5 Colo. Code Regs. § 1002-37.25
The provisions of C.R.S. 25-8-202 (1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; 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 Commission split lakes/reservoirs from segments that contained both streams and lakes/reservoirs so that new temperature standards could be adopted. Lakes and reservoirs were deleted from the following segments that previously encompassed both streams and lakes/reservoirs:
Lower Yampa/Green River segments: 3a, 3c, 4, 6a, 7, 8, 9, 12a, 18, and 20.
White River segments: 1, 4, 6, 8, 10b, 12, 13a, 16, and 22.
Lower Colorado segments: 5, 7a, 8, 9b, 10, 14a, 14c, 15, 17a, and 18.
The following lakes/reservoirs segments were created:
Lower Yampa/Green River segments: 23-33.
White River segments: 13d, 24-27.
Lower Colorado segments: 20 and 21.
Some renumbering and/or creation of new segments was made due to information which showed that:
Lower Yampa/Green River 1: This segment was deleted and the mainstem of the Yampa encompassed by this segment was moved to segment 2. The Commission determined that this segment had been mis-classified as cold-water habitat. The Commission combined the listings in segment 1 with segment 2 because they are both warm-water habitat, cover a geographically contiguous area, and the Commission determined they should have identical anti-degradation designation, use classifications, and standards.
Lower Yampa/Green River 2: The segment description was amended to include the mainstem of the Yampa between Elkhead Creek and Lay Creek, which was deleted from segment 1. The Commission combined these segments because they are warm-water habitat, cover a geographically contiguous area, and the Commission determined they should both have identical antidegradation designation, use classifications, and standards. This segment now encompasses all portions of the Yampa mainstem that are critical habitat for the federally endangered razorback sucker.
Lower Yampa/Green River 3a: The segment description was amended to include all tributaries and wetlands to the Yampa River between Lay Creek and the Little Snake River, which were deleted from segment 14. The Commission combined these segments because they cover a geographically contiguous area, and the Commission determined they should both have identical antidegradation designation, use classifications, and standards. Segments 17a, 17b, and 18 were added to the listings specifically excluded from this segment.
Lower Yampa/Green River 3b: Ben Morgan Creek, Boxelder Gulch, Collom Gulch, Hale Gulch and Jubb Creek were deleted from this segment and moved to a new segment 3g. The creeks and gulches that remain in this segment drain the Williams Fork Mountains and have inorganic and metals standards that are protective of livestock watering only.
Lower Yampa/Green River 3q: This segment was created to encompass Ben Morgan Creek, Boxelder Gulch, Collom Gulch, Hale Gulch and Jubb Creek. The creeks and gulches in this new segment drain the Danforth Hills and now have inorganic and metals standards that are protective of irrigated agriculture instead of livestock watering only.
Lower Yampa/Green River 4: The segment description was amended to include the North Fork of Fortification Creek and Little Cottonwood Creek. The Commission determined that these streams are cold-water habitat and moved them to this segment from segment 6a to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 6a: The North Fork of Fortification Creek was removed from this segment. The Commission moved the North Fork of Fortification Creek to segment 4 to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 6b: This segment was deleted and Freeman Reservoir was moved to a newly created cold-water lakes/reservoirs segment 24 where it was combined with Aldrich Lakes.
Lower Yampa/Green River 9: The South Fork of the Williams Fork River, including tributaries and wetlands, within the Routt National Forest was moved to this segment from segment 11. The Commission combined segments 9 and 11 because they cover a geographically contiguous area, and the Commission determined they should both have identical antidegradation designation, use classifications, and standards.
Lower Yampa/Green River 10: The segment description was amended to include tributaries and wetlands to the East Fork of the Williams Fork River from the boundary of the Routt National Forest to the confluence with the South Fork. The Commission determined these tributaries are cold-water habitat and moved them to this segment from segment 3a to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 11: This segment was deleted and the South Fork of the Williams Fork River, including tributaries and wetlands, were incorporated into segment 9. The Commission combined segments 9 and 11 because they cover a geographically contiguous area, and the Commission determined they should both have identical antidegradation designation, use classifications, and standards.
