University of Colorado at Boulder
BMP of Oil and Gas Development

Regulating Stormwater -
The Role of Federal, State, and Local Governments

In some cases, implementation of the NDPES creates a complex permitting scheme for oil and gas operators. This page uses Douglas County, CO to explain the federal, state, and local regulatory schemes in place.  For a more detailed description and analysis of the federal, state, local government interaction, including citations to statutes, regulations and other documents, see the paper Water Quality and the Interaction of Federal, State and Local Regulation of Oil and Gas in Colorado. 

Federal Regulatory Scheme – The National Pollutant Discharge Elimination System (NPDES)

The EPA’s National Pollutant Discharge Elimination System (NPDES) regulates stormwater discharges from sources including municipal separate storm sewer systems (MS4) and construction projects disturbing one acre or more. Several states, including Colorado, are authorized to implement the NPDES for EPA (Colorado “has primacy” over the program.)

An MS4 is “a conveyance or system of conveyances that is owned by a state, city, town, village, or other public entity that discharges to waters of the U.S. and is designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.…). An MS4 is not a combined sewer and is not part of a sewage treatment plant.”

Phase I of the NPDES permit program, established in 1990, requires medium and large cities with populations of 100,000 or more to obtain an NPDES permit for stormwater discharges associated with their MS4s. In 1999, the NPDES permit program was expanded (Phase II) to include smaller construction activities including smaller MS4s in urbanized areas. Each regulated MS4, under either Phase I or II, is required to develop and implement a stormwater management program (SWMP) to reduce stormwater contamination and illicit discharges.

For more information on federal stormwater management, see the EPA NPDES Stormwater Program webpage.

The Role of State Agencies Implementing NPDES –
The Colorado Department of Public Health and Environment (CDPHE)

Some states, including Colorado, are authorized to manage the NPDES program in their territorial boundaries. In Colorado the Colorado Department of Public Health and Environment (CDPHE) manages the NPDES through the Colorado Discharge Permit System (CDPS). Under CDPS, the Water Quality Control Division (WQCD) of CDPHE issues permits for, among other discharges, MS4s and construction projects disturbing one acre or more.

The regulation creating CDPS, “Regulation 61,” outlines the requirements and administration of the CDPS. The regulation outlines the minimum requirements for all Phase II MS4 permits.

  • “Construction activities” that disturb five or more acres of land require a Phase I permit;
  • “small construction activities” that disturb between one and five acres of land require a Phase II permit;
  • “large or medium [MS4s]” require a Phase I permit; and
  • “regulated small [MS4s]” require a Phase II permit.

Phase I and Phase II MS4s require a CDPS General Permit issued by the CDPHE. This permit requires the MS4 operator to develop and implement the following six stormwater management programs and measures, consistent with NPDES program requirements:

  •  Public education and outreach 
  •  Public participation/involvement
  •  Illicit discharge detection and elimination
  •  Construction site stormwater runoff control
  •  Post-construction stormwater management
  •  Pollution prevention/good housekeeping for municipal operations.

The Role of State Oil and Gas Regulatory Agencies – The COGCC

The Colorado Water Quality Control Act recognizes the Colorado Oil and Gas Conservation Commission (COGCC) as an “implementing agency” that must, through its own programs and in consultation with the CDPHE/WQCD, implement the water quality standards and classifications for state waters adopted by the CDPHE/WQCD. The COGCC has promulgated rules governing stormwater management requirements for oil and gas operators in the state. Specifically, COGCC rules require operators to employ certain stormwater BMPs at all oil and gas locations and develop a post-construction stormwater program prior to the termination of any stormwater permits issued by CDPHE for the construction of oil and gas facilities.

Additional Colorado Complexity – Cherry Creek Reservoir Control Regulation

CDPHE also imposes more stringent water quality control standards for parts of Colorado. For example, in the Cherry Creek Watershed through the Cherry Creek Reservoir Control Regulation. This regulation requires that MS4 permittees in the Cherry Creek Watershed incorporate additional requirements into their stormwater management programs beyond those required under the CDPS General Permit. The additional requirements of the Cherry Creek Reservoir Control Regulation for construction and post-construction stormwater management are outlined in the Authority’s Cherry Creek Reservoir Watershed—Stormwater Quality Model Stormwater Ordinance (revised version April 19, 2001), an ordinance reviewed by the WQCD.
The Cherry Creek Reservoir Control Regulation and CDPS General Permit both contain language suggesting that the requirements they set forth for the permittee’s stormwater program are minimum standards for the MS4 permittee to meet, suggesting that permittees may set more stringent standards than those contained in the regulations, to the extent allowable under state statutes creating and defining local government authority.

The Role of Counties – Compliance and Regulation in Douglas County, CO

In order to comply with the requirements of CDPHE, including special area regulations like the Cherry Creek Watershed Regulation, counties in Colorado have developed stormwater permit programs.  For example, Douglas County, Colorado operates a regulated MS4 and must therefore comply with an MS4 permit issued by CDPHE. The MS4 Phase II permit requires the county to implement a program to manage stormwater runoff from construction sites. Furthermore, because portions of Douglas County are located within the Cherry Creek drainage basin, the county’s stormwater programs must also comply with the Cherry Creek Reservoir and Chatfield Reservoir Control Regulations.

To comply with the requirements for construction site stormwater runoff control under both the CDPS General Permit and the Cherry Creek Reservoir Control Regulation, Douglas County has passed Zoning Resolution Section 31, which outlines the county’s “Grading, Erosion, and Sediment Control Program" (GESC). The GESC Program is a permitting program for grading, erosion, and sediment control on public and private construction projects in the unincorporated limits of Douglas County. Depending on the extent of potential land-disturbance, a given construction project will require the developer to obtain one of three types of permits: (1) Low Impact GESC Permits, (2) Temporary Batch Plan/GESC Permit, and (3) Standard GESC Permits. GESC permits require that the developer employ BMPs approved by Douglas County throughout the duration of the construction project.

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