detecting antimony and arsenic concentrations in the … · detecting antimony and arsenic...

Detecting antimony and arsenic

concentrations in the water column

of Wild Cattle Creek

Final Report

June 2015

Darren Ryder and Sarah Mika

Attachment 9.8 A

ii

Detecting antimony and arsenic concentrations in

the water column of Wild Cattle Creek

Final Report

June 2015

A/Prof. Darren Ryder and Dr Sarah Mika

School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351

This report should be cited as:

Ryder, D. and Mika, S. (2015). Detecting antimony and arsenic concentrations in the water column of

Wild Cattle Creek. Final Report. University of New England, Armidale.

Project contact:

Associate Professor Darren Ryder

School of Environmental and Rural Science

University of New England, Armidale, NSW, 2351

Email: [email protected]

Cover Photo: Wild Cattle Creek (S. Mika, 2013).

iii

Acknowledgements

Clarence Valley Council and Coffs Harbour City Council provided support and financial contributions

to this project.

Seven private landholders supported this project by allowing Bellingen Shire Council to access

waterways through their properties for sampling. Bellingen Shire Council appreciates their

cooperation and local knowledge.

Daan Schiebaan (Manager Sustainable Environment and Waste) and Jane Eales (River and

Biodiversity Projects Officer for Bellingen Shire Council), carried out the field sampling and organized

the transport of water samples to the NATA accredited Environmental Analysis Laboratory at

Southern Cross University, Lismore. Like all event-based sampling programs, it is difficult to manage

resources around unpredictable events and Daan and Jane achieved this.

iv

Table of Contents

Acknowledgements .............................................................................................................. iii

Table of Contents ................................................................................................................. iv

Summary ............................................................................................................................... v

1.0 Introduction ................................................................................................................ 1

1.1 Background ................................................................................................................... 1

1.2 Scope ............................................................................................................................. 1

1.3 Objectives ...................................................................................................................... 1

2.0 Study design and methods .......................................................................................... 2

2.1 Study design .................................................................................................................. 2

2.2 Sampling schedule ......................................................................................................... 7

2.3 Monitoring of contaminants .......................................................................................... 8

2.4 Field methods ................................................................................................................ 9

2.5 Laboratory methods ...................................................................................................... 9

3.0 Results ....................................................................................................................... 10

3.1 Antimony (Sb) .............................................................................................................. 10

3.2 Arsenic (As).................................................................................................................. 11

3.3 Contaminant relationships with discharge ................................................................... 12

3.4 Other heavy metals ..................................................................................................... 12

3.5 Reach-scale export of contaminants ............................................................................ 14

4.0 Summary of main findings, management issues and recommendations .................. 16

4.1 Main findings ............................................................................................................... 16

4.2 Recommendations ....................................................................................................... 17

References .......................................................................................................................... 19

UNE Draft Wild Cattle Creek Anitimony and Arsenic Report 2015

v

Summary

Bellingen Shire Council resolved to undertake independent water quality testing in response to the

proposed Anchor Resources’ antimony mine on Wild Cattle Creek in the Bellingen Shire. The aim of

the monitoring program was to collect baseline information on the concentrations of Antimony (Sb)

and Arsenic (As) originating from the site of the proposed mining operations adjacent to Wild Cattle

Creek.

It is unknown whether contaminants are transported short distances resulting in localized impacts,

or large distances and exported from the Wild Cattle Creek catchment to the broader Clarence

catchment. Therefore, five (5) sample locations were established including sites upstream and

downstream of the impact site on Wild Cattle Creek, one site on White’s Creek within the area

impacted by past mining, and an upstream-downstream pair on the Bielsdown River to mimic the

upstream-downstream pair of sites on Wild Cattle Creek. Net gains/losses between these two points

act as a control and can be compared to the paired ‘impact’ sites on Wild Cattle Creek.

Samples for Arsenic and Antimony were collected from surface water samples at Sites 1 to 4 on six

(6) occasions and Site 5 on four (4) occasions between 2 May 2014 and 13 February 2015. Sample

collection was targeted at different discharge levels to identify if mobilization and transport of

contaminants were linked to rainfall and discharge events. The range of discharge captured during

the study ranged from 16th to 84th percentile flows.

Results

Background concentrations of Sb and As are below the Australian guideline values for

healthy aquatic ecosystems of 9 μg/L and 24 μg/L respectively in the Bielsdown River and in

Wild Cattle Creek upstream of historic and proposed mine inputs.

