The Devils River NFCA is situated in an ecological transition zone at the confluence of three biotic provinces (Chihuahuan, Balconian and Tamaulipan) and as a result supports a high level of aquatic biodiversity and endemism. This NFCA includes the Devils River which extends 100 km from its headwaters at Pecan Springs to Amistad International Reservoir and San Felipe Creek in Del Rio. The springs of the Devils River and surrounding area are fed by the Edwards-Trinity Plateau Aquifer, which produces the largest number of springs in Texas, with 46 occurring in Val Verde County alone, as well as the third (Goodenough Springs) and fourth (San Felipe Springs) largest springs in the state (Brune 1981).

Goodenough Springs, now covered by Amistad Reservoir, still maintain a significant discharge under the lake surface (Ashworth and Stein 2005). Amistad Gambusia Gambusia amistadensis was endemic to the headsprings and the 1.3-km spring run downstream to its confluence with the Rio Grande (Peden 1973), but inundation by the reservoir resulted in its extinction. The primary threat is groundwater extraction and the resultant reduction or loss of spring flows. Biodiversity is well represented by the fishes of this region including the federally endangered Mexican Blindcat Prietella phreatophila, federally threatened Devils River Minnow Dionda diaboli and state threatened Proserpine Shiner Cyprinella proserpina, Spotfin Gambusia Gambusia krumholzi, Blotched Gambusia Gambusia senilis, Conchos Pupfish Cyprinodon eximius, Rio Grande Darter Etheostoma grahami as well as  Manantial Roundnose Minnow Dionda argentosa, Tamaulipas Shiner Notropis braytoni, Rio Grande Shiner Notropis jemezanus, West Texas Shiner Notropis megalops, Longlip Jumprock Moxostoma albidum, Headwater Catfish Ictalurus lupus, and Rio Grande Largemouth Bass Micropterus salmoides nuecensis. In addition to the focal fish species, other species of concern include the Rio Grande Cooter Pseudemys gorzugi, Spring Salamander Eurycea spp. and endemic spring invertebrates. American Beaver Castor canadensis also inhabit the river, but suffer from habitat loss, changes to the natural hydrological regime, competition with non-native Nutria Myocastor coypus, decreased food supply and the presence of the invasive and exotic Giant Reed and Saltcedar.

Although most of the Devils River flows through private property, several conservation areas and initiatives exist within the basin. The Texas Parks and Wildlife Department currently protects 15,000 ha in the Devils River State Natural Area. In addition, The Nature Conservancy owns and manages the 1,900 ha Dolan Falls Preserve and a total of 63,000 ha of private and public lands are currently under conservation easements (Garrett et al. 2014).

Sources

Ashworth, J.B., and W.G. Stein. 2005. Springs of Kinney and Val Verde counties. Prepared for Plateau Regional Water Planning Group, LBG-Guyton Associates.

Brune, G. 1981. Springs of Texas. Vol. I. Fort Worth: Branch-Smith.

Garrett, G.P., J. Karges, and E. Verdecchia. 2014. Devils River. Pages 29-30 in M. D. Wesson, C. Hallmich, J. Bennett, C. Sifuentes Lugo, A. Garcia, A. M. Roberson, J. Karges, and G. P. Garrett, editors. Conservation Assessment for the Big Bend-Río Bravo Region: A Binational Collaborative Approach to Conservation. Montreal QC: Commission for Environmental Cooperation.

Peden, A.E. 1973. Virtual extinction of Gambusia amistadensis n. sp., a poeciliid fish from Texas. Copeia 1973: 210-221.