The Colorado River Municipal Water District submitted a petition to delist the snake to the Service in June 1998, after funding and conducting research on the species from 1987 through 1996.
The petition cited research indicating that the snake was found in new locations, is surviving and reproducing in recently created reservoir habitats, and has maintained stable populations at 15 monitoring sites within its range.
In reviewing the petition, the Service found that the snakes range in the past 10 years has essentially remained the same. While the water snake has been found in a few new areas, these habitats are on the periphery of the main populations and may not survive in the long-term. While the stable population at 15 monitoring sites is good news, other criteria in the species recovery plan have not been met, such as ensuring adequate instream flows.
"The petition didnt address one of the most serious threats remaining to the snake and its fish prey base: inadequate protection of stream flows in the Colorado and Concho Rivers," said Nancy Kaufman, the Services Regional Director for the Southwest Region. "However, as additional conservation measures are implemented, including protection of river flows, the Service will reassess the need for listing this species as threatened.
Low stream flows can diminish populations of fish on which the snake feeds. Other threats to the species include sedimentation of river beds and banks, which covers the rocks where the snakes typically hide and feed, and fragmentation of the snakes habitat that can lead to genetic isolation of populations.
"The Concho water snake is one of the most thoroughly studied reptiles on the threatened and endangered species list, thanks to the research of the Colorado River Municipal Water District and graduate students at Texas A&M University," Kaufman said. The Water Districts researchers monitored 15 sites annually over a 10-year period. Texas A&M researchers intensively studied fewer sites over a 4-year period. Their combined field work has led to a better understanding of the snakes reproduction, life history, habitat associations and local population dynamics.
The range of the snake was well known prior to its addition to the threatened species list in 1986. Research through 1996 indicates that its range remains essentially the same with some changes in the San Angelo area and in the Spence and Ivie Reservoirs.
The Service published its decision in todays Federal Register.
The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting, and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 93-million-acre National Wildlife Refuge System comprised of more than 500 national wildlife refuges, thousands of small wetlands, and other special management areas. It also operates 66 national fish hatcheries, 64 fish and wildlife management assistance offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state wildlife agencies.