Export of Sb from White’s Creek was observed on all four sampling occasions. Each

exceedance was more than two orders of magnitude above the guideline value of 9 μg/L

with a mean water column concentration of 400 μg/L. This indicates contamination that may

originate from historic mining.

Export of As from White’s Creek was observed on all four of the sampling occasions. Each

exceedance was more than double the guideline value of 24 μg/L with a mean water column

concentration of 113.8 μg/L. This indicates contamination that may originate from historic

mining.

Export of Sb (≥ guideline value of 9 μg/L) or As (≥ guideline value of 24 μg/L) from Wild Cattle

Creek to the Nymboida River was not observed during the study. This indicates that

contaminants remain within Wild Cattle Creek between its confluence with White’s Creek

and the downstream site on Wild Cattle Creek (Site 4). These contaminants may be

associated with sediment deposits. The potential for these sediments and their associated

contaminants to move downstream into the Nymboida River is unknown.

There was no clear correlation between contaminants and discharge at Site 5 (White’s

Creek) despite the sampling program capturing a range of discharges.

UNE Draft Wild Cattle Creek Anitimony and Arsenic Report 2015

vi

Recommendations

Improve the spatial (additional sites) and temporal (time period, range of discharge, and

replication of percentile flows) design of the monitoring program. This will improve the

understanding of White’s Creek as a point source contributor of contaminants, and improve

understanding of the relationships between concentrations of contaminants in the water

column and discharge.

Include water column (soluble) and suspended and benthic (insoluble) sediments as sources

of contamination.

Include in situ measurements of water column pH, conductivity, dissolved oxygen and

temperature to assist in determining the processes driving peak contaminant mobilization

and transport.

Install a hydrometric gauge in Wild Cattle Creek, with a priority at the downstream reach to

enable quantification of exported contaminant loads to the Nymboida River.

UNE Final Wild Cattle Creek Antimony and Arsenic Report 2015

1

1.0 Introduction

1.1 Background

Bellingen Shire Council (BSC) resolved on 28 November 2012 to undertake independent water

quality testing in response to the proposed Anchor Resource’s antimony mine (the Bielsdown

Project) on Wild Cattle Creek located 12 km north of Dorrigo, west of the mid north coast New South

Wales. Anchor Resources’ exploration license (EL 6388) includes the historic small-scale antimony

mine on Wild Cattle Creek which was discovered in the late 1800s and mined until the 1970s. The

Bielsdown Project is in the Bellingen Shire but Wild Cattle Creek is a tributary of the Nymboida River

that flows via the Mann River into the Clarence River. As such, any contaminant issue affects three

Local Government Areas (LGAs): Bellingen Shire Council (BSC), Coffs Harbour City Council and the

Clarence Valley Council.

BSC has initiated a monitoring program with the purpose of collecting baseline information on the

concentrations of Antimony (Sb) and Arsenic (As) originating from the site of the Anchor Resources

proposed mining operations adjacent to Wild Cattle Creek. This includes the historic mine inputs.

This program has been supported by Coffs Harbour City Council and the Clarence Valley Council.BSC

has engaged the University of New England (UNE) to design the monitoring program, train BSC staff

in field sample collection procedures, and interpret and report on the data analysed by a NATA

accredited laboratory (Environmental Analysis Laboratory, Southern Cross University, Lismore).

1.2 Scope

This report describes the monitoring program undertaken by BSC as designed and trained by UNE

(Section 2.0). The data as supplied to UNE by the NATA accredited lab (via BSC) are reported in

Section 3.0 and appropriate interpretations are provided along with the relevant data. The main

findings of this monitoring program as well as recommendations for future monitoring are presented

in Section 4.0.

1.3 Objectives

1. Provide information regarding background concentrations of Sb and As in Wild Cattle

Creek including inputs from the historic mine site.

2. Clearly describe the monitoring program undertaken and recommend improvements in

the spatiotemporal resolution for future monitoring.


