The Port Phillip Bay, Western Port and Gippsland Lakes Report Card was developed to report on the water quality at sites in Port Phillip Bay, Western Port, the Gippsland Lakes and their surrounding catchments. Click on the map or list below to explore.
Included on the map are the locations of water quality monitoring sites. Click on a site to see further information.
See ‘Gippsland Lakes and Catchments’ page for a detailed description of the catchments.
This Report Card is the first for the Gippsland Lakes and provides a snapshot of water quality in the Gippsland Lakes and its associated catchments from 1 July 2016 to 30 June 2017.
Water Quality Index (WQI) Scores are calculated and interpreted for individual water monitoring sites within the catchments and lakes. Water quality at each monitoring site is given an overall score by combining the results of a number of standard water quality parameters: nutrients, water clarity, dissolved oxygen, salinity, pH, metals and algae. See the scoring method for more information.
In the other report cards, the individual site WQIs are combined to give an overall catchment WQI. This is not the case for the East and West Gippsland catchments or the combined eastern lakes (Lake Victoria and Lake King) due to the methods used in calculating the overall scores in the other reports not being compatible with, and potentially misleading, the assessments of the Gippsland Lakes and Catchments.
In 2016–2017, routine monitoring occurred across 30 sites in the Gippsland Lakes and associated catchments. Site-specific details within the Gippsland Lakes and catchments can be accessed directly from the map.
While this is the first Report Card for the Gippsland Lakes region, the section Changes over time compares the 2016-2017 Report Card scores and indicators, from the monitoring sites, with site scores generated since 2000. More detail on the catchments and Gippsland Lakes is provided in their individual reports.
See the Water Quality Index section for information on general water quality trends and sources of pollution.
Changes in rainfall can have a big impact on water quality. Heavy rainfall leads to increased runoff, which contains sediments, nutrients and pollutants, and transports these to waterways, potentially lowering water quality. Increased river discharges containing elevated levels of nutrients also stimulate phytoplankton growth and algal blooms.
In 2016–2017, rainfall in the northern catchment areas of the Great Dividing Range was above average, while rainfall in the lower catchment and the Latrobe Valley was below average. In July 2016, heavy rainfall in the northern catchment areas inundated the lower floodplains through the townships of Sale and Bairnsdale. During this event, large volumes of sediment and nutrients were deposited on the floodplain and into the Gippsland Lakes. Within the Gippsland Lakes, water quality also declined slightly due to increased inputs of sediment and nutrients from the catchment, and increased algal growth.
During times of low rainfall, water quality in catchment streams and lakes may improve as inputs from run-off decline. Low catchment flows result in lower levels of nutrients and pollutants, and improved water clarity. However, lower river flows may lead to reductions in dissolved oxygen concentrations, impacting aquatic life. Extended dry periods, characterised by lower river inflows into the Lakes, are often associated with reduced stratification within Lake Victoria and Lake King, as well as increased salinity, particularly in Lake Wellington.
Conversely, during above average rainfall, the increased runoff may impact water quality by decreasing water clarity and increasing nutrients and pollutants flowing into the catchment streams. For the Gippsland Lakes, high stream-discharges deliver increased sediment, nutrients and pollutants, and high freshwater inflows increase stratification between saline bottom and fresh surface layers.
Within the Gippsland Lakes there are also complex internal cycling processes associated with increased stratification. Stratification can lead to reductions in dissolved oxygen levels and a build-up of nutrients in the bottom layer. When released, these nutrients stimulate algal growth which can lead to blooms, as occurred during 2007, 2011 and 2012; this was evident in both eastern lakes and can be seen in the time-series for Lake King North (Point Dawson) and Lake Victoria.
Heavy rainfalls in the northern catchment of the Great Dividing Range in June 2012 and July 2016 resulted in flooding of the lower floodplain. These flood events resulted in large volumes of sediment and nutrients being delivered to the Gippsland Lakes, reducing water quality. Large volumes of sediment and nutrients were also delivered to the lakes in 2003 and 2006 following heavy rainfall in the bushfire affected northern catchment.
The Government, authorities and community have implemented a number of initiatives to improve waterway health in the Gippsland Lakes and catchments, including these outlined below:
A number of priority areas and actions have been identified for the Gippsland Lakes and catchments that will build on existing projects and initiatives. Priority management actions include: