Assessment of the effects of wastewater discharge on water quality and biological conditions of the upper Blue River in Johnson County, Kansas and Jackson County, Missouri

The Blue River watershed is predominantly rural in Johnson County, Kansas, but receives wastewater discharge prior to entering Jackson County, Missouri, where the watershed becomes increasingly urban. In 2007, the wastewater facility was upgraded to include biological nutrient removal and increase capacity; regulatory requirements stipulate an evaluation of effluent impacts on the receiving stream after upgrades are complete. During 2008, water-quality and biological conditions were assessed at 3 sites (1 upstream and 2 downstream) along a 6-km reach of the Blue River. Relations between continuously-monitored water-quality variables and discrete samples were used to determine the contribution of nutrients in wastewater discharge to total nutrient loads in the Blue River. Periphyton and macroinvertebrate community metrics, algal biomass, and habitat characteristics were used to describe biological conditions along the reach. Nutrient concentrations were consistently larger downstream of the wastewater discharge than upstream. Periphyton communities had an increased proportion of eutrophic taxa and algal biomass was largest at the downstream locations, which is indicative of the larger nutrient concentrations. Similarly, the proportion of tolerant macroinvertebrate taxa increased at downstream sites. Collection of water-quality and biological data allowed assessment of both the chemical and resulting ecological impacts of wastewater discharge on the Blue River.