Let salt water in the Lakes? Build a weir at Clayton or Laffin Point on the Goolwa channel? “No way,” say members of the River, Lakes and Coorong Action Group (RL&CAG).
Local fisherman and spokesperson for the RL&CAG, Henry Jones, points out that the August rains brought just enough water down Currency Creek and the Finniss River to freshen Lake Alexandrina, cover the acid sulfate soils, revive aquatic plants, induce local birds to breed, stop the tubeworms growing on turtles and refresh the mussels. “It had a major impact on congollis, the most I have seen for 20 years,” he said. “The golden perch and bony bream are spawning now. There are small yabbies in the system and flat headed gudgeon in good numbers.”
“Before contemplating letting salt water into lakes that have been predominant fresh water for 7,500 years, before the construction of another weir in the Lower Lakes region, we must have a proper assessment of the impact on these sites of international importance,” says Professor Diane Bell of the RL&CAG.
The Coorong, Lakes Alexandrina and Albert wetlands were recognised as a wetland of international importance under the Ramsar Convention in 1985. The Environmental Protection and Biodiversity Conservation Act is federal legislation triggered by actions that are likely to have a significant impact. “The Environmental Impact Statement regarding the proposed weir at Pomanda Island is yet to be released for public scrutiny and that process started well over a year ago.” Bell points out. “And now there are plans for further potentially damaging interventions.”
With all these proposals the RLCAG has argued that local knowledge regarding the importance of the wind-driven movement of water upstream is under-estimated. Water above a weir at Pomanda Island on the River Murray would be cut off from this process and become a stagnant pool with algal blooms. It would not be a source of potable water for Adelaide.
A weir at Clayton would lock in salt water from the Goolwa barrage to Laffin’s Point. It would be constantly recharged with saline seepage from the barrage and probable seepage from the ocean. This highly saline water will enter Currency Creek and the Finniss River, killing their fresh water estuaries. It would also prevent the water of the Finniss and Currency Creek from freshening Lake Alexandrina, providing the massive environmental benefits they produced this year. The RLCAG agrees that there are unique species in this part of the River Murray which are at risk.
However, if the goal is to save the River, then what is needed is fresh water from upstream and the local tributaries. Cutting the system into little pieces will not protect the environment.
