5 Colo. Code Regs. § 1002-33.11
Use Classification
The evidence in this proceeding as well as prior proceedings have established that the Climax discharge, Segment 13, does not have sufficient flow to sustain a classification of aquatic life, Cold Water Class 1 on a year round basis. It is contemplated that Climax will not discharge during the period December 25 through February 28. These months are generally low flow months of the year. Hence, the flow conditions are not present to support an aquatic life, Cold Water Class 1 designation on a year round basis on Segment 13.
The Commission has received testimony and exhibits in this and previous hearings concerning Ten Mile Creek which establish that the number and kind of aquatic species in Segment 13 is limited and that few, if any, sensitive species are found in Segment 13. The Commission believes that the Water Quality standards for Segment 13 that it is adopting today will protect existing species and encourage the establishment of more sensitive species which are compatible with the flow and streambed characteristics of Segment 13.
Testimony has also been presented in a previous hearing on Ten Mile Creek as to the cost of achieving a Class 1 Classification for Segment 13. In weighing these costs together with the cost already expended to improve the water quality of Ten Mile Creek against the low flow and limited aquatic life conditions presently found in Segment 13, the Commission concludes that it would not be economically reasonable to retain a classification of aquatic life, Cold Water Class 1 for Segment 13. Hence, the Commission adopts aquatic life, Cold Water 2 to apply to Segment 13 of Ten Mile Creek. The Commission does not find that classifying this Segment with a goal of aquatic life is appropriate. The Segment does contain aquatic life and any upgrading from Class 2 to Class 1 could proceed during periodic review to reflect any possible improvements.
Segmentation
The evidence in these proceedings on Ten Mile Creek have shown that Ten Mile Creek for all intents and purposes begins at Climax property boundary at a place designated as the "Parshall Flume". It is at this point that the natural flows that are intercepted by Climax in the Ten Mile Creek Basin are channelled together and form the source of Ten Mile Creek. Hence, the Commission believes Parshall Flume to be the source of the mainstem of Ten Mile Creek. Also, included in this segment are all tributaries to Ten Mile Creek including those natural tributaries intercepted by Climax.
Water Quality Standards
The evidence of Climax and the Division in this proceeding has shown that water quality standards in Ten Mile Creek vary considerably during certain periods of the year. The principal cause of this variation is the hydrological condition, mainly the spring run-off (snowmelt bypass). During this period it becomes economically unreasonable, if not impossible, to provide treatment for the large flow of runoff water that comes into contact with the Tailings Ponds located in the Ten Mile Creek Basin. Hence, the Commission has adopted seasonal water quality standards for both Segments 13 and 14 of Ten Mile Creek.
Segment 13
The Commission has been presented with Climax data and calculations of such data for various pollutants during the period November, 1979 thru April, 1982. No STORET exists for Segment 13, hence only the Climax data was used. All Climax data was analyzed according to the total method.
The water quality standards for the non-runoff period are based on data including all ambient data obtained during the time the Climax Wastewater Treatment facility was operating with the exception of the bypass periods associated with the runoff in the months of January and February during which Climax will not discharge in the future. The Commission recognizes that this period varies from year to year and that it will be determined annually by the Division and Climax. This period shall generally commence not earlier than May 1 and extend approximately 60 days as more specifically defined by the Climax water balance computer model. Historically a bypass has not been necessary every year and may not always be necessary in the future.
The Commission has also been presented with Climax data covering the snowmelt bypass periods of 1980 and 1982. In view of a seasonal variability of the ambient water quality, the Commission adopts x[BAR] + s of the snowmelt bypass data as water quality standards to apply during this period.
In adopting the above water quality standard for Segment 13, the Commission is mindful of its goals to protect the use classifications in Segment 14. The Commission finds that the water quality standards it has adopted for Segment 13 are based on historical data gathered during a period when there was general improvement in stream quality. Hence, the water quality standards based on such data should be sufficient to protect and maintain the uses assigned to both Segments 13 and 14, including water supplies in Segment 14.
Segment 14
The Commission has been presented with STORET and Climax data and calculations for various pollutants during the period November, 1979, through April, 1982. As with Segment 13 data, these have been split according to the snowmelt bypass and non-runoff periods. Climax data was analyzed by the total method. The State data was analyzed according to the State methodology. For the snowmelt bypass period the Commission adopts the x[BAR] + s of the combined non-runoff data.
Evidence indicates the standards as adopted do not require additional technology, and are economically reasonable.
FISCAL IMPACT STATEMENT
Revision of Aquatic Life Classification and Certain Numeric Standards Segments 13 and 14 of Ten Mile Creek
The principle fiscal impact of the adoption of the aquatic life class 2 classification and revised water quality standards is a significant potential cost savings to be realized by Climax Molybdenum Company. Evidence submitted by Climax Molybdenum Company suggests that without these modifications, Climax would be faced with a strong probability of additional treatment to cost from $8.2 million to $14.6 million in capital expenses and from $3.8 million to $6.6 million in annual operating and maintenance costs. Because evidence suggests that the beneficial uses that are identified and in place will be adequately protected and possibly enhanced with these changes, and because potential beneficial use improvements to be realized by additional treatment do not bear a reasonable relationship to the costs to attain them at this time, the Commission concludes that it is economically reasonable to support the change of the aquatic life classification and revision of certain numeric standards on these segments.
5 CCR 1002-33.11