Maribyrnong Catchment
About the Maribyrnong catchment
The Maribyrnong catchment lies northwest of Melbourne. It covers an area of approximately 143 square kilometres and yields an average annual flow of 120,000 million litres. Rainfall in the catchment exceeds 1000mm in the ranges on average, declining to less than 500mm on the lower plains.
The Maribyrnong River has two main branches, Deep Creek and Jacksons Creek. Both are fed by a number of major tributaries including Boyd Creek and Konagaderra Creek. All rivers and creeks tend to be deeply incised, exhibit a high variability in flow and are subject to extended periods of low flow. Around 10% of the catchment retains natural vegetation, 80% is agricultural and 10% urban. A small forestry industry (both hardwood and plantation) occurs in the upper reaches.
The Rosslynne Reservoir is located on Jacksons Creek, just west of Gisborne, and supplies both irrigation and domestic water. Valuable areas of remnant vegetation are found in these deeply cut valleys, including the highly valued river red gum. The rivers and creeks are characterised by poor water quality, changed flows and loss of riverbank and aquatic habitat. A rich Aboriginal culture exists and some of the most significant sites in the region are found in this catchment. Brimbank Park contans evidence of human and animal occupation extending back 40,000 years, including two of the oldest known sites in Australia.
Waterway health
The health of the rivers and creeks in the upper catchment is moderate to poor and many tributaries and the middle and lower reaches of the river have declined as a result of rural and urban development.
Flora and fauna
Many indigenous plants have disappeared and introduced plants such as willows and blackberries now dominate streams. Drawing water for domestic and agricultural use has noticeably altered the pattern of flows in a number of the waterways. In areas that are being urbanised, changes are also expected as increased run-off generates more flows into rivers and creeks. Such changes in flow patterns can impact on the fish, frogs and other species living in our waterways. Recent studies in the catchment have focused on the importance of ensuring there is enough flow through the catchment to protect the animals and plants that live there.