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NPDES Permits

The National Pollutant Discharge Elimination System (NPDES) stormwater permitting program regulates three types of activities: industrial activities that fall in one of 10 categories; municipal separate storm sewer systems (MS4s); and construction activities that disturb an acre or more.

EPA requires local governments with populations over 10,000 that own or operate an MS4 with an urbanized area to submit an application for a Phase II Stormwater Discharge Permit. Phase II permits were introduced in 1999 following the rollout of Phase I in 1990 for medium and large MS4s (population greater than 100,000 and 250,000 respectively).

The term MS4 does not solely refer to municipally-owned storm sewer systems, it can also cover State departments of transportation, universities, local sewer districts, hospitals, military bases, and prisons. An MS4 is also not always just a system of underground pipes – it can include roads with drainage systems, gutters, and ditches.

See this factsheet for further information about the definition and requirements of Phase II. The EPA also provides extensive guidance for developing a MS4 program.

NC DEQ MS4 Sustainability Strategy

The NC DEQ is the permitting authority for the Phase II MS4s in North Carolina. The NC DEQ promotes six elements for sustainable MS4 programs, and their NPDES MS4 Permitting web page provides resources for implementation.

Six elements for sustainable MS4 programs

Six elements for sustainable MS4 programs. Source: NC DEQ.

WNC Phase II Communities

Each of these communities provide information about their stormwater services on their municipal website:

Asheville Black Mountain Canton Clyde


Laurel Park Montreat
Waynesville Weaverville Woodfin  

State Stormwater Permits

The State Stormwater Permitting Program regulates site development and post-construction stormwater runoff control, especially in the 20 coastal counties, but also in several jurisdictions in WNC. There are currently 56 permits in several of the Phase II communities above, as well as for sites in Swannanoa, Flat Rock, E. Flat Rock, Etowah, Mills River, Brevard, Sapphire, and unincorporated areas of Henderson, Madison and Transylvania counties. These mostly apply to schools, commercial properties, subdivisions, and state road improvements.

The NC DEQ hosts an interactive permit map, illustrated below.

Permit Map

Example of interactive map, which can be used to determine areas covered by permits, and the type of permit issued.

Minimum Design Criteria and Stormwater Design Manual

The NC DEQ and a team of stakeholders have developed Minimum Design Criteria (MDC) for stormwater control measures (SCMs), high quality waters (HQW), and outstanding resources waters (ORW). These have been codified in new stormwater rules and regulations, effective January 1st, 2017. The Stormwater Design Manual has been updated to incorporate the MDC.

NC Stormwater Rules

Overview of new NC Stormwater Rules. Source: NC DEQ.