An environmental flow (or e-flow) is any managed change in water flow pattern intended to maintain or improve the health of a river or wetland and with the aim of achieving key ecological objectives such as:
Environmental flows in Victoria are regulated under Bulk Entitlements that provide rivers and wetlands with water exclusively for environmental use. Environmental Entitlements in Victoria are held by the Victorian Environmental Water Holder (VEWH), established under an amendment to Section 33DZA of the Victorian Water Act 1989. Additional water holdings, such as the Living Murray Entitlement, can be sourced through a competitive bidding process.
The Commonwealth Environmental Water Holder (CEWH) also holds environmental water in north central Victorian storages (including wetlands and built storages).
In addition to these formally recognised water holdings, the environment can benefit from river operations, such as the delivery of consumptive water to licensed irrigators.
In the North Central CMA region environmental flows are delivered to our regulated waterways, including the Campaspe and Loddon Rivers, Birch's Creek, and wetlands such as the Boort District wetlands, Central Murray wetlands and Gunbower Forest.
Environmental flow recommendations for river systems and wetlands are based on the current best science. For rivers they are generally broken down into seasonal components including:
Bank full and Overbank flows are never delivered as managed environmental flows, rather we rely on nature to provide them.
Wetland environmental watering is based on defined watering regimes which may run over a number of years. Environmental flows for wetlands include filling from empty, top-ups and periods of drying, sometimes to completely dry. This is in an attempt to mimic natural wetland filling patterns.
Regulation of Victoria's river systems and wetlands has had significant impacts on river and wetland health. Storing water and releasing it for irrigation during seasonally dry periods (spring and summer) has altered flow characteristics, leading to declines in fish numbers, riparian vegetation health, water quality and aquatic ecosystem health.
Many wetlands in northern Victoria have been used for water storage or as outfalls for irrigation water, meaning their natural filling and drying cycles have been significantly altered. This has had ramifications for waterbirds, particularly breeding and feeding, fringing and aquatic vegetation and water quality.
Environmental flows help river and wetland ecology by triggering fish movement and breeding, enhancing the condition of riparian and aquatic vegetation, reducing black water and algal bloom risks and providing enhanced feeding and breeding opportunities for waterbirds.
Environmental flows also perform important chemical and physical functions, such as nutrient and carbon cycling, bed and bank maintenance and scouring of pools to provide habitat and refuge.
Rivers and wetlands are important to local communities, providing water for stock and domestic supply, recreational and cultural uses. Environmental flows are one of the ways the North Central CMA manages waterways to enhance both the ecological and human values.
Combined with a range of river and wetland restoration activities, such as fencing, revegetation, off-stream watering and erosion control, we can look forward to healthier catchments with improved water quality and ecological conditions, which benefit the whole community.
Water is delivered to a number of assets in the North Central CMA region:
General information about all Victoria's proposed watering activities for 2012-13 can be found in the VEWH's Seasonal Watering Plan which is available for download at http://www.vewh.vic.gov.au/news-and-resources/resource-library/seasonal-watering-plan.
The North Central CMA acknowledges its partners and stakeholders in environmental watering across north central Victoria: