The objective of the Environmental Water Reserve is to preserve the environmental values and health of water ecosystems, including their biodiversity, ecological functioning and quality of water and the other uses that depend on environmental condition.
The Environmental Water Reserve is the environment’s legally protected share of water in both rivers and groundwater systems (aquifers). The Environmental Water Reserve was declared in October 2005 under the Water (Resource Management) Act 2005.
The Environmental Water Reserve can be held in storage (regulated rivers that have reservoirs), as run-of-river flows (unregulated rivers that don’t have reservoirs) or a groundwater level.
Regulated Environmental Water Reserve in a river is a volumetric entitlement plus a capacity share of a storage reservoir. Water is released to provide the environmental flow components of a river. These flow components commonly include summer low flows (baseflows), summer freshes (pulsing flows of short duration), winter low flows, winter freshes, bankfull flows and overbank flows.
Unregulated Environmental Water Reserve
Unregulated Environmental Water Reserve in a river is managed by protecting minimum environmental flow levels from harvesting at storage reservoirs or restricting/banning licensed private diversions when river flows meet environmental flow trigger levels. Examples include passing flow requirements stipulated in Wannon Water’s Bulk Entitlement for Hamilton and rosters defined within the Merri Streamflow Management Plan.
The Environmental Water Reserve for Groundwater
The Environmental Water Reserve for Groundwater is provided by capping the amount of water for extraction at or below a sustainable limit. Examples include Permissible Consumptive Volumes defined during the development of the Yangery, Nullawarre and Condah Groundwater Management Plans.
Catchment Management Authorities have the delegated responsibility for operational management of the Environmental Water Reserve. Management of the Environmental Water Reserve will:
- Aim to achieve ecological objectives for the protection and/or restoration of priority river, wetland and aquifer assets;
- Be undertaken as one key component of an integrated program of river, wetland, and aquifer restoration aimed at achieving ecological objectives;
- Aim to achieve the most effective use of environmental water, achieving the greatest level of environmental benefits possible and minimising as far as possible any adverse impacts on water users; and
- Engage communities, particularly where these are likely to be affected by the water management regime.