Adelaide coastal waters
The Adelaide coastal waters include the Port waterways and metropolitan beaches, and extend from Sellicks Beach in the south to Port Gawler in the north. They include the waters approximately 20 km offshore.
Adelaide coastal waters make up part Gulf St Vincent and include areas of seagrass and subtidal reef environments supporting important feeding grounds and nurseries for fish, crustaceans, molluscs and marine mammals.
Maintaining good water quality is essential for the maintenance of these marine habitats and important for industry and the recreational uses of Adelaide coastal waters and metropolitan beaches.
What are the problems facing Adelaide coastal waters
Historically the area of the Port River and the broader area of Adelaide coastal waters have been impacted by poor water quality from discharges from industry, wastewater and stormwater. The EPA has previously studied and monitored water quality in this area quite extensively.
The EPA established the Adelaide Coastal Waters Study (ACWS) in 2001 in response to concerns about the decline in coastal water quality and loss of more than 5,000 hectares of seagrass, around 200 times the area of the playing grounds at the new Adelaide Oval.
The ACWS final report summarises the key findings highlighting that discharges into Adelaide coastal waters from wastewater treatment plants, industry and stormwater outlets are high in nutrients and suspended solids and were causing loss of seagrass along the Adelaide coastline.
The study revealed that there needed to be a 75% reduction in nutrients, specifically nitrogen, and a 50% reduction in suspended solids for there to be a return of seagrass. In general, the industrial sources contribute the more nutrient, while stormwater the bigger contributor of suspended solid pollution to the coast.
The importance of seagrass
Seagrass provides habitat for a large variety of marine animals including fish, and stabilises the sand, reducing erosion. Seagrasses also reduce wave energy, which can help to stop coastal damage during storms.
It is estimated that seagrass ‘meadows’ cover 5,000 km² of the sheltered waters of Gulf St Vincent. The dominant seagrasses are ribbon weed (Posidonia spp) and wire weed (Amphibolis spp) and in the shallower regions, paddle weed (Halophila spp) and eel grass (Zostera and Heterozostera spp).
Seagrasses are vascular, flowering plants with roots, making them quite different from seaweed, which is an alga. Their large root system is essential for the uptake of nutrients and for anchoring them to the sand.
Excess nutrients cause algal blooms and epiphyte growth on seagrass leading to loss of seagrass. Discharges of high levels of suspended solids into the Adelaide coastal waters increase turbidity levels contributing to challenges for re-establishing seagrass, poor recreational water quality and may result in beach closures at times after rain events.
Loss of seagrass has implications in terms of sediment instability for the management of Adelaide beaches, and on a global scale, loss of seagrass results in more carbon released into the atmosphere. The carbon storage value of seagrass beds is greater than equivalent-sized terrestrial based carbon stored in areas such as rainforest or woodland.
What has been done to improve water quality in the Adelaide coastal waters
The EPA completed the Port Waterway Water Quality Improvement Plan in 2008 which is focused on water quality improvement for the Port Waterways.
To further the recommendations from the ACWS and provide a long-term strategy to achieve and sustain water quality consistent with community expectations for Adelaide’s coastal waters, the Adelaide Coastal Water Quality Improvement Plan (ACWQIP) was released in mid-2013. The plan was a culmination of over 5 years of work on consultation with key stakeholders and the community for the improvement of water quality along Adelaide's coastline.
The ACWQIP was developed in partnership with relevant government agencies, business and industry. A summary overview of the ACWQIP has been provided for your information.
The ACWQIP includes 8 strategies which are underway in partnership with key stakeholders and the community:
- reduce nutrient, sediment and coloured dissolved organic matter (CDOM) discharges
- promote integrated use of wastewater and stormwater across Adelaide
- further investigate sources and volumes of sediment and CDOM
- integrate monitoring for cumulative impact assessment across the Adelaide region
- model and evaluate the impacts of climate change, new human impacts and population growth implications for Adelaide coastal waters
- establish planning and funding priorities for water initiatives for Adelaide’s coastal waters
- undertake seagrass mapping and rehabilitation work
- build community capacity to take action to improve coastal water quality.
In the ACWQIP the EPA is identified as the agency to lead the reduction of nutrients from point source discharges from the wastewater treatment plants operated by SA Water and (the now closed) Penrice Soda Products. However, addressing the issues associated with stormwater involves many players and needs a more integrated approach.
