Iowa Stormwater Management Law: Statewide Environmental Rules Rules (2026)

Key Facts

Permit threshold: 1 acre disturbance
Permit name: General Permit No. 2
Statute: Iowa Code 455B.173
Coverage area: Entire state
Regulator: Iowa DNR

Full Breakdown

Under Iowa Code 455B.103A, 455B.105, and 455B.173, the Iowa Department of Natural Resources issues NPDES general permits covering all areas of the state. Stormwater General Permit No. 2 authorizes discharges from construction activities disturbing one or more acres, including smaller sites that are part of a larger common plan of development. Operators must file a Notice of Intent, prepare a Stormwater Pollution Prevention Plan, provide public notification, and pay general permit fees. General Permits No. 1 and No. 3 cover industrial activity and asphalt or concrete plants. Iowa cities may add MS4 controls but cannot waive the state permit requirement.

Violations & Penalties

Discharging construction stormwater without coverage, ignoring SWPPP requirements, or failing to file a Notice of Intent can trigger DNR administrative penalties, civil fines under 455B.191, and EPA enforcement.

Frequently Asked Questions

Does my project need an Iowa stormwater permit if the city already has an MS4?

Yes. Construction sites disturbing one or more acres still need DNR NPDES General Permit No. 2 even within MS4 cities, in addition to local stormwater controls and erosion ordinances.

What documents must I keep onsite during construction?

Keep the signed Notice of Intent, NPDES authorization letter, current Stormwater Pollution Prevention Plan, inspection records, and any rain event logs available for DNR or EPA inspectors during the project.

How much does the Iowa stormwater general permit cost?

Fees are set by Iowa DNR rule and depend on permit type and site characteristics. Check the DNR NPDES Fees page for current general permit application fees and annual fees.

Iowa NPDES Stormwater Permit Under Code Chapter 455B