Longhorn Dam is a

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, a ...

crossing the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid drainage basin, watershed that encompasses parts of ...

Austin Austin is the capital city of the U.S. state of Texas, as well as the seat and largest city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the 11th-most-populous city ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, 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 Central Texas is a region in the U.S. state of Texas surrounding Austin and roughly bordered by San Saba to Bryan and San Marcos to Hillsboro. Central Texas overlaps with and includes part of the Texas Hill Country and corresponds to a ph ...

begun during the

Great Depression The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagio ...

. The name refers to its location on a ford used for longhorn cattle drives as a part of the

Chisholm Trail The Chisholm Trail was a trail used in the post-Civil War era to drive cattle overland from ranches in Texas to Kansas railheads. The trail was established by Black Beaver, a Lenape guide and rancher, and his friend Jesse Chisholm, a Cheroke ...

in the late 19th century.

History

Longhorn Dam was constructed in the late 1950s to establish a cooling reservoir for Austin's

Holly Street Power Plant The Holly Street Power Plant was initially constructed in 1958 to serve the growing Austin Community. This electric power plant ran off natural gas and petroleum. It was constructed from 1958 till 1974, but began to produce electricity in 1960. Th ...

, a 570-megawatt

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

and

fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...

-fired electrical

power plant A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many pow ...

. The reservoir it created, Lady Bird Lake, was also originally used as a source of drinking water for the city. It is not a

hydroelectric dam Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

and generates no electrical power. In 2007 the power plant was decommissioned and subsequently demolished to make way for a new lakeside

urban park An urban park or metropolitan park, also known as a municipal park (North America) or a public park, public open space, or municipal gardens ( UK), is a park in cities and other incorporated places that offer recreation and green space to resi ...

; today the reservoir's major uses are recreation and fishing. The stabilization of the

downtown ''Downtown'' is a term primarily used in North America by English speakers to refer to a city's sometimes commercial, cultural and often the historical, political and geographic heart. It is often synonymous with its central business distric ...

shoreline that the dam afforded enabled substantial parkland development along the newly created lake, including

Auditorium Shores Auditorium Shores is an urban park located in downtown Austin, Texas, within the larger Town Lake Park. Its name refers to its location between the former Palmer Auditorium and the shores of Lady Bird Lake. The park is known as the site of major ...

and other parts of Town Lake Park. In the 2000s and 2010s the aging 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). The dam was originally constructed and operated by

Austin Energy Austin Energy is a publicly owned utility providing electrical power to the city of Austin, Texas and surrounding areas. Established in 1895, the utility is a department of the City of Austin and returns its profits to the city's general fund to ...

, the city power utility, but Austin Water took over operations of the dam in April 2018. Since 2013, Austin Energy made several maintenance and upkeep projects to the dam such as replacing all major parts and rebuilding both hydraulic bascule systems. Austin Energy also repaired one of the gates and overhauled the mechanical lifting system. City officials have estimated the cost of replacing the dam in the tens of millions of dollars. Between 2013 and 2018, Austin Energy spent $1.6 million in maintenance and repair costs.

Geography and hydrography

Longhorn Dam is located at 30.2504°, -97.7135° ( WGS 84

datum In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted. ...

), with a full water level at above

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

. The reservoir impoundment length is , creating Lady Bird Lake (formerly called Town Lake), a freshwater lake with a surface area of . Water release through the dam varies with rainfall and with the seasonal demand for irrigation water downstream.

Structure and function

The dam stands high and runs a length of 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.

References

{{Crossings navbox , structure=Crossings , place=

, bridge=Longhorn Dam , bridge signs= , upstream=Interstate 35 Bridge , upstream signs= , downstream=

Montopolis Bridge The Montopolis Bridge is a historic Parker through truss bridge in Austin, Texas. It is located in the Montopolis neighborhood where a bicycle and pedestrian walkway crosses the Colorado River in southeastern Travis County. The bridge consists ...

, downstream signs= Dams in Texas Buildings and structures in Austin, Texas Dams completed in 1960