5 Colo. Code Regs. § 1002-33.28
The provisions of 25-8-202(1)(b) and (2); and 25-8-204 and 25-8-402, C.R.S. provide the specific statutory authority for adoption of these regulatory amendments. The Commission also adopted, in compliance with 24-4-103(4), C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
The changes described below were adopted by the Commission as proposed by the Water Quality Control Division during the rulemaking hearing:
Corrected several errors in the tables for segments not classified for water supply use. The action entailed deletion of NO3, Cl, and SO4 and revision of As, Crlll, and Se of certain standards applied to these segments that reflected protection of a water supply use. The segments whose standards were modified are: Upper Colorado segment 6c, Blue River segments 11 and 13, North Platte River Segment 6, and Yampa River segments 5, 7, and 13b.
The chronic ammonia (NH3) standard in the Yampa River Basin segment 7 was raised from 0.02 to 0.05 to correct a typographical error. The Commission had adopted the 0.05 standard for the segment in 1985 and it was subsequently inadvertently dropped from the table.
On all segments classified for water supply and aquatic life uses, the total recoverable manganese standard of 1000 ug/l is stricken. On segments classified for aquatic life and not water supply the 1000 ug/l standard is designated as dissolved. The aquatic life manganese criterion was changed in 1991 revisions to the Basic Standards from total recoverable to dissolved and on these segments classified for water supply and aquatic life, a more stringent dissolved manganese water supply standard of 50 ug/l is in place.
Mercury standards designated as total recoverable (Trec) are changed to Total (tot). This change reflects the Basic Standards designation of total mercury as the appropriate form of mercury for final residual value (FRV) standards.
The following Water Quality Control Division and Northwest Colorado Council of Governments (NWCCOG) joint proposals were adopted by the Commission.
Upper Colorado segment 7b (Rock Creek) was deleted. Segment 7a was renumbered as segment 7. This segment was no longer requires separate segment designation due to elevated mercury.
Extended (reestablished) the temporary modifications for Blue River segments 2 (Blue River below French Gulch) and 7 (Peru Creek) which had expired on April 30, 1996 in anticipation of improved water quality in these segments in the future as existing or proposed project are fully implemented. These temporary modifications were given a new expiration date of December 31, 1998.
At the request of Viacom International, Inc. the Commission extended (reestablished) the temporary modifications of the numeric standards for dissolved manganese on segments 5 and 9 of the Eagle River for an additional three-year period, from May 1, 1996 until December 31, 1998. The Commission found that the underlying numeric standard for dissolved manganese is not being met in these segments, largely as a result of the effects of past mining in the area, now mostly inactive. The former Eagle Mine and its associated tailings disposal areas have been, and continue to be the subject of remediation actives being implemented under the terms of two consent decrees by Viacom International Inc., the successor to the mine=s former owner. The remediation is still in progress, and while continued water quality improvement is expected, both the extent and the timing of such improvement are unknown at this time.
The Water Quality Control Division is planning to perform water quality measurements in the Eagle River as part of a basin-wide water quality monitoring effort during 1996 and data collected by Viacom, EPA, and the State of Colorado, and others, will be used in a comprehensive review of the classifications and standards for these segments in a rulemaking now anticipated to occur in 1998, at which time these temporary modifications can be reconsidered. Therefore, the Commission has determined that it is appropriate to retain the temporary modifications for dissolved manganese on the affected segments.
In response to the petition of Pittsburg & Midway Coal Mining Company (P&M), the Commission decided to revise the segmentation and classifications of Yampa River 13a, by adding a new segment 13c. P&M had asked the Commission to remove the water supply designation for these waters. P&M argued that there is no water supply use currently in place for this segment, that such use is unlikely in the future, that existing quality does not meet water supply standards, and that water supply standards would result in unreasonable treatment costs for P&M. NWCCOG argued that the legal requirements for downgrading had not been met, and instead recommended that a temporary modification of sulfate standard be adopted.
The Commission decided to retain the water supply classification for this segment for the period June through February annually, while removing this classification and corresponding numerical standards on a seasonal basis, for the period March through May. The evidence presented indicated that P&M should not have a problem meeting the effluent limitations associated with a seasonal sulfate standard, so long as that standard is properly implemented as a 30-day average concentration.
Finally, the Commission notes that its decision to remove the water supply classification on a seasonal basis is influenced by the fact that the critical standard at issue--sulfate--is based on a secondary drinking water standard rather than a health-based primary standard.
The Commission agreed to consider a proposal by the Water Quality Control Division for a proposed designation of outstanding waters for Upper Colorado segment 9 in the scheduled basin-wide rulemaking in 1998.
Climax Molybdenum Company withdrew their proposal to bifurcate Upper Colorado River segment 8. The concerns with manganese and iron standards will be addressed in a request for a rulemaking hearing on this segment next year.
PARTIES TO THE RULEMAKING HEARING 1996
5 CCR 1002-33.28