Abundant winter rains in 2010 and 2011 have replenished water levels in Lake Alexandrina and Lake Albert.
Before the barrages were built in 1940, the Lower Lakes were part of the River Murray estuary, a vast estuarine ecosystem connected with the Coorong. The Lower Lakes and Coorong supported a range of ecosystems from freshwater to marine ecosystems. Learn why the mixing of fresh and salt water is so important. Read our collection of newspaper stories from the early 1900's at our blog.
Fact: A large percentage of the known Acid Sulphate Soil sites would not be exposed if the Lower Lakes were maintained at sea level by opening the barrages
During a drought the current management plan is to allow the Lower Lakes to 'dry down' to -1.5 AHD, or below sea level, and keep the barrages shut. Then use 'bioremediation' techniques to control the ASS that would not have formed in the first place if the barrages were open and seawater allowed to mix with the freshwater creating an estuary. A map of acid sulphate sites and the bathymetry of the Lower Lakes.
ecology of the Lower Lakes and the Coorong has been suffering biodiversity loss for decades, with loss of habitat, invasive fish species, such as carp, and declining native fish species. The presence of the barrages causes an abrupt change in the water environment and reduced tidal range, and is believed to be one of the major factors contributing to habitat degradation (ref MBDC).
Fact: There is not enough freshwater during an extended drought to sustain the artificial freshwater regime of the Lower LakesDuring drought, there is not enough water in the Murray-Darling Basin storages to meet everyone's water needs. The CSIRO forecasts a long-term decline in flows at the Murray Mouth of 24% to 30% (ref CSIRO). Read the FAQ for more information
Disconnecting the Lower Lakes from the ocean has produced an annual requirement for 750 to 950 GL of freshwater to replace evaporative losses, which could instead be refilled by seawater (ref MDBC). It is estimated that the Lower Lakes require 4000 to 6000 GL per year (or thousands of billions of litres) of environmental flow to maintain a freshwater ecosystem.