Ranking of U.S. Reservoirs Relative to Fish Habitat Condition, and Its Application to Decision-Making Criteria

Reservoir fish habitat in the U.S. has become degraded and requires broad-scale assessment to facilitate habitat rehabilitation efforts.  To help prioritize habitat projects in reservoirs, we sought to develop an assessment system for large reservoirs in the contiguous U.S. Using a fish habitat survey of 1,299 large U.S. reservoirs, we conducted oblique component analysis (OCA) to identify major habitat impairments. Resulting habitat impairment constructs included point source pollution, nonpoint source pollution, excessive nutrients, algae blooms, siltation, limited nutrients, mudflats and shallowness, limited connectivity to adjacent habitats, limited littoral structure, invasive species, anomalous water regimes, and large water fluctuations.  Construct scores represented the degree of impairment for each reservoir, and construct scores were combined to yield an overall index of reservoir habitat impairment.  In addition, geographic regions were characterized by their unique fishery composition, and priority species for each region were identified, scored, and ranked by relative “popularity.”  The resulting index and fishery scores are useful in prioritizing rehabilitation and enhancement projects and have been incorporated into the decision-making process used by the Reservoir Fish Habitat Partnership.