Windamere Dam

Windamere Dam is a minor ungated rock fill with clay core embankment dam with an uncontrolled unlined rock cutting spillway across the Cudgegong River at Cudgegong, upstream of Mudgee in the Central Tablelands of New South Wales, Australia. The dam's purpose includes hydro-power, irrigation, water supply, and conservation. The impounded reservoir is called Lake Windamere.

Location and features
Commenced in 1974 and completed in 1984, the Windamere Dam is a minor ungated dam, located approximately 19 km south-west of Rylstone. The dam was built by Abignano Pty Ltd on behalf of the New South Wales Department of Land and Water Conservation to supply water for irrigation and potable water for the towns of Mudgee and Gulgong. Windamere Dam operates in conjunction with Burrendong Dam to supply water to the Cudgegong and Macquarie valleys.

The dam wall constructed with 1740 m3 of rock fill with clay core is 67 m high and 825 m long. The maximum water depth is 58 m and at 100% capacity the dam wall holds back 368120 ML of water at 552 m AHD. The surface area of Lake Windamere is 2030 ha and the catchment area is 1070 km2. The uncontrolled unlined rock cut spillway is capable of discharging 6270 m3/s.

Geotechnical problems included excessive grout takes in highly fractured rock in the dam foundation. The dam foundations are weathered Devonian conglomerates, sandstones and shales. The spillway is located about 1 km away from the dam wall in mostly unweathered Ordovician andesite. The spillway is an unlined rock cutting that provided all the rock fill required for the construction of the dam embankment. If a spillway had been built in the weathered sedimentary rocks at the dam site full concrete lining would have been required.

To allow the dam's construction, a 15 kilometre deviation of the Castlereagh Highway opened in December 1982.

Power generation
A hydro-electric power station generates up to 2 MW of electricity from the flow of the water leaving Windamere Dam.