High up in the Wombat State Forest, not far from Daylesford, the Wirribi Yaluk/Werribee River begins as a stream flowing from a damp gully filled with ferns. Here the land is over 730m above sea level, as the water begins its journey over 110km to Nerm/Port Phillip Bay. It travels along Wadawurrung, Wurundjeri Woi Wurrung and Bunurong Country. Passing through many ecosystems along the way, both rural and urban, the river is the lifeblood for the many creatures, plants, wetlands and people who inhabit the catchment.
All the water that fills the river comes from rainfall. In drier years, there is less. The Iramoo/Werribee Plains have some of the lowest average annual rainfall south of the Great Dividing Range. Along the river, diversions, weirs, dams and other engineering features divert water for irrigation, agriculture and other human needs. In places such as the Melton Dam, with a height of 35 metres, these structures become a barrier to the migration of species like fish and platypus.
Regulating rivers is necessary for protecting water supplies and infrastructure yet it denies waterways the drying and flooding cycles they, and many of their dependent species, have evolved with. Environmental flow releases seek to mimic these natural cycles and replenish the system when water levels are low. Fish passages allow movement of species around human-made obstacles.
Traditional irrigation methods, when water flows through open channels, can lead to loss of water through evaporation or leakages. Modernisation of irrigation systems, including capping of channels, can help reduce this loss. Recycled water is processed from urban areas and added to the river, or provided as an alternative to extracting water. Finding ways to conserve water at home such as storing rainwater to use on gardens and planting indigenous species suited to the local climate can also support habitat and nourish groundwater reserves.
The Wirribi Yaluk/Werribee River is an important place for community, for social, recreational, cultural and tourism activities. It is home to many fish, mammal and insect species, and dozens of types of birds throughout its length. The river has undergone many changes and faced challenges since European settlement. With careful, informed and co-operative management, restoration of land and waterways, and conservation projects designed to support individual species, the river may thrive into the future.
Photo: C. Williamson (2022)