 2010)

10

15

20

25

14-10-2009 03-12-2009 22-01-2010 13-03-2010 02-05-2010 21-06-2010 10-08-2010

Date

Te

mp

era

ture

(o

C)

DPI nutrient cycling surface data EPA water quality data (probe) EPA water quality data (CTD)

Water temperatures in February 2010 at most sites were the highest recorded for the WQBMP, particularly at

Long Reef, Corio Bay and Hobsons Bay (Figure A3.11). Water temperatures at these sites were 2-4°C

higher than those recorded in 2008 and 2009. The warmer temperatures in 2010 are also evident in the

IMOS shipborne data when compared to 2009, with warmer temperatures throughout the bay for a longer

period of time (Figure A3.12).

Figure A3.11 February surface water temperature across PPB and the Yarra River (2008 – 2010)

15 17 19 21 23 25

Long Reef

Patterson River

Central Bay

Dromana

Corio Bay

Hobsons Bay


PoM DMG

MGS

Sorrento

Popes Eye

Sit

e

Temperature (oC)

Feb 2008

Feb 2009

Feb 2010


56

Figure A3.12 IMOS shipborne water temperature measurements for PPB (August 2008 – July 2009 and September 2009 – June 2010)

Salinity in PPB also follows a seasonal pattern with peaks in salinity generally occurring during the autumn

months (Figure A3.13). Due to the return of average rainfall over the last 12 months, the autumn increase in

salinity was lower than seen in the drier years of 2008 and 2009.

Figure A3.13 Average salinity for PPB (January 2008 – June 2010)

34.5

35

35.5

36

36.5

37

37.5

38

Jan

-08

Ma

r-0

8

Ma

y-0

8

Jul-

08

Se

p-0

8

No

v-0

8

Jan

-09

Ma

r-0

9

Ma

y-0

9

Jul-

09

Se

p-0

9

No

v-0

9

Jan

-10

Ma

r-1

0

Ma

y-1

0

Jul-

10

Date

Sa

lin

ity

(p

su)

Salinity (all sites)

Salinity (exYarra River at Newport)

57

The influence of rainfall and associated catchment inputs on salinity is most evident at sites close to rivers

(Yarra River at Newport, Hobsons Bay (Figure A3.14) and Patterson River) and also at Long Reef in the

vicinity of the WTP. NCBMP data from Hobsons Bay (Figure A3.14) and Long Reef and CTD profile data

from the WQBMP at the Yarra River at Newport site (Figure A3.15) and Patterson River show the influence

of freshwater, with lower salinity recorded in surface waters (e.g. 28-35 psu). In contrast, salinity at the

entrance to the Bay is influenced by Bass Strait with salinity levels closer to 35 - 36 psu, and is more

consistent with depth (Figure A3.16).

Figure A3.14 Hobsons Bay surface and bottom salinity measurements (December 2009 – June 2010)

30

32

34

36

38

40

14-10-2009 03-12-2009 22-01-2010 13-03-2010 02-05-2010 21-06-2010 10-08-2010

Date

Sa

lin

ity

(p

su)

0

8

16

24

32

40

Ra

infa

ll (

mm

)

DPI nutrient cycling surface salinity data DPI nutrient cycling bottom salinity data

Viewbank Rainfall

Figure A3.15 Yarra River at Newport CTD salinity profiles (January – June 2010)

0

1

2

3

4

5

6

7

8

28 30 32 34 36 38

Salinity (psu)

De

pth

(m

)

Jan-10 Feb-10 Mar-10 Apr-10 May-10 Jun-10


58

Figure A3.16 Popes Eye CTD salinity profiles (January – June 2010)

0

2

4

6

8

10

12

14

35 35.5 36 36.5 37 37.5

Salinity (psu)

De

pth

(m

)


The IMOS shipborne data also shows the influence of the Yarra River and Bass Strait as reflected in the

lower salinities. The influence of the Yarra River on salinity in the Bay is most evident and extends further

into the Bay when catchment inflows are high and consistent as seen in late 2009. During the current

reporting period, the influence of the Yarra did not extend as far into the Bay as there were less consistent

freshwater inputs (Figure A3.17).

Figure A3.17 IMOS shipborne salinity measurements for PPB (August 2008 – July 2009 and September 2009 – June 2010)

59

Decreases in salinity associated with rainfall also influenced chlorophyll-a concentrations in Hobsons Bay.

Data from the NCBMP show increased chlorophyll fluorescence in January, February and March 2010

coinciding with low salinity (Figure A3.18).

Figure A3.18 Hobsons Bay surface salinity and chlorophyll-a measurements (December 2009 – June 2010)

32

33

34

35

36

37

38

14-10-2009 03-12-2009 22-01-2010 13-03-2010 02-05-2010 21-06-2010 10-08-2010

Date

Sa

lin

ity

(p

su)

0

2

4

6

8

10

12

Ch

loro

ph

yll

-a (

ug

/L)

DPI nutrient cycling surface salinity data DPI nutrient cycling surface chl-a data

Stratification

The Detailed Design states that stratification is deemed to occur where there is a difference of greater

than 10 psu in salinity or the temperature differs by more than 0.5°C between surface and bottom

waters.26

During this reporting period (January – June 2010) there were a number of instances of

temperature stratification, most notably in February (Table A3.4).

Table A3.4 Temperature Stratification in PPB (January – June 2010)

Month Location Temperature Change Salinity Change

Feb-10 Yarra River at Newport 0.97 -1.35

Feb-10 Hobsons Bay 1.19 -0.06

Feb-10 Central Bay 1.86 0.02

Feb-10 PoM DMG 1.81 0.03

Feb-10 Corio Bay 0.68 -0.07

Feb-10 Long Reef 0.80 0.03

Mar-10 Yarra River at Newport 1.66 -5.86

Mar-10 Hobsons Bay 1.08 -0.60

Mar-10 Long Reef 0.86 -0.87

Apr-10 Yarra River at Newport 1.11 -6.57

Apr-10 Hobsons Bay 0.51 -0.54

May-10 Patterson River -0.70 -2.29

26

PoMC 2010. Water Quality – Detailed Design CDP_ENV_MD_023 Rev 5.0 Port of Melbourne Corporation.


60

Temperature stratification is most common from August to February in low wind conditions when the air

temperature exceeds the water temperature.27

At sites close to rivers the temperature stratification was

correlated to salinity with fresh water overlaying the seawater. This was most evident at the Yarra River at

Newport site in March and April (Figure A3.19).

Figure A3.19 Yarra River at Newport stratification (February 2010)

0

1.5

3

4.5

22.4 22.6 22.8 23 23.2 23.4 23.6 23.8 24

Temperature (oC)

De

pth

(m

)

34.2

34.8

35.4

36

Sa

lin

ity

(P

SU

)

Temperature-depth

Salinity-temperature

In March at the Yarra River at Newport and Long Reef sites the increase in salinity also coincided with a

decline in DO from the surface to the halocline and then an increase in DO in the lower waters.

Chlorophyll fluorescence measurements at these sites also followed the same pattern (Figure A3.20 and

Figure A3.21).

Figure A3.20 CTD profile of salinity, DO and fluorescence at Yarra River Newport (March 2010)

27

Black and Mourtikas 1992 Literature review of the physics of Port Phillip Bay, Port Phillip Bay Environmental Study Technical Report No.3

61

Figure A3.21 CTD profile of salinity, DO and fluorescence at Long Reef (March 2010)

Dissolved Oxygen (DO)

Under natural conditions, DO concentrations may vary greatly over a daily (or diurnal) period depending on

water temperature, salinity, photosynthetic and microbial activity.28

There were two occasions when the

WQBMP DO dropped below 90% at the Yarra River at Newport site in April and May 2010 (Table A3.3).

