Water Resources
The South Central Texas Region includes parts of six major river basins (Rio Grande, Nueces, San Antonio, Guadalupe, Lavaca, and Lower Colorado) and overlies the Edwards-Balcones Fault Zone, Gulf Coast, and southern parts of the Trinity, and Carrizo-Wilcox Aquifers. In addition to these water resources, the area also overlies two minor aquifers (Queen City and Sparta Aquifers). Details about these water resources are presented in South Central Texas Water Management Plan Report.
Springs also serve as a significant water resource in the South Central Texas Region. The two most noteworthy springs are the Comal and San Marcos Springs, which both contribute to flow in the Guadalupe River. The San Marcos Springs have the greatest flow dependability and environmental stability of any spring system in the southwestern United States. Constancy of its spring flow is apparently key to the unique ecosystem found in the uppermost San Marcos River. Comal Springs, located in New Braunfels, serve as the source for the Comal River, which is a tributary of the Guadalupe River. Unlike the San Marcos Springs, Comal Springs are more responsive to drought conditions and ceased flowing in June of 1956 in response to severe drought conditions.
Land Resources
About 21 percent of the 20,025 square miles of land area in the planning region is in cropland, one-tenth of which is irrigated. Corn, grain sorghum, wheat, rice, soybeans and vegetables are major crops. Rangeland grazing is important in about 38 percent of the area. Cow-calf operations are the most predominate type of livestock industry, although beef cattle, hogs and pigs, sheep and lambs, and poultry are also produced. Urban land uses constitute only about 2.6 percent of the land area with other uses making up the remaining 38.4 percent.
Wildlife Resources
Virtually all wildlife habitat in the South Central Texas Region is on privately-owned farm and ranch land. Common types of wildlife found in the area include white-tailed deer, raccoons, ringtails, gray foxes, coyotes, beaver, bobcats, and several species of skunks. Wintering songbirds such as robins and cedar waxwings may also be found. A key concern in the South Central Texas Region is that of threatened and endangered species. There are approximately 123 species listed in the planning region by the U.S. Fish and Wildlife Service or the Texas Parks and Wildlife Department as threatened or endangered (See Appendix A*). Some of the more common endangered species include the Bald Eagle, Golden-Checked Warbler, Guadalupe Bass, American Peregrine Falcon, Arctic Peregrine Falcon and the Sheep Frog.
The subterranean aquatic habitats associated with the Edwards Aquifer support a diverse ecosystem. Vertebrates and macroinvertebrates have been found at depths ranging from 190 to 2,000 ft in the artesian parts of the aquifer. The Edwards Aquifer is the only underground aquatic habitat in Texas in which vertebrate species live. Several Edwards springs support populations of Eurycea neotenes, the Texas Salamander, a rare species that is restricted to, and dependent on spring habitats. This type of adaptation is not uncommon in constant temperature spring habitats, and may go even farther, to endemism, wherein a species may be entirely restricted to a particular spring. See Appendix B* for a listing of threatened or endangered species found in the Edwards Aquifer and related springs.
