The primary raw data are aerial counts of beaver (Castor canadensis) colonies on streams across the Chequamegon-Nicolet National Forest (CNNF). These aerial counts were performed in the fall of each year from 1987 (Nicolet side of CNNF) or 1997 (Chequamegon side of CNNF). Based on the colony counts, we also provide derived beaver colony density values. The surveyed streams were classified into four categories: managed trout, non-managed trout, managed non-trout, and non-managed non-trout. Trout versus non-trout status was assigned by the CNNF using Wisconsin Department of Natural Resources information. Managed streams were those on which targeted removal of beavers was conducted in the spring of each year under a contract with USDA-Wildlife Services. Data also include proportion of stream-side aspen, temperature, snowfall, and soil moisture as measured by the Palmer Drought Severity Index.