crab run is a tributary of mahanoy creek in schuylkill county, pennsylvania, in the united states. it is approximately long and flows through barry township. the watershed of the stream has an area of . despite being listed as impaired by abandoned mine drainage, the stream is not impacted by this; no mining has been done in its watershed. however, some stream reaches in its watershed do experience agricultural impacts. the stream is not far from the western middle anthracite field. its watershed is designated as a coldwater fishery and a migratory fishery. as of 2001, the stream contains macroinvertebrates, but no fish.