Johnson County
for Water Quality

Time Here
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What is an MS4?

Under the 1987 Clean Water Act Amendments, the U.S. EPA developed new regulations to address storm water that might impact water quality. These new “Municipal Separate Storm Sewer System” (MS4) regulations were set up in two Phases dependent upon population and are enforced by the U.S. EPA, and more specifically in Indiana, through the Indiana Department of Environmental Management (IDEM).

In Indiana, MS4 entities are governed by 327 IAC 15-13 a/k/a Rule 13. The Johnson County MS4 is known as the Johnson County Partnership for Water Quality and was established in 2008. The JCPWQ includes the following entities and municipalities: The City of Franklin, The City of Greenwood, The town of Bargersville, The Town of Whiteland, The Town of New Whiteland, The Town of Edinburgh, Johnson County, The Johnson County Soil and Water Conservation District (JCSWCD), and The Johnson County Solid Waste Management District (JCSWMD).

MS4 designation includes cities, towns, universities, colleges, correctional facilities, hospitals, conservancy districts, homeowner’s associations and military bases located within mapped urbanized areas, as delineated by the U.S. Census Bureau, or, for those MS4 areas outside of urbanized areas, serving an urban population greater than 7,000 people. In addition to these generalized criteria, designation of MS4 entities is potentially determined by other factors, including population growth and documentation which indicates water quality impairments.

MS4 Requirements

Pursuant to Rule 13, each MS4, is required to develop a Storm Water Quality Management Plan (SWQMP) which is basically an action plan for the MS4 entity to institute six requirements, or minimum control measures (MCM):

  1. Public Education and Outreach

  2. Public Involvement and Participation

  3. Illicit Discharge Detection and Elimination

  4. Construction Site Storm Water Runoff Control

  5. Post-Construction Storm Water Management in New Development and Redevelopment

  6. Pollution Prevention/Good Housekeeping for Municipal Operations Maintenance.

For specific information on MS4 requirements go to (click on links – close new page when done)