Catchment-to-coast focus for water quality improvement across urban Adelaide
Between 2013 and 2018 the EPA implemented many of the strategies in the ACWQIP with funding of $2 million from the Australian Government National Landcare Programme.
The 'Catchment to coast focus for water quality improvement across urban Adelaide’ (Catchment to Coast) focused on building community capacity for water quality improvement as its main strategy. The project involved ground action, signage at specific sites and some monitoring to inform managers of stormwater on how to best reduce sediment, coloured dissolved organic matter (CDOM) and nutrient loads from stormwater in the Adelaide region.
Through 6 sub-projects, improvements to Adelaide's urban waterways and coastal waters led to implementation of strategies 1, 3, 4 and 8 from the Adelaide Coastal Water Quality Improvement Plan (ACWQIP):
- provided information through the steering group and online communities such as Water Sensitive SA
- supported community awareness and education of catchment to coast issues through activities with the Marine Discovery Centre
- Developed water sensitive urban design (WSUD) demonstration sites with the City of Unley, City of West Torrens and Adelaide City Council
- Collaborated with the Kaurna people of the Adelaide region
- Managed Rain Garden 500, a 3-year devolved grant program (link to modified page)
- Monitored water quality across catchments and subcatchments in Adelaide.
The EPA worked in partnership with other agencies and local government to support implementation of water sensitive urban design (WSUD) and better sediment management across the Adelaide region to improve coastal water quality
Increasing our understanding of stormwater discharge to Adelaide coastal waters
In 2005, as part of the ACWS, an audit report was commissioned in 2015 to investigate the available data in the ACWS area and identify data gaps. The report summarised the monitoring programs undertaken in the ACWS and provided recommendations for future monitoring programs. In 2015 another audit was undertaken to summarise the data collected in the 10 years since the last audit.
The report noted that:
- The availability and quality of flow and water quality data has improved substantially since the previous audit and this improvement has made comparisons between this and the earlier audit complex.
- Water quality monitoring was not performed at all sites for the reporting period, and a reduced period of 2009–14 was used as the data set for water quality.
- There are still gaps in the data for the southern coastal catchments, the Patawalonga Coastal stormwater drainage systems (Holdfast drains) and the Buckland Park Lake (Gawler River discharge).
- Data in later years included environmental flows – controlled releases of water into some rivers in the system to improve overall catchment health
Although it is difficult to compare the two audits, the 2015 report may indicate some trends. Monitoring into the future will assist in consolidating trends. Some possible trends are:
- Overall there is an increase in stormwater outflows. Taking into account environmental flows, there is still an upward trend in flow volumes into Gulf St Vincent. This upward trend occurred despite significant years of very low rainfall.
- Generally pollutant loads increase as flow volumes increase.
- While only 5 years of consistent data on water quality is available, this data shows that the majority of pollutants were discharged through the Torrens, Gawler and Onkaparinga Rivers and the Barker Inlet Wetland.
- The 3 river systems, Torrens, Gawler and Onkaparinga account for over 50% of the total pollutant loads.
- The Torrens River is the most significant catchment contributor for both total suspended solids and total nitrogen contributing 36% and 30% respectively.
Water quality monitoring of nearshore marine waters
The EPA's water quality monitoring program is now focused on a monitoring, evaluation and reporting program (MERP) for aquatic ecosystems which assesses the condition of seagrass and reef habitats in Gulf St Vincent.
This monitoring information is released as Aquatic Ecosystem Condition Reports (AECRs), and provides a better indication of what is happening for Adelaide coastal waters in terms of water quality and condition of seagrass and reef areas, identify pressures to on the condition, and helps the EPA to work with industry, local government and other relevant state government agencies to manage and improve that condition.