Lower Yampa/Green River 12a: The segment description was amended to include all wetlands and tributaries to the South Fork of the Williams Fork River and Beaver Creek. The Commission moved these wetlands and tributaries from segment 3a to facilitate the adoption of appropriate temperature standards. The segment description was also amended to move the boundary for Milk Creek upstream to Clear Creek. The Commission moved Milk Creek between Clear Creek and County Road 15 in Thornburg to segment 12b.
Lower Yampa/Green River 12b: Aldrich Lakes were moved to a newly created cold-water lakes/reservoirs segment 24, where they were combined with Freeman Reservoir. The portion of Milk Creek between the confluence with Clear Creek and County Road 15 in Thornburg was moved to this segment from segment 12a to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 14: This segment was deleted and wetlands and tributaries to the Yampa between Lay Creek and the Little Snake River were incorporated into segment 3a. The Commission combined segments 3a and 14 because they cover a geographically contiguous area, and the Commission determined they should both have identical antidegradation designation, use classifications, and standards.
Lower Yampa/Green River 17b: The segment description was amended to remove the exclusion for specific listings in segment 18. None of the listings in segment 18 would otherwise be encompassed by this segment.
Lower Yampa/Green River 18: Slater Creek, including all wetlands and tributaries, between Second Creek and the Little Snake River were moved from this segment to segment 17a to facilitate the adoption of appropriate temperature standards. The segment description was also amended to include the mainstems of Fourmile and Willow Creeks, including all wetlands and tributaries, from their sources to the boundary of the Routt National Forest. The Commission moved these sections of Fourmile and Willow Creeks to this segment from segment 17a to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 19a-19b: Segment 19 was split into segments 9a and 19b to facilitate the adoption of appropriate temperature standards. Segment 19a is a cold-water segment that includes the Green River from its entrance at the Colorado/Utah border to the confluence with the Yampa River. Segment 19b is a warm-water segment that includes the Green River from the Yampa River to its exit at the Colorado/Utah border.
Lower Yampa/Green River 20: Segments 22a, 22b, and 22c were added to the listings specifically excluded from this segment.
Lower Yampa/Green River 22a: Vermillion Creek, including all tributaries and wetlands, from the confluence with Talamantes Creek to the confluence with the Green River were removed from the segment description. The Commission moved this portion of Vermillion Creek to a newly created segment 22b to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 22b: This segment was created to encompass Vermillion Creek, including all tributaries and wetlands, from the confluence with Talamantes Creek to the confluence with the Green River, except for specific listings in segment 22c. The Commission created this segment from portions of Vermillion Creek split from segment 22a to facilitate the adoption of appropriate temperature standards.
Lower Yampa/Green River 22c: This segment was formerly segment 22b, but was changed to segment 22c to facilitate the splitting of segment 22a.
Lower Yampa/Green River 23: This segment was created to encompass lakes and reservoirs tributary to the Yampa River from the confluence with Elkhead Creek to a point below the confluence with the Little Snake River. This segment includes lakes/reservoirs formerly in segments 3a and 14.
Lower Yampa/Green River 24: This segment was created to encompass Freeman Reservoir and Aldricin Lakes. Freeman Reservoir was formerly in segment 6b, and Aldricin Lakes were formerly in segment 12b. The Commission combined segments 6b and 12b because they have identical antidegradation designations, use classifications, and standards.
Lower Yampa/Green River 25: This segment was created to encompass cold-water lakes tributary to the North and South Forks of Fortification Creek, Little Cottonwood Creek, and Little Bear Creek from the source to the confluence with the Dry Fork. The lakes/reservoirs tributary to the South Fork were formerly in segment 4. Lakes and reservoirs tributary to the North Fork and Little Cottonwood Creek were formerly in segment 6a. Lakes and reservoirs tributary to Little Bear Creek were formerly in segment 7.
