Springs from the Edwards Aquifer are the sources of tributary rivers to the Guadalupe River. Water from the Edwards Aquifer flows from Comal Springs in New Braunfels into the Comal River. Water from the Edwards Aquifer flows from San Marcos Springs in San Marcos into the San Marcos River. The Comal and San Marcos Rivers are major tributaries to the Guadalupe River.
The average annual contribution of Comal & San Marcos Springs discharge to the Guadalupe River is 373,000 acft. The average discharge of the Guadalupe is 1.25 million acft. While the contribution of the springs during droughts decreases as surface water runoff is unavailable, it actually increases in terms of the proportion of the flow that is provided during droughts. For example, during portions of 1996 the springs accounted for 70% or more of the flow reaching Victoria and nearly 40% of what reached San Antonio Bay. There are seven endangered and one threatened species that live in Comal and San Marcos Springs. These aquatic species are protected by the federal Endangered Species Act.
Below you will find information regarding the regulation, management, hydrology, policy and natural history of the Edwards Aquifer.