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Health of the HunterHunter River estuary report card 2016

Hunter River estuary report card 2016 – Office of Environment & Heritageii

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ISBN 978 1 76039 642 8

OEH 2017/0189 July 2017

Hunter River estuary report card 2016 – Office of Environment & Heritage1

Top: Creek estuary, Hunter River (NCC)

Bottom: Mangrove seedling (LLS)

About this report cardThis report card provides a snapshot overview of the health of the Hunter River estuary in 2014–16, based on the findings of the Lower Hunter River Health Monitoring Program and a preliminary ecological assessment. The water quality and ecological data collected forms a baseline against which future developments in the catchment can be assessed.

Hunter River estuary – activities and pressuresEstuaries occur along the coast where freshwater flows from inland rivers and rainfall meet oceanic water. The Hunter River estuary is a riverine estuary and includes the tidal section of the Hunter River and its tributary rivers and creeks. The estuary extends 64 kilometres inland, to its tidal limits at Oakhampton on the Hunter River, Gostwyck on the Paterson River and Seaham Weir on the Williams River.

The catchment for the Hunter River and its estuary is one of the largest in coastal New South Wales, covering an area of 22,000 square kilometres. The catchment has been highly modified by human activity and includes many land uses (Figure 1). The upper catchment is predominantly agricultural land whereas the lower catchment includes the extensive urban area of Newcastle and industrial areas around the Port of Newcastle.

Each land use or ‘activity’ in the catchment exerts a ‘pressure’ on the estuary’s ecosystem. Most activities generate pollutants that are transported to the estuary in urban stormwater, rainfall runoff and groundwater (Figure 1). This type of pollution is known as diffuse pollution. Discharges of wastewater from industrial sites and wastewater treatment works are known as point source pollution. The main pollutants that generally affect estuary health are excess nutrients and sediments. Dissolved inorganic nutrients, such as ammonia, nitrate and phosphates, are of particular concern as they fuel rapid plant growth. This may lead to toxic algal blooms or nuisance algal growth. Industrial pollutants or toxicants, such as heavy metals, organochlorine and hydrocarbon compounds produced in heavily urbanised and industrialised catchments, also impact estuary health. High levels of dissolved inorganic nutrients, sediment or toxicants in estuary waters become ‘stressors’ on the ecosystem (Figure 1). Identification of stressors (Table 1) and their impact on ecological processes in the Hunter River estuary (Table 2) are the major components of this report card.

This report card is based on data collected for the Lower Hunter River Health Monitoring Program between 2014 and 2016. The Lower Hunter River Health Monitoring Program was funded in part by an environmental service order issued to Orica Australia Pty Ltd by the NSW Land and Environment Court in 2014.

Hunter River estuary report card 2016 – Office of Environment & Heritage2

Lower Hunter River Health Monitoring ProgramThe Office of Environment (OEH) was engaged to conduct the Lower Hunter River Health Monitoring Program to assess the current status of water quality in the Hunter River estuary. The program included:

• a literature and data review to assess the impact of industrial pollution (past and present) on the current condition of the Hunter river estuary1

• a water quality monitoring program to assess the condition of the lower, mid and upper estuary (August 2014 to March 2015)2

• a stormwater quality monitoring program to assess current sources of pollutants to the lower estuary (April to June 2015)3.

To complement the Lower Hunter River Health Monitoring Program, OEH conducted a preliminary ecological assessment in 2015–16 to determine whether ecological processes in the lower to mid estuary were impaired4.

The literature review and technical reports that comprise the Lower Hunter River Health Monitoring Program are available OEH Lower Hunter River Health Monitoring Program webpage1-4,7.

OEH has been collecting water quality data in NSW estuaries since 2006 as part of the NSW Natural Resources Monitoring, Evaluation and Reporting (MER) program5. These protocols provide a standardised approach to monitoring estuary ecosystem health (or condition), and for the analysis and reporting of results collected across the state. Turbidity and chlorophyll-a are used as condition indicators to assess estuary health. Turbidity is a measure of water clarity or the ‘muddiness’ which increases as more sediment enters the estuary. Chlorophyll-a is a plant pigment that is used as a proxy measure for the abundance of microscopic plants

Figure 1 Conceptual diagram of the Hunter River estuary showing activities in the catchment (‘pressures’) which lead to inputs of nutrients, sediment and toxicants to the estuary delivered in stormwater (‘stressors’).

Hunter River estuary report card 2016 – Office of Environment & Heritage3

called microalgae. Chlorophyll-a in estuary waters increases in response to increasing levels of nutrients. Turbidity and chlorophyll-a data collected from NSW estuaries by OEH for the MER program have been used to develop trigger values specific to NSW estuaries6. Compliance against a guideline or trigger value is commonly used to assess the status of a condition indicator. Exceeding the trigger value frequently, or by a large extent, should ‘trigger’ further investigation or management action. Using MER protocols, OEH calculated grades for estuary water quality based on the level of compliance of the condition indicators (turbidity, chlorophyll-a) to NSW trigger values. OEH used the turbidity and chlorophyll-a data collected during the water quality monitoring program in the Hunter River estuary in 2014–15 to calculate a grade for water quality in the lower, mid and upper Hunter River estuary.

