Ecological response to the Lake Victoria bypass trial 2015–2017

About the document

In the lower River Murray, the operation of Lake Victoria, a large off-channel water storage downstream of the junction of the Murray and Darling rivers, has the potential to profoundly influence longitudinal connectivity, riverine hydraulics and associated ecological processes. Under natural conditions, Lake Victoria only received inflows during periods of high river flow. The lake is now one of the River Murray’s four major water storages and is used to manage flows to the lower River Murray.

The aim of this project was to investigate how current operation of Lake Victoria influences riverine hydraulics (e.g. water velocity) and zooplankton communities. Zooplankton provide a key link between primary producers and higher trophic organisms (e.g. fish), and riverine hydraulics are a major driver of zooplankton community composition and abundance.

The diversion of flow may alter longitudinal connectivity, riverine hydraulics and downstream matter transport, with associated ecological impacts. In recognition of this, the Commonwealth Environmental Water Office (CEWO) and Murray–Darling Basin Authority (MDBA) River Murray Operations Division are exploring potential changes to the operation of Lake Victoria. New operating rules are currently being considered and developed that aim to:

• Improve environmental outcomes associated with increased longitudinal and lateral connectivity of river flows downstream of Lock 9 (increased flow past Lock 9);
• Improve water quality delivered to South Australia during periods of low river flow; and
• Improve water quality in Lake Victoria and the main channel during periods of high river flow.