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Municipal Separate Storm Sewer Systems (MS4)

A municipal separate storm sewer system (MS4) is a publicly-owned conveyance or system of conveyances (i.e., ditches, curbs, catch basins, underground pipes, etc.) designed or used for collecting or conveying stormwater and that discharges to surface waters of the state. Examples of MS4 operators include, but are not limited to, municipalities, counties, community development districts, universities, military bases or federal correctional facilities.

Operators of large, medium and regulated small MS4s are required to obtain NPDES permit coverage to discharge to waters of the state.

As implemented by Chapter 62-624, F.A.C., Phase I addresses discharges of stormwater runoff from "medium" and "large" MS4s (i.e., those MS4s located in areas with populations of 100,000 or greater). Under Phase II, the program regulates discharges from certain MS4s not regulated under Phase I, and that meet designation criteria set forth in Chapter 62-624, F.A.C. Get a list of permitted Phase I (individual) and Phase II MS4 permits and contacts in Florida.

Phase I MS4s

Provides the regulatory definitions of Phase I large and medium MS4s, outlines the stormwater management program requirements and the permit re-application requirements.

Regulated Phase II MS4s

Explains which Phase II MS4s are regulated under the program, including automatic designation and designation by the permitting authority. Outlines stormwater management program requirements and details on how to obtain coverage under the Generic Permit.

NPDES Stormwater Program
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 3585
Tallahassee, FL 32399-2400

Last Modified:
October 5, 2023 - 2:48pm

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