Results from the NCBMP show the variability that can occur in DO readings that is not evident in single

samples collected for the WQBMP (Figure A3.22).

Figure A3.22 Hobsons Bay surface DO measurements (January – June 2010)

70

80

90

100

110

120

14-10-2009 03-12-2009 22-01-2010 13-03-2010 02-05-2010 21-06-2010 10-08-2010

Date

Dis

solv

ed

Ox

yg

en

(%

sat)

DPI nutrient cycling surface data EPA water quality data (lab) EPA water quality data (CTD)

28

ANZECC 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000), Australian and New Zealand Environment Conservation Council


62

In February and April 2010 reduced oxygen concentrations were detected in the centre of PPB. During

February the decline in DO at depth corresponded to an increase in chlorophyll fluorescence (Figure A3.23

and Figure A3.24).

Figure A3.23 CTD profile of DO and chlorophyll fluorescence at Central Bay (April 2010)

Figure A3.24 CTD profile of DO and chlorophyll fluorescence at PoM DMG (April 2010)

63

During April 2010, the reduced oxygen concentrations coincided with colder temperature and higher salinity

(Figure A3.25 and Figure A3.26) similar to the same period in 2009.29

Figure A3.25 CTD profile of salinity, temperature and DO at Central Bay (April 2010)

Figure A3.26 CTD profile of salinity, temperature and DO at PoM DMG (April 2010)

29

EPA 2009 Baywide Water Quality Monitoring Program Milestone Report No.4


64

Water Clarity - Secchi disc

Secchi disc depth is the measure of water clarity for which SEPP (WoV) objectives are set in Schedule

F6. These objectives are applied as control values for water clarity as there are no Shewhart limits

available and also no EWMA applicable for these measurements.

Water clarity as measured by Secchi disc was generally good across the bay with SEPP (WoV) objectives

met at most sites. An improvement in water clarity was seen at the Yarra River at Newport with the SEPP

(WoV) objective of greater than 2m met in May and June 2010 (Figure A3.27).

Figure A3.27 Water clarity (Secchi depth) at Yarra River at Newport (November 2007– June 2010)

A decline in water clarity was observed at Corio Bay from February to May 2010 (Figure A3.28). Natural

and site specific processes including wind, storms, local currents and tides and increased phytoplankton

growth can all influence Secchi disc depth measurements.

Figure A3.28 Water clarity (Secchi depth) at Corio Bay (November 2007– June 2010)

65

Water Clarity - Turbidity

Turbidity is the measure of water clarity for which SEPP objectives are set in Schedule F7 for the Yarra Port

segment of the Yarra River. Turbidity measurements at the Yarra River at Newport site remained below 10

NTU for the last six months, a significant difference when compared to the same period in 2009 (Figure

A3.29). The annual median (3.8 NTU) and annual 90th percentile (5.4 NTU) for the last 12 months of

monitoring were well below the SEPP objectives of less than 20 NTU and 50 NTU respectively (Table A6.1).

Figure A3.29 Yarra River at Newport CTD turbidity profile (January - June 2009; January - June 2010)

0

2

4

6

8

10

12

14

16

0 5 10 15 20 25

Turbidity (NTU)

De

pth

(m

)



CTD limit of recording

Total suspended solids (TSS)

The TSS SEPP F7 objectives for Yarra River at Newport were met with the median (6.7 mg/L) and 90th

percentile (8.3 mg/L) below the SEPP objectives of less than 25 mg L-1

and 60 mg L1 respectively (Table

A6.1).

Light - Photosynthetically active radiation (PAR)

PAR is a measure of light penetration through the water column. The SEPP (WoV) objectives for PAR were

met at all sites with the exception of Yarra River at Newport and Sorrento Bank (Appendix 6). At the Yarra

River at Newport, high light attenuation is consistent with proximity to freshwater (turbid) inflows and higher

chlorophyll-a concentrations, while Sorrento Bank is a very shallow site.


66

Nutrients

Control limits in the form of Shewhart and EWMA have been derived for nutrients using historic and site

specific data to detect changes in water quality outside natural variability in PPB. SEPP (WoV) Schedule F6

excludes nutrient objectives (and default ANZECC values) in recognition of the limited value current

ANZECC water quality guidelines for nutrients have in PPB.30

Rather the effects of increased nutrients are

assessed through their primary response (increased phytoplankton production) with SEPP (WoV) objectives

for chlorophyll-a concentrations. The expected variation in water quality for nutrients in PPB is most

effectively expressed via the control limits.

Ammonium

Throughout the current reporting period, concentrations of ammonium have remained relatively steady

and below the Shewhart control limits. The exception was an isolated Shewhart exceedence in May 2010

at the PoM DMG (Figure A3.30). EWMA exceedences were again observed at Dromana (Figure A3.31).

A small underlying increase was also observed in ammonium EWMA values from January to May 2010 at

sites along the east coast (Figure A3.31), central PPB (Figure A3.32) and the Yarra River (Figure A3.33).

Figure A3.30 Ammonium Shewhart control chart for PoM DMG (November 2007 – June 2010)

30

EPA 2002 Port Phillip Bay Water Quality. Long-term Trends in Nutrient Status and Clarity 1984–1999.

67

Figure A3.31 Ammonium EWMA control chart for Dromana (November 2007 - June 2010)

Figure A3.32 Ammonium EWMA control chart for Central Bay (November 2007 - June 2010)


68

Figure A3.33 Ammonium EWMA control chart for Yarra River at Newport (November 2007 - June 2010)

Nitrate plus Nitrite

Concentrations of NOx have remained below Shewhart control limits at all sites for the past six months

(Figure A3.34). EWMA exceedences continued at the Yarra River at Newport site (Figure A3.35) following

peaks associated with catchment inputs (Figure A3.36). Data from Melbourne Water for the Yarra River

also shows the influence of rainfall on nutrient concentrations in the river with a large peak in NOx (and

other nutrients) coinciding with the storm event in March (Figure A3.37).

Figure A3.34 NOx Shewhart control chart for Central Bay (November 2007 - June 2010)

69

Figure A3.35 NOx EWMA control chart for Yarra River at Newport (November 2007 - June 2010)

Figure A3.36 River flow and NOx measurements for Yarra River at Newport (May 2006 - June 2010)

0

1000

2000

3000

4000

5000

6000

De

c-0

5

Ma

r-0

6

Jul-

06

Oct

-06

Jan

-07

Ap

r-0

7

Au

g-0

7

No

v-0

7

Feb

-08

Jun

-08

Sep

-08

De

c-0

8

Ma

r-0

9

Jul-

09

Oct

-09

Jan

-10

Ma

y-1

0

Au

g-1

0

Date

Riv

er

flo

w (

ML/

da

y)

0

50

100

150

200

250

300

Co

nce

ntr

ati

on

(u

g/L

)

Mean Daily Flow Jan 06 - April 07 Mean Daily Flow November 07 - June 10 Historical NOx Current NOx


70

Figure A3.37 Melbourne Water and EPA NOx data (January – June 2010)

0

100

200

300

400

500

600

700

800

900

1000

1/01/2010 21/01/2010 10/02/2010 2/03/2010 22/03/2010 11/04/2010 1/05/2010 21/05/2010 10/06/2010 30/06/2010

Date

Co

nce

ntr

ati

on

(u

g/L

)

0

1000

2000

3000

4000

5000

6000

Riv

erf

low

(M

L)

Yarra River at Princes Bridge (MW) Yarra River at Newport (EPA) Fairfield Riverflow

In the south of the bay, small peaks in NOx, corresponding with lower water temperature and salinity,

were again observed (Figure A3.38). Seasonal winter peaks of varying magnitude have been previously

observed.31

Figure A3.38 NOx Shewhart control chart for Popes Eye (November 2007 - June 2010)

31

EPA 2010 Baywide Water Quality Monitoring Program Milestone Report No.5

71

Total Nitrogen

Total Nitrogen concentrations over the past six months were below the control limits at all sites except the

Yarra River at Newport and Corio Bay. As with NOx, high concentrations of total nitrogen at the Yarra River

at Newport site were associated with catchment inputs. This resulted in exceedences of the Shewhart

(Figure A3.39) and EWMA control limits at this site (Figure A3.40).

