When do I need a stormwater permit in Mississippi?

Any construction activity that disturbs one acre or more of land, or is part of a larger common plan of development, requires NPDES coverage through MDEQ.

Can cities impose stricter stormwater rules than the state?

Cities can adopt stricter local stormwater ordinances, but they cannot weaken state minimum NPDES requirements set by MDEQ under Miss. Code Title 49.

Mississippi Stormwater Management (2026)

Key Facts

Construction Threshold: One acre disturbed
Statute: Miss. Code 49-17-1 et seq.
Regulator: MS Dept of Environmental Quality
Max Penalty: $25,000 per day
Federal Authority: Clean Water Act NPDES

Source: Justia Law

Full Breakdown

Under Miss. Code Sections 49-17-1 et seq. (Mississippi Air and Water Pollution Control Law), the Mississippi Department of Environmental Quality administers the National Pollutant Discharge Elimination System (NPDES) for stormwater. Construction sites disturbing one or more acres must obtain a Large Construction General Permit and implement a Stormwater Pollution Prevention Plan. Industrial facilities with stormwater exposure require coverage under the MSR000000 industrial general permit. Municipal separate storm sewer systems (MS4s) in regulated areas must obtain Phase II NPDES coverage. MDEQ has primacy and sets statewide minimum requirements that local jurisdictions cannot relax.

Violations & Penalties

Discharging without required NPDES coverage or violating permit conditions exposes operators to civil penalties up to $25,000 per day per violation under Miss. Code 49-17-43.

Mississippi Stormwater Discharge State Permitting

Key Facts

Full Breakdown

Violations & Penalties

Frequently Asked Questions

Sources

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