Water quality investigations
Central Coast Council completes water quality investigations at sites where water quality is reduced to determine potential contamination sources
Investigating poor water quality
Periodically reduced water quality is detected at Central Coast beach and estuary sites during routine monitoring. In such cases, further research is conducted to determine causes, sources and means of remediation.
Council completes water quality investigations at sites where water quality is reduced to determine potential contamination sources. These investigations involve additional water quality sampling and testing in addition to routine monitoring.
Council undertakes water quality investigations at sites where poor water quality has been detected with the aim of determining the cause or possible contamination sources. These investigations can involve physical inspection of infrastructure, advanced scientific investigations such as Environmental DNA tracking and monitoring of standard chemical and biological water quality markers.
Factors that impact water quality
Water quality in our lakes, beaches, lagoons, estuaries, creeks and rivers can be impacted by many natural and human-related factors such as:
- rainfall and resultant stormwater
- tides and oceanic exchange
- wind, waves and water currents
- land use of adjacent catchments
- flows from rivers and creeks
- impacts from animals – wild, domestic and farmed
- seasonal and climatic fluctuations
- geology and land form
- extreme weather events such as drought, bushfire and floods
- pollution from pesticides, herbicides, chemicals, litter and sewage (including on-site sewage systems).
Because each site is different, water quality investigations and monitoring programs are designed specifically for the location and the issue being studied.
Temporary signs may be installed at sites where poor water quality investigations are taking place giving further information or investigation details.
Current water investigations:
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Recent poor water quality in November and December 2025 at Canton Beach has been linked to bird and dog waste, which is believed to be the primary cause of elevated bacteria in the water.
Poor water quality has been an ongoing issue at Canton Beach, as noted in the State of the Beaches report. In response, Council began water quality investigations at this site in 2024 to understand the causes.
As part of this investigation, Council is:
- conducting Environmental DNA (eDNA) testing of lake and stormwater to help identify possible bacteria sources
- testing lake water for Enterococci bacteria
- inspecting nearby Council‑owned sewerage infrastructure
- reviewing past environmental incidents in the area
Results to date indicate that poor water quality at Canton Beach is caused by a combination of factors. Monitoring has identified contributions from:
- Bird and dog activity, believed to be the main cause of elevated bacteria levels during November and December 2025
- Low water levels and reduced circulation in the lake, caused by dense seagrass, which limits flushing and allows pollutants to remain near the shore
- Intermittent sewage contamination, confirmed by positive human DNA results
- Stormwater runoff from surrounding urban areas
Council’s Water and Sewer and Catchment to Coast teams continue to investigate these issues to better understand and manage the impacts of both urban and natural factors on water quality at Canton Beach.
Investigations are ongoing, and recreational water quality continues to be monitored as part of the Beachwatch NSW program. Visit the Beachwatch NSW website for daily water quality results and pollution forecasts to help decide if it is safe to swim or splash at Canton Beach.
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The realisation of the Terrigal Lagoon audit commenced in June 2025 aiming to undertake water quality monitoring comparative of previous investigations to understand and quantify the benefit to the estuary of the asset remediation works completed between 2019 and 2023 under the Terrigal Lagoon Audit. The findings will assist in identifying if poor water quality in this coastal lagoon continue to be impacted by sewer related sources and direct further investigations if required.
This project is being undertaken by Council’s Water and Sewer Team.
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Terrigal Beach is currently undergoing reassessment to evaluate water quality improvements achieved between 2010 and 2025 (pre to post remediation). The focus is to determine whether remediation efforts have resulted in measurable improvements to water quality at Terrigal Beach.
This project is being undertaken by Council’s Catchments to Coast Team.
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Once the Terrigal Lagoon investigation is completed, the project will move into the Avoca Lagoon catchment to investigate potential sources of sewage contamination and identify high priority locations based on the review and opportunities from Terrigal Lagoon program. The findings will inform a program of works to investigate the source of the contamination (private Sewage Pump Stations, on-site sewer management systems or Council-owned sewer assets). The investigation will assist in the remediation of sewer assets that may suffer from stormwater infiltration and inform compliance officer to further investigate private sewer services.
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Council’s Sewage Treatment Environmental Protection Licences (EPLs), have conditioned monitoring programs for the human and ecological impacts of effluent discharged to the marine environment from Council’s licenced ocean outfalls. The University of Newcastle have been engaged to undertake the monitoring program seasonally throughout 2026. This work is being undertaken by specialist staff within Council’s Water and Sewer team.
The specific regulatory conditions of Councils EPLs relating to this project are:
- EPL 1802 - Pollution Reduction Study 9 - Ecological and Human Health Investigations into Impacts of Winney Bay Ocean Outfall
- EPL 1942 - Pollution Reduction Study 1 - Ecological and Human Health Investigations into Impacts of Bateau Bay Ocean Outfall
- EPL 2647 - Pollution Reduction Study 9 - Norah Head Ocean Outfall Monitoring Program
How we assess water quality concerns
Council uses a range of methods to investigate water quality concerns, including Environmental DNA (eDNA). This is a non invasive way to identify possible sources of water contamination. It involves collecting water samples and testing them for tiny traces of DNA left behind by animals in the environment.
DNA can come from both living and dead animals. Living animals shed DNA through mucus, faeces, urine and skin cells. DNA is also released when animal cells break down after death. By analysing this DNA, Council can identify which animals are using our waterways and may be influencing water quality.
eDNA is increasingly used at popular swimming and recreation sites to help identify contamination sources and guide management activities.
Council also tests water for Enterococci, a type of bacteria that can indicate possible faecal contamination. Enterococci is the bacteria used in the Beachwatch NSW program to determine whether water is safe for swimming. Because Enterococci can come from both human and animal waste, it is important that pet owners pick up after their pets to help prevent pollution entering our waterways.
Historic investigations:
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The Terrigal and Coastal Lagoons Audit, which was a comprehensive water quality improvement program in partnership between Central Coast Council, the NSW Department of Planning, Industry and Environment (NSW DPIE) and the University of Technology Sydney (UTS). The project was initiated due to routine poor water quality results detected as a part of the Beachwatch NSW Program and the State of the Beaches report. The program ran from 2019 until 2020 and aimed to assess possible sources of pollution at Terrigal Beach, Terrigal Lagoon, Terrigal Haven, Wamberal Lagoon, Avoca Lagoon and Cockrone Lagoon. The research results were then used to identify focus areas for remediation to improve water quality.
This work was completed as a part of licence conditions:
- EPL 1802 - Pollution Reduction Program 7 - Investigation and Improvement Works for the "Terrigal Bowl" Sewerage Reticulation System
- EPL 1802 - Pollution Reduction Program 8 - Investigations and Upgrades to the Sewerage Reticulation within the Terrigal Lagoon Catchment
More information is available at:
What you can do to help
You can help to keep our waterways healthy by:
- picking up after your dog
- putting litter in the bin
- not washing chemicals down the drain
- minimising fertiliser use and using it responsibly
- planting native vegetation in your backyard to help capture stormwater runoff.
Water quality for swimming
Council participates in the Beachwatch program which monitors water quality at beaches and swimming sites. To determine if it is safe to swim, use the interactive map to find your nearest beach or swim site and check conditions before you go.