Water quality in the Blue River basin, Kansas City metropolitan area, Missouri and Kansas, July 1998 to October 2004

Abstract

Stream-water quality in the Blue River Basin is influenced by a variety of factors including urbanization, point and nonpoint source pollution, physical stream conditions, and complex water-quality processes. The Blue River Basin encom­ passes 280 square miles and roughly onehalf of the Kansas City metropolitan area south of the Missouri River. Fifty-four percent of the basin is located in Kansas and 46 percent is located in Missouri. The U.S. Geological Survey (USGS), in coop­ eration with the City of Kansas City, Mis­ souri, Water Services Department, col­ lected water-quality data from July 1998 to October 2004 to provide an assessment of the chemical, bacteriological, and bio­ logical conditions of basin streams, iden­ tify sources of selected constituents, and provide an understanding of factors affecting water quality. The results of these studies are described in Wilkison and others (2002; 2005; 2006), and are summarized in this fact sheet. Kansas City, Missouri, is 1 of approxi­ mately 750 municipalities in the United States with a combined sewer system. Such systems carry sanitary wastewater and stormwater runoff and function differently during dry and wet weather conditions. In dry weather, combined systems convey sewage from homes, businesses, and indus­ try to a wastewater-treatment plant (WWTP). After treatment, the water is dis­ charged to a receiving stream in accordance with applicable water-quality standards. During wet weather, runoff from streets, rooftops, parking lots, and lawns enters the combined system and is delivered to the WWTP for treatment and discharge. How­ ever, if runoff and sewage volumes exceed the pipe or WWTP capacity then excess flow (a mixture of stormwater and untreated sewage) is diverted and discharged to receiving streams, events referred to as combined sewer overflows (CSOs). Roughly 90 percent of the CSO outfall points in Kansas City, Missouri, are located within the Blue River Basin. Communities with combined sewer systems are required under federal and state regulations to develop a plan to con­ trol overflows and to monitor their effects on receiving waters. Control plans include analysis of current water-quality conditions based on a watershed perspec­ tive and characterization of other pollutant sources that might inhibit the attainment of applicable water-quality standards (U.S. Environmental Protection Agency, 1999). Laboratory and hydrologic analy­ sis of Blue River Basin stream samples collected during base flow (defined as streamflow unaffected by storm runoff) and stormflow events were undertaken to understand the effects of wastewater on urban receiving streams and to support development of a control plan. Analyses included physical properties, nutrients, selected organic wastewater compounds (OWCs), selected prescription and overthe-counter pharmaceutical compounds, Escherichia coli (E. coli) and fecal coliform bacteria, and benthic macroinver­ tebrates (fig. 1). Selected base-flow E. coli samples were analyzed for host source using genotypic, geographic-specific, librarybased methods (Dombek and others, 2000; Carson and others, 2003). Vertical water­ qualityprofilesweredetermined for selected impounded reaches of Brush Creek. (fig. 2). Sample locations were determined based on a variety of factors including proximity to tributaries, the combined sewer system area, and WWTPs (fig. 1). Six sites on the main stem of the Blue River (sites 1, 2, 7, 8, 13, and 14), four sites on the tributary Brush Creek (sites 9 to 12), and three sites on the tributary Indian Creek (sites 3, 4, and 6) were sam­ pled. Two stream sites, one in the basin (site 5, Tomahawk Creek) and one outside of the basin (site 19, South Grand River) were sampled as controls for aquatic-biota measurements. Data from four WWTPs (sites 15 to 18) located in the basin also were analyzed.