Their mountain tributaries have been diverted in full or part for hydro-electricity generation and irrigation, including the upper Snowy, upper Murrumbidgee and Goodradigbee, and upper Murray and Geehi rivers.
These rivers flow from Kosciuszko National Park, the largest national park in NSW, with extensive wilderness areas and unique plants and animals. The park encompasses the NSW ski fields.
From 1947 the upper catchments of the Snowy, Murray and Murrumbidgee rivers were diverted and regulated with the development of the Snowy Mountains Hydro-electric Scheme. Using a combination of weirs, tunnels and dams, the scheme directs water into storages and diverts east-flowing water from the Snowy and upper Murrumbidgee catchments into the west-flowing Murray and Tumut rivers for hydroelectricity generation and irrigation supply.
The Snowy Water Inquiry was commissioned in 1998 to investigate a range of issues including environmental concerns arising from the altered flow patterns of the rivers and creeks caused by the operation of the Hydro-electric Scheme. The Snowy Water Inquiry Outcomes Implementation Deed (SWIOID) is the legally binding intergovernmental agreement between NSW, Victoria and the Commonwealth that provides a framework for the implementation of the outcomes arising from the inquiry. A revised balance between electricity generation and environmental management was established by the NSW parliament in the Snowy Hydro Corporatisation Act 1997 (the Act), and between the NSW, Victorian and Commonwealth governments in various bilateral and multilateral deeds, principally the Snowy Water SWIOID.
The Act requires Snowy Hydro to hold the Licence which must give effect to the SWIOID. The Licence is administered by the Ministerial Corporation. The NSW Minister for Water delegates the functions of the Ministerial Corporation to the Department of Planning and Environment–Water (DPE–Water).
The Act requires Snowy Hydro Limited to manage the storage and release of water in the Snowy and montane waterways in accordance with a Snowy Water Licence administered by the Ministerial Corporation, and by delegation Department of Planning and Environment - Water (DPE–Water). This licence implements the agreement of Commonwealth, NSW and Victorian governments to provide environmental flows to the Snowy River and to selected montane rivers, set in place at the corporatisation of Snowy Hydro Limited (now wholly owned by the Australian Government).
NSW DPE–Biodiversity Conservation & Science works closely with DPE Water, the Snowy Advisory Committee, Snowy Hydro Limited and partner agencies in NSW and Victoria to plan for and manage these environmental flows to achieve positive environmental outcomes for the Snowy and montane rivers.