Figure A3.39 Total nitrogen Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)

Figure A3.40 Total nitrogen EWMA control chart for Yarra River at Newport (November 2007 - June 2010)


72

The single Shewhart exceedence in February (Figure A3.41) and EWMA exceedence in May at Corio Bay

(Figure A3.42) was also influenced by increased rainfall over the catchment.

Figure A3.41 Total nitrogen Shewhart control chart for Corio Bay (November 2007 - June 2010)

Figure A3.42 Total nitrogen EWMA control chart for Corio Bay (November 2007 - June 2010)

Phosphate

Phosphate concentrations at all sites, except Dromana, have either remained steady (Figure A3.43 and

Figure A3.44) or increased slightly over the past six months (Figure A3.45 and Figure A3.46). Data from the

WTP has shown an increase in phosphate and total phosphorous loads over the last six months peaking at

the end of May (Figure A3.47). WTP is a significant source of phosphate into PPB (Figure A3.48). The

73

greatest peaks in phosphate concentrations at Long Reef coincide with the lowest salinities, indicative of

WTP (freshwater) discharges (Figure A3.49). Yarra River nutrient data from Melbourne Water show

phosphate concentrations are generally lower than those in PPB with no observable peak during the storm

event as seen for other nutrients (Figure A3.50).

Figure A3.43 Phosphate Shewhart control chart for Corio Bay (November 2007 - June 2010)

Figure A3.44 Phosphate EWMA control chart for Corio Bay (November 2007 - June 2010)


74

Figure A3.45 Phosphate Shewhart control chart for Central Bay (November 2007 - June 2010)

Figure A3.46 Phosphate EWMA control chart for Central Bay (November 2007 - June 2010)

75

Figure A3.47 WTP nutrient loads (January – June 2010)

0

2000

4000

6000

8000

01/01/10 21/01/10 10/02/10 02/03/10 22/03/10 11/04/10 01/05/10 21/05/10 10/06/10 30/06/10

Date

To

tal

loa

d

(kg

/da

y)

WTP PO4 WTP TP WTP NH3 WTP TN WTP NOx

Figure A3.48 WTP phosphate loads (May 2008 – June 2010)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Feb-08 Jun-08 Sep-08 Dec-08 Mar-09 Jul-09 Oct-09 Jan-10 May-10 Aug-10

Date

PO

4 l

oa

d (

kg

/da

y)


76

Figure A3.49 Long Reef salinity and phosphate measurements (November 2007 – June 2010)

0

50

100

150

200

250

300

350

400

450

35.5 36 36.5 37 37.5 38 38.5

Salinity (PSU)

PO

4 C

on

cen

tra

tio

n (

ug

/L)

Figure A3.50 Melbourne Water and EPA phosphate water quality data (January – June 2010)

0

10

20

30

40

50

60

70

80

90

100

1/01/2010 21/01/2010 10/02/2010 2/03/2010 22/03/2010 11/04/2010 1/05/2010 21/05/2010 10/06/2010 30/06/2010

Date

Co

nce

ntr

ati

on

(u

g/L

)

0

1000

2000

3000

4000

5000

6000

Riv

erf

low

(M

L)


The general decline in phosphate concentrations across the Bay observed during previous reporting periods

is only continuing at Dromana (Figure A3.51 and

77

Figure A3.52). Phosphate concentrations in the south of PPB appear to be diluted by ocean water with the

lowest concentrations correlated to low salinities (Figure A3.53).

Figure A3.51 Phosphate Shewhart control chart for Dromana (November 2007 - June 2010)

Figure A3.52 Phosphate EWMA control chart for Dromana (November 2007 - June 2010)


78

Figure A3.53 PPB salinity and phosphate concentrations (November 2007 - June 2010)

0

20

40

60

80

100

35 36 37 38 39

Salinity (psu)

Ph

osp

ha

te (

ug

/L)

Central Bay

Dromana

Corio Bay

PoM DMG

MGS

Sorrento

Popes Eye

Dilution

Evaporation

Total Phosphorus

The concentrations of total phosphorus are below the Shewhart and EWMA control limits at all sites. Similar

to phosphate, total phosphorus concentrations at all sites except Dromana have remained steady (Figure

A3.54 and Figure A3.55) or increased slightly (Figure A3.56 and Figure A3.57) over the past six months.

Dromana continues to show a decline in total phosphorus concentrations (Figure A3.58 and Figure A3.59).

External data from Melbourne Water shows there was a high concentration of total phosphorus in the Yarra

River following the storm event in March (Figure A3.60) and an increase over the last six months from the

WTP (Figure A3.47).

Figure A3.54 Total Phosphorus Shewhart control chart for Hobsons Bay (November 2007 - June 2010)

79

Figure A3.55 Total Phosphorus EWMA control chart for Hobsons Bay (November 2007 - June 2010)

Figure A3.56 Total Phosphorus Shewhart control chart for PoM DMG (November 2007 - June 2010)


80

Figure A3.57 Total Phosphorus EWMA control chart for PoM DMG (November 2007 - June 2010)

Figure A3.58 Total Phosphorus Shewhart control chart for Dromana (November 2007 - June 2010)

81

Figure A3.59 Total Phosphorus EWMA control chart for Dromana (November 2007 - June 2010)

Figure A3.60 Melbourne Water and EPA total phosphorus water quality data (January – June 2010)

0

100

200

300

400

500

600

700

1/01/2010 21/01/2010 10/02/2010 2/03/2010 22/03/2010 11/04/2010 1/05/2010 21/05/2010 10/06/2010 30/06/2010

Date

Co

nce

ntr

ati

on

(u

g/L

)

0

1000

2000

3000

4000

5000

6000

Riv

erf

low

(M

L)


Silicate

There are no control limits or SEPP (WoV) objectives for silicate. Highest silicate concentrations were

reported at the Yarra River at Newport site (Figure A3.61), with smaller peaks also observed in early 2010 at

Corio Bay (Figure A3.62), Patterson River (Figure A3.63) and Popes Eye (Figure A3.64).


82

Figure A3.61 Silicate control chart for Yarra River at Newport (November 2007 - June 2010)

Figure A3.62 Silicate control chart for Corio Bay (November 2007 - June 2010)

83

Figure A3.63 Silicate control chart for Patterson River (November 2007 - June 2010)

Figure A3.64 Silicate control chart for Popes Eye (November 2007 - June 2010)

Phytoplankton and Algal Pigments

Phytoplankton activity is measured through cell counts, chlorophyll-a measurements and in-situ chlorophyll

fluorescence.