- Metropolitan Bathing Waters Quality Report No. 1
- Metropolitan Coastal Waters Quality Report No. 2
- Metropolitan Coastal Waters Quality - Community Summary
- Gulf St Vincent metropolitan bathing waters – Report No 1
- Gulf St Vincent metropolitan coastal waters – Report No 2
- Protecting Gulf St Vincent
- Water quality of Adelaide's metropolitan coastal waters – community summary
- Changes in seagrass coverage
- The health of subtidal reefs
- Technical Report No 1 – Audit of the quality and quantity of treated wastewater discharging from Wastewater Treatment Plants (WWTPs) into the marine environment
- Technical Report No 2 – A review of seagrass loss on the Adelaide metropolitan coastline
- Technical Report No 3 – Audit of contemporary and historical quality and quantity data of stormwater discharging into the marine environment, and field work programme
- Technical Report No 4 – Estimation of groundwater and groundwater N discharge to the Adelaide Coastal Waters Study area
- Technical Report No 5 – Distribution of Suspended Matter in Adelaide Coastal Waters Using SeaWiFS Data
- Technical Report No 6 – Remote sensing study of marine and coastal features and
interpretation of changes in relation to natural and anthropogenic processes
- Technical Report No 7 – In-situ field measurements for Adelaide Coastal Waters Study
- Technical Report No 8 – Physical oceanographic studies of Adelaide coastal waters using high resolution modeling, in-situ observations and satellite techniques
- Technical Report No 9 – Responses to reduced salinities of the meadow forming seagrasses Amphibolis and Posidonia from the Adelaide metropolitan coast
- Technical Report No 10 – Reconstruction of Historical Stormwater Flows in the Adelaide Metropolitan Area
- Technical Report No 11 – Elevated nutrient responses of the meadow forming seagrasses, Amphibolis and Posidonia, from the Adelaide metropolitan coastline
- Technical Report No. 12 – Turbidity and reduced light responses of meadow forming seagrasses Amphibolis and Posidonia, from Adelaide metro coastline
- Technical Report No. 13 – Nutrient fluxes in the meadow forming seagrasses Posidonia and Amphibolis from the Adelaide metropolitan coast
- Technical Report No. 14 – Field surveys 2003-2005: Assessment of the quality of Adelaide's coastal waters, sediments and seagrasses
- Technical Report No. 15 – Assessment of the effects of inputs to the Adelaide coastal waters on the seagrasses, Amphibolis and Posidonia
- Technical Report No. 16 – Sediment budget
- Technical Report No. 17 – The loads of particulate matter and atmospheric nitrogen deposited from wet and dryfall to Adelaide metro coastal waters
- Technical Report No. 18 – Volumes of inputs, their concentrations and loads received by Adelaide metropolitan coastal waters
- Technical Report No. 19 – An integrated environmental monitoring program for Adelaide's coastal waters
- Technical Report No. 20 – Physical oceanographic studies of Adel coast waters using high-res modelling, in-situ observations and satellite techniques
- Adelaide Coastal Waters Study, Final Report Volume 1
- Adelaide Coastal Waters Study
- Monitoring for coastal protection
Adelaide coastal waters information sheets
Following the completion of the ACWS, information sheets on Adelaide coastal waters and some of the findings of the study are now available:
ACWQIP supporting documents
The development of the draft ACWQIP included collation of considerable background information provided as separate consultant reports and statements. These are listed below as reports 1 to 8. Some of this information has undergone minor editing to remove names or other information to protect privacy. Most of the work for these reports was undertaken between 2006 and 2008, and as such, some of the content is not necessarily current for and does not reflect the views of the South Australian Government or current government policy.
- Report 1 – Community consultation executive summaries
- Report 2 – Draft water quality objectives
- Report 3 – Sample of programs and activities relevant to water quality improvement for Adelaide's coastal waters
- Report 4 – Modelling the catchments of Adelaide's coastal waters
- Report 5 – Adelaide Coastal Water Quality Improvement Plan Monitoring and Assessment Framework
- Report 6 – Understanding the possible impacts of climate change and population growth by the year 2030 on nearshore water quality of metropolitan Adelaide
- Report 7 – Statutory capacity to implement the Adelaide Coastal Water Quality Improvement Plan
- Report 8 – Reasonable assurance statement for the Adelaide Coastal Water Quality Improvement Plan
- Port River Water Quality Report No. 1
- Port River Water Quality Report No. 2
- Port River Sediment Quality Report
- Port River: heavy metals and PCBs in dolphins, fish and sediment
- Port River Water Quality Improvement Plan
- Department of Environment and Water
- Natural Resources Adelaide and Mount Lofty Ranges
- Water Sensitive SA
- City of Onkaparinga
- City of Marion
- City of Holdfast Bay
- City of West Torrens
- City of Charles Sturt
- City of Port Adelaide Enfield
- City of Salisbury
- City of Playford
- Adelaide Plains Council