MURRAY RIVER: by Patrick J. ByrneNews Weekly
Science overturns need for big environmental flows
, March 27, 2004
Last year protests and lobbying by farmers and communities in the Murray-Darling basin saw the Council of Australian Governments (COAG) back away from The Living Murray proposals to take up to 1,500 gigalitres of farmers' water for environmental flows.
Farmers, communities and scientists were deeply sceptical of the quality of the science behind this proposal.
Instead, COAG proposed creating a number of pristine "icon sites" along the Murray River. COAG allocated up to 500GL of environmental flows as a "first step" towards improved river health.
While COAG continued to emphasise the importance of increased environmental flows, it also agreed to examine other appropriate "efficiency gains, infrastructure improvements and rationalisations" for improved river health.MDBC Report
Late last year the Murray Darling Basin Commission (MDBC) issued a key scientific report on the environmental "flow reference points" of up to 1,500GL. Ecological Assessment of Environmental Flow Reference Points for the River Murray System
was produced by a scientific review panel.
Shortly after, Murray Irrigation Limited, a leading irrigators group, commissioned a leading environmental scientist, Dr Lee Benson of Ecology Management Pty Ltd, to review this key MDBC report.
Recently released, Benson's findings, in essence, show that from the MDBC's own key scientific report:
- the Murray River is not as degraded as commonly portrayed;
- there is little demonstrable benefit to be gained from much larger environmental flows;
- measures other than increased environmental flows would be more effective in improving river health;
- localised work on icon sites based on shared experience of groups working on river health are likely to deliver more environmental gains than "a one solution fix all approach" as proposed by The Living Murray; and
- there is absolutely no need for "immediate attention" requiring hasty, large increases in river flows.
Benson said the MDBC report showed that the Murray was not as degraded as some scientists had thought, and that the "whole river" did not need fixing.
He said the MDBC report showed that increasing river flows by up to 1,500GL made little net improvement in the river's health. Even when there was selective modelling of wetlands and flood plains, that presumably would benefit most from increased environmental flows, there was no significant environmental improvement.
There was such statistical uncertainty in the calculations on the benefits of increased environmental flows as to make "the vast majority" of the discussion on the benefits of additional environmental flows "invalid and therefore redundant".
Dr Benson said that river flow volume was only one of 22 acknowledged issues in determining river health.
He said that the MDBC report did examine other actions (e.g., improving instream habitat, quality and temperature of the water), structural operations (e.g.,bridges, locks and offtakes) and operational options (e.g., modifying rate of change of flow rates and river heights) as ways to improve river health. The MDBC report's own findings showed that modification of these issues of river health "could be as beneficial in their own right as flow actions [increasing environmental flows], and at times more so."
Indeed, the MDBC report appears "to support the concept that non-flow actions can achieve the same environmental benefit as flow actions," Benson says. For example, it concludes that changes to barrage operations on the Murray should be implemented immediately. "This is a clear recommendation that a structural and operational action be prioritised over a volumetric flow action and it also clearly acknowledges that environmental benefits can accrue from such targeted actions irrespective of volume" flows for the environment.
Despite this recommendation, the report provided "no trade-offs" between increased environmental flows and other "non-flow" measures. It continued to insist that environmental flows were needed to improve river health.
"This tenet is fundamentally wrong from ecological and managerial perspectives and must be changed if river health management is going to be balanced and successful," Benson says.
He adds, "the environmental benefits of many options were underestimated" because they were never properly evaluated to test what benefits they would generate for the river.
Further, the results of the MDBC report provide "no justification for the return of more than a minimal volume of water to the river or floodplain."
The object of the MDBC report was to provide the best possible outcome for the environment, with the least impact on water users in the basin. To that end, Dr Benson says that the COAG decision last year to commit up to 500GL for environmental flows may well achieve that end if used according to locally determined measures with a holistic and balanced environmental framework that includes options beyond just increased river flows.
Dr Benson was critical of the MDBC report for being over reliant on the Murray Flow Assessment Tool (MFAT), used to model the effect on river health of increased environmental flows. He said the MFAT results cannot be validated in the real world. It is a limited tool as it primarily models flow related habitat, where as in the real world there are 22 key factors that together determine river health.
Dr Benson recommended that the MDBC report be rewritten following a realistic evaluation of the many uncertainties that make the results of the MFAT model very limited.
He said that the aims of The Living Murray
should be modified to include the many other issues important in river health, rather than just focusing on environmental flows.
Further, more time should be allocated to getting the science right so as to determine the best policy. The MDBC report "was extraordinary for the number of times it mentioned the time constraints placed on the process and for the caveats put on outcomes ... 'Best scientific information available' should not be interpreted to mean 'best guess' or best opinion." To this end it is essential that the results of decided actions be measurable against meaningful targets. Those targets cannot be based on the defective MFAT model.
Dr Benson was supportive of the COAG decision to focus on improving the health of "icon sites", rather than the whole river. This was conducive to a "bottom up" management approach involving local communities and to coordination across the different icon sites, rather than to a top down approach.
He said that these sites logically would become the test sites for a range of measures needed to achieve environmental targets.
"Some of the sites already have a significant bank of knowledge regarding their structure and function, even to the stage of having management plans in place. This should be used to maximum benefit," Dr Benson concluded.