Environmental DNA (eDNA) is potentially a powerful tool for use in resource management, including for tracking the recolonization dynamics of fish populations. USGS and partners used eDNA to assess the effectiveness of dam removal to restore fish passage on the Elwha River in Washington State, and showed that most targeted anadromous species were able to pass upstream of both former dam sites. The timing and spatial extent of recolonization differed among species during the four years of post‐dam removal monitoring. More abundant species migrated farther into the upper portions of the watershed than less abundant species. Environmental DNA from Brook Trout, a non‐native species was detected downstream of Elwha dam but rarely upstream of the Glines Canyon Dam suggesting that the species has not expanded its range appreciably in the watershed following dam removal. We found that eDNA was an effective tool to assess the response of fish populations to large‐scale dam removal on the Elwha River.
