5 Colo. Code Regs. § 1002-34.24
The provisions of 25-8-202(1)(a), (b) and (2): 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for the 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 Water Quality Control Division (Division) proposed that the Water Quality Control Commission consider the following changes to the Classifications and Numeric Standards for San Juan River and Dolores River Basins, 3.4.0. The basis and purpose for the changes are organized by topic.
Several of the segments contained waters that crossed into or were on the Southern Ute and Ute Mountain Indian Reservations. Both tribes are in the process of developing classifications and standards for waters within their reservations and it was agreeable to both tribes that those segments should be bi-furcated to indicate which portions are on tribal lands and to ease their future removal from the state standards system when the tribes' standards are approved by the U. S. Environmental Protection Agency. The segments on the Southern Ute Reservation, at the request of the Southern Ute Tribe, have been maintained at the classifications and standards in effect prior to this rulemaking hearing. The standards on some segments on the Ute Mountain Reservation, after discussion with tribal representatives, were changed to parallel the changes made by the state on the adjacent segments. These were all related to changes from total recoverable to dissolved metals standards where data indicated table value standards for metals were appropriate.
In addition to the bifurcation of segments, all segments, new and old, which delineate tributaries have added wetlands to their descriptions to clarify that all tributary wetlands have the same classifications and standards as the tributary streams, lakes and reservoirs.
The DOW identified several areas requiring resegmentation or changes to standards in order to protect fisheries. Therefore, the following changes were made. Mill Creek and Echo Canyon Reservoir were reassigned from San Juan segment 11 to San Juan segment 6a. Weber Canyon was reassigned from Mancos segment 6 to Mancos segment 5a. Summit Reservoir was reassigned from Dolores segment 11 to Dolores segment 4. Narraguinnep, Puett and Totten Reservoirs are reassigned from McElmo Creek segment 8 to McElmo Creek segment 11. According to new information, these waters support fisheries, fish consumption, and intensive recreation, and are suitable for domestic use. Therefore, this new segment 11 was assigned classifications of Recreation class 1, Aquatic Life Warm 1, Water Supply and Agriculture, with appropriate table value standards.
There were several segments which still had metals standards based on the old total recoverable criteria. Review of metals data submitted to the hearing allowed the metal standards on the following segments to be appropriately converted from total recoverable to dissolved standards:
San Juan River segment 6a
Piedra River segment 4a
La Plata River segment 2a
Mancos River segments 5a and 5b
McElmo Creek segment 7
Dolores River segments 2, 3, 5, 6, and 9
Several segments in the San Juan-Dolores river basins did not have use classifications which met the swimmable goals of the Clean Water Act. Consistent with strategies adopted by the Commission, these segments which are designated recreation class 2 and have no point source dischargers to the segment have had their fecal coliform standard set equal to 200/100 ml. These segments are:
La Plata River segment 2a
Dolores River segments 2, 3, 5, 6, 8, and 9
On all segments classified for water supply and aquatic life uses, the total recoverable manganese standard of 1,000 ug/l was stricken. The aquatic life manganese criterion was changed in 1991 revisions to the Basic Standards from total recoverable to dissolved and on these segments a more stringent dissolved manganese water supply standard of 50 ug/l is in place.
Mercury standards designated as total recoverable (Trec) were 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.
One segment classified aquatic class 1, Piedra River segment 7, was found to have a use-protected designation which was based on prior basic standards requirements pertaining to waters classified as warmwater aquatic life class 1, recreation class 2. The designation was removed to conform to the requirements now in effect.
New data on several segments showed the water quality to be suitable for a water supply classification. The water supply classifications and standards were added to the following segments:
San Juan River segment 6a
Piedra River segment 4a
McElmo Creek segment 11
PARTIES TO THE MARCH, 1995 RULEMAKING HEARING
5 CCR 1002-34.24