This study investigated macroinvertebrate populations in a heavily grazed area and an area being restored on Boulder Creek near Donnelly, Idaho. Cattle are known to increase erosion, which pollutes water and affects macroinvertebrates by altering and eliminating in-stream habitat. Manure can run off into the water, adding nitrogen and altering the ecosystem. On October 22, 2011 we collected 17 samples from each site by stirring up sediment and capturing macroinvertebrates in collection nets. We investigated the macroinvertebrate orders Ephemeroptera, Trichoptera, Plecoptera, Diptera, and Amphipoda. Ephemeroptera, Tricoptera,Plecoptera, and Amphipoda have lower tolerance to pollutants, making their presence indicative of water quality. Out of the 806 macroinvertebrates collected, Diptera was the most common, comprising 52.3% from the unrestored site and 42.0% from the restored site. A Spearman Ranks test did not find the communities to be similar in composition. Amphipoda were significantly more abundant in the unrestored site. We found no significant differences between the abundances of Ephemeroptera, Trichoptera, Plecoptera, or Diptera between the two study areas. We suspect cattle grazing around the unrestored area may lead to aquatic macrophyte growth, which provides food and shelter for Amphipoda. We advise further monitoring of sedimentation rates and abundance of pollutant sensitive macroinvertebrates.

SHORT-TERM IMPACTS OF STREAM RESTORATION ON AQUATIC MACROINVERTEBRATE RICHNESS AND ABUNDANCE IN BOULDER CREEK, IDAHO