Port Phillip Bay
EPA regularly samples from four to eight sites within Port Phillip Bay. All of these sites have been sampled since 1990 (some as far back as 1976). These sites provide a balance between areas that are close to potential human inputs and major riverine inflows (Hobsons Bay, Newport, Patterson River, Long Reef and Corio Bay) and remote from them (Popes Eye, Dromana and Central Bay).
EPA regularly samples two to three sites within Western Port. Monthly sampling of water quality within Western Port commenced in 1984. Water quality monitoring sites located in the northern (Hastings, Barrillier Island) and eastern (Corinella) regions of Western Port provide information on potential inputs from human activity to Western Port from the surrounding catchments. The south-west region is not sampled as the water quality is maintained by the diurnal tidal exchange with Bass Strait.
EPA regularly samples five sites within the Gippsland Lakes. Monthly sampling of water quality within the Gippsland Lakes commenced in 1986. Three water quality monitoring sites in Lake King (Lake King North, Lake King South, and Shaving Point) provide information on catchment derived inputs and marine inflows, and monitoring sites in Lake Wellington and Lake Victoria provide information on catchment inputs from the western catchment.
Catchments of Port Phillip Bay and Western Port
Melbourne Water samples more than 130 sites regularly in the Werribee, Maribyrnong, Yarra, Dandenong, Mornington and Western Port catchments as part of their waterways water quality monitoring program.
Some monitoring sites in this region have continuous record since the early 1990’s. The dedicated Melbourne Water program was established in 1993 with more than 60 sites and expanded in 2008 to include sites in Melbourne Water’s expanded territory to the west to encompass the Werribee River catchment and to the south east, to encompass the Bass Coast.
A significant number of the sites are located on waterways that flow through urban areas, where water quality is typically impacted by urban land use. Waterways in forested areas are often in near natural condition however there are relatively few monitoring sites in these areas.
Catchments of the Gippsland Lakes
The Regional Water Monitoring Partnerships (RWMP) is a collaborative partnership between more than 40 Victorian organisations that require surface water monitoring and laboratory analysis services. These organisations include the Department of Environmental, Land, Water and Planning, Water Corporations, Catchment Management Authorities, Bureau of Meteorology and local government.
The beginnings of the RWMP date back to 1996. In 2001, the coordinating committee became the Gippsland Regional Water Monitoring Partnership (GRWMP). In 2004 the partnership model was expanded to cover the rest of the state with three additional partnerships - North East, North West and South West. The two northern partnerships merged in 2014 to form the Northern RWMP. In 2017 the three partnerships - Gippsland, Northern and South West are managed by DELWP. Data collected under the partnership now includes rainfall, river level and flow and a range of water quality parameters. Sixty-nine sites are monitored across the catchments of the Gippsland Lakes.
Keeping the balance
The monitoring program, analysis of data and production of the Report Cards employs methods to ensure the information conveyed is robust and accurate at the time of publication.
Monitoring of Port Phillip Bay, Western Port and the Gippsland Lakes can be a challenge at times due to inclement weather, fouling of equipment or equipment failure, leading to an inability to collect the data or loss of data. Refinements in the number of sites monitored have also occurred over the period covered in the Report Cards.
Any changes that have occurred in the monitoring program over the reporting period are assessed to ensure the data is comparable between years. At times, the data is deemed inaccurate or incomplete; in this situation, the data is assessed to determine if reliable extrapolations can be applied (to EPA monitoring data only). If this is not possible, the data is rejected and no Water Quality Index is calculated for the monitoring site or for the Report Card year.
Monitoring of the waterways that discharge to Port Phillip Bay, Western Port and the Gippsland Lakes can also be challenging at times. Over the period of the Report Cards the number of sites monitored can vary. There are several reasons for this, ranging from an expansion of the network in 2008, when Melbourne Water took on new areas of responsibility, to an inability to access the monitoring site for safety reasons.
The methods employed in calculating the Water Quality Index score at the sub-catchment level aim to provide an approach in determining the overall waterway Water Quality Index score by reducing any potential bias created by exclusion of a site. For both the east and west Gippsland catchments an overall Water Quality Index score was not calculated due to a small number of sites located in the lower catchments. This created a bias in the score that was not fully representative of the water quality at the catchment level.
Sampling frequency has also changed in some waterways over the period of the Report Cards. Setting a minimum number (six) of samples for inclusion ensures reliability and comparability between years.
For further information about the Monitoring Programs, contact the program administrator.
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