Lower Yampa/Green River 26: This segment was created to encompass warm-water lakes and reservoirs tributary to Fortification Creek. This segment includes most of the lakes and reservoirs that were formerly in segment 6a.
Lower Yampa/Green River 27: This segment was created to encompass warm-water lakes and reservoirs tributary to Milk Creek between Thornburgh (County Rd 15) and the Yampa River. This segment includes lakes/reservoirs formerly in segments 3c and 12a.
Lower Yampa/Green River 28: This segment was created to encompass cold-water lakes and reservoirs within the boundaries of the Flat Tops Wilderness Area and tributary to the East Fork of the Williams Fork River. The lakes and reservoirs in this segment were formerly in segment 8.
Lower Yampa/Green River 29: This segment was created to encompass cold-water lakes and reservoirs tributary to the East and South Forks of the Williams Fork River, and the mainstem of the Williams Fork River from the source to the Highway 13/789 bridge at Hamilton. Lakes and reservoirs tributary to the East Fork were formerly in segment 9. Lakes and reservoirs tributary to the South Fork were formerly in segment 11. Lakes and reservoirs tributary to the Williams Fork from the boundary of the Routt National Forest to the bridge in Hamilton were formerly in segment 3a.
Lower Yampa/Green River 30: This segment was created to encompass cold-water lakes and reservoirs tributary to Milk Creek from the source to the confluence with Clear Creek, and lakes and reservoirs tributary to Morapos Creek from the source to the confluence with the Williams Fork River. Lakes and reservoirs tributary to Milk Creek were formerly in segment 12a. Lakes and reservoirs tributary to Morapos Creek were formerly in segment 3a.
Lower Yampa/Green River 31: This segment was created to encompass cold-water lakes and reservoirs tributary to Slater Creek from the source to Second Creek, and lakes and reservoirs tributary to Fourmile and Willow Creeks within the Routt National Forest. Lakes and reservoirs tributary to Slater Creek were formerly in segment 18. All lakes and reservoirs tributary to Fourmile and Willow Creeks were formerly in segment 14.
Lower Yampa/Green River 32: This segment was created to encompass warm-water lakes and reservoirs tributary to the Yampa River from a point just below the confluence with the Little Snake River to the confluence with the Green River, and lakes and reservoirs tributary to the Green River. Lakes and reservoirs in this segment were formerly in segment 20.
Lower Yampa/Green River 33: This segment was created to encompass cold-water lakes and reservoirs tributary to Beaver Creek and Vermillion Creek from the Colorado/Wyoming border to the confluence with Talamantes Creek. Lakes and reservoirs in this segment were formerly in segment 20.
White River 9a: The tributaries and wetlands to the White River, and not within a national forest, between Flag Creek and Piceance Creek were removed from the segment description. The Commission moved these tributaries and wetlands to segment 9b to facilitate the adoption of appropriate temperature standards. Segments 9c and 9d were added to the list of segments specifically excluded from this segment, and segment 9b was removed from that list.
White River 9b: This segment was created to encompass the tributaries and wetlands to the White River between Flag Creek and Piceance Creek, and not within a national forest. The Commission moved these tributaries and wetlands to this segment from segment 9a to facilitate the adoption of appropriate temperature standards. Segments 9c and 9d were added to the list of segments specifically excluded from this segment.
White River 9c: This segment was formerly numbered 9b, but was changed to segment 9c to facilitate the splitting of segment 9a. Sulphur Creek and Flag Creek between the East Fork Flag Creek and the White River were moved to segment 9d.
White River 9d: This segment was created to encompass Sulphur Creek, and Flag Creek from the confluence with East Fork Flag Creek to the confluence with the White River. The Commission moved Sulphur Creek and the lower portion of Flag Creek to this segment from segment 9c to facilitate the adoption of appropriate temperature standards.
