Water Quality Monitoring

The Nitrate Monitoring Project began in 2015, due to a growing public concern in South Dakota and surrounding states regarding nitrate contamination of drinking water sources. Numerous public water systems in Iowa and Minnesota are dealing with nitrate concentrations in source waters that exceed acceptable levels. The District began an intensive program of testing for nitrates in the Big Sioux River from its headwaters to the confluence with the Missouri River. Samples are collected April through November at 28 sites along the Big Sioux River and 12 sites on major tributaries entering the river. Depending on the site, weekly or bi-weekly samples are being collected. 

The Brookings Area TMDL Sampling Project was a one year sampling project that began in the Spring of 2012, and then extended an additional year. The project involved sampling 10 storm sewer locations within the City of Brookings, two sites on Six Mile Creek, and one site on the Big Sioux River. The sites were monitored for water quality (sediment and bacteria), stage, and discharge during > 0.10 inch rain events. The storm water outflows in the southern part of Brookings, flow through constructed wetlands before entering waterways. The study showed lower bacteria and sediment concentrations from these areas. The monitoring location on Six Mile Creek (above Brookings) showed higher concentrations of bacteria and sediment than at the monitoring location on Six Mile Creek below Brookings. A follow-up study in 2015, determined the drop in pollutant levels between the two monitoring sites on Six Mile Creek were due to the creek itself flowing through the South Dakota State University ponds just northwest of Brookings. These ponds are acting as a filter and reducing the pollutants in Six Mile Creek as it flows through.