October Murray Darling Report South Australia water to get saltier and saltier as rising seawater splashes over the end-of-river barrages: Lake Alexandrina undrinkable at 2300 to 2500 EC

South Australia water to get saltier and saltier as rising seawater splashes over the end-of-river barrages: Lake Alexandrina undrinkable at 2300 to 2500 EC
Salinity in South Australia’s Lower Lakes was now in the range of 2300 to 2500 EC, with much higher levels immediately upstream of the barrages, where leakage over, under or through the structures had resulted in seawater mixing with the much fresher water of Lake Alexandrina, warned the River Murray System Drought Update No. 10 October 2007.

Monitoring will warn of problems: “Considerable efforts have gone into minimising leakage, but seepage under, and storm waves over, the barrages cannot be prevented and will continue to bring salt in to the lake. Regular water quality monitoring undertaken along the entire River Murray will provide early indications of salinity increases or any other problems, such as algal blooms.

Salted water now a part of life: “All people using the waters of the River Murray should be aware of the increased potential for water quality problems and the difficulty dealing with these issues while flows remain very low. Since May there has been very little flow beyond Wellington into Lake Alexandrina. The lake level was steady over winter due to local rain and low rates of evaporation, but has now begun to gradually fall.

Between Lock 1 and Wellington OK, but to get worse: The water in the reach between Lock 1 and Wellington has been of reasonably good quality, with salinities of less than 500 EC. As water from this reach evaporates or is pumped to Adelaide and other urban centres in South Australia, it is slowly replaced with poorer quality water from upstream,” warned the River Murray System Drought Update No. 10 October 2007.

What’s ahead: Under continuing dry conditions, salinities are forecast to rise, and flows to South Australia will be aimed at maintaining the water quality within levels suitable for human consumption. In isolated areas of the lakes salinity levels may also be higher due to local groundwater inflows.

MDBC will provide further drought updates in coming months. Additional information is available at http://www.mdbc.gov.au and from the relevant Australian and State Government Agencies.