White River 10a: The segment description was clarified by indicating that the lower segment boundary occurs at a point immediately above the confluence with Piceance Creek so that lakes and reservoirs tributary to Piceance Creek are specifically excluded from this segment. Additionally, segments 25 and 27 were added to the listings specifically excluded from this segment.
White River 10b: The segment description was clarified by deleting the exclusion for Lake Avery and adding wetlands to the segment description.
White River 11: The segment description was amended to include Taylor Draw Reservoir (a.k.a Kenney Reservoir). The Commission moved Taylor Draw from segment 12 as part of a basin-wide effort to split lakes/reservoirs from stream segments to facilitate the adoption of appropriate temperature standards.
White River 12: Taylor Draw Reservoir was removed from the segment description. The Commission moved Taylor Draw to segment 11 as part of a basin-wide effort to split lakes/reservoirs from stream segments to facilitate the adoption of appropriate temperature standards.
White River 13b-13d: Segment 13b was split into three segments (see Section P.). Segment 13b includes Yellow Creek from the source to Barcus Creek, and all tributaries to Yellow Creek. Segment 13c includes Yellow Creek from Barcus Creek to the mouth. Segment 13d includes Violett Springs Ponds.
White River 14a-14b: Segment 14 was split to facilitate the adoption of appropriate temperature standards. Segment 14a includes Piceance Creek from the source to Hunter Creek. Segment 14b includes Piceance Creek between Hunter Creek and Ryan Gulch. The Emily Oldhand diversion dam was removed from the segment description because its location is unknown. The segment boundaries at Hunter Creek and Ryan Gulch are based upon current information about fish distributions and their associated temperature standards. However, the fish data in Piceance Creek are limited and there is some uncertainty associated with these segment boundaries. These boundaries should be re-evaluated if additional temperature or fish data are collected.
White River 15: The upper boundary for the mainstem of Piceance Creek in this segment was moved from the Emily Oldlnand diversion dam to Ryan Gulcln. The Emily Oldhand diversion dam was removed from the segment description because its location is unknown. Ryan Gulch was selected as the segment boundary between warm and cold water on the mainstem of Piceance Creek based on current information about temperature and fish distributions in Piceance Creek. However, the fish data in Piceance Creek are limited and there is some uncertainty associated with the segment boundary at Ryan Gulch. This boundary should be re-evaluated if additional temperature or fish data are collected. The segment description was also amended to include the Dry Fork of Piceance Creek, including all tributaries and wetlands, from the confluence with Little Reigan Gulch to the confluence with Piceance Creek. The Commission moved the mainstem of the Dry Fork mainstem from segment 17, and the tributaries and wetlands to this portion of the Dry Fork from segment 16, to facilitate adoption of appropriate temperature standards.
White River 16: The segment description was amended so that segments 15 and 18 were added to the listings specifically excluded from this segment.
White River 17: Willow Creek, and the Dry Fork of Piceance Creek were removed from this segment. The Commission moved Willow Creek to segment 18, and moved the Dry Fork of Piceance Creek to segments 15 and 18, to facilitate adoption of appropriate temperature standards.
White River 18: Willow Creek, Hunter Creek, and the Dry Fork of Piceance Creek from the source to the confluence with Little Reigan Gulch were added to this segment. The Commission moved Willow Creek and this portion of the Dry Fork to this segment from segment 17, and Hunter Creek from segment 20 to facilitate the adoption of appropriate temperature standards.
White River 20: The segment description was amended to include all wetlands and tributaries to Black Sulphur Creek. The Commission moved these tributaries from segment 16 to facilitate the adoption of appropriate temperature standards. Hunter Creek was also moved from this segment to segment 18 to facilitate the adoption of appropriate temperature standards.
White River 24: This segment was created in encompass cold-water lakes and reservoirs tributary to the White River that are within the boundaries of the Flat Tops Wilderness Area. Lakes and reservoirs within this segment were formerly in segment 1.
