Werribee Catchment
About the Werribee catchment
The Werribee catchment lies west of Melbourne and covers an area of approximately 2700 square kilometres. Basalt plains dominate the region's geology and the landscape varies from steep sided hills and gorges to flat plains. Rainfall varies from about 1000mm per year to as low as 450mm in the southern plains.
The catchment includes all rivers and creeks to the west of the Maribyrnong River through to Little River, such as the Werribee and Lerderderg rivers, and Kororoit and Skeleton creeks. The Lerderderg River, a major tributary of the Werribee River is one of two Victorian Heritage Rivers and the only 'representative river' in the Port Phillip and Westernport region, reflective of its significant geological, landscape and conservation attributes. A representative river is a river in ecological healthy condition that can be used to represent the major river classes that once occurred naturally across Victoria.
Around 25% of the catchment retains natural vegetation, 67% is agricultural and 5% urban. Extensive grasslands were once a feature of the lowland plains, but now only scattered remnants remain. Forestry occurs in the upper areas of the catchment. Water storages include the Melton, Pykes Creek and Merrimu reservoirs.
Many of the major rivers and creeks flow through coastal wetlands listed under the international Ramsar convention, including Melbourne Water's Western Treatment Plant, Point Cook Marine Sanctuary, Avalon Airport and the Spit Wildlife Reserve. A feature of the catchment is the presence of several remnant grasslands that are of national or state significance for their flora values, such as the Derrimut Grasslands, William Angliss and the Altona Native Grass reserves.
The condition of rivers and creeks within the cachment is highly variable. Most rivers and creeks are generally moderate to poor. The catchment is located in a comparatively low rainfall area and stream flow is a major issue. Reduced stream flows have been exacerbated by the current, long-running drought. The southern portion of the catchment is affected by urban growth from the western fringe of Melbourne and expansion of rural towns.
History of the Werribee catchment area
Aboriginal people inhabited the rivers and creeks at least 30,000 years ago. The Werribee River is an important clan estate boundary forming the natural boundary between the Woi Wurrung and Boon Wurrung clans. The high density of archaeological material, including fish traps, artefacts and burial sites, along their banks and escarpments demonstrate that both Kororoit Creek and the Werribee River had large campsites.