2

2.0 Study design and methods

2.1 Study design

The aim of the monitoring program was to collect baseline information on the concentrations of Sb

and As originating from the site of the proposed mining operations adjacent to Wild Cattle Creek

(Figure 2.1). It is unknown whether these contaminants are transported very short distances

resulting in localized impacts, or large distances and exported from the Wild Cattle Creek catchment

to the Nymboida River and broader Clarence catchment. Thus, the monitoring program was

designed to test both of these spacial scales (Figure 2.2 and Tables 2.1 and 2.2). Sites were located

with the following purpose:

Site 1 is the upstream sampling location on Bielsdown River.

Site 2 is the downstream sampling location on Bielsdown River. Together, Site 1 and

Site 2 act as control sites for naturally occurring longitudinal (upstream-downstream)

changes. This upstream-downstream pair mimics the upstream-downstream pair of

sites on Wild Cattle Creek (Sites 3 and 4), being the same distance apart, comprising

similar geomorphology and land use, and effected by the same climatic conditions. Net

gains/losses between these two points can be compared to the paired ‘impact’ sites on

Wild Cattle Creek.

Site 3 is on Wild Cattle Creek located upstream of lease EL 6388 (that is, upstream of

the confluence of White’s Creek and Wild Cattle Creek).

Site 4 is on Wild Cattle Creek located downstream of the confluence of White’s Creek

and Wild Cattle Creek. The difference in concentrations between Site 3 and Site 4 is the

net gains/losses from all land uses (natural and human) between these two points. The

concentration at Site 4 defines the concentration of contaminants exported from Wild

Cattle Creek into the Nymboida River.

Site 5 is located at the end of White’s Creek and quantifies local-scale runoff to Wild

Cattle Creek. BSC’s River and Biodiversity Projects Officer received consistent feedback

from land holders and other members of the community that it was important to

include this location. Site 5 was then included in the following four sampling occasions

after Council sought advice from UNE.

From the design of the monitoring program, a contaminant impact from the proposed mine is

detected if:

The net gain in contaminants between the upstream site (Site 3) and downstream site

(Site 4) on Wild Cattle Creek are higher than that found between the upstream site

(Site 1) and downstream site (Site 2) on the Bielsdown River.

The concentrations (and net export) of contaminants are higher at the downstream

site on Wild Cattle Creek (Site 4) than the downstream site on the Bielsdown River

(Site 2).

Concentrations of contaminants discharged from White’s Creek (Site 5) are higher

than those recorded for Wild Cattle Creek upstream of the confluence with White’s

Creek (Site 3).

Figure 2.1 The location and extent covered by Anchor Resources’ exploration license EL 6388 (supplied by BSC).


4

Figure 2.2 The location of monitoring sites. Site 5 is on White’s Creek.


5

TABLE 2.1 Site locations for water column sampling in Wild Cattle and White’s Creeks and the

Bielsdown River.

Site

Number Location and Purpose Easting (m E) Southing (m S)

1

Upstream control site on Bielsdown River: detect

background concentrations of Sb and As input in

nearby river system to demonstrate natural

longitudinal change in the absence of a mine.

470496 6652401

2

Downstream control site on Bielsdown River: detect

background concentrations of Sb and As export in

nearby river system to demonstrate natural

longitudinal change in the absence of a mine.

472204 6655280

3

Upstream control site on Wild Cattle Creek: detect

background concentrations of Sb and As input above

EL 6388 mine lease.

474597 6655746

4

Downstream impact site on Wild Cattle Creek: detect

concentrations of Sb and As exported to the

Nymboida River from EL 6388 mine lease and

upstream.

472727 6656912

5

End-of-system impact site on White’s Creek: detect

export from White’s Creek subcatchment including

historic mine area in Wild Cattle Creek catchment.

473496 6656647


6

TABLE 2.2 Photos of the sampled sites.

Site 1: the upstream control site on the Bielsdown River.

Site 2: the downstream control site on the Bielsdown River.

Site 3: the upstream control site on Wild Cattle Creek

Site 4: the downstream impact site on Wild Cattle Creek.

Site 5: impact site on White’s Creek.


7

2.2 Sampling schedule

The monitoring program was designed to encompass a range of discharge magnitudes to determine

the contribution of background concentrations of contaminants in the catchment in comparison to

the local mobilization and transport of contaminants from the historic and proposed mine site. As

such, the monitoring program was designed to sample a range of discharges and percentile flows,

and opportunistically sample runoff events to capture the higher discharges. Sampling was therefore

intended to include multiple seasons within a 12-month period (Table 2.3).

