This dataset accompanies the manuscript Unintended consequences of selective water withdrawals from reservoirs alter downstream macroinvertebrate communities in Water Resources Research. Benthic macroinvertebrates were collected from samples taken annually during the first two weeks of August from 2002-2007 and again in 2017 at six sites in the South Fork McKenzie River. Taxonomy of samples collected prior to 2017 have been updated to be consistent with 2017 taxa designations.