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ISSUED MAY 7, 2014

The comment submission period for the Virtual Workshop ended on July 16, 2014. Thank you.


Discharges from municipal separate storm sewer systems (MS4's) are regulated under the federal Clean Water Act, through the National Pollutant Discharge Elimination System (NPDES) program. In Delaware, the Department of Natural Resources and Environmental Control (DNREC) is delegated by the U.S. Environmental Protection Agency (EPA) to issue NPDES permits for stormwater discharge to MS4 operators in urbanized areas. Under these permits, the MS4 owner/operator must implement a collective series of programs to reduce the discharge of pollutants from the given storm sewer system to the maximum extent practicable in a manner that protects the water quality of nearby streams, rivers, wetlands and bays.

MS4 regulations were developed and implemented in two phases. Implementation of the Phase I program began in the early 1990s and required that operators of MS4s serving populations of greater than 100,000 people (per the 1990 decennial census) apply for and obtain a permit to discharge stormwater from their outfalls. Phase II MS4 regulations became effective in 2003, and required that operators of small MS4s in "urbanized areas" (as defined by the latest census) obtain a permit to discharge stormwater from their outfalls.

On May 7, 2013, DNREC issued a five-year, Phase I MS4 permit for New Castle County (NPDES Permit DE 0051071/State Permit WPCC 3063A/96). The Principal Permittees are New Castle County and DelDOT. Six municipalities in the county are Co-permittees: the towns of Bellefonte, Elsmere and Newport, and the cities of Delaware City, New Castle and Wilmington.

The permit requires the permittees to prepare a Stormwater Pollution Prevention and Management Plan (SWPP&MP) that describes how the quality of stormwater discharged from the MS4 in New Castle County will be controlled. A draft SWPP&MP was required to be submitted to DNREC by May 7, 2014. The Permittees are required to invite public review and comment on the draft SWPP&MP. A final version of the plan must be submitted by August 7, 2014.

Draft SWPP&MP:

The draft SWPP&MP posted here for public review describes the programs and practices proposed by the Permittees to fulfill the permit requirements. Under the permit, New Castle County, DelDOT and the Co-permittees must develop, implement and enforce a program that includes the following elements:

  • Public education and public involvement
  • Illicit discharge detection and elimination
  • Stormwater management during construction
  • Post-construction stormwater management
  • Pollution prevention/good housekeeping
  • Inspection of industrial facilities
  • Wet weather performance monitoring
  • Pollutant Minimization Plan (PMP) for polychlorinated biphenyls (PCBs)
  • A Watershed Priority List for development of Water Quality Improvement Plans


Documents pertaining to the draft SWPP&MP may be found at all New Castle County public libraries, or online at the links below:

A PowerPoint presentation that provides an overview of the elements contained in the SWPP&MP can be downloaded and viewed here:

Submission of Comments:

All comments must be submitted by July 16, 2014.

Online form
By email
Written comments by mail

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