Because Wild Cattle Creek and White’s Creek are ungauged, the monitoring program based its

discharge triggers on the Bielsdown River gauge at Charlestead (number 204071; 472165.1 mE,

6655248.1 mS (Zone 56J)) as representative of discharge percentiles in the study river. This gauge

has a catchment area of 131 km2. Rainfall and discharge are shown in Figure 2.3. The first three

months of the study period were characterized by low rainfall and decreasing discharge while the

last six months of the study period were characterized by regular small rainfall and runoff events

(Figure 2.3).

TABLE 2.3 Sampling regime for field collection of water column contaminants in Wild Cattle and

White’s Creeks and the Bielsdown River.

Sampling Event Date Discharge (ML/day) Percentile Flow

1 02/05/2014 113.9 78th

2 01/09/2014 329.8 24th

3 02/10/2014 91.2 84th

4 18/12/2014 91.2 84th

5 16/01/2015 175.2 50th

6 13/02/2015 456.3 16th


8

Figure 2.3 Daily rainfall (mm/day) at Dorrigo (BOM gauge number 59144) and discharge (ML/day) of

the Bielsdown River for the study period May 2014 to February 2015 (Office of Water stream gauge

at Charlestead (gauge number 204071)).

2.3 Monitoring of contaminants

Soluble forms of antimony (Sb) as trivalent or pentavalent form, and arsenic (As) are often found

together from geological parent material and are mobilized in water. They can also occur as less

soluble species adsorbed onto clay or soil particles and sediments, and can be transported with flow

as part of the suspended sediment load in rivers.

Concentrations of Sb in surface water in natural systems range from 0.1 to 0.2 μg/L, although they

are rarely measured as part of routine water quality testing. Testing for these via a NATA accredited

laboratory will provide analyses with detection limits of 1 μg/L. The low reliability trigger value for

maintaining healthy aquatic ecosystems is 9 μg/L (ANZECC 2000b, Table 2.4). This value was derived

from ecotoxicological data on five taxonomic groups and should only be used as an indicative interim

working value (ANZECC 2000b). The trigger value for Sb in drinking water is 3 μg/L (NHMRC, NRMMC

2011, Table 2.4). For As, the high reliability trigger value to maintain healthy aquatic ecosystems is

24 μg/L and the trigger value for drinking water is 10 μg/L (Table 2.4). Given that Wild Cattle Creek

flows into the Nymboida River upstream of the town water supplies, it is worth noting drinking

water guidelines as well as the guidelines for maintaining healthy aquatic ecosystems.

0

20

40

60

80

100

120

140

0

500

1000

1500

2000

2500

3000

3500

Apr-14 Jun-14 Jul-14 Sep-14 Nov-14 Dec-14 Feb-15

Dis

char

ge (M

L/d

ay)

Discharge

Sampling occasion

Rainfall (mm/day)


9

TABLE 2.4 Trigger values of antimony, arsenic and other metals for drinking water and to maintain

healthy aquatic ecosystems.

Contaminant Australian Drinking Water

Guideline (NHMRC, NRMMC 2011)

Healthy Aquatic Ecosystems

(ANZECC 2000a,b)

Antimony (Sb) Health consideration value

3 μg/L

Low reliability trigger value

9 μg/L

Arsenic (As) Health consideration value

10 μg/L

High reliability trigger value

24 μg/L

Aluminium (Al) Aesthetic consideration value

200 μg/L Health consideration under review

Moderate reliability trigger value

55 μg/L at pH > 6.5

Low reliability trigger value 0.8 μg/L at pH < 6.5

Iron (Fe) Aesthetic consideration value

300 μg/L

Canadian guideline trigger value

300 μg/L

Manganese

(mn)

Aesthetic consideration value

100 μg/L

Moderate reliability trigger value

1700 μg/L

Zinc (Zn) Aesthetic consideration value

3000 μg/L

High reliability trigger value

8 μg/L

2.4 Field methods

Samples were collected at near surface (0.2 to 0.3 m depth) using a hand-held sampling pole to

ensure that samples were collected at least 1.5 m from the river bank edge. Duplicate 1-L PET

bottles were thrice rinsed in sample (river water) and filled. These were immediately placed in an

esky and transported back to Council. They were stored in the dark below 4 °C until transport to the

NATA accredited laboratory (Environmental Analysis Laboratory, Southern Cross University,

Lismore).

