The Western Pond Turtle (Actinemys marmorata) has been declining throughout its range due to several stressors, including habitat degradation and loss, exotic competitors, nonnative predators, and epidemic disease. California's only native turtle is listed as a Species of Special Concern and a candidate species for listing under the federal Endangered Species Act. Few studies have examined their population ecology in lentic environments subject to livestock grazing. From 2011 through 2016, staff and volunteers from the East Bay Regional Park District used radiotelemetry or tracked visually the seasonal movement patterns, habitat use, and nest site selection of Western Pond Turtles (n = 38) in eastern Contra Costa County, California. Statistical analyses of this multiple-year database showed that male and female turtles used the pond environment differently; however, they all overwintered in the same relative location. Gravid females on average moved 24.4 m (s = 17.5 m.) away from the ponds during the first 2 wk of June to oviposit on south-facing slopes (aspect = 134°, s = 31.9°), with mean residual-dry-matter levels of 1345 lbs/ac (1510 kg/ha) and vegetation heights ranging between 26.6 and 39.5 cm. These findings on how Western Pond Turtles used their pond and upland environments may have significant conservation and management implications for rangelands.