Streams were sampled throughout the Upper Black Warrior River basin to (1) determine the current distribution of Necturus alabamensis (Black Warrior Waterdog) and (2) identify its habitat requirements. Individuals were observed at 14 of 112 localities within 60 streams. Discriminant function analysis of stream characteristics revealed that waterdog populations were associated with the presence of ephemeropteran larvae on a local scale and with water depths of 1–4 m, large leaf packs, and low percentage of fine sediments on a regional scale. Where present, N. alabamensis occurs at relatively low population densities, and populations monitored in our survey exhibited a 1:1 sex ratio with no apparent age-class structure or sexual size dimorphism. We conclude that this species is rare on the basis of its restricted geographic range, low abundance, and unpredictable occurrence in suitable habitat; as such, N. alabamensis should be considered for federal protection.