2.5 Laboratory methods

Samples were filtered in the laboratory (0.45 μg GF/C glass fibre filter paper. Samples were then

stabilized with nitric acid (HNO3) for the analysis of cations. Soluble basic cations (manganese Mn2+)

and acidic cations (aluminium Al3+ and Iron Fe2+) were analsyed by inductively coupled plasma

optical emission spectroscopy (ICP-OES) and metals including antimony (Sb) and arsenic (As) were

analysed by inductively coupled plasma mass spectrometry (ICP-MS) as per APHA (2012) “Standard

Methods for the Examination of Water and Wastewater”.


10

3.0 Results

3.1 Antimony (Sb)

The low reliability trigger value for antimony (Sb) to maintain healthy aquatic ecosystems is 9 μg/L

(Table 2.4). The detection limit of the NATA accredited laboratory is 1 μg/L. Concentrations of Sb in

the water column were below the detection limit (<1 μg/L) on all sampling occasions in the

Bielsdown River (Sites 1 and 2), and the upstream site on Wild Cattle Creek (Site 3). Sb was detected

at a concentration of 1 μg/L at the downstream site on Wild Cattle Creek (Site 4) on one sampling

occasion during low flows (02 October 2014).

In contrast, concentrations of Sb in the water column of White’s Creek (Site 5) exceeded the

guideline threshold on all four sampling occasions (Figure 3.1). Each exceedance was greater than

two orders of magnitude of the guideline threshold (mean exceedance of 400 μg/L). The highest

water column concentration of 543.5 μg/L was observed one month after the highest rainfall and

runoff event in August 2014 (Figure 2.2). This runoff event was preceded by a 3-month period of low

rainfall and discharge (Figure 2.3). Site 5 was not sampled in August 2014 when the largest rainfall

and runoff event occurred. However, there was very little rainfall and falling discharge between the

second and third sampling events (Figure 2.3), suggesting that the peak concentration of Sb

recorded for the fourth sampling event was residual from the August 2014 runoff event.

Figure 3.1 Mean concentrations of antimony (Sb, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Concentrations at Sites 1 to 4 were at or below 1 μg/L on all sampling occasions. Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the low reliability trigger value for maintaining healthy aquatic ecosystems.

0

10

20

30

40

50

60

70

80

90

100

0

50

100

150

200

250

300

350

400

450

500

550

600

Per

cen

tile

flo

w

Co

nce

ntr

atio

ns

of

An

tim

on

y (μ

g/L)

Site 1

Site 2

Site 3

Site 4

Site 5


11

3.2 Arsenic (As)

The high reliability trigger value for arsenic (As) to maintain healthy aquatic ecosystems is 24 μg/L

(Table 2.4). The detection limit of the NATA accredited laboratory is 1 μg/L. Concentrations of As in

the water column were below the detection limit (<1 μg/L) on all sampling occasions in the

Bielsdown River (Sites 1 and 2). The background water column concentration in Wild Cattle Creek

(Site 3) only exceeded the detection limit on one sampling occasion with a concentration of 1 μg/L in

December 2014. At the downstream site on Wild Cattle Creek (Site 4), water column concentrations

of 1 μg/L were consistently observed (Figure 3.2).

In contrast, concentrations of As in the water column of White’s Creek (Site 5) exceeded the

guideline threshold on all four sampling occasions (Figure 3.2). Each exceedance was almost five

times the guideline value (mean exceedance of 113.8 μg/L). The pattern of exceedances differed

slightly from that of Sb. The highest concentration of As in the water column of White’s Creek was

observed in January 2015, after a series of several small rainfall and runoff events (Figure 2.3).

Figure 3.2 Mean concentrations of arsenic (As, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Concentrations at Sites 1 to 4 were at or below 1 μg/L on all sampling occasions. Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the high reliability trigger value for maintaining healthy aquatic ecosystems.

0

10

20

30

40

50

60

70

80

90

100

0

50

100

150

200

250

300

350

400

450

500

550

600

Per

cen

tile

flo

w

Co

nce

ntr

atio

ns

of

Ars

enic

(μ

g/L)

Site 1

Site 2

Site 3

Site 4

Site 5


12

3.3 Contaminant relationships with discharge

Although the event-based monitoring regime sampled flows ranging from the 16th to 84th percentile

flows, four sampling events were not sufficient to determine correlations between antimony or

arsenic concentrations in the water column of White’s Creek (Site 5) and discharge (Figure 3.3).

