Natural flow patterns of the Maribyrnong River have been altered in recent human history. Reduced rainfall, a loss of native plants (and dominance of exotic willows and blackberries), disruption of the river course and quality by industrial manufacturing until the 1970s, urban stormwater run-off, and water diversion for agricultural and domestic use, have all contributed to changing the river’s natural flow.
Environmental flows are releases of water into rivers and wetlands in order to improve water quality for plants and aquatic life. These flows are not intended to return rivers to their pre-European condition, but rather they assist the maintenance of important life cycles, and serve to mitigate further decline in river health. The Maribyrnong River catchment is home to significant populations of platypus, frogs, migratory short-finned eels, and small-bodied native fish. Low river flows risk the health and movement of these species. There are currently no environmental water entitlements for the Maribyrnong River. However, in recent periods of low river flow, 302 ML of unused water was purchased and released (by the Victorian Environmental Water Holder and Melbourne Water), restoring oxygen levels within the Jacksons Creek reach. The current environmental water deficit of the Maribyrnong catchment is estimated to be 7000 ML/year. This represents the minimum environmental water flow critical for the survival of important species in the catchment within the next 10 years.
The Victorian Sustainable Water Strategy (2022) commits to the return of 7 GL of water to the Maribyrnong River by 2032 with the expected outcomes of maintaining native frog and platypus populations, an increase in native freshwater fish species (galaxiids) and to provide refuge and water quality of refuge pools during dry periods.
Central and Gippsland Region Sustainable Water Strategy (2022)
Victorian Environmental Water Holder