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Are environmental water requirements being met in the Murray-Darling Basin, Australia?

Fran Sheldon , Eytan Rocheta, Celine Steinfeld, Matthew Colloff , Brad Moggeridge, Emma Carmody, Terry Hillman, Richard Kingsford , Jamie Pittock

Abstract

Context: In implementing the Murray–Darling Basin Plan jurisdictions have defined environmental water requirements (EWRs) for sites along Basin rivers. EWRs are the flows (frequency, magnitude, duration, and timing) required to achieve environmental outcomes; they are derived from flow-ecology relationships using best available scientific knowledge. Aims: To assess EWR achievement across the Murray-Darling Basin over a 43.5-year period (01.07.1979 – 31.12.2022) that included periods of drought as well as widespread flooding. Methods: Using a published EWR assessment tool we analysed the achievement of EWRs for small fresh, large fresh, bankfull and overbank flows for 23 sites. Key Results: At 65% of stream gauge sites assessed, most EWRs evaluated had not been met. We also compared analyses of different time periods: a 43.5-year period, and a 10-year period since the Basin Plan was legislated. This highlighted some improvement in EWR achievement for the small fresh EWR. Conclusions: Despite some improvements, the continued lack of achievement in meeting EWRs is likely a major contributing factor to the ongoing poor health of channel, wetland (including Ramsar wetlands) and floodplain ecosystems across most of the rivers of the Murray–Darling Basin.

MF23172  Accepted 24 April 2024

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