Figure 3.3 Mean concentrations of antimony and arsenic in the water column of White’s Creek (Site 5) in relation to percentile flow as estimated from the Bielsdown River gauge (Office of Water gauge 204071 used as a surrogate for Wild Cattle Creek).

3.4 Other heavy metals

The range and means of concentrations of other heavy metals analysed by the NATA accredited

laboratory as part of its analytical package are given in Table 3.1. Selenium (never observed above

the detection limit of 2 μg/L), mercury (never observed above the detection limit of 0.5 μg/L), zinc

and manganese did not exceed guideline values at any site on any sampling occasion. Water column

concentrations of iron exceeded aesthetic guideline values at both sites on the Bielsdown River

(Sites 1 and 2), and both sites on Wild Cattle Creek (Sites 3 and 4).

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80 90 100

Co

nce

ntr

ati

on

(μg/

L)

Percentile flow

Antimony Concentration

Antimony Threshold

Arsenic Concentration

Arsenic Threshold


13

TABLE 3.1 Range and means of concentrations (μg/L) of heavy metals in the water columns of Wild

Cattle and White’s Creeks and the Bielsdown River.

Metal Site 1 Site 2 Site 3 Site 4 Site 5

Aluminium 50-226

(121)

41-251

(115)

85-412

(209)

71-343

(186)

18-38

(26)

Iron 269-703

(525)

232-572

(452)

168-490

(305)

166-436

(279)

55-225

(142)

Manganese 6-23

(11)

5-14

(8)

3-13

(7)

3-14

(8)

32-345

(131)

Zinc 0-3

(1)

0-5

(1)

0-6

(2)

0-5

(2)

2-9

(4)

Without simultaneous measurement of water column pH, relationships between acidic or alkaline

conditions and aluminium mobilisation cannot be determined. In the 2012-2013 Ecohealth program

(Ryder et al. 2014), water column pH ranged from 7.35 to 9.33 in the Bielsdown River (mean = 8.12)

and 7.58 to 9.24 in Wild Cattle Creek (mean = 8.30). This suggests that the moderate reliability

trigger value for these systems is likely to be 55 μg/L for pH > 6.5, with a deleterious trigger of

100 μg/L (Table 2.4).

Aluminium (Al) concentrations in the water column exceeded deleterious levels of 100 μg/L on two

sampling occasions in both sites on the Bielsdown River (May 2014 and September 2014, Figure 3.4).

Concentrations of Al in Wild Cattle Creek exceeded 100 μg/L at both sites on four sampling occasions

(May, September and December 2014, and February 2015), with higher concentrations commonly

observed at the upstream site (Site 3) than downstream site (Site 4, Figure 3.4). Al concentrations

never exceeded the moderate reliablility trigger value of 55 μg/L for pH > 6.5 in White’s Creek

(Figure 3.4).


14

Figure 3.4 Mean concentrations of aluminium (Al, μg/L) in the water columns of the Bielsdown River (Sites 1 and 2), Wild Cattle Creek (Sites 3 and 4) and White’s Creek (Site 5). Percentile flow (blue line) is estimated from the Bielsdown River (Office of Water gauge 204071). The red line is the moderate reliability trigger value of 55 μg/L for pH > 6.5 for maintaining healthy aquatic ecosystems.

3.5 Reach-scale export of contaminants

The monitoring program was designed to test the impact of the historic and proposed mine site on

contaminants in the water column through the following analyses:

Site 2 – Site 1: the background longitudinal patterns (upstream-downstream) of

contaminants in the water column of the Bielsdown River (control).

Site 4 – Site 3: the background longitudinal patterns (upstream-downstream) of Wild

Cattle Creek (impact).

Site 4 – Site 2: determines whether there are higher concentrations of contaminants

being exported from Wild Cattle Creek than the Bielsdown River.

Site 5 – Site 3: determines whether the concentrations of contaminants discharging

from White’s Creek (impact) are higher than background concentrations in Wild Cattle

Creek upstream of the confluence (control).

