Lake Lyndon B. Johnson (or Lake LBJ) is a reservoir on the Colorado River in the Texas Hill Country in the United States. The reservoir was formed in 1950 by the construction of Granite Shoals Dam by the Lower Colorado River Authority. The Colorado River and the Llano River meet in the northern portion of the lake. The lake was originally called Lake Granite Shoals. The dam would be renamed Wirtz Dam in 1952 for Alvin J. Wirtz, the first general counsel of the LCRA, and the lake was renamed to Lake Lyndon B. Johnson in 1965 in honor of U.S. President Lyndon Baines Johnson. In addition to his work to enact the Rural Electrification Act that formed the basis for building the Highland Lakes, President Johnson owned a ranch on the lake (which was separate and apart from the LBJ Ranch in Stonewall, Texas), and he and Mrs. Johnson entertained national and foreign dignitaries on the lake during his vice presidency and presidency.
The towns of Granite Shoals, Kingsland, Horseshoe Bay, Highland Haven, and Sunrise Beach are located on the lake, which is also near Marble Falls. The lake is used as a venue for aquatic recreation and provides cooling water for the Thomas J. Ferguson power plant operated by the LCRA. The boundary line separating Burnet County and Llano County runs down the center of the lake.
Lake LBJ has been stocked with several species of fish intended to improve the utility of the reservoir for recreational fishing. Fish present in Lake LBJ include largemouth bass, white bass, catfish, and crappie. Lake LBJ is one of the Texas Highland Lakes infested with hydrilla, a non-native aquatic plant species, and the LCRA is undergoing treatment to eradicate the hydrilla.