5 Colo. Code Regs. § 1002-35.40
The provisions of C.R.S. 25-8-202 (1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide tine specific statutory autlnority for adoption of tinese regulatory amendments. Tine Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose.
BASIS AND PURPOSE
Pursuant to the requirements in the Basic Standards (at 31.7(3)), the Commission reviewed the status of temporary modifications scheduled to expire before December 31, 2016, to determine whether the temporary modification should be modified, eliminated or extended. Temporary modifications of standards on 2 segments were reviewed.
No Action: The Commission took no action on the temporary modifications for the following segments.
Upper Gunnisonn River segment 12, metals standards (type B): The Commission took no action on the existing Type B Temporary Modifications for cadmium, copper, and zinc, which were adopted for Upper Gunnison River Basin Segment 12 during the December 10, 2012 Rulemaking. These temporary modifications are scheduled to expire on June 30, 2016. U.S. Energy presented evidence that sufficient progress is being made on implementation of the Study Plan to Evaluate Metals Loading in the Coal Creek Watershed in the Vicinity of the Keystone Mine (the "Study Plan"). The Study Plan, as approved by the Commission, is intended to identify and quantify sources of cadmium, copper, and zinc that may be affecting water quality in Segment 12, including groundwaterdowngradient of the flooded Keystone Mine workings. U.S. Energy also informed the Commission of certain modifications to the sampling approach set forth in the Study Plan. Changes include:
Upper Gunnison River segment 20, acute and chronic uranium standards (type B): Homestake Mining Company is currently conducting reclamation of the Pitch Uranium Mine in Saguache County and evidence was presented indicating progress is being made toward resolving uncertainty regarding the underlying standard in Upper Gunnison River segment 20. The Commission made no change to the expiration date of 6/30/2015 because the original time allotment was deemed adequate.
New Temporary Modifications: To remain consistent with the Commission's decisions regarding arsenic at 35.36, arsenic temporary modifications were added to the following two segments, which had an existing chronic arsenic standard of 0.02 ug/l and a permitted discharger with a predicted water quality-based effluent limit compliance problem:
San Miguel segment 3a Uncompahgre segment 3b
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-35.40