Total phytoplankton cell counts in the past six months have declined from the high numbers seen at some

sites in November and December 2009 (Figure A3.65). Phytoplankton cell counts did remain above

bloom levels (nominally >1,400,000 cells/L)32

at the Yarra River at Newport and Hobsons Bay sites in

32

Hale 2006 Supplementary Environment Effects Statement, Head Technical Report: Nutrient Cycling- Appendix 1 Phytoplankton Blooms


84

January and February 2010 and Corio Bay in March 2010. Phytoplankton blooms are a natural

occurrence within PPB with previous studies finding higher concentrations of phytoplankton in warmer

months with peaks in late summer/ early autumn.33

Early 2010 was the first occasion during the WQBMP that potentially harmful phytoplankton were detected

above the Victorian Shellfish Operations Manual (VSOM) action levels. The potentially harmful diatoms,

Pseudo-nitzschia species, made up 35% and 87% of the phytoplankton community at the Yarra River at

Newport and Hobsons Bay sites, respectively in January. Pseudo-nitzschia species have occurred

previously in PPB with large blooms detected in 1988, 1991/92, 1993/94 and 1996 (Figure A3.66).35

The

largest bloom of Pseudo-nitzschia species was recorded in 1991/92 with the bloom extending across many

areas of PPB (Figure A3.67). 35

The highest cell counts for this species were measured at St Kilda in

December 1991 with a peak of approximately 4,250,000 cells/L and Hobsons Bay in February 2010 with a

peak of 3,650,000 cells/L (Figure A3.68). 34

Following the presence of Pseudo-nitzschia spp. in January, the toxic dinoflagellate, Alexandrium catenella,

first identified in PPB in 1986, was detected at the Yarra River at Newport site in February 2010. A. catenella

blooms have only been recorded in Hobsons Bay during summer (December to mid-April), and cysts are

known to be abundant near the Yarra mouth.35

Another potentially harmful dinoflagellate, Karlodinium

species (not reported in Progress reports), was detected above VSOM levels in March and April 2010 in

Corio Bay. Pseudo-nitzschia species were again detected above VSOM levels in Corio Bay in April 2010

making up 40% of the phytoplankton community.

Figure A3.65 Total phytoplankton cell numbers across PPB (February 2008 – June 2010)

0

2000000

4000000

6000000

8000000

10000000

12000000

Fe

b-0

8

Ma

r-0

8

Ap

r-0

8

Ma

y-0

8

Jun

-08

Jul-

08

Au

g-0

8

Se

p-0

8

Oct

-08

No

v-0

8

De

c-0

8

Jan

-09

Fe

b-0

9

Ma

r-0

9

Ap

r-0

9

Ma

y-0

9

Jun

-09

Jul-

09

Au

g-0

9

Se

p-0

9

Oct

-09

No

v-0

9

De

c-0

9

Jan

-10

Fe

b-1

0

Ma

r-1

0

Ap

r-1

0

Ma

y-1

0

Date

To

tal

Ph

yto

pla

nk

ton

(ce

lls/

L)

Yarra River at Newport Hobsons Bay Central PoM DMG

Corio Bay Long Reef Patterson River Dromana

Middle Ground Shelf Sorrento Popes Eye

33

Elias et al. 2004 Port Philip Bay Channel Deepening Project Environmental Effects Statement – Marine Ecology Specialist Studies, Volume 8 Plankton and Nekton studies. 34

Longmore 2010 DPI phytoplankton data 1987 - 1996 35

Arnott et al. 1995 Phytoplankton composition, distribution and abundance in Port Phillip Bay from March 1990 to February 1995.

85

Figure A3.66 Average Pseudo-nitzschia species cell counts from PPB (1998 – 1996; 2008 -2010)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

CDP - 2010

CDP - 2008

1995

1993

1991

1989

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

To

tal

Pse

ud

o

nit

zsch

ia (

cell

s/L)

CDP - 2010

CDP - 2009

CDP - 2008

1996

1995

1994

1993

1992

1991

1990

1989

1988

Figure A3.67 Pseudo-nitzschia species cell counts across PPB (1991)


86

Figure A3.68 Pseudo-nitzschia species cell counts in PPB (1988-1996; 2008-2010)

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

1988 1989 1990 1991 1992 1993 1994 1995 1996 2008 2009 2010

Date

Ph

yto

pla

nk

ton

(ce

lls/

L)

Beaumaris St Kilda Dromana Balcolmbe Bay Williamstown Popes Eye Patterson River Hobsons Bay

Phytoplankton growth and productivity are primarily influenced by temperature, light and nutrients with

salinity stratification potentially initiating blooms.36

.

36

Wood and Beardall 1992 Phytoplankton ecology of Port Phillip Bay Port Phillip Bay Environmental Study

87

Figure A3.69 and Figure A3.70 provide a general view of the spatial variation seen in temperature,

salinity, silicate, phosphate, dissolved inorganic nitrogen (DIN), chlorophyll-a and phytoplankton in

Hobsons and Corio Bay, the two most productive areas during the current reporting period, using data

interpolated with the Spline method.37

37

The interpolation of data presented here is intended to give a general impression of spatial variation across the bay. It is developed from the sampling data collected at the 11 WQBMP sites over a number of days each month and does not account for minor temporal changes caused by environmental factors.


88

Figure A3.69 Hobsons Bay interpolated water quality data (January – June 2010)

89

Figure A3.70 Corio Bay interpolated water quality data (January – June 2010)

The phytoplankton cell counts from the above two sites once again did not correspond to the chlorophyll-

a data. Significant shifts in phytoplankton community composition may explain the disparity in results.

Figure A3.71 show the change in species composition at these two sites from January – March 2010 as

an example.


90

Figure A3.71 Yarra River at Newport and Corio Bay phytoplankton species composition (January – March 2010)

Yarra River at Newport January 2010

Diatoms

85%

Pseudo-nitzschia

delicatissima group

34.8%

Skeletonema

43.7%

Diatoms

(% of total Phytoplankton)

Cryptophytes

9.9%

Yarra River at Newport February 2010

Diatoms

77%

Chaetoceros spp .

11.3%

Skeletonema

57.2%

Cryptophytes

15.5%

Diatoms


Yarra River at Newport March 2010

Diatoms

62%

Chaetoceros spp .

27.4%

Skeletonema

25.7%

Cryptophytes

35%

Diatoms


Corio Bay January 2010

Diatoms

64%

Other Diatoms 7%

Chaetoceros spp. 6%

Cyl. Closterium 6%

Skeletonema

45%

Diatoms


Cryptophytes

15%

Dinoflagellates

15%

Corio Bay February 2010

Diatoms

19%

Other Diatoms 8%

Cyl. Closterium 8%

Cryptophytes

34%

Diatoms


Dinoflagellates

33%

Corio Bay March 2010

Diatoms

87%

Other Diatoms 15%

Cyl. Closterium 50%

Diatoms


Dinoflagellates

8%

Chaetoceros spp. 19%

91

The chlorophyll-a concentrations from the WQBMP and chlorophyll fluorescence from the IMOS shipborne

data also indicate continued phytoplankton activity throughout the Bay (Figure A3.72). The SEPP (WoV)

annual 90th percentile objectives were exceeded at Yarra River at Newport, Corio Bay and Patterson River

(Appendix 6). High chlorophyll-a concentrations and EWMA exceedences continued at the Yarra River at

Newport (Figure A3.73 and Figure A3.74) and elevated chlorophyll-a concentrations and EWMA

exceedences were also reported at Corio Bay for each of the last five months (Figure A3.75 and Figure

A3.76).

Figure A3.72 IMOS shipborne in-situ chlorophyll fluorescence measurements for PPB (August 2008 – July 2009 and September 2009 – June2010)


92

Figure A3.73 Chlorophyll a control chart for Yarra River at Newport (November 2007 - June 2010)

Figure A3.74 Chlorophyll a EWMA control chart for Yarra River at Newport (November 2007 - June 2010)

93

Figure A3.75 Chlorophyll a control chart for Corio Bay (November 2007 - June 2010)

Figure A3.76 Chlorophyll a EWMA control chart for Corio Bay (November 2007 - June 2010)

The seasonal winter peaks in chlorophyll-a in the south of PPB also resulted in EWMA exceedences at

Sorrento Bank (Figure A3.77) and MGS in June.


