Rivers & Ecology
The San Marcos River supports rare species found nowhere else
The San Marcos River runs about 75 miles from the springs in San Marcos and carries water that supports species that live nowhere else on Earth.
The river starts at the Edwards Aquifer springs in San Marcos and flows southeast to join the Guadalupe River near Gonzales. Because it is spring-fed, it keeps flowing even during droughts when other rivers in the area dry up. Texas wild rice and the Texas salamander live only in this river system.
Most of the riverbank is privately owned. Public access points include spots in downtown San Marcos and at Palmetto State Park near Luling (outside the county). Any drop in spring flow from aquifer depletion could permanently harm these species. For current access information, check with the City of San Marcos or TPWD.
Source to confirm: Handbook of Texas — San Marcos River