Johnson Creek, a first order tributary which enters the Blackfoot River at river mile 3.0, is the only spawning tributary in the lower 10 miles of river.    Johnson Creek supports spawning runs of westslope cutthroat and low densities of bull trout; these species migrate during spring and early summer periods usually during the peak of the hydrograph.  In the summer, Johnson Creek's cold water plume provides thermal refuge for bull trout in the Blackfoot River.

At stream mile 0.2 a road crosses Johnson Creek over a series of undersized culverts.  Flow velocities were recorded in excess of 10 feet/second in June 1997.   These culverts are seasonal fish passage barriers that inhibit the migrations of spring migrating Blackfoot River fish.

The culverts were removed in the winter of 1997 and replaced with a bridge.  This project has restored access to six miles of important spawning and rearing habitat.