94

Figure A3.77 Chlorophyll a EWMA control chart for Sorrento Bank (November 2007 - June 2010)

Metals

Most of the metal samples collected during the last six months were below the limit of reporting (LOR) and

control limits. There was only one reported metal exceedence, total chromium at the Yarra River at Newport

in March, following the storm event. Peaks in other metal concentrations associated with the storm event in

March 2010 reported by the Melbourne Water (Figure A3.78) and the Beach monitoring programs (Figure

A3.79) were not reflected in the WQBMP data.

Figure A3.78 Yarra River Melbourne Water metals data (January – June 2010)

0

10

20

30

40

50

60

70

1/01/2010 21/01/2010 10/02/2010 2/03/2010 22/03/2010 11/04/2010 1/05/2010 21/05/2010 10/06/2010 30/06/2010

Date

Co

nce

ntr

ati

on

(u

g/L

)

0

1000

2000

3000

4000

5000

6000

Riv

erf

low

(M

L/d

ay

)

Cr As Cu Pb Zn Ni Cd Fairfield Riverflow

95

Figure A3.79 St Kilda Beach monitoring metals data (January – June 2010)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

1/01/2010 21/01/2010 10/02/2010 2/03/2010 22/03/2010 11/04/2010 1/05/2010 21/05/2010 10/06/2010 30/06/2010

Date

Co

nce

ntr

ati

on

(u

g/L

)

0

1000

2000

3000

4000

5000

6000

Riv

erf

low

(M

L/d

ay

)

As Cd Cr Cu Pb Hg Ni Zn Yarra River at Fairfield Riverflow

Summary statistics for metals have been calculated for comparison against SEPP objectives. Regionally

specific SEPP (WoV) objectives apply to total metals. Where there is no regionally specific objective in SEPP

(WoV), the SEPP (ANZECC) objective is applied to dissolved metals (Appendix 6). Summary statistics are

calculated using the last 12 months of data (July 2009 – June 2010) and include the mean, median, 90th

percentile, minimum and maximum value. SEPP (WoV) objectives for metals are based on maximum values.

Arsenic

Arsenic concentrations during the current reporting period were all below the Shewhart and EWMA control

limits (where available). Concentrations generally remained steady (Figure A3.80 and Figure A3.85) or

showed a small increase since the previous reporting period (Figure A3.86 and Figure A3.83). Summary

statistics based on the last 12 months of data show the SEPP (WoV) F6 objective of less than 3µgL/L was

not met at Corio Bay (Appendix 6) with a maximum value of 3.2 µg/L reported in March 2010. The SEPP

(WoV) objective for arsenic in PPB is based on background measurements, rather than on toxicity and there

is currently no evidence that exceeding the SEPP (WoV) objective by a small margin constitutes a risk to

marine biota.38

38 Gibbs et al 2007 Port of Melbourne Corporation Channel Deepening Project Baseline Water Quality Monitoring 2006-

2007


96

Figure A3.80 Arsenic control chart for Dromana (November 2007 - June 2010)

Figure A3.81 Arsenic EWMA control chart for Dromana (November 2007 - June 2010)

97

Figure A3.82 Arsenic control chart for Central Bay (November 2007 - June 2010)

Figure A3.83 Arsenic EWMA control chart for Central Bay (November 2007 - June 2010)

Cadmium

All samples in the current reporting period were below the LOR (0.2 µg/L) and within both control limits and

SEPP (WoV) objectives. Summary statistics based on the last 12 months of data show the SEPP (WoV) F6

objective of less than 0.15µg/L (which is below the LOR) was met at all sites (Appendix 6).

Chromium

There was only one recorded chromium exceedence during the reporting period with total chromium

exceeding the Shewhart control limit at the Yarra River at Newport in March (Figure A3.84). Summary


98

statistics based on the last 12 months of data show the SEPP (WoV) F6 objective of less than 5.0 µg/L was

met at all sites (Appendix 6).

Figure A3.84 Total chromium control chart for Yarra River at Newport (November 2007 - June 2010)

Copper

The majority of samples in the current reporting period were below the LOR (1.0µg/L) and within both control

limits and SEPP (ANZECC) objectives. Dromana and the Yarra River at Newport (Figure A3.85 and Figure

A3.86) were the only sites where copper concentrations were greater than or equal to the LOR. Summary

statistics based on the last 12 months of data show the SEPP (ANZECC) F6 objective was met at all sites

(Appendix 6).

Figure A3.85 Total copper Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)

99

Figure A3.86 Dissolved copper control chart for Yarra River at Newport (November 2007 - June 2010)

Lead

The majority of samples in the current reporting period were below the LOR (0.2 µg/L) and within both

control limits and SEPP (ANZECC) objectives. The Yarra River at Newport was the only site that consistently

reported values above the LOR for total lead (Figure A3.87). Dissolved lead was generally below the LOR

(Figure A3.88). Summary statistics based on the last 12 months of data show the SEPP (ANZECC) F6

objectives were met at all sites (Appendix 6).

Figure A3.87 Total lead Shewhart control chart for Yarra River at Newport (November 2007 - June 2010)


100

Figure A3.88 Dissolved lead control chart for Yarra River at Newport (November 2007 - June 2010)

Mercury

All mercury samples were below the LOR and control limits throughout the current reporting period.

Summary statistics based on the last 12 months of data show the SEPP (WoV) F7 and SEPP (ANZECC) F6

objectives were not met at a number of sites due to mercury results in November 2009 reported at

concentrations equal to the LOR (Appendix 6).

Nickel

All nickel samples in the current reporting period were below the Shewhart control limits. Summary statistics

based on the last 12 months of data show the SEPP (ANZECC) F6 objectives were met at all sites

(Appendix 6).

Zinc

The majority of samples in the current reporting period were below the LOR (5.0 µg/L) and within derived

control limits. Summary statistics based on the last 12 months of data show the SEPP (WoV) objectives were

not met at Corio Bay and the Yarra River at Newport due to high concentrations recorded during the

previous reporting period (Appendix 6).

TBT

All TBT samples, from the Yarra River at Newport and Hobsons Bay sites, were below the LOR and/or

within both the Shewhart control limits and the SEPP (ANZECC) objectives throughout the reporting

period (Appendix 6)

101

APPENDIX 4 - QA/QC DATA AND DISCUSSION

Laboratory QA/QC

The respective laboratories for this monitoring program have reported their quality control for the sample

batches covered by this report to be within acceptable limits.

Phytoplankton Analysis

Microalgal Services laboratory protocols and procedures aim to comply with AS ISO/IEC 17025-2005

(General Requirements for the competence of testing and calibration laboratories). Equipment is calibrated

to NATA traceable standards and method validation has been undertaken.

Nutrient Analysis

Department of Primary Industries (DPI) Queenscliff laboratory’s QA/QC program includes:

• Laboratory blanks, analysed with each batch of samples;

• Laboratory spikes, analysed with each batch of samples;

• Spike recovery analysed periodically;

• Algorithm checks are carried out periodically to assure the accuracy of nutrient calculations; and

• All samples analysed in duplicate.

Metals Analysis

Ecowise (now a subsidiary of Australian Laboratory Services (ALS)) employs a QAQC program as follows:

• Method Blanks, analysed with each batch of samples;

• Laboratory Duplicates, analysed with each batch of samples;

• Laboratory Control Samples (LCS), analysed with each batch of samples; and

• Matrix Spikes (MS), analysed with each batch of samples.

