Iowa Statewide Rule

Iowa NPDES Stormwater Permit Under Code Chapter 455B

Heavy RestrictionsApplies statewide across Iowa (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

Last verified: August 21, 2026Source: Iowa Legislature

Summary

Iowa Code chapter 455B authorizes the DNR to administer NPDES stormwater permits statewide. Construction sites disturbing one or more acres need state General Permit No. 2, regardless of which Iowa city or county the site sits in.

If a permit is required pursuant to this chapter or chapter 459, 459A, or 459B for storm water discharge or an air contaminant source and a facility to be permitted is representative of a class of facilities which could be described and conditioned by a single permit, the director may issue, modify, deny, or revoke a general permit for all of the following conditions:

Source: Iowa LegislatureView official code

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.

Sources

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