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Program for Regulated Phase II MS4s

A Phase II MS4 is any MS4 not already covered by the Phase I Program as a medium or large MS4. Phase II MS4s are automatically designated if any parts or the entire MS4 is located in an urbanized area as defined by the U.S. Bureau of the Census (based on the latest decennial census). An urbanized area (UA) is a central place (or places) and the adjacent densely surrounding territory that together has a minimum residential population of 50,000 and a minimum average density of 1,000 people/square mile.

MS4s that are located outside of the UA may also have potential for being designated by the NPDES Permitting Authority (DEP). For more information on Phase II MS4 designation, see Rule 62-624.800, F.A.C.

Operators of a regulated MS4 are required to:

  • Reduce the discharge of pollutants to the "maximum extent practicable" (MEP)
  • Protect water quality
  • Satisfy the water quality requirement of the Clean Water Act

Phase II MS4 Permit Requirements

A generic permit is a general permit issued by DEP under the authority of Section 403.0885, Florida Statutes (F.S.), which is the provision authorizing the state to implement the NPDES program.

The Generic Permit for Stormwater Discharge from Phase II MS4s (DEP Document 62-621.300 (7)(a)) was updated in 2021.

The Phase II MS4 GP requires regulated MS4 operators to develop, implement and enforce a Stormwater Management Program (SWMP) that includes the six minimum control measures:

  1. Public Education and Outreach
  2. Public Participation/Involvement
  3. Illicit Discharge Detection and Elimination
  4. Construction Site Stormwater Runoff Control
  5. Post-Construction Stormwater Management in New Development and Redevelopment
  6. Pollution Prevention/Good Housekeeping for Municipal Operations

The GP also requires activities to address impaired water bodies with Total Maximum Daily Loads (TMDLs) for regulated MS4s that discharge into TMDL water bodies.

Annual reports are required using the measurable goals for each minimum control measure for evaluating program effectiveness. During the first term of coverage, regulated Phase II MS4s must submit reports annually as specified in the GP. Reports are due within six months of the anniversary of the date of permit coverage. In subsequent terms, the permittee must submit reports in years two and four, unless otherwise requested by DEP. Reports are required to be submitted using DEP Form 62-621.300(7)(d).

Obtaining Permit Coverage Under the Generic Permit

  1. Review the Generic Permit for Stormwater Discharge from Phase II Municipal Separate Storm Sewer Systems, (DEP Document 62-621.300 (7)(a))
  2. Complete a Notice if Intent (NOI) (DEP Form 62-621.300(7)(b)) and SWMP (Appendix A of the NOI)
  3. Submit NOI with applicable fees as required by Rule 62.4.050, F.A.C. to the NPDES Stormwater Program via check or through the DEP Business Portal
  4. Re-apply for coverage 180 days prior to expiration of permit coverage

Frequently Asked Questions (FAQs): Provides answers to the most commonly posed questions to DEP regarding the Phase II MS4 permit.

NPDES Stormwater Program
Florida Department of Environmental Protection

2600 Blair Stone Road, MS 3585
Tallahassee, FL 32399-2400
Phone: 866-336-6312 (toll-free)

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Last Modified:
January 19, 2023 - 1:27pm

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