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Stormwater Permits for Municipal Separate Storm Sewer Systems (MS4s)

Permits required to discharge stormwater from small, medium, and large systems. Phase I and Phase II requirements. Waivers for qualified small systems.

Municipal Separate Storm Sewer System (MS4) Discharges: Am I Regulated?
Which MS4s are required to obtain permit coverage for their stormwater discharges.

Types of MS4s

Stormwater Permitting Requirements for Medium and Large (Phase I ) MS4s
Requirements and steps for applying for a permit to authorize stormwater discharges from Phase I (medium and large) MS4s as well as annual reporting and discharge monitoring report requirements.

Stormwater Permitting Requirements for Phase II (Small) MS4s
Authorization options, control measures required, annual reporting requirements, and links to best management practices for operators of Phase II MS4s.

General Permit TXR040000 for Phase II (Small) MS4s
Requirements and steps necessary to obtain authorization for stormwater discharges from small MS4s.

Possible Waivers for Permits

Waiver Option 1 from MS4 Permitting Requirements (Small Systems Only)
Explains the waiver from the permitting requirement available to small MS4s that serve a population of less than 1,000.

Waiver Option 2 from MS4 Permitting Requirements (Small Systems Only)
Explains the waiver from the permitting requirement available to small MS4s which serve a population of less than 10,000.