Googong Dam

Googong Dam is a minor ungated earth and rock fill with clay core embankment dam with concrete chute spillway plus a nearby 13 m high earthfill saddle embankment across the Queanbeyan River upstream of Queanbeyan in the Capital Country region of New South Wales, Australia. The dam's purpose includes water supply for Canberra and Queanbeyan. The impounded reservoir is called Googong Reservoir.

Googong Dam was created through enabling legislation enacted via the passage of the Canberra Water Supply (Goodong Dam) Act, 1974.

History
A green ban was briefly imposed by the Builders Labourers Federation for a few days until adequate assurances that marine life in Lake Burley Griffin would not be harmed.

Location and features
Completed in 1979, the Googong Dam is a minor dam on the Queanbeyan River and Bradleys Creek and is located approximately 5 km south of the city of Queanbeyan on the lower reaches of the river. The dam was built by Thiess based on designs developed by the Commonwealth Department of Construction; and is now managed by Icon Water.

The dam wall height is 66 m and is 417 m long. At 100% capacity the dam wall holds back 121083 ML of water at 663 m AHD. The surface area of Googong Reservoir is 696 ha and the catchment area is 873 km2. The ungated concrete chute spillway is capable of discharging 10500 m3/s. Successive flood events in 1978 and through the 1980s resulted in extensive erosion in the unlined section of the spillway chute, including a large erosion hole, up to 19 m deep and 25 m wide, in the upper part of the spillway chute. Staged remedial works were undertaken in the 1980s to protect the eroded structure. Remediation of spillway facilities occurred from 2006 through to 2010 that resulted in an increase in the capacity of the spillway, construction of walls in the spillway chute extension up to 17 m high, and a range of other enhancements to meet extreme flood events.

In 2016, with more regular spillway overflows, the dam's managing authority Icon Water, installed a 240m floating safety barrier, with authorised vessel access gate, across the spillway, to improve safety for waterway users.