Summary of findingsThere has been an improvement in water quality in the Hunter River estuary in the past decade. This is due to significant changes in portside land use, improved site management practices through pollution reduction programs, better monitoring and regulation of discharges and remediation of contaminated lands and sediments. Restoration of natural tidal flows and rehabilitation of estuarine habitats and riparian (riverside) vegetation in the catchment have improved the condition of the estuary significantly. For example, concentrations of nitrates and ammonia in the main channel of the Hunter River’s South Arm are 5 to 10 times lower than pre-2000 levels. However, water quality is the first component of aquatic ecosystems that improves in response to reduced pollution. Ecological processes which may have been impaired for decades will take longer to recover. Sediments that form the river bed play a vital role in aquatic ecosystems. Healthy sediments produce more oxygen than they consume and recycle ammonia and nitrates to nitrogen gas, thereby removing excess nutrients from estuary waters. Unhealthy sediments, on the other hand, consume more oxygen than they produce and are unable to recycle nutrients and instead become a source of nutrients to estuary waters. Sediments in the North Arm adjacent to the Hunter Wetlands National Park appear to be reasonably healthy. However, the heavily contaminated sediments of Throsby Creek and the South Arm are unhealthy and will remain a legacy of the industrial past4.

Diffuse pollution from agricultural, urban and industrial areas surrounding the estuary is substantial following rainfall in the catchment. Point source pollution from industrial sites, however, contributes large amounts of pollutants daily to the lower estuary in wastewater discharges. Point source pollution differs from diffuse pollution in that it is a constant source of pollutants to the estuary resulting from continuous discharges of wastewater. Point source pollution is also easier to manage and reduce than sources of diffuse pollution. Further gains in the condition of the Hunter River estuary in the short to medium term can best be achieved by reducing pollution from industrial sources. Education could lead to behaviour change among farmers and the community, resulting in a reduction in diffuse pollution from agricultural and urban areas. More research is required to identify diffuse sources of pollution to the lower Hunter River estuary, such as from contaminated groundwater draining from reclaimed land in-filled with industrial waste1.

Volunteer working on saltmarsh (LLS)

Hunter River estuary report card 2016 – Office of Environment & Heritage4

Legend

0 1 2 3 Km

±

WQ Sites

Stormwater Sites

Ecological Sites

Hunter Estuary

Catchment

Mangroves

Saltmarsh

Williams River

Hunt

er R

iver

Ironb

ark

Creek North Arm

Throsby Creek

South Arm

Tasman Sea

Fullerton Cove

Raymond Terrace

Heatherbrae

Tomago

Kooragang Island

MayfieldNewcastle

Newcastle CBD

Hexham

Figure 2 Locations of the sampling points for the water quality monitoring program (orange triangle), stormwater monitoring program (yellow square) and ecological assessment (blue circle). Not all sites used for ecological assessment are shown. Further details can be found in the technical reports2-4.

This report card provides a snapshot overview of the health of the Hunter River estuary in 2014–16, based on the findings of the Lower Hunter River Health Monitoring Program (Figure 2) and a preliminary ecological assessment. The water quality and ecological data collected forms a baseline against which future developments in the catchment can be assessed2-4. Future monitoring of water quality and ecological processes in the estuary is recommended to build a long-term dataset. This would allow stakeholders to detect changes in conditions that result from management and regulatory actions in the catchment.

Since the collection of this water quality data, some contamination of parts of the Hunter River by substances known as ‘PFAS’ has been identified by other agencies. This group of manufactured chemicals was used, until recently, in firefighting foams. The impacts of these substances on the Hunter River is still under investigation.

Hunter River estuary report card 2016 – Office of Environment & Heritage5

Stressors in the Hunter River estuary Table 1 Stressors and their current status and sources

Stressor Current status Sources

High levels of dissolved inorganic nutrients (ammonium, nitrates and phosphates) in estuary waters

Levels of nitrate and phosphate usually exceed NSW trigger values6 across the entire estuary with highest exceedances in the upper estuary after rainfall.

Levels of ammonia in the lower estuary usually exceed NSW trigger values but only exceed the trigger value in the mid to upper estuary after rainfall.

• Stormwater from agricultural, industrial and urban areas

• Industrial wastewater discharges

• Sewage treatment plant (STP) discharges

• Contaminated groundwater

• Sediments

High levels of dissolved metals (copper, zinc, manganese) and arsenic in lower estuary waters

High levels of dissolved copper occur in lower estuary waters after rainfall which can exceed the ANZECC Guidelines8 for 80% protection of marine species.

