We present the first robust estimates of apparent survival of western cottonmouths (Agkistrodon piscivorus leucostoma) in central Texas. Estimates presented were obtained using the Cormack–Jolly-Seber Model that accounts for detectability. Apparent annual probability of survival of western cottonmouths located at Honey Creek, Comal County, Texas, a spring-fed stream flowing 3.2 km to its confluence with the Guadalupe River, was 0.81 and was consistent with estimates for similar species of snakes. Despite low probability of detection (0.12) and relatively small sample (n  =  51), the estimate of survival was reasonably precise (coefficient of variation was 4%). One benefit of our study is that we used a long-term dataset (11 years) that encompassed multiple floods and droughts, and therefore, represents a relatively wide range of conditions to which western cottonmouths are exposed at this locality.