Regional Municipal Separate Storm Sewer System (MS4) Monitoring Project



Under the scope of the Clean Water Act (CWA), a decree in 1990 established the National Pollutant Discharge Elimination System (NPDES), this storm water program is intended to reduce the adverse impacts of storm water discharges, especially as related to water quality and aquatic habitat, through the use of added controls on previously unregulated sources such as impervious surfaces in urbanized areas and areas of construction activity.
There are two phases of the program. Storm water runoff sources under Phase I include construction activities disturbing 5+ acres of land, municipal separate storm sewer systems (MS4s) that serve populations of 100,000+ people, and ten specific categories of industrial activity. Phase II extends "runoff sources requiring a permit" to include urbanized areas as defined by the United States Census Bureau, small MS4s located outside of urbanized areas designated by NPDES permitting authorities, and small construction activities disturbing  between 1 - 5 acres of land.
Greene and Christian Counties, as well as the Cities of Battlefield, Nixa, and Ozark are included in Phase II of the storm water program as urbanized areas (UA) based upon their population densities. All municipalities were required to apply for NPDES permit coverage and to implement storm water discharge management controls.
OEWRI generated Monitoring Plans to address water quality requirements specific to watersheds within the two counties in addition to the general requirements under MS4 Phase II. The Monitoring Plans address pollutants of concern including total phosphorus, total nitrogen, total coliform, total suspended solids, chloride, specific conductivity, and pH. Each pollutant of concern will be used to assess the temporal and spatial variability of water quality within the respective watersheds.


  1. Characterize storm-water quality from urban point sources to local streams,
  2. Reduce adverse impacts on aquatic habitats, and
  3. Use data to establish Total Maximum Daily Loads (TMDLs) within the municipalities.