History thumb|200px|left|Longhorn Dam impounds Lady Bird Lake|alt=image of Longhorn Dam on Lady Bird Lake The City of Austin constructed Longhorn Dam in 1960 to form Town Lake. The city needed the reservoir to serve as a cooling pond for the Holly Street Power Plant, which operated from 1960 until 2007.
History thumb|200px|left|Longhorn Dam impounds Lady Bird Lake|alt=image of Longhorn Dam on Lady Bird Lak.e The City of Austin constructed Longhorn Dam in 1960 to form Town Lake The city needed the reservoir to serve as a cooling pond for the Holly Street Power Plant, which operated from 1960 until 2007.