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    State of Colorado

    Colorado's Stormwater Permitting Program

    The Colorado Water Quality Control Act (25-8-101 et seq., CRS 1973, as amended) established the Colorado Water Quality Control Commission (CWQCC) within the Colorado Department of Public Health and Environment (CDPHE) to develop water quality regulations and standards, classifications of state waters for designated uses, and water quality control regulations. The Act also established the Colorado Water Quality Control Division (CWQCD) to administer and enforce the Act and administer the discharge permit system, among other responsibilities. Violations of the Act are subject to significant monetary penalties, as well as criminal prosecution in some cases.

    Colorado's stormwater management regulations have been implemented in two phases and are included in Regulation No. 61 Colorado Discharge Permit System (CDPS) Regulations (CWQCC 2009). After the 1990 EPA "Phase I" stormwater regulation became effective, Colorado was required to develop a stormwater program that covered specific types of industries and storm sewer systems for municipalities with populations of more than 100,000. Phase I affected the City of Colorado Springs, Denver, Aurora, Lakewood, and the Colorado Department of Transportation (CDOT). Phase 1 requirements included inventory of stormwater outfalls, monitoring and development of municipal stormwater management requirements, as well as other requirements. Construction activities disturbing five or more acres of land were required to obtain construction stormwater discharge permits.

    Phase II of Colorado's stormwater program was finalized in March 2001, establishing additional stormwater permitting requirements. Two major changes included regulation of small municipalities (≥10,000 and <100,000 population) in urbanized areas and requiring construction permits for sites disturbing one acre or more. The Phase II regulation resulted in a large number of new permit holders including MS4 permits for El Paso County, City of Fountain, Town of Monument, and City of Manitou Springs. In addition, there are also non-standard MS4 permittees that include entities that are not cities or counties. Non-standard MS4 permittees include entities such as Academy School District 20, Widefield School District 3, Pikes Peak Community College, Harrison School District 2, Falcon School District 49, Cheyenne Mountain School District 12, University of Colorado at Colorado Springs, and Colorado Springs School District 11.

    MS4 permit holders are required to develop, implement, and enforce a CDPS Stormwater Management Program designed to reduce the Stormwater Management and Planning Designed to reduced the discharge of pollutants from the MS4 to the maximum extent practicable, to protect water quality, and to satisfy the appropriate water quality requirements of the Colorado Water Quality Control Act (25-8-101 et seq., C.R.S.) and the Colorado Discharge Permit Regulations (Regulation 61). Non-standard MS4 permittees may elect to comply with their construction program and post-construction program requirements by following the requirements of the City’s or County’s construction and post-construction programs.

    CDOT is required to comply with the requirement of the CDOT Colorado Municipal Separate Storm Sewer System (MS4) permit. CDOT's MS4 permit authorizes discharges from the municipal storm sewer system within the permit area. The permit requires CDOT to use control measures to prevent or reduce the discharge of pollutants to state waters. The permit does this by requiring CDOT to comply with seven MS4 programs. CDOT has several different programs to make sure the amount of pollutants being discharged is reduced, as part of the permit that allows discharges from the roadway storm drain system. These include: 

    Construction Sites

    The MS4 permit requires CDOT to implement a program to reduce or prevent the discharge of pollutants to the MS4 from covered construction activities. The requirements include assuring adequate design, implementation, and maintenance of Control Measures at CDOTs construction sites.

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    Illicit Discharges

    The Illicit Discharge Detection and Elimination  (IDDE) Program requires CDOT implement a program to detect and remove (or advise the discharger to the MS4 to obtain a separate CDPS permit for) illicit discharges and improperly disposed materials into the MS4.

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    Industrial Facilities 

    CDOT requires all facilities that discharge stormwater into CDOT's storm drain system to obtain a specific authorization. The program prioritizes education to promote minimization of pollutants in the stormwater that the facilities are contributing to the system.

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    Permanent Water Quality (PWQ)

    This program is required under CDOT's Municipal Separate Storm Sewer System Permit MS4). Each CDOT Region is responsible for evaluating new construction and redevelopment sites in the CDOT MS4 permit area to determine if stormwater controls are required. These controls are referred to as Permanent Water Quality Control Measures (PWQ CM) or permanent Best Management Practices (BMP).

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    Pollution Prevention and Good Housekeeping 

    CDOT prioritizes minimization of pollutants in stormwater by developing runoff control plans for maintenance facilities, requiring the proper application of herbicides, pesticides and fertilizers, maintaining permanent BMPs, and operating public streets, roads, highways, and parking lots to promote both safety and stormwater quality protection.

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    Public Education and Outreach 

    CDOT must implement a public education program to promote behavior change by the public to reduce pollutants in discharges from the MS4. CDOT conducts a variety of outreach activities for employees and the public. Outreach activities include brochures, fact sheets, posters, newsletters, workshops, conferences, and this website.

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    Colorado Stormwater Fact Sheet- Construction