EPA requires large and medium cities with a population of 100,000 or more in an urbanized area to get an MS4 permit. In Colorado, the state issues these "Phase I MS4" permits as individual permits. Individual permits are written to each individual MS4 permittee. Some large government entities that are not cities or counties need individual permits to cover the work that they do.
In Colorado there is one large MS4 permittee:
- City and County of Denver.
There are three medium MS4 permittees:
- City of Aurora.
- City of Colorado Springs.
- City of Lakewood.
Due to the nature and size of projects by the Colorado Department of Transportation, there is also one for CDOT.
Active MS4 Individual permits
- City and County of Denver (COS000001)
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The City and County of Denver MS4 permit is the only large MS4 permit in Colorado. Denver is east of the Rocky Mountains and is in the South Platte River Basin. The permit addresses impaired stream segments that receive discharges from Denver.
Important links
- Denver’s stormwater program webpage.
- City and County of Denver (COS000001).
- 2022 Annual report (COS000001).
Final Denver MS4 permit issued: Dec. 31, 2020.
Permit effective date: April 1, 2021.
Permit end date: March 31, 2026.
Modification #2: effective April, 1, 2022
Modification #1: effective June 30, 2021
Correction issued: March 31, 2021Review COS000001 documents
The permit, fact sheet, response to comments, and other Denver MS4 records.
- City of Lakewood (COS000002)
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The City of Lakewood is a medium-sized MS4 permit. Lakewood borders Denver to the west and is in the South Platte River basin. The permit addresses impaired stream segments that receive discharges from Lakewood.
Important links
- Lakewood’s stormwater program webpage.
- City of Lakewood (COS000002).
- 2022 Annual report (COS000002).
Lakewood’s MS4 permit expired in 2014. The state has extended it from 2014. This is an administrative extension. This means the old permit stays active until renewal. Renewal will happen in the next couple of years.
The permit, fact sheet, response to comments, and other Lakewood MS4 records. To sort by date, click on the “Date Created” column.
- City of Aurora (COS000003)
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The City of Aurora is a medium-sized MS4 permit. Aurora borders Denver to the east and is in the South Platte River basin. The permit addresses several impaired stream segments that receive discharges from Aurora.
Important links
- Aurora’s stormwater program webpage.
- City of Aurora (COS000003).
- 2022 Annual report (COS000003).
Aurora’s MS4 permit expired in 2014. The state has extended it from 2014. This is an administrative extension. This means the old permit stays active until renewal. Renewal will happen in the next couple of years.The permit, fact sheet, response to comments, and other Aurora MS4 records. To sort by date, click on the “Date Created” column.
- City of Colorado Springs (COS000004)
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The City of Colorado Springs MS4 permit is a medium-sized MS4 permit. Colorado Springs is south of Denver and is in the Fountain Creek Watershed.
Important links
- Colorado Springs’ stormwater program webpage.
- Colorado Springs consent decree.
- 2022 Annual Report (COS000004).
Final Colorado Springs MS4 permit issued: July 29, 2022.
Permit effective date: September 1, 2022.
Permit end date: August 31, 2027.
The permit, fact sheet, response to comments, and other Colorado Springs MS4 records. To sort by date, click on the “Date Created” column.
- Colorado Department of Transportation (COS000005)
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It is common for transportation departments to have individual permits across the nation. Colorado Department of Transportation (CDOT)'s MS4 permit includes interstate and state highways. It also includes the rights-of-way in urbanized areas across the state’s river basins. The permit addresses impaired stream segments that receive discharges from CDOT projects.
Important links
- CDOT’s stormwater program webpage.
- Colorado Department of Transportation (COS000005).
- 2022 Annual report (COS000005).
CDOT’s MS4 permit expired in 2020. The state has extended it from 2020. This is an administrative extension. This means the old permit stays active until renewal. Renewal will happen in the next couple of years.
The permit, fact sheet, response to comments, and other CDOT MS4 records. To sort by date, click on the “Date Created” column.
How to get involved
All permits are required to go to public notice, so anyone can comment and provide feedback on the permit. Permits that are up for public notice and accepting public comments can be found on the Draft Permit Actions page. Some permits have more public interest and a more robust engagement process. You can find those on the Water Quality Engagement page.
Some ways you can get involved:
- Submitting comments on draft permits that are on public notice. Please make sure to submit these comments by the deadline.
- Submitting comments on other permitting actions that may be out for public notice, like draft policies or draft Clean Water Act Section 401 certifications for EPA permits in Colorado.
- Participating in a stakeholder process for a large-scale general permit, regulatory changes, or other issues.
- Participating in one of our quarterly permittee webinars, which provide updates on permitting issues. These are focused on permittees but anyone is welcome.
Please feel free to contact christine.forney@state.co.us with any questions or comments.
Permittee Resources
Resources for permittees for permit management and compliance assistance
MS4 permit links
- MS4 updates - 10/27/21 presentation
- MS4 compliance assistance and guidance
- MS4 Annual report forms
- MS4 urban area maps
- Permitting forms page
Permit information
Contacts
- Mary Welch
mary.welch@state.co.us
- Christine Forney
christine.forney@state.co.us
Email updates
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