Water Quality at Wildlife Water Sources in the Sonoran Desert, United States

Abstract

Surface water is an important limiting factor for wildlife populations in desert environments where water sources are uncommon or have been lost or degraded due to human activities. To address this need, wildlife water developments have been constructed in many areas of the southwestern United States, particularly in the Sonoran Desert. Previous studies of wildlife water developments are limited and critics have asserted that water quality at these facilities may be deleterious to animal health. Water quality was evaluated at natural, modified natural, and constructed water sources in the Sonoran Desert of southwestern Arizona and southeastern California. Samples were taken from primary sources of surface water available to wildlife, including natural tinajas (rock basins), modified tinajas, springs, rainwater catchments (‘‘guzzlers’’), and wells. Water samples were tested for 21 chemical constituents known to affect animal health, blue-green algal toxins, and a presumed waterborne pathogen, the protozoan avian parasite Trichomonas gallinae. Seven chemical constituents were absent or below detection limits. The majority of constituents detected (10/13, 77%) occurred at levels below recommended guidelines for domestic animals. Elevated pH, alkalinity, and fluoride were found in rainwater catchments, springs, and wells, respectively, but at relatively low levels unlikely to affect animal health. Blue-green algal toxins were not detected and there was no evidence of Trichomonas. Although specific water quality guidelines for wildlife are lacking, these results do not support hypothesized negative impacts to wildlife populations from developed water sources.