The Town of Firestone has implemented a program to manage stormwater quality and mitigate common pollutant sources following a phased approach. This program is referred to as a Municipal Separate Storm Sewer System (MS4).

The original federal legislation that ultimately led to the requirement to manage the Town’s MS4, was the 1972 Clean Water Act. Initially, the EPA’s focus on stormwater quality was to manage industrial and municipal wastewater. Under Section 402 of the Clean Water Act, a permitting system was established and called the National Pollutant Discharge Elimination System (NPDES). The EPA did not see enough reduction in pollutants in federal and state waters, so additional measures were taken to address municipal non point-source stormwater runoff. NPDES Phase I and II were the resulting programs implemented to address municipal stormwater runoff. Phase I of the NPDES program was issued in 1990, and focused on medium to large cities with populations greater than 100,000. Phase II of the NPDES program was issued in 1999, and was designed to regulate stormwater discharges from small MS4s. The EPA defines ‘Small MS4s’ as cities or towns with populations greater than 10,000 but less than 100,000, and as having a population density of at least 1,000 people per square mile.

  1. Ashley Tucker

    Stormwater Coordinator
    Phone: 303-531-6289

With the implementation of Phase II of the NDPES program, the EPA was not able to regulate the many thousands of small MS4 entities throughout the country, so regulatory authority was passed down to the individual states. The Water Quality Control Division (WQCD) as part of the Colorado Department of Public Health and Environment (CDPHE) has been tasked with overseeing Colorado’s NPDES Phase II program. Permits are issued to approved MS4 entities by the WQCD under Colorado’s Regulation 61.

Illicit Discharges & Spills

An illicit discharge is defined as any discharge to the Town’s stormwater system that is not composed entirely of stormwater, with the exception of a few exclusions. Common illicit discharges include motor oil, grease, antifreeze, dirt/sediment, grass clippings, leaves and paint. To report an illicit discharge or non-emergency spill, please email or call (303)-531-6289.

Construction Sites & Stormwater Quality

Construction activities associated with land disturbing activities increase the potential for stormwater pollutants to enter our waterways. The Town of Firestone requires construction activities larger than one acre or smaller than one acre but part of a larger common plan of development to first obtain a Stormwater Quality Permit prior to the start of construction. As part of your permit, you will need to develop a Stormwater Management Plan. Please submit your SQP application packet to

Public Notice

One of the requirements for maintaining the Town’s MS4 permit is to notify the public of any changes and/or additions to the Town’s program. Each year, the Town Board adopts or reauthorizes several methods for notifying the public, currently notices are found at Town Hall and on the Town’s website. The current resolution authorizing places for public notice is found here.

Municipal Separate Storm Sewer System (MS4)

The Town’s MS4 Permit requires that the Town address Pollutant Restrictions, Prohibitions, Reduction Requirements, and Record Keeping.  

As a condition of the permit, the five measures listed below must be met.  As the Town implements each measure, the Program Description Document (PDD) is updated to provide a record of the Town’s MS4 compliance.

1.  Public Education and Outreach: Implement a public education program    that promotes a reduction in pollutant discharges into the Town’s MS4.

2.  Illicit Discharge Detection and Elimination: Implement a program that defines illicit discharges, and educates both the public and certain Town staff on detecting and eliminating an illicit discharge.  The program also allows the Town to enforce the requirements of the MS4 Permit which prohibits illicit discharges into the Town’s Mapped Storm Sewer System.

3.  Construction Sites: Implement a program that defines applicable construction activities, and educates owners, developers, and or operators on methods to reduce or prevent the discharge of pollutants to the Town’s MS4. The program allows the Town to enforce the requirements of the MS4 Permit on applicable construction activities that result in a land disturbance of greater than or equal to one acre or that is less than one acre, but is part of a larger common plan of development.

4.  Post-Construction Stormwater Management in New Development and       Redevelopment

5.  Pollution Prevention/Good Housekeeping for Municipal Operations

Program Description Document Availability

The Town is required to maintain a current document, called the ‘Program Description Document’ (PDD), which must be available to residents upon request. The PDD document can be viewed here.

Additional Stormwater Quality Resources