Laboratory comparison on filtered and unfiltered nitrates

The current WQBMP measures filtered inorganic nutrients whereas historically, inorganic nutrients were

measured using unfiltered samples. This inconsistency prompted an investigation as detailed in EPA

(2009)39

. Filtered and unfiltered samples for nitrates (nitrate and nitrite) were analysed due to the potential

contamination of filtered samples in April – June 2009. A further comparison using new filters was completed

from January – June 2010.

The first comparison in 2009 found that for 98% of the NOX samples, the filtered result was greater than the unfiltered result. This indicated that the control limits based on unfiltered samples may not be adequate as there was the potential for false exceedences. In contrast, the second comparison undertaken in 2010 found that for 57% of the NOX samples, the filtered result was greater than the unfiltered result. Since implementation of the new filters, the difference between the filtered and unfiltered samples has been within the measurement of uncertainty provided by the laboratory and has not caused any control limits to be exceeded. The change in filters has decreased the risk of contamination and therefore the potential for false exceedences. The control limits remain conservative and are fit for purpose.

39

EPA 2009 Filenote Comparison of filtered and unfiltered nutrient data


102

Sample blanks and replicates

Field sampling quality control measures include the collection of field blanks and replicates to test for

contamination and laboratory precision.

Field Sample blanks

The majority of field blanks analysed by the laboratories have come back with values less than the LOR. The

only exception was:

• A positive result for filtered chromium (0.8µg/L) was reported in the Day 3 field blank in May 2010.

Re-analysis of the sample resulted in a reported value of <0.5µg/L. When applying the measurement

uncertainty (MU) (0.644 µg/L) to the original sample result, the two values are consistent and were

accepted as valid.40

Field replicate samples

Most metal replicate samples for the period January – June 2010 were found to be in agreement with the

original value. There were two occasions, in January and March 2010, when internal QAQC investigations of

the replicate data found that the samples may have been contaminated and no results were reported.

• January 2010: The replicate filtered and unfiltered value for lead at Hobsons Bay was outside of the

MU of the original sample. The reported original unfiltered result for lead (1.2 µg/L) exceeded the

Shewhart control limit of 0.95 µg/L while the replicate value was reported as <0.2 µg/L. The re-

analysed results were consistent and the data was rejected.41

• March 2010: The laboratory automatically re-analysed the samples for Central Bay and the Northern

Replicate (PoM DMG) when filtered results for chromium, nickel and zinc were higher than the

unfiltered results. Internal QAQC procedures identified the following issues:

1. The original filtered zinc result for PoM DMG was not consistent with the Northern Replicate

collected at the same site indicating that the zinc was not at the sample site but from an external

source.

2. The filtered zinc results for Central Bay and the Northern Replicate (PoM DMG) were

considerably greater (and outside of MU) than the unfiltered.

3. The filtered chromium result for Central Bay was outside of the measurement uncertainty (MU) of

the unfiltered result.

The source of the contamination of the samples is unknown. No results were reported in March 2010

for filtered chromium, nickel and zinc data for Central Bay. The Northern Replicate results for these

parameters were also considered invalid.42

Nutrient replicate samples for the period January – June 2010 were also generally found to be in agreement

with the original value. The exceptions were:

• The Sorrento Bank particulate nitrogen replicate result was outside of the MU of the original result in

March 2010. As particulate nitrogen is not reported and the result was below the LOR the data was

accepted.43

40

EPA 2010 May 2010 QAQC Report 41

EPA 2010 January 2010 QAQC Report 42

EPA 2010 March 2010 QAQC Report (Ecowise)

103

• The Northern Replicate (Yarra River at Newport) results for carotenoid, chlorophyll-b and

phaeopigments and Southern Replicate (Popes Eye) phaeopigment result were not within 10% or

the MU of the original results. All results, except carotenoid which is not reported, were accepted as

valid based on expert advice from the laboratory.44

Field QA/QC

Comparability of CTD and laboratory results

A small number of discrepancies were found between the CTD and laboratory results. It is expected that

differences in results will arise due to the different methodology used in collecting the samples and the time

of the analysis. Further factors that may also cause discrepancies include turbulence off the hull, differences

in sampling times and differences in collection point of the sample.

Calibration of the CTD

The regular CTD used for water quality monitoring was sent to America for an annual manufacturer’s

calibration following the February 2010 sampling.

Use of back-up CTD in March, April and May 2010

A back-up CTD was used to collect in-situ data for the water quality monitoring program in March, April and

May 2010 while the regular CTD was undergoing annual calibration.

A scalar (spherical) PAR sensor rather than the usual planar (flat) sensor was used for recording PAR during

these months. The use of the spherical sensor allows light to be captured from all directions resulting in

higher PAR readings. The PAR data, while not directly comparable, can be converted to attenuation

(assuming R2 >0.8) allowing for assessment against the SEPP (WoV) F6 90

th percentile objectives

(Appendix 6).

Comparability of regular and back-up CTD

An inter-comparison of the two CTDs used for the Water Quality Monitoring Program was undertaken during

the February 2010 sampling event. The two CTDs were lowered through the water column side by side at

each site by different operators. Overall the two CTDs showed good comparability for most parameters.

Differences between the CTDs were observed for turbidity, fluorescence and dissolved oxygen at the Yarra

River at Newport site. The Yarra River at Newport site is in the Yarra River estuary, which can be affected by

freshwater inflows, tides and shipping, creating large amounts of variability over small distances.

43

EPA 2010 March 2010 QAQC Report (DPI) 44

EPA 2010 June 2010 QAQC Report


104

APPENDIX 5 - RESULTS OUTSIDE OF NATURAL/EXPECTED VARIABILITY

As outlined in the Detailed Design (Decision Framework for Management) an assessment was undertaken of

results flagged as outside of natural/expected variability. This is reported monthly in Assessment

Reports.45,46

In summary, the assessment undertakes the following basic steps:

1. Are the results outside natural/expected variability? This is a two part question:

a. Are results outside of expectations based on our understanding of ‘natural’ historical background

conditions in the Bay? - This is determined by assessing results against control limits. If the results

exceed control limits then they are deemed to be ‘outside of natural variability’.

b. Are such results outside of our expectations based on the predicted effects of the CDP, as defined in

the Supplementary Environment Effects Statement (SEES) – This assessment is based on expert

opinion.

2. If results are deemed to be ‘outside expected variability’, then a decision is made to determine if these

changes are significant to the environment. This will consider issues such as:

• The accuracy of the results

• The magnitude of deviation from expectations

• The temporal and spatial extent of changes

• The biological significance of changes.

3. Under the Decision Framework for Management, if an assessment concludes that results are of

significance to the environment then further risk-based investigations are initiated to identify flow on effects

to the ecosystem, the causal factor/s and any required management measures.

Assessment

Multiple lines of evidence are considered to assess whether the results are outside of expected variability. All

results up to June 2010 have been reviewed by the EPA and PoMC with the identification of the following

issues and outcomes summarised in Table A5.1. In all instances, the assessments concluded that the water

quality results identified to be outside of expected variability are not of significance to the broader bay

environment.

45

PoMC 2010a, b, c, d, Assessment of results outside of expected variability, Progress Report #25-#28 46

EPA 2010a, b, Assessment of results outside of expected variability, Progress Report #29 and #30

105

Table A5.1 PoMC/EPA Assessment (January – June 2010)

PARAMETER SITES EXCEEDENCE TYPE DATES ASSESSMENT OUTCOME

Dromana EWMA March - June 2010

Sustained exceedences of ammonium EWMA are considered to be associated with a stepwise increase in concentrations from the 1990's to now and the relatively low control limit at this site.

