The Guadalupe Delta Wildlife Management Area consists of approximately 6,200 acres of marshes. It is basically a freshwater marsh subject to flooding from the Guadalupe River and its adjacent bayous. The volume of freshwater the Guadalupe River discharges, along with the shallowness of adjacent bays, contribute to extremely low salinity in those bay systems as compared to other bay systems in Texas. The estuary at the upper end of San Antonio Bay provides valuable spawning and nursery habitat for red drum, Atlantic croaker, spotted seatrout, brown shrimp, white shrimp, blue crab, and other marine species. The first recorded inhabitants of the Guadalupe Delta area were the Karankawa Indians. Campsite remains are still evident at prominent points and high banks along bay shores.