The bull trout is an ESA-listed species with a historical range that encompasses many waters across the northwestern U.S. Though once abundant, bull trout have declined in many locations from an array of factors —habitat degradation, population isolation, and nonnative species invasions (USFWS 2014)— and there is recent evidence of range contraction in response to climate change (Eby et al. 2014). Federal listing mandates that agencies have reliable and precise information about the distribution of bull trout in thousands of streams, but bull trout surveys are expensive because the fish are often rare and difficult to collect (USFWS 2008). Consequently, many potentially or historically occupied habitats have been sampled infrequently or not at all. The uncertainty about bull trout distributions comes at a cost; agencies may not be able to efficiently target their limited conservation resources, may forego or delay land management critical for other objectives, and may even avoid monitoring populations because of the added burden of obtaining sampling permits.