White River 25: This segment was created to encompass Lake Avery (a.k.a. Big Beaver Reservoir), which is the only cold lake in the White River basin greater than 100 acres surface area. Lake Avery was formerly in segment 10a.
White River 26: This segment was created to encompass other cold-water lakes and reservoirs tributary to the North and South Forks of the White River, from the boundary of the Flat Tops Wilderness Area to the confluence of the North and South Forks. The lakes and reservoirs tributary to the North Fork were formerly in segment 4, and the lakes and reservoirs tributary to the South Fork were formerly in segment 6.
White River 27: This segment was created to encompass warm-water lakes and reservoirs tributary to the White River from Piceance Creek to the Colorado/Utah border. The lakes and reservoirs tributary to the White River from the confluence with Piceance Creek to the confluence with Douglas Creek were formerly in segment 13a. The lakes and reservoirs tributary to Piceance Creek were formerly in segment 16. The lakes and reservoirs tributary to the White River from the confluence with Douglas Creek to the Utah/Colorado border were formerly in segment 22. Segment 13d was specifically excluded from the segment description.
Lower Colorado 1: The Colorado River between Rifle Creek and Parachute Creek was moved from this segment to segment 2a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 2a-2b: Segment 2 was split into segments 2a and 2b at Rapid Creek to recognize changes in water quality due to the presence of selenium bearing shales in the vicinity of Rapid Creek. Segment 2a includes the mainstem of the Colorado River from Rifle Creek to Rapid Creek. Segment 2b includes the mainstem of the Colorado River from Rapid Creek to the Gunnison River. The upper boundary of segment 2a was moved upstream from Parachute Creek to Rifle Creek to facilitate the adoption of appropriate temperature standards.
Lower Colorado 4a: Segments 4c, 4d, 4e, 7a, 7b, 9a, 9c, and 12a were added to the listings specifically excluded from this segment.
Lower Colorado 4c: This segment was created to encompass the mainstem of South Canyon Creek from the South Canyon Hot Springs to the confluence with the Colorado River. The Commission split this portion of South Canyon Creek from segment 4a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 4d: This segment was created to encompass the mainstem of Dry Hollow Creek, including all tributaries and wetlands, from the source to the confluence with the Colorado River. The Commission decided to split Dry Hollow Creek from segment 4a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 4e: This segment was created to encompass Dry Creek, including all tributaries and wetlands (37.25. Q.). The Commission split Dry Creek from segment 4a because Dry Creek does not have a Water Supply use, and has no irrigated agriculture.
Lower Colorado 7a-7b: Segment 7 was split into segments 7a and 7b to facilitate the adoption of appropriate temperature standards. Divide Creek from the boundary of the White River National Forest to the confluence with the Colorado River, including all tributaries and wetlands, was moved from segment 7a to segment 7b. Additionally, Battlement Creek was moved from segment 7a to a new segment 9c to facilitate and Outstanding Waters designation.
Lower Colorado 8: The East Middle Fork of Parachute Creek, including all tributaries and wetlands, from the source to the boundary of the White River National Forest was moved to this segment from segment 11 d to facilitate the application of an Outstanding Waters designation (see Section O.).
Lower Colorado 9a: West Rifle Creek and the lower portion of East Rifle Creek were moved from this segment to segment 10 to facilitate the adoption of appropriate temperature standards.
Lower Colorado 9b: The segment description was clarified by indicating that the lower segment boundary ends at a point immediately below the confluence of the Colorado River and Parachute Creek, so that lakes and reservoirs tributary to Parachute Creek are specifically included. The segment description was also amended to include all lakes and reservoirs within the White River National Forest and the Grand Mesa National Forest. Lakes/reservoirs within the National Forests were moved to this segment from segments 5, 15, 16 and 19, to facilitate the adoption of appropriate temperature standards. The segment description was also amended to remove Rifle Gap Reservoir and Harvey Gap Reservoir. The Commission moved these large cold lakes to segment 20 to facilitate the adoption of appropriate temperature standards. Segment 20 was added to the list of segments specifically excluded from this segment, and segments 5, 6, 7, 8, 10, 1 la-h, and 12 were removed from that list.
