Purgatory Creek flows into the San Marcos River just south of the rapidly-growing central Texas City of San Marcos. The creek is part of an extensive series of watersheds and rivers located in the southern portion of Hays County, and it lies directly over the Edwards Aquifer Recharge Zone. The aquifer is a massive underground river, and a vital source of drinking water for Central Texans. Bounded by limestone outcrops, the creek's meander also supports open savannas and dense woodlands of oak, juniper, and mesquite, and provides critical habitat for the endangered golden-cheeked warbler, black-capped vireo, and many other rare and endemic species.
In 2003, the City of San Marcos acquired the 463-acre Purgatory Creek Natural Area (PCNA), a favorite destination for hikers and naturalists. Recently, the Trust for Public Land acquired a 107-acres near the PCNA, which has been incorporated into this protected open space. An additional 93 acres are expected to be acquired and protected by the end of 2013. The Trust for Public Land intends to continue its work with the City of San Marcos, Hays County, and many other advocates, to expand the PCNA and ultimately help create an unfragmented 1000-acre stretch of habitat, watersheds, and hiking trails for residents and visitors alike.