High levels of dissolved zinc, manganese and arsenic occur in some areas after rainfall which can exceed the ANZECC Guidelines for 80% protection of marine species.

• Stormwater from industrial and urban areas

• Industrial wastewater discharges

• Shipping (anti-fouling paints, production and dispatch of metal concentrates)

• Contaminated landfill

• Sediments

High levels of turbidity in estuary waters

Turbidity of surface waters often exceeds NSW trigger values, but not by far. The greatest exceedances of NSW trigger values occur in the upper estuary following rainfall.

• Land erosion in the upper catchment and bank erosion

• Stormwater runoff from agricultural, industrial and urban areas

• Industrial wastewater discharges

High levels of industrial pollutants in sediments

Sediments from Throsby Creek and mid South Arm – former industrial areas which are not dredged – are highly contaminated, exceeding interim sediment quality guidelines (ISQG) trigger values8 for zinc, nickel, copper, lead and total polyaromatic hydrocarbons (PAH).

Levels of zinc in Throsby Creek exceed the ISQG ‘high risk’ values8. Port areas are dredged regularly which has reduced the pollutant load in these sediments. North Arm sediments contain the lowest levels of metals and PAH in the estuary.

• Legacy contamination from industrial past

• Current sources as listed above for dissolved metals

• Contaminated landfill

Oxygen demand in sediments Sediments in Throsby Creek (Hannell St area) and mid South Arm have high respiration rates and consume more oxygen than they produce. Organic matter and pollutants have accumulated in these sediments which has changed the metabolism of microbes within. Sediments from the North Arm and lower South Arm (dredged) are healthier, producing more oxygen than they consume.

• Stormwater from agricultural, industrial and urban areas

• Industrial wastewater discharges

Hunter River estuary report card 2016 – Office of Environment & Heritage6

Ecological status of the Hunter River estuaryTable 2 Status of water quality, pollutant inputs and biological indicators in

the Hunter River estuary 2014–16

Assessment

Upp

er e

stua

ry

Mid

Est

uary

Thro

sby

Cre

ek

Sout

h A

rm

Low

er N

orth

arm

Comment on ecological status

Condition indicators2,6

Turbidity D C B B B

Chlorophyll B C C B B

NSW MER water quality grade

C C C B B‘B’ water quality grade for South Arm and North Arm does not take into account high levels of nutrients and dissolved metals in the water.

Estuary form and function4

Estuary morphology C B D D DEstuary morphology has been modified extensively. Reclaimed land and dredging for port operations has completely removed intertidal mudflats and sand shoals from the lower estuary, drastically reducing ecological function.

Pollutant inputs1-3

Nutrients (ammonia, nitrates, phosphates)

D D D D DNutrients can lead to excessive algal growth and poor sediment health, with potential for toxic algal blooms.

Metals (zinc, copper, manganese, arsenic)

D D CMetals have the potential for toxic effects on marine organisms, for example, reducing microalgal growth rates. Metals accumulate in sediments causing toxicity.

Biological indicator4,6

Microalgal growth (in water)

B C C B BMicroalgal growth in waters was lower than expected estuary-wide, given high nutrient levels. A combination of stressors, for example metals and low light from turbidity, may be reducing microalgal growth rates.

Microalgal growth (on riverbed)

D B CMicroalgal growth on riverbed sediments was in high abundance in Throsby Creek and North Arm, in response to high levels of nutrients. Increased organic matter in riverbed sediments when algae decompose leads to poor sediment quality.

Algal growth (on surfaces)

A A A

Algal growth on artificial surfaces was less than expected. Most algal growth occurred on well-lit artificial surfaces in Throsby Creek. A combination of stressors, for example metals and low light from turbidity, may be reducing macroalgal growth rates.

Sediment condition (oxygen demand)

D C BSediments in Throsby Creek, near Hannell St, and mid-South Arm are net consumers of oxygen and are likely to be a source of nutrients. Healthy sediments in shallow areas produce oxygen and recycle nutrients, releasing nitrogen gas.

Mangrove health D D C

Mangrove leaves appeared to be in poor condition. Low rates of herbivory and other insect activity. Leaves from South Arm and Kooragang Island were coated with fine black particles and branches were grey in colour. Leaves from all sites, except North Arm, bore large amounts of dead leaf tissue.

Fish diversity/abundance B A ALower numbers of fish species occurred in Throsby Creek and South Arm compared to North Arm. Seagrass is known to be an important habitat for some fish. However, there is no seagrass in the Hunter River estuary

Note: Grades were assigned by OEH and were based on comparison of data to known standards (e.g. ANZECC Guidelines), published data or research by OEH1-8.

