A Rulemaking Hearing by the Water Quality Control Commission on the “Nutrients Management Control Regulation”, Regulation #85 and Section 31.17 of “The Basic Standards and Methodologies for Surface Water”, is scheduled on October 10, 2017. In 2012, these regulations established nutrient regulatory provisions for Colorado. Regulation #85 established total phosphorus and total inorganic nitrogen technology-based effluent limits and monitoring requirements for larger wastewater treatment facilities (those treating over two million gallons per day). At the same time in 2012, Regulation #31 established numerical values for nutrients to protect classified uses, which set lower limits for total phosphorus, total nitrogen, and chlorophyll α in Colorado’s lakes, reservoirs, rivers and streams. These provisions are being adopted in phases and are classified as “interim values”. It is anticipated that by 2022, effluent limits will be adopted into the permits of approximately 100 existing domestic facilities and numeric standards will be adopted upstream of existing dischargers. Changes to these regulations will be promulgated at the October, 2017 Rulemaking Hearing.
In preparation for the Rulemaking Hearing in October, 2017, the Colorado Water Quality Forum has hosted five stakeholder workgroup meetings to collaborate on the proposal for the rulemaking effort. The major proposed changes to the regulations are as follows (May 3, 2017 Draft Regulation 85 and 31.17 Statement of Basis and Purpose):

Regulation #85:

  • Update the definition of “Disadvantaged Community”
  • Include definitions of “Existing Domestic Wastewater” and “New Treatment Facility”
  • Include a Voluntary Incentive Program for Early Nutrient Reductions
  • Include effluent limits for existing and new non-domestic dischargers with a Standard Industrial Classification code in the Major Group 20 (SIC 20)
  • Include monitoring requirements for federal facilities
  • Remove the monitoring requirements for cooling towers
  • Include total inorganic nitrogen as a requirement for instream monitoring
  • Include a monitoring end date of December 31, 2027
  • Remove nutrient reduction requirements for MS4s

Regulation #31 (Section 31.17):

  • Extend the effective date of interim nitrogen values from May 31, 2017 to December 31, 2027
  • Include language that interim phosphorus values for standards adoption, prior to December 31, 2017, will be applicable to: A) waters located upstream of all permitted domestic wastewater treatment facilities discharging prior to May 31, 2012 or with preliminary effluent limits requested prior to May 31, 2012, B) waters located upstream of cooling tower discharges, and C) waters located upstream of any non-domestic facility subject to Regulation #85 effluent limits and discharging prior to May 31, 2012
  • Include language stating that the Water Quality Control Commission can adopt phosphorus standards for circumstances where it has determined that adoption of numerical standards is necessary to address existing or potential nutrient pollutant because the provisions of Regulation #85 will not result in adequate control of such pollution
  • Extend the chlorophyll α values for standards adoption date from May 31, 2022 to December 31, 2022
  • Include language that cooling tower discharges are subject to chlorophyll α values for standard adoption
  • Amend the use of Interim nitrogen values for standards adoption date from “after May 31, 2017 and prior to May 31, 2022” to December 31, 2017
  • Include language that after December 31, 2022, interim chlorophyll α values will be considered by the Water Quality Control Commission when applying numeric standards to individual segments
  • Include language that after December 31, 2022, interim phosphorus and nitrogen values for lakes and reservoirs will be considered by the Water Quality Control Commission when applying numeric standards to Direct Use Water supply reservoirs and lakes or reservoirs with public swim beaches
  • Include language that after December 31, 2027, interim phosphorus and nitrogen values will be considered by the Commission when applying numeric standards to individual segments where total phosphorus and total nitrogen standards have not yet been adopted
  • Amend the date of “Site-Specific Flexibility to Consider Alternatives to the Interim Values” from May 31, 2022 to December 31, 2027

To participate and provide comments at the October 10, 2017 Rulemaking Hearing, Party Status requests are due on August 7, 2017. For more information, visit the Water Quality Control Division website at: https://www.colorado.gov/pacific/cdphe/clean-water-nutrient-stakeholder-meetings.

Need more information on how these changes may affect you or your organization? Contact Jojo La at jojo.la@lrewater.com.


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