Natural History

The Water

halftonefish NATURALJust as the San Antonio River is central to the area’s history, it is at the heart of the basin’s natural resources. It provides the most precious of those resources: water. The river is formed by the conjoined spring waters of the Blue Hole and Olmos Creek, and fed by 4,186 square miles of watershed, including the Medina River and creeks with lyrical Spanish names: Alazán, Medio, Leon, Salado, San Pedro, Marcelinas, Conquista, Cibolo, Ecleto, Escondido and Manahuilla.

The full course of the River flows 240 miles through Bexar, Wilson, Karnes, Goliad and Refugio counties, converging with the Guadalupe River before finally spilling into San Antonio Bay on the Gulf of Mexico. Beneath the river basin counties lie South Texas’ other water source, the aquifers: Edwards, Carrizo-Wilcox, Trinity and Gulf Coast.

The Wildlife

dillopear NATURALThe San Antonio River creates a rich riparian environment that provides a menagerie of South Texas wildlife with water and cover. Daylight may expose deer, nutria, beavers, turkeys, quails and doves to human sight, but nighttime conceals the activities of raccoons, opossums, bobcats, owls, coyotes and, rarely, pumas. A king’s ransom of avifauna attracts birders from around the world, eager to add a Crested Caracara or vibrant Painted Bunting to their life lists. While whitetail and bird hunting has always been an important part of the basin economy, ecotourism is also making its mark, with birders, hikers and river paddlers coming to basin communities to pursue their interests. All the more reason to protect, preserve and promote the river basin habitat.

The Land

Most of the San Antonio River Basin runs through a hardscrabble land of deep soil, scant rain and short, tough, brushy vegetation. Balcones Canyonlands associated with the Edwards Plateau tip into the northern edge of the Basin with limestone hills, live oaks and ash juniper. A swath of rich Blackland Prairie occurs a little farther south, providing a gently rolling, exuberantly fertile area for farming. To the east, Post Oak Woodlands make a slender inroad into northeast Wilson County and account for the hickory trees and gray squirrels found there. All the way to the south, as the river approaches the sea, it meanders through flat coastal prairies and marshes, where the air is laden with moisture and the growing season is long.