Northern Prairie Wildlife Research Center
This nonvenomous snake is endemic to the Concho and Colorado River systems. The free-flowing riverine habitat upon which it depends faces a number of threats, primarily reservoir inundation and flow modifications. Other dangers to the snake include water quality degradation, fragmentation and isolation of populations following habitat disturbance, and sedimentation coupled with encroachment of vegetation.
The Fish and Wildlife Service conducted a formal section 7 consultation with the Army Corps of Engineers on construction of the O.H. Ivie Reservoir. Although the project as proposed was found likely to jeopardize the snake, the Service suggested reasonable and prudent alternatives that allowed construction to continue. One alternative was the creation of artificial riffles (shallow shoals) to provide habitat favored by Concho water snake juveniles. Six artificial riffles were built in August 1989, accompanied by minimum flows and channel maintenance flows from Robert Lee Dam as required under the reasonable and prudent alternatives. In 1990, the fish prey base in the riffles was found to be similar to that in undisturbed habitat occupied by the snake. In 1991, four of the six riffles had been naturally colonized by Concho water snakes of all ages. By 1992, all six riffles were occupied. These sites will be monitored to determine whether silt and vegetation will encroach again.
Needed recovery actions include securing adequate stream flows in the Colorado and Concho Rivers; monitoring and evaluating snake populations and habitat rangewide; identifying, monitoring, and eliminating or reducing threats to snake populations (including habitat degradation such as sedimentation, vegetation encroachment, and water quality) through consultation, permitting, and cooperative programs; reestablishing the snake in river segments and creeks where it has been extirpated; and maintaining gene flow among the three nearest neighbor populations through snake translocations.
Army Corps of Engineers: The Corps implements the reasonable and prudent alternatives developed under formal section 7 consultation for construction of the O.H. Ivie Reservoir.
Colorado River Municipal Water District: The municipal water district created Concho water snake habitat in its historic range, and continues to conduct studies on the biology, physical habitat requirements, and genetic viability of snake populations, as well as analysis of various management alternatives.
Technical/Agency draft plan.