Melbourne Water are investigating a range of opportunities to recover water for the environment in response to environmental water shortfalls identified in the Healthy Waterways Strategy 2018. Amongst these opportunities, alternative water sources such as stormwater generated in urban growth areas are being considered.
Streamology and Melbourne Water developed a framework for distributed environmental flow delivery using alternative water sources such as excess urban stormwater. The project proposed the use of distributed storage and treatment assets to harvest and release stormwater strategically to improve flow conditions in stressed river systems and mitigate the impacts of urbanisation in a dual benefit solution. Recommendations draw on the latest research and technology in stormwater, environmental flows, and urban waterway health to ensure the protection and net benefit for the surplus source catchment and shortfall waterway.
The flexible framework guides the identification, assessment and delivery of distributed e-flow opportunities across seven stages - from understanding the catchment and flow regimes to identifying risks, developing opportunities and applying adaptive management. The framework is underpinned by principles of e-flow compliance, climate resilience, urban impact reduction, feasibility, consultation and governance.
The framework was applied to two contrasting catchments, the high value but low urban growth catchment in the Eastern Yarra, and a significant growth area in Sunbury. The analysis demonstrated the viability in achieving meaningful e-flow outcomes, while demonstrating how to prioritise sub-catchments with both stormwater surpluses and e-flow shortfalls. Constraints such as terrain, land availability, and infrastructure feasibility were also explored in multi-criteria and cost-benefit analyses.