Method to assess the marine water quality of Western Port
This method measures the condition of water quality by assessing the attainment of State Environmental Protection Policy (SEPP) objectives each calendar year. The attainment of SEPP objectives is deemed to show that the beneficial uses which the community expects from fresh and marine waters have been protected. Beneficial uses of the waters in Port Phillip Bay and Western Port include the maintenance of marine ecosystems, contact recreation and commercial fishing. SEPP objectives set maximum and minimum levels for a selected range of physio-chemical, nutrient and metal contaminants and conditions which pollute or impact freshwater and marine environments.
The SEPP objectives for Western Port were set out in the Victorian Government Gazette on the 2nd of November 2001 under Schedule F8.
The assessment for this strategy has used data provided by EPA Victoria from its Fixed Site Water Quality Monitoring program. This program monitors water quality in Port Phillip Bay and Western Port. This assessment uses water quality data collected at each monitoring site on every monitoring occasion during a given year. Western Port has three monitoring sites at Barillier, Hastings and Corinella. Data from the Fixed Site Water Quality Monitoring program is assessed at the end of each financial year to determine the percentage attainment of SEPP objectives for the previous twelve months.
It should be noted that water quality monitoring records for Western Port from 2002 to 2010 contain inconsistencies. These inconsistencies are in the parameters sampled as well as in the number and timing of monitoring events occurring each year. On occasions a parameter may have only been sampled once in a twelve month period which skews the results either favourably or detrimentally depending when the sample was taken. The most comprehensive data set is for 2010.
In that year, many more monitoring events occurred which made available 308 data points for assessment as compared to the preceding years from 2001 where an average of 70 data points was available. The inconsistencies and small data sets restrict a robust assessment against SEPP objectives for Western Port and qualifies confidence in the report’s evaluation of Western Port water quality, particularly for those years where few monitoring events occurred, and between years where different parameters were measured.