Port Phillip Bay, Western Port Bay and the Gippsland Lakes are Victoria’s largest coastal waterbodies.  

EPA, Melbourne Water, and Department of Energy, Environment and Climate Action monitor water quality for these bays and lakes. 

Report Card 2022-23 looks at water quality between July 2022 and June 2023. We compare results to data from the past 23 years, dating back to 2000.  

The Report Card uses the monitoring data, to calculate an annual Water Quality Index (WQI) – Very Poor, Poor, Fair, Good or Very Good. These refer to the Environmental Reference Standards (2021). 

In 2022–23, water quality in bays, lakes, and waterways changed. Gippsland Lakes and Western Port saw improvements, while the Port Phillip Region experienced a decline. Rainfall in central Victoria was above average, and in Gippsland, it was average. Heavy rain in certain areas around Port Phillip caused flooding in spring 2022, leading to increased sediment and nutrient levels in Port Phillip Bay. This resulted in Fair water quality scores at 4 out of 6 bay sites.

In general, water quality was Very Good or Good in the elevated areas where most rivers originate. Water quality declined to Poor or Very Poor, as the rivers moved through rural, and urban low-lying areas.  In the bays and lakes, water quality was Very Good or Good for areas that mix with the open ocean. Water quality was generally worse in rivers polluted by urban and industrial areas.  

EPA also forecasts water quality for recreation. These forecasts use microbiological indicators which are not reported here. For more information, see our Yarra Watch and Beach Report programs. 

Read more about EPA’s annual Report Card and the work we are doing to improve Victoria’s water quality.