Quality of stormwater runoff in the Blue River basin, Missouri and Kansas, July-October 1981 and April-July 1982

Stormwater-runoff sampling was done at three mainstem stations on the Blue River, Missouri, and three stations on urban tributaries. Concentrations of lead, iron, manganese, zinc, and ammonia nitrogen consistently exceeded Missouri water-quality standards. Many constituents were significantly correlated with large concentrations of suspended sediment from the agricultural areas in the upstream part of the basin. However, mean concentrations of lead increased 200% and mean concentrations of zinc increased 100% in the urban reach of Blue River for some storms. Combined sewer overflows along Brush Creek, one of the urban tributaries, caused large concentrations of nutrients, suspended sediment, metals, and 5-day biochemical oxygen demand in the initial runoff. After extended dry periods, surface flushing caused concentrations of lead and zinc to be largest during initial runoff at all three urban tributaries. However, large flushes of most constituents were not detected at the mainstem stations. The large percentage of impervious surfaces and lined channels in urban areas caused increased volumes of runoff per unit of drainage area and limited the availability of sediment to streams. Consequently, concentrations of most constituents were small, but the loads per unit of drainage area were large when compared with those in Blue River. (USGS)