Snowy River environmental flows - 2011
Department Sustainability, Environment, Water, Population and Communities - November 2011
The Australian, New South Wales and Victorian governments are working to restore the Snowy River's mighty flows and the aquatic habitats they support.
Over 19 days in October 2011, 84 billion litres of water - about 42,000 Olympic swimming pools worth - was released from the dam in an exercise carefully managed by Snowy Hydro Limited and the New South Wales Office of Water.
The Snowy River is raging once again thanks to an agreement by the New South Wales, Victorian and Australian governments.
In the 40 years Jill and Bruce Hodges have lived by the Snowy River, they've never seen it quite like this before.
Bruce Hodges: “Well a granddaughter came down yesterday and said ‘Oh you're not beside the river, you look like you're beside the ocean,’ when she could see it from the house. It's quite a different view. We can normally hear the river at home, but at night time now …”
Jill Hodges: “It's quite loud.”
Bruce Hodges: "Even me with my bad hearing can hear what's going on."
The river started roaring past the Hodges' property after a mass of water was let loose from Jindabyne Dam, just upstream, to increase environmental flows.
Over 19 days in October 2011, 84 billion litres – about 42,000 * Olympic swimming pools worth – were released from the dam in an exercise carefully managed by Snowy Hydro Limited and the New South Wales Office of Water.
The river's headwaters run from Mount Kosciuszko, Australia's highest peak, and historically its naturally fast flows are a result of rain and melting snow gathering speed in the mountainous catchment.
But with regulation of the Snowy River in the sixties, these fast snow-fed flows have all but disappeared.
Without strong flows to flush the system, silt and rocks have built up, smothering habitat for native species.
In 2010, top-layer silts were effectively dislodged from the river bed by a smaller release of nearly 17 billion litres of environmental water, the first of its kind in the Snowy River.
This 84-billion-litre release is five times bigger and strong enough to flush out rocks the size of footballs, allowing silt trapped underneath to also be washed away.
Simon Williams, New South Wales Office of Water: “All the rocks on the top are heavily armoured, they're all locked together, and below those rocks is a series of heavy silts and muds. We want to move the rocks and scour the silt and mud out of the bottom of the river.”
The clean river bed will provide habitat for the invertebrates that native animals, including platypus, feed on.
Scientific monitoring will track the long-term success but already there are promising signs.
Simon Williams, New South Wales Office of Water: “A lot of the plants that are growing into the river channel, we actually saw them when the water was first released actually being picked up and moved down the river, which is what we want; we want to be able to create a more defined river channel, we want that vegetation out of the channel.”
The releases are timed in spring to mimic the high flows the river experiences under natural conditions as snow melts off the Snowy Mountains and runs into the river channel.
Spring releases of this year's scale are set to become an annual event for the Snowy River, except in dry years, thanks to investment by the New South Wales, Victorian and Australian governments.
* based on 1 GL or 1 billion litres = 500 Olympic swimming pools