Stormwater Quality

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

The past year was particularly active in terms of municipal stormwater permit activities. All of the cities and counties within the District needed to discuss permit requirements with the Colorado Water Quality Control Division (WQCD) during the year. The cities of Denver, Aurora, and Lakewood negotiated terms for the renewal of their permits that were initially issued in 1996. The "Phase II" municipalities, those with less than 100,000 population, needed to consider the management programs they will be responsible for developing and implementing under Clean Water Act regulations, and the implications of compliance under a general permit that was just recently proposed by the WQCD on December 13, 2002. The District assisted its member governments in 2002 with these efforts, and will continue to do so in 2003.

Phase I Municipalities

The cities of Denver, Aurora, and Lakewood are classified as "Phase I" municipal separate storm sewer systems (MS4s) under the EPA discharge regulations because of their population size (greater than 100,000). The WQCD, as state agency with regulatory authority designated by EPA, issued permits to the three cities in June 1996 after applications were submitted in November 1992. The individual 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. A number of meetings were held to discuss permit conditions during the first half of 2002. The cities continued implementation of their stormwater management programs under previous permit conditions and expect their permits to be renewed early in 2003.

The Phase I cities have fully implemented all of their current permit requirements. There will likely be a few additions and changes made, primarily to shift emphasis to education of industries, when the permits are reissued. A wet-weather monitoring program conducted for the cities by the District with assistance from the U.S. Geological Survey will continue. This monitoring is intended to assess long-term trends and provide data for watershed planning.

Phase II General Permit

A major effort this year was to provide assistance to municipalities within the District that fall under the regulatory definition as Phase II municipalities, often referred to as small MS4s. They are required to apply for and be issued a general permit by WQCD in 2003. This affects most of the cities and counties within the District, with the exception of Phase I cities and those with less than 1000 population that were granted waivers (Bow Mar, Lakeside, Morrison, and Mountain View).

EPA published the federal regulations for Phase II municipalities on December 8, 1999. In contrast to Phase I regulations that defined what information must be included in an application for an individual permit to be written, the Phase II regulations defined the terms and conditions a Phase II MS4 would be subject to under a general permit that applied to all small MS4s. The six management programs that must be developed, implemented, and enforced by a small 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.

Colorado adopted similar regulations, with some refinements, on January 8, 2001. Acting under a consent decree, EPA was required to provide a "menu" of best management practices (BMPs) and the "measurable goals" that small MS4s could select from in defining their management programs. EPA also had to prepare a "model general permit" in December 2002, and the consent decree set March 10, 2003 as the deadline for MS4s to submit permit applications.

These regulations established a short timeframe for small MS4s to prepare application materials and to provide comment on the exact terms to be included in these general permit. During the latter half of 2002, the District supported and coordinated a number of meetings of the Municipal Workgroup of the Colorado Stormwater Task Force. This group provided a forum to discuss with WQCD the stormwater management program elements that Phase II MS4s will need to decide upon and propose in their permit applications to comply with the general permit. Each of the six management programs was discussed; in addition to the discussion of permit application forms and draft general permit in time to provide meaningful comment to the WQCD. Phase II MS4s have 5-years to fully implement their programs and the District intends to continue providing assistance to them during this period as needed and requested.

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