6 June 2010
DEH released its long-awaited report "Securing the future: a long term plan for the Coorong, Lower Lakes and Murray Mouth" (CLLMM) on Friday June 4th.
The purpose of the report is to provide a "clear direction for the future of the CLLMM region as a healthy, productive, resilient Wetland of International Importance" [sic]. Regrettably, the report's length is no substitute for the clarity of its direction nor the vision of its recommendations.
The recommendations contained in the report are numerous, but the key recommendations, in order, are:
Lake Alexandrina and Lake Albert remain predominantly freshwater and operate at variable water levels.
The Murray Mouth is predominantly kept open by end-of-system river flows.
There is a return of salinity gradients along the Coorong that are close to historic trends with a corresponding response to species abundance.
There is a dynamic estuarine zone.
What is not clearly stated in the report, but is implied, is that it is business as usual as far as the operation of the Barrages is concerned. In other words, the Barrages will continue to hold back seawater in times of low river flows, i.e., creating the same situation that currently plagues the Lower Lakes.
Taken separately, at face value, the above recommendations seem like worthy goals. Taken collectively, the conflicting and inconsistent nature of these goals becomes readily apparent.
Firstly, there can be no "dynamic estuarine zone" while "Lake Alexandrina and Lake Albert remain predominantly freshwater", for as long as the barrages hold back seawater, the estuarine zone is limited to the Murray Mouth and Coorong, a mere tenth of the area of the historic (pre-1940) Murray estuary.
Secondly, operating the Lower Lakes at variable (fresh)water levels, is an artificial and ugly solution in stark contrast to nature's own. Absent the barrages, the water levels naturally vary in accordance with the ebb and flow of the tides through the Murray Mouth, regardless of river flows. In other words the much ballyhooed freshwater "wetland of international importance" is actually a man-made construct, that would otherwise be an estuarine wetland, mixing freshwater and seawater in harmony with the seasons.
Thirdly, the report glosses over the deleterious impact of the Barrages on the ecosystem of the Coorong and Lower Lakes. While the "return of salinity gradients along the Coorong that are close to historic trends" is a stated goal, the return of the historical salinity gradients that existed in the channels of the Lower Lakes is abandoned, thus condemning the estuarine habitat to a fraction of its former size. In other words, more freshwater carp and less mulloway.
Finally, the credibility of the report is undermined by its almost complete reliance on the 2004 Sim and Muller paper "A fresh history of Lakes" and the 2006 Phillips and Muller paper "Ecological Character of the Coorong, Lakes Alexandrina and Albert" as evidence for the freshwater history of the Lower Lakes. While these papers begrudgingly acknowledge that before the barrages were constructed, seawater did enter the Lower Lakes when there were severe droughts, they downplay the significance and extent of such reverse flows. In reality, there is ample evidence both from historical records of explorers, such as Sturt and 1900's fishermen as well as scientific evidence, from scientists such as Gell, for an estuarine view of the Lower Lakes.
In summary, we find the report's recommendations both inconsistent and short-sighted.
What do you think? Leave a comment on our blog post or read the case for seawater.