The Werribee River catchment has three main bioregions of note. The river’s headwaters begin in the Wombat Forest, part of the Central Victorian Uplands. The river is joined by other tributaries just south of Bacchus Marsh, where the river has cut its way down onto the Victorian Volcanic Plain and formed gorges.
As the river approaches Werribee, it flows over an old delta, and winds its way into Port Phillip Bay across the Otway Plain.
Central Victorian Uplands
The Central Victorian Uplands bioregion covers 1.2 million hectares extending over 21 local government areas and seven Catchment Management Authorities, stretching from the Grampians and Ararat in the west, to Porepunkah in the east, and from Lurg in the north, to the You Yangs and Lara in the south. It has a unique and relatively early history of European settlement due to the gold rushes in nearby regions in the 1850’s and soldier settlements after World War I and II. The settlers of the gold rush period and soldier settlements were quick to recognise the productive potential of the Central Victorian Uplands bioregion woodlands and dry grassy forest complexes and, consequently, the landscape has been radically and rapidly changed within the last 150 years.1 In the Werribee River catchment this bioregion is in the municipalities of Moorabool and Melton. Wombat Forestcare is a community group dedicated to protecting and enhancing the natural ecosystems of the Wombat Forest and surrounding areas.
Victorian Volcanic Plains
The Victorian Volcanic Plains cover a large part of western Victoria from Melbourne to Portland, Colac and Beaufort.
Most of the northern and central sections of Wyndham are covered by the Victorian Volcanic Plains bioregion. This bioregion has formed over old lava flows and the landscape is dominated by fl at or undulating plains, extinct volcanoes and a variety of grasslands and woodland vegetation. The dominant vegetation in this bioregion are open grasslands, open woodland, shrublands, riparian vegetation and extensive wetlands. Most ecosystems have been cleared for agriculture, particularly grazing and cropping, leaving them severely degraded. Grasslands in the Victorian Volcanic Plains are often species rich and are dominated by Kangaroo Grasses. Native grasslands have been cleared to a large extent so that only small, fragmented remnants remain. They are mostly located in rail and road reserves. The major fauna found in this bioregion are reptiles, birds of prey and waterbirds.2 In the Werribee River catchment this bioregion is in the municipalities of Melton and Wyndham. Pinkerton Landcare & Environment Group (PLEG) is concerned with the restoration of native grasslands and grassy grey-box woodlands, and sections of the Werribee River Volcanic Gorge.
The Otway Plains are located across southern Victoria, from the Bellarine Peninsula to Princetown. A small isolated component of the Otway Plain bioregion is located near Werribee, covering a large area of the coastal section of Wyndham and floodplain area of the Werribee River. Vegetation in this bioregion consists mainly of coastal heathland and woodland, covering coastal plains, rivervalleys and foothills. Vegetation has largely been cleared for agriculture. The biodiversity values in this bioregion are threatened by grazing, drainage, salinity, pest plants and urban development.2
The plain is rapidly being overtaken by urban expansion in Wyndham, with a number of groups interested in preserving its natural values.
2 City of Wyndham Environmental Planning Atlas