Benthic macroinvertebrates (i.e., bottom-dwelling animals that lack a backbone and are large enough to be visible with the naked eye) are commonly used as indicators of water quality conditions, as they are sensitive to pollution and spend most (if not all) of their time in water. The Louisville District Water Quality Team utilizes assessments of benthic macroinvertebrate communities to better understand the water quality conditions of tributaries flowing into reservoirs as well as conditions flowing out of reservoirs via tailwaters. The methods of these studies are consistent with the appropriate state water quality authorities for Kentucky, Indiana, and Ohio, depending on the jurisdiction of a reservoir. Each year, a subset of the 20 Louisville District reservoirs are assessed.
In 2016, the four Green River Basin reservoirs (Barren River Lake, Green River Lake, Nolin River Lake, and Rough River Lake) were assessed using benthic macroinvertebrate communities. The results of this study can be seen at Water Quality Data and Reports. In 2017, Brookville Lake and Cecil M. Harden Lake were assessed using benthic macroinvertebrate and fish communities (these results are pending).
Left - Collecting benthic macroinvertebrates, including a stonefly larva and a hellgrammite. Right - Relic shells of freshwater mussels.