Murray Darling Basin Plan

November 2010

Extension of comments deadline on the Murray Darling Basin Plan to 17 December 2010.

Senate Inquiry "The management of the Murray Darling Basin" has a deadline for submissions of 15th of December 2010.  Details regarding the inquiry and information about making a submission are here.

October 2010

The MDBA has released A Guide to the Proposed Basin Plan on 8th October 2010.  Go to the MDBA website to view online or download. Or download here from our site The 'Guide to the Basin Plan'  (16MB) 

Volume 2 released 22 Oct 2010. 

Compare this new Basin Plan of 2010 with the information from ten years ago in this plan titled, "Murray River Barrages Environmental Flows - An evaluation of environmental flow needs for the Lower Lakes and Coorong" released in the year 2000 for the Murray Darling Basin Commission. 

A few excerpts below are from this report and clearly acknowledge that the Lower Lakes were once part of a much larger estuary that included the Coorong.  Separating the Coorong from the Lower Lakes with the barrages has caused all kinds of environmental problems that were known ten years ago.

From page 10, Key Issues:

"The Scientific panel identified four key issues driving the serious degradation of environmental values in the Lower Lakes and Coorong. These are:

    • the reduced area of the estuary

    • changed water regimes of the lakes and river

    • freshening of brackish and saline habitats

    • reduced habitat for aquatic plants

The first two issues are the most significant in terms of their impact and their influence in driving the other key issues."

From page 43:

"The reduction in the size of the estuary has reduced the size of the tidal prism by around 90% of its original pre-barrage size. In 1914 the lake area affected by tides was 97.3 km2 (75 000 hectares), with a spring tidal prism of 20 000 ML (Walker 1990). These figures indicate that the original tidal prism produced a twice-daily exchange of similar magnitude to the flows of 20 000 ML/day for a month or more which would now be required to substantially clear the mouth of accumulated deposition (Harvey 1988)."

From: page 44, Opportunities for Improvement:

Options for rehabilitation measures to address the key geomorphological issues - Long Term

"Enlarge the diversity of habitat in the estuary by increasing the size of the tidal prism and the flushing effects of tides at the mouth. An option for management is to relocate the barrage system to Wellington or to Pt Sturt–Pt McLeay."

From page 62, Ecological Needs:

"The changes in water regime and the presence of the barrages have both led to a reduced extent of the estuarine system, now approximately 11% of the former area (Bourman ibid). Along with the changes, there has been an increase in the extent of the freshwater environment behind the barrages and an increase in the spatial and temporal occurrence of hypermarine conditions in the Southern Lagoon. There has been the establishment of unvarying marine salinities for long periods in the remnant estuary when the barrages are closed. Clearly, management of the region needs to enhance the environment for estuarine macro-invertebrates and for estuarine-marine fish."

From page 64, Long-term Changes:

"Consider removal of present barrages and investigate options for new structures at Wellington or Pt Sturt. This would greatly enlarge the estuary and return it to its historical form. More information on hydrology, geomorphology and biology of the system is needed before this major change could be implemented."