Urban effects on macroinvertebrate community attributes in the upper Blue River in Johnson County, Kansas and Jackson County, Missouri

The upper Blue River flows through rural Johnson County, Kansas and a municipal wastewater discharge enters the stream near the Kansas-Missouri state line.  Directly downstream of the discharge in Jackson County, Missouri, urbanization and impervious surfaces in the watershed increase rapidly.  Effects of these urban features on aquatic biota were assessed at 3 sites (1 upstream and 2 downstream of the discharge) along a 6-km reach of the upper Blue River in 2008.  Continuous and discrete water-quality monitoring was used to determine the contribution of wastewater discharge to total nutrient loads.  Macroinvertebrate communities were evaluated with the Kansas bioassessment protocol and metrics related to richness, composition, abundance, tolerance, and functional feeding groups were determined for the sites.  Statistically significant differences between sites were detected for 15 metrics, 8 of which the site upstream of the wastewater discharge was different than the 2 sites downstream.  Both downstream sites had decreased Plecoptera abundance and decreased total EPT richness.  Abundance and dominance of Trichoptera families shifted from Rhyacophilidae at the upstream site to Hydropsychidae at the 2 downstream sites.  Macroinvertebrate results indicated a decrease in stream quality at downstream sites, which was consistent with water quality changes and algal community indicators.