Stormwater Program

General Information

Years after the Clean Water Act of 1972 was adopted, EPA completed rules to include stormwater discharges in the NPDES permit program. 

Since Iowa was delegated the NPDES program for wastewater discharges, delegation was requested for stormwater discharges as well. Information regarding the stormwater permit program and how it is managed by the Iowa DNR can be found in the following pages:

• Stormwater General Permit Database - Submit Notices of Intent and search for authorizations under stormwater General Permit Nos. 1, 2, and 3
• Who Must Apply for a NPDES Stormwater Permit?
• Municipal Separate Storm Sewer System (MS4) Permits - Cities/Universities Required to Obtain MS4 Permits
• Stormwater General Permits, Forms, and Application Materials
• Stormwater Permit Application Options
• Iowa Stormwater Management Manual
• Construction Site Erosion Control and Streambank Erosion Control Manuals
• State Revolving Fund - Offers low-interest loans for stormwater practices that protect water quality. Eligible borrowers include both public and private entities.

Renewal of the Stormwater General Permits

The DNR is hosting an informal stakeholder meeting on April 14, 2026, regarding the proposed five-year renewals of stormwater NPDES General Permits #1, #2, and #3. The purpose of this meeting is to accept comments and answer questions on possible changes to the general permits. The DNR is specifically seeking comments on the clarity, feasibility, and potential impact of the proposed changes. Formal rulemaking to renew these general permits is expected to begin in mid 2026.

The meeting will be held on Tuesday, April 14 at 11:00 am.  The meeting is open to the public and will be held virtually via Google Meet.

• Tuesday, April 14 · 11:00am
• Video call link: https://meet.google.com/uxj-mzkm-uqq
• Or dial: ‪(US) +1 414-909-7229 PIN: ‪161 729 810#
• More phone numbers: https://tel.meet/uxj-mzkm-uqq?pin=6153220581983

Questions and comments regarding the draft renewals or the meeting may be directed to David Schelling at stormwater@dnr.iowa.gov. Comments will be accepted until Friday, April 17th.

• GP #1 - Stormwater Discharge Associated With Industrial Activity (Excludes Construction)
  • Redline-strikeout version of the draft renewal of GP #1 (2026-3-27) (594.94 KB) .pdf
  • Clean version of the draft renewal of GP #1 (2026-3-27) (505.48 KB) .pdf
• GP #2 - Stormwater Associated With Industrial Activity For Construction Activities (Land Disturbing 1 Acre Or More)
  • Redline-strikeout version of the draft renewal of GP #2 (2026-3-27) (452.15 KB) .pdf
  • Clean version of the draft renewal of GP #2 (2026-3-27) (362.56 KB) .pdf
• GP #3 - Stormwater Discharge Associated With Industrial Activity From Asphalt Plants, Concrete Batch Plants, Rock Crushing Plants, And Construction Sand And Gravel Facilities
  • Redline-strikeout version of the draft renewal of GP #3 (2026-3-27) (469.75 KB) .pdf
  • Clean version of the draft renewal of GP #3 (2026-3-27) (375.81 KB) .pdf

History of Stormwater NPDES Permitting Requirements

Amendments made in 1987 to the Federal Clean Water Act required the U.S. Environmental Protection Agency (EPA) to develop regulations for stormwater discharges from "industrial activities." Stormwater regulations were established by EPA under the National Pollutant Discharge Elimination System (NPDES) permit requirements for certain types of industrial facilities and industrial activities. 

These federal regulations established NPDES permit application requirements for industrial facilities and industrial activities. Since 1978, the Iowa Department of Natural Resources (DNR) has been delegated by the EPA to administer the federal NPDES wastewater discharge permit program. In August 1992, the DNR received authorization from EPA to issue general permits for stormwater discharges. The DNR continues to issue NPDES permits to all stormwater discharges subject to the federal NPDES permit requirements.

The intent of the federal stormwater regulations is to improve water quality by reducing or eliminating contaminants in stormwater. Stormwater is defined as precipitation runoff, surface runoff and drainage, street runoff, and snow melt runoff.

Stormwater runoff from areas where industrial activities occur may contain the following contaminants:

• toxic substances (lead, zinc, etc.),
• conventional pollutants (oil and grease, fertilizers, sediment from construction sites), or
• industrial site contaminants, when material management practices allow exposure to stormwater.

In addition, illicit connections to storm sewers may also exist and can introduce contaminants through storm sewer systems. Contaminants introduced in stormwater runoff or into storm sewers may impact drinking water sources, waters protected for recreation or aquatic life, and other beneficial water uses.