0

10

20

30

40

50

60

70

80

90

100

0

50

100

150

200

250

300

350

400

450

500

550

600

Pe

rce

nti

le f

low

Co

nce

ntr

atio

ns

of

Alu

min

imu

m (

μg/

L)

Site 1

Site 2

Site 3

Site 4

Site 5


15

Because aluminium was the only contaminant consistently found outside of White’s Creek (Site 5),

the reach-scale analyses can only be performed for aluminium. There was a consistent longitudinal

loss in aluminium concentrations between the upstream and downstream control sites in the

Bielsdown River, with the only net gain in aluminium occurring in May 2014 (Site 2 – Site 1, Figure

3.5). Similarly, there was a consistent longitudinal loss in aluminium concentrations between the

upstream and downstream sites on Wild Cattle Creek, with the only net gain in aluminium occurring

in February 2015 (Site 4 – Site 3, Figure 3.5).

Wild Cattle Creek exported higher concentrations of aluminium than the Bielsdown River control on

all sampling occasions, with the largest difference coinciding with the largest runoff event (Site 4 –

Site 2, Figure 3.5). This may be partially explained by the four occasions that White’s Creek (Site 5)

was sampled, where White’s Creek had higher aluminium concentrations than the background

concentrations at the upstream site on Wild Cattle Creek (Site 5 – Site 3, Figure 3.5). However,

higher concentrations of aluminium were consistently observed in the water column of upstream

Wild Cattle Creek than upstream Bielsdown River (Site 3 – Site 1, Figure 3.5).

Figure 3.5 Net gains (positive values) or losses (negative values) of water column concentrations of

aluminium (Al, µg/L).

-200

-150

-100

-50

0

50

100

150

200

250

300

Ne

t ga

in (p

osi

tive

) or

loss

(ne

gati

ve) Site 2 - Site 1

Site 4 - Site 3Site 3 - Site 1Site 4 - Site 2Site 5 - Site 3


16

4.0 Summary of main findings, management issues and

recommendations

4.1 Main findings

Antimony

Background concentrations of Sb are below the low reliability trigger value of 9 μg/L in the

Bielsdown River and in Wild Cattle Creek upstream of historic and proposed mine inputs.

Export of Sb from White’s Creek was observed on all four sampling occasions (October and

December 2014, and January and February 2015). Each exceedance was more than two

orders of magnitude above the low reliability trigger value of 9 μg/L with a mean water

column concentration of 400 μg/L. This indicates contamination that may originate from

historic mining.

Export of Sb from Wild Cattle Creek to the Nymboida River was observed once during the

study (02 October 2014), but was below the trigger values for maintaining healthy

ecosystems and Australian drinking water standards (at 1 μg/L). This is despite significant

inputs from White’s Creek.

Arsenic

Background concentrations of As are below the high reliability trigger value of 24 μg/L in the

Bielsdown River and Wild Cattle Creek (only once exceeding the detection limit of 1 μg/L at

the downstream site on Wild Cattle Creek).

Export of As from White’s Creek was observed on all four sampling occasions (similar to Sb).

Each exceedance was approximately five times the guideline value of 24 μg/L with a mean

water column concentration of 113.8 μg/L. This indicates contamination that may originate

from historic mining.

No export of As from Wild Cattle Creek to the Nymboida River was observed during the

study, despite significant inputs from White’s Creek.

Contaminant relationships with discharge

There was no clear correlation between contaminants and discharge at Site 5 (White’s

Creek) despite the sampling program capturing a range of discharges.

Aluminium

Background concentrations of Al in the Bielsdown River exceeded the moderate reliability

trigger value of 55 μg/L for pH > 6.5 and the deleterious level of 100 μg/L on two sampling

occasions (May and September 2014).

Background concentrations of Al in Wild Cattle Creek exceeded the deleterious level of

100 μg/L on four sampling occasions (May, September and December 2014, and February

2015), with higher concentrations consistently observed at the upstream site.

Water column concentrations of Al in White’s Creek never exceeded the moderate reliability

trigger value of 55 μg/L for pH > 6.5.


17

4.2 Recommendations

Spatial extent of monitoring

Two additional sites located on Wild Cattle Creek immediately upstream and downstream of

its confluence with White’s Creek should be added to the monitoring program. The purpose

of these sites is to provide an immediate control site upstream and an immediate impact site

downstream of historic and proposed mine inputs to improve analyses of White’s Creek as a

point source contaminant to Wild Cattle Creek.