Lower Colorado 9c: This segment was created to encompass Battlement Creek, including all tributaries and wetlands, from the source to the White River National Forest boundary (see Section O.).
Lower Colorado 10: West Rifle Creek and East Rifle Creek from the White River National Forest boundary were moved to this segment from segment 9a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 11 a: The segment description was amended to include tributaries and wetlands to the East Fork of Parachute Creek to facilitate the adoption of appropriate temperature standards.
Lower Colorado 11 d: The East Middle Fork of Parachute Creek, including all tributaries and wetlands, from the source to the boundary of the White River National Forest was moved from this segment to segment 8 to facilitate the application of an Outstanding Waters designation.
Lower Colorado 11 e: The segment description was amended to include tributaries and wetlands to the existing segment description for the East Fork of Parachute Creek to facilitate the adoption of appropriate temperature standards.
Lower Colorado 11 g: The segment description was clarified by excluding the specific listings in segment 7a. This exclusion was added to remove a double listing of Battlement Creek.
Lower Colorado 11h: The segment description was amended to include tributaries and wetlands to the existing segment description. These tributaries were moved from segment 4a so that all tributaries to the Parachute would be included in segments 11a-h.
Lower Colorado 12b: This segment was created to encompass tributaries to the Colorado River, including wetlands, from the confluence with Parachute Creek to the confluence with Roan Creek. The Commission moved these tributaries to this segment from segment 13a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 13a: The segment description was amended to remove the tributaries to the Colorado River, including wetlands, from the confluence with Parachute Creek to the confluence with Roan Creek. The Commission moved these tributaries and wetlands to a newly created segment 12b to facilitate the adoption of appropriate temperature standards.
Lower Colorado 13b: The segment description was clarified by adding an "and" to the segment description so that it is clear that both conditions must be met for waters to be included in this segment (between Government Highline Diversion and Salt Creek AND down-gradient from the canals). The exclusion for segment 13c was removed from the segment description since those listings would not otherwise be included in this segment.
Lower Colorado 13d: This segment was created to encompass lower Coal Canyon Creek downgradient of the Government Highline Canal (37.25. S.). The Commission split lower Coal Canyon Creek from segment 13b because lower Coal Canyon Creek has a Recreation P use classification, site-specific copper standards, and has no irrigated agriculture.
Lower Colorado 14a: Clear Creek from the source to Tom Creek was added to the segment description to facilitate the adoption of appropriate temperature standards. Segment 14b was added to the list of segments specifically excluded from this segment.
Lower Colorado 14b: This segment was created to encompass lower Clear Creek, including all wetlands and tributaries, between Tom Creek and Roan Creek. The Commission moved lower Clear Creek, Kimball Creek, and a portion of Roan Creek to this segment from segment 14a to facilitate the adoption of appropriate temperature standards.
Lower Colorado 14c: This segment was formerly 14b, but was changed to 14c to facilitate the splitting of segment 14a. Additionally, the upper boundary of the segment was moved from Clear Creek to Kimball Creek.
Lower Colorado 15-16: Segment 15 was split to facilitate the adoption of appropriate temperature standards. Plateau Creek, including all tributaries and wetlands, between the HWY 330 bridge in Collbran and the Colorado River, except Kimball Creek, Grove Creek, Big Creek, Cottonwood Creek, Bull Creek, Spring Creek, Coon Creek, and Mesa Creek were moved from segment 15 to segment 16.
