Cherry Creek pollution spill – when detergent is dirty!
A major spill of detergent in March 2022 led to a large fish kill and incident response in Cherry Creek and Cherry Lake, in the Laverton and Altona.
An investigation is ongoing into this incident and to determine any breaches of the law. The interagency response included Environment Protection Authority Victoria (EPAV), Melbourne Water and Hobsons Bay City Council.
The clean-up process involved extensive flushing and diversion of water to the sewer network, as well as high pressure washing of concrete drains. Bunding was placed at locations to stop the movement of the detergent and allow its removal by pumping. The spill resulted in a large number of dead fish in the creek and lake which also required clean up and removal.
During the incident, Melbourne Water removed approximately 20 tonnes of dead fish from Cherry Lake and entrance from the creek to the bay, and 36 megalitres (ML) of contaminated and washdown water was pumped to sewer.
The community were advised to avoid contact with the waterway as far downstream as Altona Dog Beach. Community information sessions were held in March and April 2022 to provide the community with the latest information regarding the removal of bunding, return of normal water flows and the reduction in pollution.
EPA deployed water quality monitoring equipment into Cherry Creek and Lake as part of its incident environmental response capability which enabled real-time monitoring of the conditions. EPA water quality monitoring results showed very high concentrations of the detergent in the water. This led to a loss in dissolved oxygen in the water, which is critical for aquatic life and contributed to the fish deaths.
EPA has been monitoring the waterways for several months since the incident and has confirmed that the clean-up efforts have successfully reduced pollution levels in the water. The conditions in the creek and lake are now suitable for people to 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 are expected to take longer to recover.
Melbourne Water monitoring has focused on the impact of the spill on the Cherry Creek and Cherry Lake ecosystem. Melbourne Water monitoring of aquatic life in the area prior to the incident has been useful for comparison after the incident. As a positive sign, Melbourne Water monitoring suggests water bugs in the creek and lake are present, which are critical to supporting the ongoing ecological recovery of the system and are necessary for fish to return.
A multi-agency recovery committee has continued to oversee actions to support the local community and ensure the creek and lake are returned to a suitable condition. EPA will continue to work with the duty holder, so they can meet their obligations under the Environment Protection Act. EPA continues to provide scientific advice to partner agencies throughout the recovery process.
Links to the Healthy Waterways Strategy - Werribee catchment
Pollution in waterways and wetlands is an issue that impacts both environmental and social values such as macroinvertebrates, fish and recreation. Incidents such as this detergent spill impact water quality for environmental values and recreation and occur more frequently in urban areas with industrial catchments and traditional stormwater connections. The work done here across agencies contributes to outcomes in the Cherry Creek sub-catchment and in Cherry Lake.