The Snowy Scheme was designed to cope with large variability in inflows.
Over the last 110 years, for which we have recorded data, annual Scheme inflows have ranged from just 683 gigalitres (GL) in 2006/07 to 5761GL over a century ago in 1917. The long-term average is just below 2800GL. Around 50% of Scheme inflows are received from runoff from snowmelt and rain during spring.
We measure ‘Active Storage’ and ‘Gross Storage’. Active storage is the water that can be accessed by either pumping, or through release via dams or through power stations. Gross storage is the total amount of water behind the dam wall, including the water that cannot be accessed under normal operation of the Scheme.
For the purposes of our business operations, active storage is used, whereas recreational users are generally more interested in, and familiar with, gross storage.
We report weekly lake levels at Jindabyne, Eucumbene and Tantangara and snow depths at Spencers Creek, Deep Creek and Three Mile Dam.