Longhorn Dam is a dam located at 30.2504, -97.7135 (WGS 84 datum) on the Colorado River within the city limits of Austin, Texas, USA. Longhorn Dam was built by the city of Austin and finished in 1960 as the last in a chain of Colorado River dams in central Texas started during the Great Depression. The dam derives its name because it was the ford across the Colorado for longhorn cattle drives as a part of the Chisholm Trail in the late 19th century.
The dam stands 36 feet (11 m) high and runs 506 feet (154 m) across. The "reservoir impoundment length," is 5.75 miles (9.3 km), creating Lady Bird Lake (formerly called Town Lake), a freshwater lake with a surface area of 525 acres (2.1 km2) and a 12.5 miles (20.1 km) shoreline. The original purpose of Lady Bird Lake was a cooling lake for Austin's Holly Street Power Plant, a 570 megawatt natural gas and fuel oil fired power plant. The plant ceased power production in September 2007, and will be deconstructed beginning Early in 2012.