A - very good, B - Good, C - Fair, D - Poor, E - Very poor4,6

Hunter River estuary report card 2016 – Office of Environment & Heritage7

Management actionsThe Hunter River estuary is an important habitat for shorebirds in New South Wales and provides refuge for over 250 bird species. A large proportion of the Hunter Wetlands National Park and the Hunter Wetlands Centre Australia (formerly Shortland Wetlands) has gained Ramsar-listing9 because it provides significant refuge habitat for 45 species of migratory birds.

A number of wetland rehabilitation projects have contributed to the improved condition of the Hunter River estuary. Shallow intertidal mudflats and saltmarsh, riparian areas and floodplain wetlands and forests act as buffers for main channels of the estuary by filtering sediments and nutrients from water flowing from the catchment.

Sealing of dirt roads, kerbing and guttering, and revegetating denuded banks in the catchment will reduce the amount of sediment entering the estuary. Minimising domestic use of chemicals, such as cleaning agents and fertilisers, and placing lawn cuttings and leaves in green waste bins will reduce the amount of nutrients entering the estuary.

Hexham Swamp Rehabilitation Project The staged opening of eight flood gates on Ironbark Creek from 2008 to 2013 has returned natural tidal flows to Hexham Swamp and restored estuarine habitat. Mangroves and saltmarsh communities are revitalised which has improved the quality of nursery habitat for fish and prawns, benefiting the local prawn and fish industry.

Kooragang Wetland Rehabilitation ProjectKooragang Wetland Rehabilitation Project commenced in 1993 as collaborative ecological restoration project to protect, restore and create fish, shorebird and other wildlife habitat across the estuary. Initial project areas were Ash Island, Tomago Wetlands and Stockton Sandspit. These restoration activities and similar work elsewhere in the estuary continue through the Hunter Estuary Program of Hunter Local Land Services. The NSW National Parks and Wildlife Service and volunteers maintain saltmarsh and shelly sand on Stockton Sandspit as roost habitat for shorebirds by removing herbaceous and woody weeds.

Tomago Wetlands Five hundred hectares of abandoned grazing paddocks at Tomago are being returned to estuarine habitats through the controlled reintroduction of tidal flows. The project involves several NSW Government agencies, university researchers and community groups. Feeding grounds have been created for migratory sandpipers and other shorebirds.

Hunter Wetlands Centre Australia Hunter Wetlands Centre Australia is a small complex of Ramsar-listed9 wetlands (43 hectares) where a predator-proof fence is almost complete and feeding stations are in place, ready for the reintroduction of native wildlife such as bush stone-curlew and wallabies, subject to approval.

industrial dischargesA number of large industries discharge treated effluent and stormwater to the estuary. Improvements by industry and increased environmental regulation have resulted in improved water quality in the lower estuary.

Top: Young mangrove tree planting (LLS)

Bottom: Working in the Hunter estuary (LLS)

Hunter River estuary report card 2016 – Office of Environment & Heritage8

References 1. Swanson RL, Potts JD & Scanes PR 2017a, Legacies of a Century of

Industrial Pollution and its Impact on the Current Condition of the Lower Hunter River Estuary, Office of Environment and Heritage, Sydney.

2. Swanson RL, Potts JD & Scanes PR 2017b, Lower Hunter River Health Monitoring Program: Water Quality Monitoring Program 2014–15, Office of Environment and Heritage, Sydney.

3. Swanson RL, Potts JD & Scanes PR 2017c, Lower Hunter River Health Monitoring Program: Stormwater Quality Monitoring Program 2015, Office of Environment and Heritage, Sydney.

4. Swanson RL, Ferguson AJP & Scanes PR 2017, Preliminary Ecological Assessment of the Lower to Mid Hunter River Estuary 2015–16, Office of Environment and Heritage, Sydney.

5. Roper T, Creese B, Scanes P, Stephens K, Williams R, Dela-Cruz J, Coade G, Coates B & Fraser M 2011, Assessing the condition of estuaries and coastal lake ecosystems in NSW, Technical report series, NSW Natural Resources Monitoring, Evaluation and Reporting Program, Office of Environment and Heritage, Sydney.

6. OEH 2016, Assessing Estuary Ecosystem Health: Sampling, Data Analysis and Reporting Protocols, NSW Natural Resources Monitoring, Evaluation and Reporting Program, Office of Environment and Heritage, Sydney.

7. Swanson RL, Potts JD & Scanes PR 2017d, Lower Hunter River Health Monitoring Program: Project Summary Report, Office of Environment and Heritage, Sydney.

8. ANZECC & ARMCANZ 2000, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, National Water Quality Management Strategy Paper No 4, Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

9. www.ramsar.org

For further information regarding the Lower Hunter River Health Monitoring Program, contact Estuary and Catchment Science, Office of Environment and Heritage at info@environment.nsw.gov.au.