Changes in Chemical Oxygen Demand of Surface Waters in Dunn County

Abstract

Chemical oxygen demand (COD) is an indicator of the amount of oxygen required to oxidize organic and inorganic substances in water. COD testing is commonly done on samples of water contaminated with domestic and industrial wastes. It is used to monitor the efficiency of wastewater treatment plants. Discharge of wastewater by industries introduces organic and inorganic substances that deplete dissolved oxygen available for aquatic life. In Dunn County, this wastewater disposal coupled with fertilizer, pesticide, and herbicide runoff from farms and residential areas are potential sources of these substances. Discharges that supply substances that are oxidized by dissolved oxygen can negatively impact aquatic ecosystems. COD analysis is an efficient way to determine the aquatic health of bodies of water where increasing levels indicate an increase in substances susceptible to oxidation.