Underwater photo of pristine looking water.The annual Water Quality Report Card uses key indicators of environmental water quality to calculate an overall annual score.

In 2022–2023, water quality in Port Phillip Bay and its waterways varied from Very Good in southern areas of the Bay and upper reaches of the Yarra catchment, to Very Poor in highly urbanised waterways, which is similar to previous years. Water quality was mostly Very Good or Good for rivers in elevated areas where rivers originate. Water quality generally declined to Poor or Very Poor as the rivers moved through rural, agricultural and urbanised areas in the foothills and coastal plains of the lowlands. In Port Phillip Bay, overall water quality was Good, but all four coastal sites closest to urbanised catchment inputs were rated as Fair. This was driven by Poor water clarity, and Fair salinity and nutrient ratings that had reduced from the previous year. In bays and lakes, water quality was mostly Very Good or Good for areas that mix with the open ocean. Significant rainfalls in some of the Port Phillip catchments during Spring 2022 resulted in localised flooding, increasing sediment and nutrient loads to Port Phillip Bay, resulting in Fair Water Quality scores for 4 of the 6 bay sites.

Data from the Bureau of Meteorology shows that the climate in Victoria during 2022-2023 had an above average rainfall across Victoria, and much higher in central and western Victoria, compared with the long-term average. For Victoria overall, it was the highest spring rainfall since records began in 1900. This caused extensive flooding in many catchments across the Port Phillip region, but particularly so for the Maribyrnong catchment where water levels represented a 1 in 100 year flood. The summer months from December 2022 to March 2023, were notably drier with below average rainfalls that continued through to autumn.

The annual Water Quality Report Card has been available on Environment Protection Authority Victoria (EPA) website since 2019. Before that, results were published on the Yarra and Bay website.

Data source: EPA
Data source: EPA

Page last updated: 11/11/24