Spawning surveys of Pacific lamprey (Lampetra tridentata) and western brook lamprey (L. richardsoni) were conducted in the Cedar Creek drainage, a tributary within the Columbia River basin in Washington State. Twenty-seven surveys were conducted in 2001, 50 in 2002, and 53 in 2003. A total of 237 Pacific lamprey nests and 58 western brook lamprey nests were examined to describe nest characteristics (area, excavation depth, and longevity) and their associated habitat (water depth, water velocity, substrate size, and gradient). Spawning behaviors (timing, adult visibility, and courtship rituals) were evaluated to determine if spawning surveys could be used as an indicator of adult abundance. Pacific lamprey nests were larger in area and were excavated deeper than western brook lamprey nests; on rare occasions the 2 types of nests were found superimposed. Although western brook and Pacific lamprey nests displayed overlap in all habitat parameters, each species primarily exploited resources not readily available to or selected by the other. Additionally, the 2 species exhibited within-basin geographic segregation, spawning in different portions of the drainage with minimal overlap. Habitats used by both species were similar to criteria established for Oncorhynchus spp., and it is likely that restoration projects focusing on improving salmonid spawning habitat will benefit lamprey as well. Spawning surveys can be used to monitor and evaluate nest characteristics, habitat use, and behavior, but due to the variability in the number of adults associated with each nest, more information is required before using them to accurately monitor adult abundance.