See the ‘Werribee Catchment’ page for a detailed description of the catchment.
The Report Card for the Werribee catchment has generated water quality index scores for the period July 2012 to June 2013. These scores are generated using a combination of standard indicators: nutrients, water clarity (turbidity), dissolved oxygen, salinity (conductivity), pH and metals.
These are sampled monthly across 15 sites as part of catchment monitoring programs.
The following section ‘Changes over time’ compares these annual index scores and indicators with the catchment's scores from 2000.
Results can also be compared to other catchments in the section below ‘Compared to other catchments’.
Site-specific details about indicators can be found via the site lists or can be accessed directly from the map.
Summary Table: The table below shows area-weighted distribution of site scores based on subcatchments. Scores are averaged in subcatchments with mutliple sites. See scoring method for more information.
Forested upper catchments
Forested upper catchment
Rural areas in the upper and mid-catchment
Urban areas in the lower catchment
Smaller creeks that drain industrial areas in the lower catchment
The routine monthly monitoring across 15 sites accounts for 73% of the catchment. The remaining 27% of unmonitored catchment is mostly rural which typically scores as Fair for this region.
Water quality scores varied across the landscape of the Werribee catchment, reflecting a variety of land uses. Two sites in the upper reaches of the Lerderderg River scored ‘Good’, whilst sites in the lower sections of the Werribee catchment scored ‘Fair’ to ‘Very Poor’. A number of sites draining urbanised sections of the catchment scored very poorly including Kororoit Creek, Laverton Creek, Lollypop Creek, and Cherry MD. Rural sites in the upper and middle catchment typically rate as Fair. Nutrient runoff is the main threat to water quality in this part of the catchment and typically originate from rural sources such as agricultural runoff, stock damage to creek or river banks and septic tanks.
As waterways flow into the more populated and industrial regions of the lower catchment, water quality declines, which is largely due to increased metal concentrations originating from the urban catchment. Metals are commonly discovered in stormwater runoff from roads and industrial areas. Put more broadly, the increased stress on waterways in the lower catchment exists due to the sediment and pollution entering them from roads, industrial and agriculture areas.
The Report Card's water quality index is based on monthly sampling which can mean short-lived environmental and weather events that can impact water quality are not always captured. This section highlights events for the 2012-13 reporting period.
In 2012-13 authorities worked with the Victorian Environmental Water Holder to deliver two environmental flows to the Werribee River and four environmental flows to Coimadai Creek (also known as Pyrites Creek) in Long Forest Nature Reserve. Environmental flows not only improve waterway habitat for aquatic species, they also boost recreational fishing, increase waterbird and wildlife numbers and improve the amenity of local parks for people to enjoy.
In the Werribee catchment there have been water quality improvements since 2010-11 following the break of the drought. The amount of nutrients initially decreased with the breaking of the drought but has since gone back to pre-drought levels, possibly as a result of irrigation and agricultural practices returning to normal.
Salinity and dissolved oxygen have also improved post-drought due to increased flows in streams. Increased flows dilute salinity and improve dissolved oxygen by increasing volume and oxygen diffusion. The levels of metals found in the smaller waterways such as Lollypop Creek and Kororoit Creek are on average consistently Very Poor because of sustained industrial activity and road runoff.
The ‘Actions’ section below outlines projects and initiatives that will contribute toward addressing the issues outlined above.
Driven by the key water quality issues identified for the Werribee catchment, major projects were implemented in the past five years to improve its waterway health in the catchments and included the following initiatives:
For more information on projects and works in the Werribee catchment in 2012-13, please see the Waterways Local Updates.
A number of priority areas and actions have been identified in the Werribee catchment that will build on existing projects and initiatives. Future priority management actions include:
For more information about actions planned for the Werribee catchment to improve the health of rivers and creeks, please see the Healthy Waterways Strategy.
The following figures show a comparison of scores for each identified water quality indicator in the catchments and Port Phillip Bay.