5 Colo. Code Regs. § 1002-32.11
The provisions of 25-8-202(1)(a)(b) and (2); 25-8-203; and 25-8-204 C.R.S. provide the specific statutory authority for adding the numeric standards adopted by the Commission in this matter.
The two year temporary modifications for the copper and lead standards on this segment which were adopted by the Commission are consistent with the Commission's established procedures for adopting water quality standards or temporary modifications based on ambient quality. The standards set represent a determination of ambient water quality where a shortage of reliable data, and discrepancies regarding analytical techniques, precluded the adoption with sufficient confidence of any more stringent standards.
Physical conditions in various portions of Segment 8a such as substrate, low flow, depth, lack of pools, freeze-out, and physical barriers preclude a viable fish population, and more stringent water quality standards than adopted cannot be justified for the protection of macroinvertebrate only, based on the aquatic life classification. The macroinvertebrate population which does exist in the segment does not appear stressed at ambient levels of pollutant concentration. Ambient levels of pollutant concentration do not now jeopardize downstream aquatic life. Testimony does not support the conclusion that the imposition of more stringent metals limits would lead to an improved aquatic habitat.
At such time as water quality improvements downstream in Segments 8b or 9 indicate either a potential for a viable fish community in Segment 8a or an approved fishery in Segment 8b or 9 and where the macroinvertebrate population in the upper segment is necessary for that fish community's survival, or during the triennial review of the basin, the standards for this segment may need to be reexamined to assure that downstream uses continue to be protected.
From evidence received at the public hearing, it appeared that the existing stream standards for copper and lead were periodically exceeded in several reaches of the segment. However, there was considerable disagreement among the parties and staff over the appropriateness and accuracy of the data presented at the hearing. Differences in analytical techniques resulted in non-comparable data, making the calculation of ambient quality, based on a determination of the mean value, difficult. The temporary modifications adopted for copper and lead reflect a continuation of ambient quality, which protect designated uses and recognize the need to protect the drinking water supply diversion at the lower end of the segment.
The agriculture use classification is retained because there is conflicting evidence regarding the existence and extent of the use necessitating further study. The standards in effect to protect this use do not impact the Sherman Tunnel discharge.
No change was made to the other pollutants for which change had originally been proposed because the data available did not conclusively support a change, and because the current stream standards adequately protect the classified uses. Evidence presented at the hearing indicated that the original classified uses remained appropriate.
BAT limits are being met by the sole discharger to the segment, the Hecla Mining Company. There has been no demonstration that more stringent water quality standards will provide any benefits to the aquatic life in the stream. The adopted temporary modifications will not require the discharger to provide additional treatment where there is in the record insufficient information to justify the adoption of standards that could result in additional treatment requirements. The adopted temporary modifications are thus determined to be economically reasonable.
It is further declared to be the Commission's intention that the temporary modifications are being established at this time to allow all interested persons to collect additional data to be analyzed in a uniform fashion and in conformance with existing Commission policies as well as upcoming modifications thereto, so that at such time as the temporary modifications expire or at any other appropriate time, the Commission will be able to determine appropriate final standards for all parameters on this segment.
FISCAL IMPACT STATEMENT - SEGMENT 8a, IOWA GULCH, UPPER ARKANSAS RIVER, ARKANSAS RIVER BASIN
The establishment of temporary modifications to the water quality numeric standards for lead and copper dramatically reduce the probability of further treatment requirements for mined located in this segment. Estimates indicate a potential savings of up to $300,000 capital costs and $16,000 operations and maintenance to accrue to the owner of the Sherman Mine. The Commission finds that these cost savings will not be had at the expense of current beneficial use degradation, based upon the evidence available.
There will be no fiscal impact on any other government or private entities.
5 CCR 1002-32.11