Regional Municipal Separate Storm Sewer System (MS4) Monitoring Project

Project investigators

  • Dr. Robert T. Pavlowsky
  • Heather Hoggard

Project scope

The Federal Water Pollution Control Act Amendments of 1972 were amended in 1977 and became commonly known as the Clean Water Act (CWA) (United States Code, 2002). The Act established the basic structure for regulating discharges of pollutants into the waters of the United States and gave the United States Environmental Protection Agency (USEPA) the authority to implement pollution control programs. The Act also requires that water quality standards are established for all contaminants in surface waters and made it unlawful for any person to discharge any pollutant from a point source into navigable waters without a permit. It also funded the construction of sewage treatment plants under the construction grants program and recognized the need for planning to address the critical problems posed by nonpoint source pollution.
A decree under the Clean Water Act established the storm water program within the USEPA in 1990. The storm water program is intended to reduce adverse impacts from storm water discharges especially related to water quality and aquatic habitat by the use of controls on previously unregulated sources such as impervious surfaces in urbanized areas and construction activity. The National Pollutant Discharge Elimination System (NPDES) program was enlisted to address storm water runoff through permitting processes.
There are two phases of the program, Phase I and Phase II. Storm water runoff sources under Phase I include construction activity disturbing 5 acres of land or greater, “medium” and “large” municipal separate storm sewer systems (MS4s) that serve populations of 100,000 or greater, and ten specific categories of industrial activity. Phase II extends runoff sources requiring a permit to include urbanized areas as defined by the Bureau of the Census, small MS4s located outside of an urbanized area that are designated by NPDES permitting authorities, and small construction activities disturbing 1 acre of land or greater but less than 5 acres.
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 an urbanized area (UA) which is based on population and population density within the County. 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 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.

Project goals

  1. Characterize stormwater 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.

Project partners

Project documents

View the MS4 Monitoring Site Map

View Information on the Different Phases of the Project