Recommended for inclusion in the proposed Texas Natural Rivers System. Flows through wild and rugged country with many sections of rapids. There are numerous canyons, the most spectacular ones occurring on the lower end. The Pecos River is included in the listing of significant state natural areas. It is a transitional zone for three biotic and botanical provinces and supports a variety of species, with ten protected species.
Numerous species reach the limits of their ranges in the watershed.
The river is bordered by limestone cliffs and formations. Numerous rock shelters and a few caves reveal prehistoric evidence, such as burned rock middens, pictographs and petroglyphs. River corridor is within migration route of the Whooping Crane, a federally listed endangered species. The Texas Blind Salamander, is known to exist in the upper part of Hays County. Recommended as potential component of National Wild and Scenic Rivers System.