5 Colo. Code Regs. § 1002-38.30
The provisions of 25-8-202(1) (a), (b) and (2); 25-8-203; 25-8-204; 25-8-207 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 considered and adopted are addressed below by segment.
Page 9, Clear Creek, Segment 6
Page 9. Clear Creek, Segment 9
Page 12, Big Dry Creek, Segment 3
Page 13, Boulder Creek, Segment 2
Page 13, Boulder Creek, Segment 3
Page 13, Boulder Creek, Segment 4b
Page 14, Boulder Creek, Segment 9
Page 15, Boulder Creek, Segment 12
Page 16, St. Vrain Creek, Segment 2
Page 19, Big Thompson River, Segment 7
Page 19, Big Thompson River, Segment 8
Page 19, Big Thompson River, Segment 11
Page 19, Big Thompson River, Segment 12
Page 20, Big Thompson River, Segment 14 (now deleted)
Page 21, Cache La Poudre River, Segment 2
Page 21, Cache La Poudre River, Segment 3
Page 21, Cache La Poudre River, Segment 4
Page 21, Cache La Poudre River, Segment 6
Page 22, Cache La Poudre River, Segment 9
Page 23, Cache La Poudre River, Segment 14
Page 23, Cache La Poudre River, Segment 15
Page 23, Cache La Poudre River, Segment 16
Page 24, Laramie River, Segment 2
Page 25, South Plate River, Segment 3
Page 26, Republican River, Segment 1
Page 26 Republican River, Segment 2
Page 26, Republican River, Segment 3
Numerical standards for metals for these segments have in most instances previously been based on table values contained in Table III of the Basic Standards and Methodologies for Surface Water. Table III has been substantially revised, effective September 30, 1988. From the information available, it appears that the existing quality of these segments meets or exceeds the quality specified by the revised criteria in table III, and new table value standards based thereon have therefore been adopted. There are also some of these segments whose previous standards were based in part on ambient quality, since their quality did not meet old table values based on alkalinity ranges. However, these segments generally have much higher hardness than alkalinity, and the new table values (based on hardness-dependent equations) are now appropriate as standards. In addition to these revisions, the segment desriptions have been clarified for Laramie River, Segment 2, and Cache La Poudre River, Segment 4. As a "housekeeping" clarification, the previous Big Thompson Segment 14 has been deleted, with these waters added into Big Thompson Segment 12. Finally, a High Quality 2 designation has been added to Cache La Poudre River, Segment 2, and the description of this segment has been revised to include waters within wilderness areas and those designated as "wild rivers" since the original hearings for this basin. This designation is appropriate in accordance with the recently revised antidegradation provision in the Basic Standards and Methodologies for Surface Water.
The table value standards for metals have been adopted for this segment, except for cadmium, copper, and zinc. This is one of a few segments in South Plate Basin that has historic dissolved metals data base. USGS station 0671, Clear Creek at Golden, shows for mean hardness of 77 mg/l. Ambient standards based on the 85th percentile are appropriate for cadmium, copper and zinc. The geometric mean of fecal coliform data at the Water Quality Control Division's routine monitoring station is 66 MPN/10 ml. This is well below the 200 MPN/100 ml criteria for Recreation Class 1 and the change in classification and standards is justified on a water quality basis.
This segment's description has been revised to add a wilderness area that has been designated since the original hearings for this segment. In addition, in accordance with the new antidegradation provisions, appropriate use classifications and table value numeric standards have been adopted for this segment, to apply in the event that degradation is determined to be necessary following an activity-specific antidegradation review.