If resources only permit one extra site to be included, it should be the site immediately

downstream of the confluence of White’s Creek and Wild Cattle Creek. Currently, Sb and As

are exported from White’s Creek to Wild Cattle Creek at concentrations exceeding guidelines

for maintaining healthy aquatic ecosystems. However, Wild Cattle Creek was not observed

to export Sb and As to the Nymboida River, suggesting these contaminants may be stored

within Wild Cattle Creek between its confluences with White’s Creek and the Nymboida

River.

If resources permit, additional sites should be located on Wild Cattle Creek between the

confluence with White’s Creek and the current Site 4 (Table 2.1). The purpose of these sites

would be to locate potential contaminant slugs accumulating in Wild Cattle Creek. This

improvement to the spatial resolution of sampling would benefit from the addition of

sediment sampling to see if contaminants are being adsorbed onto fine-grained sediments in

depositional areas (see Additional Variables below).

Temporal extent of monitoring

This study comprised six sampling events with White’s Creek (Site 5) sampled four times.

Although these six sampling occasions covered a large range of flows (16th to 84th percentile

flows), it is clear that the temporal intensity of sampling needs to be increased to assess

relationships between contaminants and discharge. Additional sampling events should be

included as the flow events occur.

Sampling events should target flows greater than 200 ML/day to increase the rigor of

relationships between contaminants and discharge.

Sampling events should also target low flows to examine potential mobilization of

contamiants into the water column during low oxygen conditions where stream sediments

become hypoxic or anoxic (see additional variables).

Additional variables

This study comprised water column samples only. To increase the rigor of assessments of

potential contamination, sediment samples should be taken simultaneously to water column

samples. These sediment samples should focus on fine-grained sediments (silts and clays) in

depositional areas where adsorbed contaminants potentially accumulate.

The addition of sediment samples (insoluble contaminants) with water column suspended

(insoluble contaminants) and (soluble contaminants) samples will enable investigation of the

relevance to contaminant mobilisation of the timing, frequency and duration of low flow and

high flow events, as well their magnitude.


18

Including in situ measurements of water column pH, conductivity, dissolved oxygen and

temperature, particularly pH and dissolved oxygen will assist in determining the processes

driving peak contaminant mobilization and transport. These variables are relatively

inexpensive to measure using a commercial water quality probe. Alternatively, BSC may

consider installing a datalogger at the end-of-system site at White’s Creek (Site 5) to

measure water level, pH, temperature and dissolved oxygen. This would provide greater

temporal resolution of the processes commonly driving contaminant mobilization and allow

BSC to time sampling events when they know exceedances are occurring.

The load of contaminants retained or transported through Wild Cattle Creek into the

Clarence catchment is important to quantify. This current study relies on a surrogate gauge

in the Bielsdown River for discharge. It is strongly recommended that a hydrometric gauge

be installed on Wild Cattle Creek, with a priority at the downstream reach to enable

exported loads to be quantified.


19

References

American Public Health Association (APHA). (2012). Standard Methods for the Examination of Water

and Wastewater. 22nd Edition, Eds: E.W. Rice, R.B. Baird, A.D. Easton and L.S. Clesceri. APHA,

Washington D.C.

Australian and New Zealand Environment and Conservation Council (ANZECC). (2000a). Volume 1.

Australian and New Zealand Guidelines for Fresh and Marine Water Quality: The Guidelines.

http://www.environment.gov.au/water/quality/publications/australian-and-new-zealand-

guidelines-fresh-marine-water-quality-volume-1.

Australian and New Zealand Environment and Conservation Council (ANZECC). (2000b). Volume 2.

Australian and New Zealand Guidelines for Fresh and Marine Water Quality: Aquatic Ecosystems –

Rationale and Background Information. http://www.environment.gov.au/water/quality/

publications/australian-and-new-zealand-guidelines-fresh-marine-water-quality-volume-2.

National Health and Medical Research Council (NHMRC) and Natural Resource Management

Ministerial Council (NRMMC). (2011). Australian Drinking Water Guidelines Paper 6 National Water

Quality Management Strategy. National Health and Medical Research Council, National Resource

Management Ministerial Council, Commonwealth of Australia, Canberra.

Ryder, D., Mika, S., Richardson M., Burns, A., Veal, R., Schmidt, J. and Osborne, M. (2014). Clarence

Catchment Ecohealth Project: Assessment of River and Estuarine Condition 2014. Final Technical

Report to the Clarency Valley Council. University of New England, Armidale.

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