In 1849, General Edward Burleson constructed a crib and rock dam at the headwaters of the San Marcos River to power a saw and grist mill, creating Spring Lake above the San Marcos Springs. Since then, Spring Lake Dam has continued to play an important role in San Marcos through power generation for the city and the creation of the Aquarena Springs theme park. The dam also has ecological importance, as the upper San Marcos River is one of the most diverse aquatic ecosystems in the United States, and Spring Lake provides critical habitat for eight endangered species. Texas State University purchased the property in 1994 and has worked to convert Spring Lake and the surrounding area into an educational center and ecological preserve. Over its 123-year lifetime, the dam has been modified and repaired several times, but the rock and crib dam remains mostly unchanged from its original construction. Portions were damaged by significant floods in recent years, and Texas State University, working with its partners, is planning repairs and modernization while seeking input from stakeholders and regulatory authorities as part of a long-term commitment to stewardship and preservation of the headwaters of the San Marcos River.