A major spill of detergent in March 2022 led to a large incident response. It occurred in Cherry Creek and Cherry Lake, in the Laverton North and Altona area. An investigation is ongoing into this incident and to determine any breaches of the law. The interagency response included EPA Victoria, Melbourne Water, Greater Western Water and Hobsons Bay City Council.

The clean-up process involved extensive flushing and diverting water to the sewer network. There was also high pressure washing of concrete drains. Strategic bunding at some locations stopped the movement of the detergent. The polluted water was then removed by pumping to sewer. The spill resulted in many dead fish in the creek and lake which also required clean up and removal.

Melbourne Water removed about 20 tonnes of dead fish from Cherry Lake. Dead fish were also removed downstream of Cherry Lake and from Altona Dog Beach. Thirty-six million litres of contaminated water went to sewer.

Signs advised avoiding contact with the waterway downstream to Altona Dog Beach. Community meetings in March and April 2022 provided the community with latest information. The waterway then returned to normal flows. This was due to the reduction of pollution and bunding removal. 

EPA placed water quality monitoring equipment into Cherry Creek and Lake. This provided real-time data of waterway conditions. Results showed very high concentrations of the detergent in the water. This led to a loss in dissolved oxygen in the water. Dissolved oxygen is critical for aquatic life. The loss of dissolved oxygen contributed to the fish deaths.

EPA monitored the waterways for several months after the incident. Results confirmed that the clean-up efforts reduced pollution levels in the water. People can now resume activities around the lake. Warning signs will remain in place around Cherry Lake and Creek to avoid eating fish.

The focus of monitoring is now on the concentration of the detergent in the creek and lake sediments. The sediment concentrations are declining but will take longer to recover.

Melbourne Water monitoring has focused on the impact on the ecosystem. Melbourne Water monitoring of aquatic life before the incident is a useful reference. Results suggest water bugs are present in the creek and lake again. The bugs are critical to supporting the ongoing ecological recovery. Presence of bugs are necessary for fish to return. 

EPA continues to work with the alleged polluter. This is so they can meet their obligations under the Environment Protection Act 2017. EPA continues to provide scientific advice to partner agencies throughout the recovery process.

Incident response

On 7 March 2022, EPA Victoria learned of a spill of approximately 12,000 litres of a detergent called Teric N9. The spill into the stormwater system affected Cherry Creek and Cherry Lake in Altona. An interagency emergency team was formed. Representatives from EPA, Melbourne Water, Greater Western Water and Hobsons Bay City Council attended. The focus of the team was on stopping the spread of the detergent. Other tasks were monitoring the spill impact and providing information on clean up.

Teric N9 contains the hazardous ingredient nonylphenol ethoxylate (NPE). NPE can degrade in the environment to form another hazardous chemical, nonylphenol (NP). EPA tested water from the Cherry Creek/Cherry Lake area (Table 1) for a range of pollutants. These included NPE, NP and water quality indicators including dissolved oxygen (DO). Dissolved oxygen was a focus for the investigation. This is because fish and other aquatic life rely on it to breathe. It is usual for a detergent spill to lead to a loss of dissolved oxygen in the water.

Testing commenced immediately following the incident until the 27th of April 2022. During the testing period, EPA's Environmental Public Health experts provided human health recommendations. Messaging included avoid contact with the waterways. EPA also advised to avoid eating fish from Cherry Creek and Cherry Lake. 

At the end of the testing period the chemical levels were below levels of concern for human health. On the 23rd of May 2022, EPA transitioned the incident to recovery phase. This phase aims to restore Cherry Creek, Cherry Lake and the surrounding environment. The control and coordination of the recovery is now with Hobsons Bay City Council. 

Water quality monitoring

Initial water quality testing covered a wide range of chemicals. This report focuses on the impact of NP and NPE. Water quality indicators such as pH, salinity and turbidity were also tested. Early results showed that the key impact was from NPE and NP and the loss of dissolved oxygen in the creek and lake. This report focusses on those chemicals and their impact on Cherry Creek and Lake.

Dissolved oxygen

Dissolved oxygen is a key indicator of water quality. Fish and other aquatic life need oxygen dissolved in the water to breathe. High concentrations of chemicals in the water use up dissolved oxygen as the chemical degrades. Measuring dissolved oxygen is a key indicator of the impact of the chemical spill. The Environment Reference Standard (ERS)  for dissolved oxygen in urban streams is at least 60%.
The dissolved oxygen monitoring results from all three sites show a similar pattern. Dissolved oxygen following the spill was very low or close to 0% in the creek and lake, well below the ERS of 60%. Following rainfall on the 18th of April 2022 dissolved oxygen concentrations improved. This resulted in monitored locations generally meeting dissolved oxygen guidelines for urban creeks.

Nonylphenol ethoxylate (NPE) and nonylphenol (NP) water monitoring

EPA investigations identified NPE and NP as the key chemicals of concern. They are toxic to aquatic life and harmful to humans if found at high concentrations. There are no current water or sediment quality standards for NP and NPE in Australia. We assessed water and sediment results using Canadian water  and sediment  standards. 
Concentrations of NPE were very high in Cherry Creek/Cherry Lake. This was following the spill on 7 March 2022. The concentration of NPE downstream of the spill reached over 10 grams per litre of water. This level is extremely high and harmful to aquatic life in the creek and lake. By the end of EPA’s testing, NPE and NP levels in water had declined. In some cases, they fell below or close to an ecosystem standard of 1.0 µg/L). 
Results for NP in water remained stable for the sampling period. NP is a degradation product of NPE and is an endocrine disrupting compound . The environmental risks associated with long term exposure to NP are not known.

Nonylphenol ethoxylate and nonylphenol sediment monitoring

We sampled from seven locations downstream of the pollution source. We also sampled three locations in the adjacent Kororoit Creek for comparison. Sediment sample dates were 29/3/22, 31/3/22, 13/4/22 and 27/4/22, although not at all locations for each date. We used assessment criteria to check the sediment results. For NP, the criteria used was the Canadian Interim Sediment Quality Guideline  of 1.4 mg/kg. For NPE, the criteria used was the highest NPE concentration in the adjacent Kororoit Creek (39 mg/kg).

NPE and NP have a strong preference to attach to sediment in waterways. We detected NPE in all samples from all sampling locations, including Kororoit Creek. Sediment testing results showed high concentrations in Cherry Creek, closer to the source of the spill. Results showed that NPE concentrations exceeded 1,000 mg/kg at some locations in March 2022.  Unlike in the water results, the sediment NPE and NP have been slow to decline. We expected this as the preference is for these chemicals to bind to sediment. Once in sediment, the chemicals undergo a slow natural degradation.

In a good sign, the sediment concentrations of NPE and NP in the Cherry Lake appear to have declined to a low level. Further monitoring of NPE/NP sediment concentrations will be required to make sure there is a continued improvement to low levels. It will be important to test in Cherry Lake to ensure NPE and NP are not moving downstream into the lake.

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Reviewed 9 September 2022