About low flows
What are low flows and why are they important?
'Low flows' are naturally occurring, regular, small flow events that are a vital part of the annual water flow pattern of a catchment. They are a small but vital portion of water that needs to flow across land through watercourses to maintain natural processes and catchment health.
The development of thousands of dams with catchments over many decades has significantly altered the timing and volume of flow provided to the environment. These days, low flows are impeded until dams fill and spill later in the flow season.
Returning to a more natural flow pattern allows catchment ecosystems to receive water at critical times. This helps maintain water quality by flushing salt and pollutants that accumulate during dry periods.
Catchment dams generally fill during medium and high flow events. A low flow device will not prevent a dam from filling during these events. Low flows are only passed when a dam is receiving flow or when there is flow past a watercourse diversion.
The Securing Low Flows project is working to secure low flows across the Mount Lofty Ranges. The Flows for the Future program provides a funding opportunity to implement the Securing Low Flows project in the EMLR & Marne Saunders Prescribed Water Resource Areas.
What is a catchment?
When rain falls, the water collects in an area of land which is often bounded by hills. The water flows across the landscape, into the soil and streams, eventually feeding a river.
How much water ultimately feeds streams and rivers depends on various factors, including rainfall, soil moisture, and topography.
Catchments are complex and when something happens in one part of the catchment then it can have a big impact on other parts.
There are 16 surface water catchments in the EMLR Prescribed Water Resource Area see them here .
Why do we need to pass low flows?
Securing low flows is one of the important policies being delivered as part of implementation of the EMLR Water Allocation Plan. EMLR water allocations have been issued on the understanding that a program to secure ‘low flows’ is implemented across the Mount Lofty Ranges to improve catchment health and support primary production for years to come.
The decision to return low flows to catchments was made in discussion with the community to maximise the amount of water for consumptive use while keeping water use within sustainable limits.
If low flows of water are not secured then the volume of current allocations will not be sustainable into the future and catchment health will continue to decline. It may become necessary to review current allocations based on a lower volume of water available.
The Flows for the Future program will contribute to the implementation of the Murray-Darling Basin Plan, ensuring that the level of water extracted from the EMLR is sustainable and that the creeks and waterways leading to the River Murray and lower lakes are able to flow.
Communications and Community Engagement Coordinator, Flows for the Future