OKR04 Municipal Stormwater


Stormwater runoff from an urbanized area is commonly transported through Municipal Separate Storm Sewer Systems (MS4s). Urbanized areas are associated with different activities that contribute pollutants to stormwater runoff. Additionally, urbanized areas are characterized by large amounts of impervious surfaces such as streets, sidewalks, driveways, parking lots, and roof tops. Stormwater runoff from impervious surfaces travels faster which results in damage to the waterbodies and causes flood­ing and hydrologic changes to the receiving waters. Elevated pollutant levels can impair waterbodies, degrade biological habitats, and pol­lute drinking water sources.

Discharges from MS4s are regulated under the Clean Water Act and OPDES Act as point source discharges. MS4 regulations were developed and implemented in two phases. Implementation of MS4 Phase I began in the early 1990s and required medium and large cities or certain counties with populations of 100,000 or more to obtain NPDES permit coverage for their stormwater discharges. The MS4 Phase II regulations became effective on March 23, 2003 and required regulated small MS4s in urbanized areas, as well as small MS4s outside the urbanized areas that are designated by DEQ, to obtain permit coverage for their stormwater discharges.

Phase I MS4s are covered by individual permits and Phase II MS4s are covered by the general permit OKR04. Each regulated MS4 is required to develop and implement a stormwater management program (SWMP) to reduce the contamination of stormwater runoff and prohibit illicit discharges to the MS4.

MS4 Phase I Program

Currently, there are two cities, City of Oklahoma City and City of Tulsa, which are regulated under the Phase I program.

MS4 Phase II Program

There are 51 small cities/counties which are regulated under the MS4 Phase II Program. A Regulated Phase II MS4 is an MS4 that is located wholly or partially within an Urbanized Area (UA) boundary as defined by the latest decennial U.S. Census and not a large or medium municipality. Regulated Phase II MS4s include systems that are operated by traditional communities such as municipalities, (such as counties, cities or towns) as wel as non-traditional communities such as military installations, universities and community development districts. Phase II MS4s located outside of UAs may also become regulated by designation by DEQ according to designation criteria set forth in the rules.An urbanized area (UA) is a central place (or places) and the adjacent densely surrounding territory that together has a minimum residential population of 10,000 and a minimum average density of 1,000 people/square mile. All UA calculations and mapping are done by the U.S. Bureau of the Census. The determination of which MS4s are automatically designated as regulated Phase II MS4s is based solely on the boundaries of U.S. Bureau of the Census urbanized areas –not political boundaries. You may view a list of regulated MS4 Phase II cities and counties which have been determined based on 2010 Census by U.S. Bureau of the Census.

For a full list of regulated MS4s within Oklahoma, please view: List of Regulated MS4 Operators

Who Needs a Permit and How to Apply

Who needs a Permit?

Per 40 CFR § 122.26(b)(8), an MS4 is a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) that is:

  • Owned by a state, city, town, village, or other public entity that discharges to waters of the U.S.;
  • Designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.);
  • Not a combined sewer; and not part of a Publicly Owned Treatment Works (sewage treatment plant)

You need an OKR04 permit if your are an operator of a small MS4 that is:

  • fully or partially located within an urbanized area
  • located outside of an urbanized area with a population of at least 10,000 but not exceeding 100,000 with a population density of 1,000/square mile or more
  • designated as an MS4 which contributes substantial pollutant loads to a regulated SM4 through interconnections
  • designated by the DEQ Executive Director

Population and population densities are determined by the most recent Decennial Census by the U.S. Bureau of Census.

How to Apply for a Permit?

Before filling out an NOI, understand the requirements of the current OKR04 permit, identify if there will be any co-permittee, assign responsible person for implementation and coordination for SWMP, identify the latitude and longitude of the centroid of the municipality/city, identify the all receiving water bodies, check whether there is an approved TMDL for an impaired waterbody, check whether municipality discharges into an Aquatic Resources of Concern (ARC) area, and prepare a Stormwater Management Program (SWMP) in accordance with the requirements of OKR04 Permit. Once the NOI and the SWMP have been completed, submit the following to DEQ:

  • Completed NOI
  • An application fee $100 and annual permit fee $748.11 (for FY15, annual fee is prorated for the new applicant based on the date of submission of an NOI to DEQ)
  • A map of your MS4 boundaries
  • A BMP outline

Attach a check for the applicable fees payable to DEQ with your NOI. You may pay the fees using a credit card (only Visa or Master Card are acceptable) by calling DEQ Finance at (405) 702-1130.

Where to Submit an NOI?

Mailing Address

Water Quality Division

Oklahoma DEQ

707 N Robinson Ave

P. O. Box 1677

Oklahoma City, OK, 73101-1677


(405) 702-8101



Municipal Templates and Additional Information

Annual Report

Your Annual Report must be submitted to DEQ by March 1 of the calendar year and by September 1 of the fiscal year.  The Annual Report can be sent to the following:

Mailing Address

Water Quality Division

Oklahoma DEQ

707 N Robinson Ave

P. O. Box 1677

Oklahoma City, OK, 73101-1677


(405) 702-8101



Useful Links


Technical Assistance & Outreach

Technical Assistance

If you would like on-site technical assistance, or have a question about stormwater enforcement, please contact the appropriate representative below:




DEQ offers various outreach and training opportunities, to schedule an event please contact:

Wayne T. Craney
(405) 702-8139

Recent Events

Oklahoma Floodplain Managers Association Stormwater Workshop

July 15, 2020

What’s New at DEQ

Phase II MS4 Evaluation Update

Contact Us

Main WQD Phone Numbers
Phone: 405-702-8100
Fax: 405-702-8101

2021 OKR04 Permit and Forms

Coming Soon

Small MS4 General Permit OKR04

2021 OKR05 General Permit

2021 OKR04 Fact Sheet

2021 OKR04 General Permit: DEQ Response to Comments

OKR04 Forms and Support Documents

2021 OKR04 Notice of Intent (NOI

2021 OKR04 Notice of Termination (NOT)