Storm Water General Permits

40 CFR Section 122.26 |  Last Updated May 2024

In 1987, Amendments to the Clean Water Act required the U.S. Environmental Protection Agency (EPA) to develop regulations for storm water discharges from “industrial activities.” These regulations established National Pollution Discharge Elimination System (NPDES) permit application requirements for certain types of industrial facilities or certain types of industrial activities that discharge storm water to surface waters. Storm water regulations are found in the Code of Federal Regulation (CFR), specifically, 40 CFR 122.26.

In August 1992 the Iowa Department of Natural Resources (DNR) received authorization from EPA to issue NPDES General Permits for Storm Water Discharges in Iowa. Iowa’s storm water regulations follow the federal regulation and can be reviewed in Iowa Administration Code (IAC) 567 Ch. 64.


permit types

Types of NPDES Permits

There are several different types of NPDES Permits and categories of activity that must be covered under some type of permit.

  • General Permit No. 1: Industrial Storm Water Discharge from any conveyance (road, yard, ditch, pipe, storm sewer, etc.) which collects and conveys storm water and which is directly related to manufacturing, processing, or raw materials storage areas at an industrial plant.
  • General Permit No. 2: Construction Activity Storm Water Discharge from clearing, grading, and excavation operations that result in the disturbance of one or more acres. It also includes sites than are less than one acre, but part of a larger plan of future development.
  • General Permit No. 3: Asphalt Plants, Construction Sand & Gravel, Concrete Batch Plants and Rock Crushing Plants Storm Water Discharge from the following processes. Manufacturing asphalt paving mixtures; manufacturing Portland cement concrete; and facilities that are primarily engaged in the crushing, grinding or pulverizing of limestone or granite.
  • Individual Permit: An individual permit is specifically tailored to an individual facility storm water discharge on a case-by-case basis. Once a facility submits an application, a permit writer develops a permit based on the application and issues the permit for a specific time period (generally five years) with a requirement that the facility reapply prior to the expiration date. If an Individual Permit is required, contact the DNR for assistance at 515-725-8415 or visit their Stormwater Program Page.

Additional Categories of NPDES General Permits Not Covered

  • General Permit No. 4: Discharge from on-site wastewater treatment and disposal systems
  • General Permit No. 5: Discharge from mining and processing facilities
  • General Permit No. 6: Discharge associated with well construction activities
  • General Permit No. 7: Pesticide General Permit (PGP) for point source discharges to waters of the United States from the application of pesticides
  • MS4 Permit: The Municipal Separate Storm Sewer System (MS4) permit is designed to regulate nonpoint source stormwater runoff at the municipal level. In Iowa, 44 communities and 3 Universities are required to obtain MS4 permits.

obtaining a permit

Obtaining a General Permit

How Do I Know If I Need a Storm Water Discharge Permit?

Industrial and commercial activities that have “storm water discharge associated with industrial activity” and that fall within a specifically listed Standard Industrial Classification (SIC) code are required to obtain permit coverage. An SIC code is a four digit number for classifying establishments by their type of economic activity. Visit the OSHA website site for help in determining your facilities SIC code.

A more complete definition of “Storm Water Discharge Associated with Industrial Activity” can be found in 40 CFR 122.26(b) (14). A summary of the types of industrial facilities and activities subject to the regulations are provided below.

When Is The Application Deadlines for New Storm Water Discharges?

For coverage under a general storm water discharge permit, a properly completed Notice of Intent (NOI) and Public Notice must be submitted to the Iowa DNR and an authorization approved and issued by the Department prior to the start of operations or soil disturbing activities as specified in 567-64.3(4)”b” of the Iowa Administrative Code.

For coverage under an Individual NPDES permit an application must be submitted 180 days prior to the start of operation.

Important Note: A Storm Water Pollution Prevention Plan (SWPPP) must be completed before the NOI and Public Notice is submitted to the Iowa DNR. The SWPPP must be fully implemented concurrently with operation at the facility (or if a new facility, with the start of operation.) Information on developing a SWPPP is covered next. Please see IDNR’s Application Options & Fees page for more information.

Obtaining a General Permit

  1. Develop and implement a Storm Water Pollution Prevention Plan (SWPPP)
  1. Make a Public Notice
  1. Submit a Notice of Intent (NOI) and Permit Fee
  • Complete an online permit application called a Notice of Intent (NOI)
  • Or download the paper form of the NOI for General Permits #1, #2 and #3 
  • Attach a copy of the public notice published in the newspaper to either the online application when requested or to your paper application
  • Choose the length of time for permit coverage (and applicable fee)
  • Submit a completed NOI, a copy of the Public Notice, along with the appropriate fee to the DNR via the online application portal or hard copy submittal

Once these three steps have been successfully completed, the Iowa DNR will respond as to the approval of the facility’s permit application. Once the approval has been received, your facility will be considered covered under the General Permit and storm water discharge can commence.