A new acute standard for ammonia has been adopted for this segment, based on the recent revisions to Table II of the Basic Standards and Methodologies for Surface Water. In addition, the chronic ammonia standard has been changed to 0.1 mg/l. The evidence indicates that this segment is correctly classified as a class 2 aquatic life segment, but that the variety of aquatic life in this segment may be adversely impacted by factors other than ammonia and does not warrant protection at the 0.06 mg/liter un-ionized ammonia level that the Division originally proposed. Standards greater that 0.06 are allowable according to footnote 1 of Table II of the Basic Standards and Methodologies for Surface Waters 3.1.0 (5 CCR 1002-8), which sets out a range of 0.06 to 0.1 mg/liter un-ionized ammonia for class 2 aquatic life, and specifies that standards greater than 0.08 mg/liter may be considered "where a higher risk of sublethal effects is justified by habitat limitations or other water quality factors". The Commission believes this to be the case for this segment and that there is uncertainty that the aquatic life would be enhanced with a standard in the 0.06 to 0.08 range, as opposed to a 0.1 mg/liter standard. The 0.1 standard is consistent with the other warm-water class 2 aquatic life streams in the vicinity.
The Division has identified three dischargers on this segment which potentially will be affected by a change in the chronic standard. A change to 0.1 from the existing 0.13 mg/liter un-ionized ammonia standard could result in additional effluent treatment being required of the City of Berthoud, but will not likely result in additional treatment for Adolph Coors Company of Johnstown.
Previously the tributaries to South Boulder Creek between Hwy 93 and South Boulder Road were listed under the description for both segments Segment 8 and 4.b. This overlap in segment description was brought to the Division's attention in May, 1988, by the Hazardous Materials and Waste Management Division of the Health Department, during negotiations over the Marshall Landfill CERCLA Consent Decree.
By listing these tributaries under Segment 4.b. it is the Commission's intent to establish classifications that are consistent with tributaries to South Boulder Creek upstream of Highway 93. One of the tributaries in 4.b. known as Cowdrey Drainage, would receive treated wastewater from a proposed treatment plant for the Marshall Landfill. Due to site-specific considerations on Cowdrey Drainage, Segment 4.b. was therefore resegmented into 4.b. (with exclusions) and new segments 4.c. and 4.d. Visits of the site and data collection indicate that intermittent surface flows from upper Cowdrey Drainage are intercepted by the Davidson Ditch and do not reach the lower portion of the drainage. Site-specific differences in use, upstream and downstream of the Davidson Ditch, account for the differences in numeric standards and use classifications.
A water supply classification has been included in segment 4.c. due to the presence of municipal water rights of the Cities of Louisville and Lafayette. According to the District 6 Water Commissioner of the Division of Water Resources, Louisville has not yet exercised its right to divert water for municipal use, but that Lafayette has diverted water for municipal use to Wanaka Reservoir, the City's storage reservoir. It is thus clear that there is a potential and existing use made of water from the upper segment (4.c.) of the Cowdrey Drainage.
Barbour Ponds have been added to the description of this segment. Barbour Ponds are open to public fishing and contain reproducing populations of fish. The change is appropriate in that there are no sludge beds on the bottom of the ponds and water level fluctuations are not extreme. Without the change of classification the Division's ability to regulate anyone who discharges or causes a fish kill by dumping a toxicant to the waterways feeding the waters would be limited.
Lon Hagler reservoir has been added to the description of this segment. Lon Hagler is open to public fishing and contains reproducing populations of fish. The change is appropriate in that there are no sludge beds on the bottom of the reservoir and water level fluctuations are not extreme. Without the change in classification the Division=s ability to regulate anyone who discharges or causes a fish kill by dumping a toxicant to the waterways feeding the waters would be limited.
Revised metals standards, based on the new Table III in the Basic Standards and Methodologies for Surface Water have been adopted for this segment. The City of Louisville requested that the new Table III be applied to Segment 7.b. as soon as possible because the City's renewed discharge permit sets forth a compliance schedule requiring the city to determine the facilities' ability to comply with water quality-based effluent limitations for each metal for which there is a stream standard. Application of the new table III methodology will allow the City to proceed with the compliance schedule required in its renewed discharge permit and determine the facilities' ability to comply with the potential limitations. Application of the new standards will provide the level of protection necessary to assure the maintenance of the use classifications (Recreation Class 2, warm Water Aquatic Life Class 2, and Agriculture), assigned to segment 7.b.
LIST OF PARTY PARTICIPANTS TO THE FEBRUARY, 1989 SOUTH PLATE
5 CCR 1002-38.30