The Mannus Lake Dam is located on Mannus Creek, approximately 4.5km south west of the town of Tumbarumba on the western side of the Snowy Mountains, NSW. The dam was originally constructed by a private developer in 1985. The former dam wall consisted of earthfill embankment with height to approximately 10m. Mannus Lake has a catchment area of around 400 km2, and a storage volume of approximately 2,300 ML.
Tumbarumba Shire Council purchased the dam from the private owner in 1999. During the 2010 natural disaster event, the dam wall failed as a result of flood water overtopping on the night of 15 October 2010. The majority of the right half of the dam embankment was lost during the flood event. Prior to the breach, Mannus Lake (created by the dam) was a popular location for recreational fishing, boating, bush walking and bird watching, creating economic benefits to industry and tourism in the Tumbarumba area.
In July 2011, Tumbarumba Shire Council was granted financial assistance under the Natural Disaster Relief & Recovery Assistance (NDRRA) Program to restore the Mannus Dam. The primary objective of re-building the dam wall was to restore the recreational amenity provided by Mannus Lake for Tumbarumba and the surrounding region.
The rebuilt Mannus Lake Dam was officially opened on 6 February 2015 by the Hon. Michael McCormack MP, Federal Memember for Riverina and the Hon. Gladys Berejiklian MP, NSW Minister for Transport.