Stormwater Permit Activities
John T. Doerfer, Project Hydrologist, Master Planning Program

On March 10, 2003, all of the cities, counties, and special districts in Colorado that operate what are defined by regulation as “small municipal separate storm sewer systems” (Small MS4s) will be required to submit permit applications for coverage under the Colorado Discharge Permit System. There are about 40 cities, towns, and counties in the state with less than 100,000 population located within Census-defined “Urbanized areas.”  Many of these municipalities are located within the UDFCD.  In addition, there are a number of special districts within these jurisdictions that have drainage responsibilities (i.e. metropolitan districts; drainage districts; water and sanitation districts; etc.) also defined as small MS4s.  Collectively, these entities are referred to as “Phase II” of EPA’s municipal stormwater control program.  The District assisted its member governments in 2001 to prepare for Phase II permit applications, and will continue to do so as the March 2003 deadline approaches.

Phase II Regulations

EPA published the federal regulations for Phase II on December 8, 1999.  The six management programs (called “minimum control measures”) that must be implemented by an MS4 are:

  1. Public education and outreach;
  2. Public involvement/participation;
  3. Illicit discharge detection and elimination;
  4. Construction site runoff control;
  5. Post-construction runoff management in new development and redevelopment; and,
  6. Pollution prevention/good housekeeping for municipal operations.

The EPA regulations also included additional “guidance” that was recommended for consideration by municipalities when developing a proposed program.  The state’s Attorney General determined that if this guidance was included in the Colorado regulations, it would be mandatory rather than discretionary.  So, the guidance provisions were not included in the Colorado Discharge Permit System Regulations (5 CCR 1002-61) for Phase II adopted on January 8, 2001.

Guidance Document

A Municipal Workgroup of the Colorado Stormwater Task Force, chaired by UDFCD with participation by many of its member governments, decided that a separate guidance document published by the state would be helpful for preparing permit applications.  The guidance has been customized for Colorado and includes descriptions of potential management program elements and methodologies.  About 50 volunteers from around the state began in February 2001 to write this document, and it was completed in November and is posted on the Water Quality Control Division’s (WQCD) website at

General Permit

The next activity that will take place during 2002 will be development of general permits.  The state plans to use two of these for Phase II.  The first will be completed by July for construction sites between 1 and 5 acres, defined as an industrial category of stormwater discharges (sites greater than 5 acres have been regulated since 1992).  The second is for small MS4s, planned for completion by December 2002.  Cities and counties within the District will want to pay attention to these general permits, and participate in their development if possible, because they will affect the ultimate outcome of permit application submittal requirements and compliance issues.  The District will participate, and sponsor a number of meetings among member governments during the year to discuss these general permits, elements of management programs and the “measurable goals” that must be proposed in the MS4 general permit applications.

Phase I Municipalities

The cities of Denver, Aurora, and Lakewood are classified as “Phase I” MS4s and were issued permits by the WQCD in 1996.  Their permits were for a 5-year permit term and expired on April 30, 2001.  The three cities submitted permit renewal applications in October 2000, but as of the current date have not yet been reissued permits for a second term.  In accordance with state regulations, they continue implementation under previous permit conditions.

The Phase I cities have fully implemented all of their permit requirements.  These include those generally described above for Phase II, as well as an industrial inspection program and monitoring requirements.  Arapahoe County, although required to submit a Phase I application in July 1997, received notice this year it will instead be permitted under Phase II.  The District has coordinated a regional water-quality monitoring program on behalf of Denver, Aurora, Lakewood, and Arapahoe County.  Under a cooperative agreement with the U.S. Geological Survey, a total of five sites have been sampled during runoff events for four years.  The program is intended to assess long-term trends, and will also provide data for watershed planning.

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