Ammonium

PoM DMG Shewhart May 2010

The raw result is outside the (limited) historical data range. When compared to the large historical dataset from the neighbouring Central Bay site, the concentration is within historical limits.

Nitrate plus Nitrite (NOx)


EWMA January - June 2010

The EWMA exceedences are a result of elevated raw values associated with increased catchment inputs. The limited historical dataset was collected during a period of lower rainfall and is therefore unlikely to represent nutrient conditions in the Yarra River during periods of increased rainfall. Raw results from prior months can have a sustained influence on EWMA values.


EWMA January - June 2010

As above for NOx the EWMA exceedences are a result of elevated raw values associated with increased catchment inputs. The limited historical dataset was collected during a period of lower rainfall and is therefore unlikely to represent nutrient conditions in the Yarra River during periods of increased rainfall. Raw values can have a sustained influence on EWMA values.

Shewhart February 2010

This marginal exceedence is likely due to increased rainfall over the catchment areas since late 2009, leading to increases in surface runoff and nutrient input into PPB. A similar trend in elevated TN corresponding with elevated rainfall was seen at the same time in 2008/09.

Total Nitrogen (TN)

Corio Bay

EWMA May 2010 This is the first EWMA exceedence at this site and is marginally above the control limit. The raw result is within the historical range.


106



January - June 2010

EWMA exceedences were localised with the raw results either within the historical range for this site or neighbouring Hobsons Bay. The exceedences from January - March were most likely a response to increased catchment inputs from increased rainfall, while the continued exceedences from April - June were most likely a result of the sustained influence of raw results on the EWMA calculation.

Corio Bay February - June 2010 Chlorophyll a concentrations were localised and within or marginally outside the historical range.

Middle Ground Shelf

Chlorophyll a

Sorrento Bank

EWMA

June 2010

Although these results were outside the historical range, these sites are informed by a small historical dataset that does not adequately characterise chlorophyll a conditions. The conditions were localised and did not extend to the neighbouring sites, Popes Eye and Dromana.

Dissolved Oxygen Yarra River at

Newport SEPP April - May 2010

These results are within the varying conditions that are observed in the Yarra River.


January - April 2010

The SEPP exceedences are a reflection of the limited historical data range available for comparison and increased rainfall and river flows during this period. When compared to the large historical dataset from the neighbouring Hobsons Bay site, the current Yarra River values are within historical limits.

Hobsons Bay

Long Reef

January 2010 Reduced water clarity may have been due of poor weather conditions in the days prior to sampling.

Secchi depth

Corio Bay

SEPP

May 2010 This exceedence is marginal and within the range previously observed at this site.

Total Chromium Yarra River at

Newport Shewhart March 2010

This is a marginal exceedence that is within the historical range. The dissolved (bio-available) fraction was below the ANZECC limit.

107



Hobsons Bay January 2010

Pseudo-nitzschia spp

Corio Bay

VSOM

April 2010

Alexandrium catenella


VSOM February 2010

These elevated levels are unlikely to be of significance to the longer-term heath of PPB. These species are known to occur in PPB and elevated results have been reported previously. Furthermore, the Yarra River and Hobsons Bay are not aquaculture areas. The species of Pseudo-nitzschia detected in Corio Bay were non-toxic and so it is unlikely that the aquaculture activities in this area would be affected.


108

APPENDIX 6. - SUMMARY STATISTICS (JULY 2009 – JUNE 2010)

Note: SEPP (WoV) Schedule F6/F7 exceedences are highlighted in blue.

Table A6.1 Yarra River at Newport summary statistics – Schedule F7 Yarra Port Segment Objectives

Dissolved Oxygen

Dissolved Oxygen Salinity Temperature Turbidity Turbidity

Suspended Solids

Suspended Solids

%sat

SEPP objective

%sat mg/L deg C NTU

SEPP objective

NTU mg/L

SEPP objective

mg/L

Mean 96 30.8 17.3 3.8 6.3

Median 96 31.5 17.8 3.8 <20 6.7 <25

90th percentile 101 34.5 23.3 5.4 <50 8.3 <60

Minimum 86 >60 25.0 11.3 2.1 2.5

Maximum 116 34.8 24.3 6.9 10.6

N 12 12 12 12 12

Dissolved Arsenic

Dissolved Chromium

Dissolved Zinc

Dissolved Cadmium

Dissolved Copper

Dissolved Nickel

Dissolved Lead

Total Mercury

SEPP objective µµµµg/L <13 <1 <8 <0.2 <1.3 <11 <3.4 <0.05

Mean 2.0

Median 2.0 <0.5 <5 <0.2 <1 0.8 <0.2 <0.1

90th percentile 2.4 <0.5 10 <0.2 1 0.9 <0.2 <0.1

Minimum 1.4 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.4 <0.5 17 <0.2 1 1.0 0.3 0.1

N 12 12 12 12 12 12 12 12

109

Table A6.2 Yarra River at Newport summary statistics – Schedule F6 Hobsons Segment objectives

Dissolved Oxygen

Dissolved Oxygen Salinity Temperature

Secchi Depth

Secchi Depth

Chlorophyll-a

Chlorophyll-a PAR PAR

%sat

SEPP objective

%sat mg/L deg C metres

SEPP objective metres µµµµg/L

SEPP objective

µµµµg/L attenuation

m-1

SEPP objective

attenuation m

-1

Mean 96 30.8 17.3 1.5 3.52 0.76

Median 96 31.5 17.8 1.3 2.10 2.5 0.64

90th percentile 101 34.5 23.3 2.5 8.09 4.0 1.16 0.50

Minimum 86 >90 25.0 11.3 0.6 >2 0.70 0.33

Maximum 116 34.8 24.3 2.7 8.87 1.72

N 12 12 12 12 12 12

Total

Arsenic Total

Chromium Total Zinc Dissolved Cadmium

Dissolved Copper

Dissolved Nickel

Dissolved Lead

Dissolved Mercury Tributyl Tin

SEPP objective µµµµg/L <3 <5 <10 <5.5 <1.3 <70 <4.4 <0.4 <0.006

Mean 2.1

Median 2.1 <0.5 <5 <0.2 <1 0.8 <0.2 <0.1 <0.002

90th percentile 2.5 0.7 14 <0.2 1 0.9 <0.2 <0.1 <0.002

Minimum 1.5 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1 <0.002

Maximum 2.6 0.7 20 <0.2 1 1.0 0.3 0.1 <0.002

N 12 12 12 12 12 12 12 12 12


110

Table A6.3 Hobsons Bay summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 99 36.3 17.0 3.2 1.86 0.38

Median 97 36.4 16.6 3.3 1.88 2.5 0.33

90th percentile 107 36.9 21.9 4.3 2.95 4.0 0.43 0.50

Minimum 94 >90 34.9 11.1 1.1 >2 0.57 0.22

Maximum 109 37.1 24.1 4.7 3.64 0.81

N 12 12 12 12 12 12

Total

Arsenic Total


Dissolved Copper

Dissolved Nickel

Dissolved Lead

Dissolved Mercury Tributyl Tin

SEPP objective µµµµg/L <3 <5 <10 <5.5 <1.3 <70 <4.4 <0.4 <0.006

Mean 2.3

Median 2.4 <0.5 <5 <0.2 <1 0.6 <0.2 <0.1 <0.002

90th percentile 2.7 0.5 <5 <0.2 <1 0.6 0.3 <0.1 <0.002

Minimum 1.7 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1 <0.002

Maximum 2.7 1.1 <5 <0.2 <1 0.7 1.2 0.1 <0.002

N 12 12 12 12 12 12 12 12 12

111

Table A6.4 Corio Bay summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 103 37.8 16.7 1.44 0.36

