Official name Longhorn Dam Impounds Colorado River Height 11 m Length 154 m Create Lady Bird Lake | Opening date 1960 (1960) Creates Lady Bird Lake Opened 1960 Surface area 191 ha Operator Austin | |
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Location Austin, Texas, United States Similar Lady Bird Lake, Colorado River, Tom Miller Dam, Mansfield Dam, Lake Austin | ||
Longhorn Dam is a dam crossing the Colorado River in Austin, Texas, United States, where it creates Lady Bird Lake. Completed in 1960, the dam was built by the City of Austin as the last in a chain of Colorado River dams in central Texas begun during the Great Depression. The name refers to its location on a ford used for longhorn cattle drives as a part of the Chisholm Trail in the late 19th century.
Contents
- Map of Longhorn Dam Austin TX 78702 USA
- History
- Geography and hydrography
- Structure and function
- References
Map of Longhorn Dam, Austin, TX 78702, USA
History
Longhorn Dam was constructed in the late 1950s to establish a cooling reservoir for Austin's Holly Street Power Plant, a 570-megawatt natural gas and fuel oil-fired electrical power plant. The reservoir it created, Lady Bird Lake, was also originally used as a source of drinking water for the city. In 2007 the power plant was decommissioned and subsequently demolished to make way for a new lakeside urban park; today the reservoir's major uses are recreation and fishing. The stabilization of the downtown shoreline that the dam afforded enabled substantial parkland development along the newly created lake, including Auditorium Shores and other parts of Town Lake Park.
In the 2000s and 2010s the ageing dam's floodgates experienced a series of malfunctions, causing on some occasions the loss of substantial amounts of water down the river (when gates failed to close properly) and on some occasions significant flooding along Lady Bird Lake (when gates failed to open). The dam is operated by Austin Energy, the city power utility, but it is not a hydroelectric dam and generates no electrical power; since the Holly Power Plant's closure the dam has received little maintenance. City officials have estimated the cost of repairing or replacing the dam in the tens of millions of dollars.
Geography and hydrography
Longhorn Dam is located at 30.2504°, -97.7135° (WGS 84 datum), with a full water level at 428 feet (130 m) above sea level. 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 471 acres (191 ha). Water release through the dam varies with rainfall and with the seasonal demand for irrigation water downstream.
Structure and function
The dam stands 36 feet (11 m) high and runs a length of 506 feet (154 m) across the Colorado River. It includes nine floodgates that are used to control water release and maintain a stable water level in the reservoir. Two are bascule gates that passively allow water to flow through to maintain Lady Bird Lake's water level; the other seven are lift gates that are controlled manually to adjust water flow in response to weather conditions and water releases for downstream ecology and irrigation.