The provisions of section 25-8-202(1)(b), 25-8-204; 25-8-402, C.R.S., provide the specific statutory authority for adoption. The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
The Commission revised the basin-wide temperature standards as part of the 2007 rulemaking hearing. These changes clarify the numeric temperature standards that will be in effect until the basin-wide rulemaking hearing in June of 2009. At that time, the Commission intends to consider segment specific temperature standards for all segments with aquatic life uses.
The Commission applied 17°C as an interim chronic standard for small, high elevation streams that are likely to be habitat for brook trout and cutthroat trout. First, second and third order streams are defined at section 31.5 in the Basic Standards.
The Commission also applied 18.2°C as an interim chronic standard to waters designated by the Colorado Wildlife Commission as "Gold Medal Fisheries". The Commission agrees that it is important to protect these fisheries that provide important recreational and tourism opportunities in the headwaters of Colorado. This standard is based on a criterion to protect rainbow trout. The Colorado Division of Wildlife presented evidence that rainbow trout thrive in Gold Medal fisheries because they are provided the necessary forage base and thermal conditions to maximize their consumption and growth. Because these thermal conditions also represent the upper temperature tolerance range for this species, it was determined that an interim standard of 20°C would not be adequate to protect these fisheries.
For the remainder of the cold water segments, the Commission left the current 20°C in place as an interim standard with the clarification that it is a chronic standard. The existing 30°C criterion for warm water segments was left in place as an interim standard with the clarification that is also to be applied as a chronic standard.
PARTIES TO THE RULEMAKING HEARING
1. The Temperature Group (City of Aurora, City of Boulder, Colorado Springs Utilities, Littleton/Englewood Wastewater Treatment, The Metro Wastewater Reclamation District, Colorado Mining Association, Colorado Rock Products Association, Tri-State Generation & Transmission Assn., Xcel Energy, Denver Water, Northern Colorado Water Conservancy District, Southeastern Colorado Water Conservancy District)2. City of Grand Junction5. Metro Wastewater Reclamation District8. Colorado River Water Conservation District9. Colorado Wastewater Utility Council10. Bear Creek Watershed Association11. Chatfield Watershed Authority12. Mountain Coal Company, L.L.C.13. Northern Colorado Water Conservancy District14. Colorado Rock Products Association15. Littleton/Englewood Wastewater Treatment Plant16. Northwest Colorado Council of Governments17. Southeastern Colorado Water Conservancy District18. Colorado Mining Association19. Colorado Division of Wildlife20. South Platte Coalition for Urban River Evaluation21. City and County of Denver22. City of Colorado Springs and Colorado Springs Utilities24. Board of Water Works of Pueblo25. Coors Brewing Company26. City and County of Broomfield27. Centennial Water and Sanitation District28. Plum Creek Wastewater Authority29. Climax Molybdenum Company30. Cripple Creek & Victor Gold Mining Company31. Tri-State Generation and Transmission Association33. Sky Ranch Metropolitan District No. 234. Parker Water and Sanitation District35. CAM-Colorado and CAM Mining LLC36. Aggregate Industries - WCR, Inc.37. Grand County Water and Sanitation District #1, Winter Park Water and Sanitation District, Winter Park West Water and Sanitation District and Fraser Sanitation District38. Trout Unlimited and Colorado Trout Unlimited39. Colorado Contractors Association40. United States Environmental Protection Agency, Region 841. Hot Springs Lodge and Pool42. Denver Regional Council of Governments38 CR 03, February 10, 2015, effective 6/30/201538 CR 17, September 10, 2015, effective 12/31/201539 CR 03, February 10, 2016, effective 3/1/201639 CR 03, February 10, 2016, effective 6/30/201639 CR 23, December 25, 2016, effective 12/30/201640 CR 03, February 10, 2017, effective 6/30/201740 CR 09, May 10, 2017, effective 6/30/201741 CR 01, January 10, 2018, effective 1/31/201841 CR 03, February 10, 2018, effective 6/30/201842 CR 04, February 25, 2019, effective 6/30/201943 CR 03, February 10, 2020, effective 6/30/202043 CR 17, September 10, 2020, effective 12/31/202044 CR 01, January 10, 2021, effective 2/14/202144 CR 05, March 10, 2021, effective 6/30/202144 CR 17, September 10, 2021, effective 12/31/202145 CR 17, September 10, 2022, effective 9/30/202245 CR 21, November 10, 2022, effective 11/30/202246 CR 10, May 25, 2023, effective 6/14/2023