Median 101 37.8 16.1 1.03 1.5 0.36

90th percentile 115 38.2 22.8 3.35 2.5 0.44 0.45

Minimum 91 >90 37.4 10.1 2.9 >3 0.63 0.22

Maximum 118 38.3 24.1 >6.4 3.50 0.53

N 12 12 12 12 12 12

Total

Arsenic Total


Dissolved Copper

Dissolved Nickel

Dissolved Lead

Dissolved Mercury


Mean 2.6 0.7

Median 2.6 <0.5 <5 <0.2 <1 0.7 <0.2 <0.1

90th percentile 2.9 <0.5 <5 <0.2 <1 0.8 0.3 <0.1

Minimum 1.8 <0.5 <5 <0.2 <1 0.5 <0.2 <0.1

Maximum 3.2 <0.5 15 <0.2 1 0.8 0.3 0.1

N 12 12 12 12 12 12 12 12


112

Table A6.5 Long Reef summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 101 37.1 16.8 1.35 0.33

Median 98 37.2 16.2 1.09 2.5 0.32

90th percentile 107 37.5 22.3 1.46 4.0 0.41 0.45

Minimum 92 >90 36.6 9.8 2.7 >3 0.60 0.24

Maximum 121 37.7 24.4 >5.9 4.92 0.43

N 12 12 12 12 12 12

Total

Arsenic Total


Dissolved Copper

Dissolved Nickel

Dissolved Lead

Dissolved Mercury


Mean 2.4

Median 2.5 <0.5 <5 <0.2 <1 0.6 <0.2 <0.1

90th percentile 2.8 0.7 <5 <0.2 <1 0.8 <0.2 <0.1

Minimum 1.8 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.8 1.0 <5 <0.2 <1 0.9 0.2 0.1

N 12 12 12 12 12 12 12 12

113

Table A6.6 Central Bay summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 97 37.0 16.7 9.3 0.69 0.16

Median 97 37.1 17.2 9.3 0.67 1.0 0.17

90th percentile 99 >90 37.3 21.3 11.6 1.15 2.0 0.24 0.35

Minimum 93 >90 36.5 10.8 5.8 >4 0.25 0.09

Maximum 102 37.3 22.9 13.0 1.26 0.24

N 12 12 12 12 12 12

Total

Arsenic Total

Chromium Total Zinc Total

Cadmium Dissolved

Copper Dissolved

Nickel Dissolved

Lead Dissolved Mercury


Mean 2.3

Median 2.3 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 2.7 <0.5 <5 <0.2 <1 0.5 <0.2 <0.1

Minimum 1.8 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.7 <0.5 <5 <0.2 <1 0.6 <0.2 0.1

N 12 12 12 12 12 11 12 12


114

Table A6.7 POM DMG summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 98 37.0 16.7 8.2 0.76 0.18

Median 97 37.0 16.8 7.8 0.72 1.0 0.18

90th percentile 101 >90 37.3 21.5 12.1 1.27 2.0 0.22 0.35

Minimum 93 >90 36.5 10.6 5.6 >4 0.26 0.09

Maximum 107 37.4 22.8 12.6 1.29 0.29

N 12 12 12 12 12 11

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 2.3

Median 2.3 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 2.7 <0.5 <5 <0.2 <1 0.6 <0.2 <0.1

Minimum 1.7 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.7 1.0 <5 <0.2 <1 0.6 <0.2 0.1

N 12 12 12 12 12 12 12 12

115

Table A6.8 Patterson River summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 98 36.2 16.5 1.36 0.28

Median 97 36.6 15.6 0.74 1.5 0.25

90th percentile 103 37.0 22.4 2.84 2.5 0.36 0.45

Minimum 92 >90 33.0 10.7 2.9 >3 0.49 0.17

Maximum 111 37.1 22.9 6.8 4.94 0.52

N 12 12 12 12 12 12

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 2.3

Median 2.3 <0.5 <5 <0.2 <1 0.5 <0.2 <0.1

90th percentile 2.6 <0.5 <5 <0.2 <1 0.6 0.2 <0.1

Minimum 1.8 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.9 0.9 <5 <0.2 <1 0.7 0.3 0.1

N 12 12 12 12 12 12 12 12


116

Table A6.9 Dromana summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 97 36.5 16.1 0.63 0.23

Median 97 36.5 15.2 0.54 1.5 0.23

90th percentile 100 36.7 21.2 0.94 2.5 0.30 0.45

Minimum 93 >90 36.1 11.1 >5.0 >3 0.35 0.15

Maximum 101 36.9 22.0 >6.8 1.16 0.35

N 12 12 12 12 12 10*

*insufficient number of data points to compare against SEPP objective

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 2.1

Median 2.1 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 2.2 0.6 <5 <0.2 <1 0.5 <0.2 <0.1

Minimum 1.7 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.4 0.7 <5 <0.2 2 0.5 0.6 0.1

N 12 12 12 12 12 12 12 12

117

Table A6.10 Middle Ground Shelf summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 97 36.6 16.4 8.3 0.75 0.18

Median 97 36.6 16.8 8.0 0.78 1.0 0.17

90th percentile 99 >90 36.9 21.0 10.3 1.09 2.0 0.22 0.35

Minimum 94 >90 36.3 11.1 5.9 >4 0.26 0.11

Maximum 100 37.0 21.4 10.5 1.19 0.25

N 12 12 12 12 12 11

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 2.2

Median 2.2 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 2.5 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Minimum 1.7 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.6 0.7 <5 <0.2 <1 0.6 <0.2 0.1

N 12 12 12 12 12 12 12 12


118

Table A6.11 Sorrento Bank summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 97 36.3 16.0 0.68 0.32

Median 97 36.3 16.2 0.62 1.0 0.30

90th percentile 101 >90 36.4 19.4 1.07 2.0 0.38 0.35

Minimum 95 >90 35.7 11.6 >2.9 >4 0.34 0.25

Maximum 101 36.6 21.0 >3.7 1.17 0.45

N 12 12 12 12 12 11

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 2.0

Median 2.0 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 2.3 0.8 <5 <0.2 <1 <0.5 <0.2 <0.1

Minimum 1.7 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.3 1.0 <5 <0.2 <1 <0.5 0.4 0.1

N 12 12 12 12 12 12 12 12

119

Table A6.12 Popes Eye summary statistics

Dissolved Oxygen


Secchi Depth

Secchi Depth

Chlorophyll-a


%sat

SEPP objective



SEPP objective


m-1

SEPP objective

attenuation m

-1

Mean 97 36.0 16.4 0.60 0.13

Median 96 35.8 16.8 0.52 1.0 0.14

90th percentile 99 >90 36.4 19.6 0.83 2.0 0.18 0.35

Minimum 93 >90 35.6 12.7 7.2 >4 0.24 0.04

Maximum 102 37.0 20.3 >12.2 0.93 0.24

N 12 12 12 9 12 11

Total

Arsenic Total


Cadmium Dissolved

Copper Dissolved

Nickel Dissolved



Mean 1.8

Median 1.8 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

90th percentile 1.9 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Minimum 1.5 <0.5 <5 <0.2 <1 <0.5 <0.2 <0.1

Maximum 2.5 0.5 <5 <0.2 <1 0.6 0.2 0.1

N 12 12 12 12 12 12 12 12

baywide water quality monitoring program milestone...

Documents