Wirtz Dam, owned by LCRA, creates Lake LBJ.

Wirtz Dam was built from 1949 to 1950 primarily to provide additional hydroelectric power. It was built in tandem with Starcke Dam downstream. Lake LBJ provides cooling water for LCRA's Thomas C. Ferguson Power Plant along Horseshoe Bay.

The dam and lake originally were called Granite Shoals. The dam was renamed in 1952 for Alvin J. Wirtz who was instrumental in LCRA's creation and served as its first general counsel. The lake was renamed in 1965 for another advocate of LCRA, President Lyndon B. Johnson.

For information about parks on Lake LBJ, see map of parks and preserves.