Our seminar in March brought us up to speed on developments and achievements in environmental flow determination and delivery in Victoria. The seminar kicked off with Paulo Lay (DEPI) presenting the Victorian Government’s perspectives on the Murray Darling Basin Plan, particularly the use of works and measures to efficiently deliver environmental water. Using works, such as pumps and other built structures, less water is required to target high priority areas such as threatened ecological communities or areas higher up on the floodplain. The constraints of environmental water delivery include available channel capacity, particularly at certain times of the year, the risks associated with flooding private land and that water delivered through works won’t always replicate ecological functions. Paulo emphasised the importance of finding the balance between providing water for the community and delivering water for the environment, and that works help to achieve the same benefits with less water.
Bill Moulden (Melbourne Water) presented a case study on the Werribee River and some of the issues in delivering flows, including determining flow objectives. The Werribee has suffered from substantial flow reductions with, for example, up to 50% of flows upstream of Melton being extracted. Objectives in the estuary focused on black bream and at creating a salt wedge. However upstream on the Pyrites Ck (a tributary), reach objectives were less clear: what environmental outcomes should you seek to achieve in a reach that has been permanently changed by regulation?
Simon Treadwell (Jacobs SKM) highlighted some of the issues that had arisen in the past FLOWS method and how the revised method sought to address these. The sparkling new version 2 FLOWS method should ensure stronger links between flow recommendations and ecological outcomes, highlight and explain areas of uncertainty, better reflect climate variability, consider the risk to objectives if flow recommendations are not met and better account for surface water – groundwater interaction. Version 2 of the FLOWS method can be downloaded here.
About a third of Victoria’s stream flow is extracted for agriculture, industry, domestic and other human uses. This, combined with our highly variable climate, can leave our waterways degraded and struggling to support vital aquatic and riparian ecosystems. Environmental flows are used to try to minimise the ecological and geomorphic impacts of unnaturally depleted stream flow throughout Victoria. How are these flows determined? How are they delivered? How effective are they? What have we learnt from past releases and how has our approach developed over time?
We will consider these issues and more as we hear about the method for determining environmental flows and how this has changed recently along with examples of environmental flows in practice in the Werribee River and the Murray Darling Basin.
Hosted by the RBMS, the seminar will include presentations from:
Simon Treadwell, SKM
Bill Moulden, Senior Environmental Flow Planner, Melbourne Water
Paulo Lay, DEPI