What are environmental flows?
Environmental flows are required to maintain river health. Whilst volume of flow is important, it is also important that flows occur at the right frequency, right time of year and for the right length of time in order to sustain ecological health.
Why are environmental flows important?
With development in Adelaide has come regulation of our rivers, including the construction of large on-stream dams and the diversion of water from rivers to supply the needs of the Adelaide population and industries. This has resulted in some devastating consequences for our rivers, with some flowing 90 per cent less than they used to. This has interrupted the flows required by aquatic animals and plants and threatens their long-term survival. The Purple Spotted Gudgeon fish has already become locally extinct, and the survival of several other species is under threat.
The environmental flows project
The environmental flows project aims to mimic natural flow patterns in the Torrens, South Para and Onkaparinga rivers. The timing and volume of flows has been carefully planned to try and mimic what would have happened under pre-development conditions. There will be periods of no flows, low flows and high volume flushes, as would have happened under natural conditions. These different flows are essential for the health of the plants, fish and other species found in and around the rivers, and ensure that the rivers get the water that they need to remain healthy. Take a look at this short video for an introduction to the environmental flows project.
What is being done?
Natural Resources Adelaide & Mt Lofty Ranges is working with SA Water and the Department of Environment, Water and Natural Resources on a three-year environmental flows trial designed to return a degree of natural flows to the Torrens, South Para and Onkaparinga rivers. The trial involves releasing water from SA Water reservoirs at carefully timed periods during the year to replicate natural conditions in these rivers. Investigations have been undertaken into the flow conditions required by aquatic animals and plants to support vital processes, from creation of habitat and food sources, through to facilitating fish movement and spawning. While the amount of flow is important, the time of year, as well as frequency and duration of the flow events are just as critical. View a short video that introduces the environmental flows trial.
The reach-specific environmental objectives of the trials in the Onkaparinga River include avoiding degradation of in-stream habitat conditions and reducing terrestrial plant species within the river channel. Here are some observations of vegetation and habitat changes in the Onkaparinga River at a Clarendon monitoring site between March 2012 and June 2013.
E-flows fact sheets
Follow current river flow conditions
Background investigations and reports
Project progress reports
Natural Resources Adelaide and Mount Lofty Ranges
SA Water, Department of Environment, Water and Natural Resources