Lower Colorado 17a-17b: Segment 17 was split to facilitate the application of an Outstanding Waters designation for segment 17a (see Section R). Segment 17a includes Rapid Creek from the source to Cottonwood Creek including flow from Kruzen Springs located at 39.05441 N latitude and 108.26180 W longitude, and elevation 8,950 feet. Segment 17b includes Rapid Creek between Cottonwood Creek and the Colorado River.
Lower Colorado 19: This segment description was clarified by specifically naming Highline Reservoir in the segment description. Segments 9b, 13c, 20, and 21 were added to the list of segments specifically excluded from this segment.
Lower Colorado 20: This segment was created to encompass Rifle Gap Reservoir, Harvey Gap Reservoir, and Vega Reservoir, which are all cold water lakes larger than 100 acres in surface area. Rifle Gap and Harvey Reservoir were formerly in segment 9b. Vega Reservoir was formerly in segment 15.
Lower Colorado 21: This segment was created to encompass those cold-water lakes and reservoirs tributary to Rapid Creek, Little Dolores River from the source to the confluence with Hay Press Creek, and Roan Creek from the source to Clear Creek. The lakes and reservoirs tributary to Roan Creek were formerly in segment 14a. The lakes and reservoirs tributary to Rapid Creek were formerly in segment 17. The lakes and reservoirs tributary to the Little Dolores were formerly in segment 18.
The Commission reviewed information regarding existing aquatic communities. The following changes to the aquatic-life use classification were made:
Lower Yampa/Green River 1 was moved to segment 2: Cold 1 to Warm 1.
Lower Yampa/Green River 17b: Cold 2 to Warm 2.
Lower Yampa/Green River 19b was split from segment 19: Cold 1 to Warm 1.
Lower Yampa/Green River 20: Warm 2 to Cold 2.
Lower Yampa/Green River 22a: Warm 2 to Cold 1.
White River 17 was split and part was moved to segment 15: Cold 2 to Warm 2.
Lower Colorado 1 was split and part was moved to segment 2a: Cold 1 to Warm 1.
Lower Colorado 4a was split and part was moved to segment 4c: Cold 2 to Warm 1.
As part of the Basic Standards hearing of 2005, recreation classifications were revised into four new classifications. The Commission reviewed the previous segment classifications (1a, 1b and 2) and determined the appropriate new classification based on classification criteria presented as part of the Basic Standards Hearing, use attainability analyses or other basis. In addition, during the 2005 Basic Standards Hearing, the transition from the use of the fecal coliform standard to E. coli standard was completed. Fecal coliform criteria were deleted from the numeric standards.
Based on information that showed existing primary contact recreation use is in place in at least a portion of the segment, the Commission converted the following segments from Recreation Class la to Recreation Class E with a 126/100 ml E. coli standard:
Lower Yampa/Green River segments: 2, 3f, 5, 8, 10, 13a-b, 15, 16, 19a-b, 20, 22c, 24, 28, 29, and 32.
White River segments: 1, 3, 4, 6, 7, 9c, 9d, 10a, 11, 12, 21, and 23-25.
Lower Colorado segments: 1 -3, 4b-c, 7a-b, 9b-c, 10, 13b-c, 15, 16, and 19-20.
The following segments were converted from Recreation Class 1b to Recreation Class P with a 205/100 ml E. coli standard:
Lower Yampa/Green River segments: 3b-c, 3e, 3g, 4, 6a, 7, 9, 12a-b, 17a, and 18.
White River segments: 7, 8, 10b, 13d, 14a-b, 15, 16, 19, and 22.
Lower Colorado segments: 5, 6, 11h, 12b, 13a, 13d, 14a-c, 17a-b, and 18.
Based on a review of existing Use Attainability Analyses showing that primary contact recreation does not occur or is not attainable, the following segments were converted to Recreation Class N classification with 630/100 ml E. coli standard:
Lower Yampa/Green River segments: 3a, 3d, 17b, 21, and 22a-b.
White River segments: 9a-d, 13a-c, 17, 18, and 20.
Lower Colorado segments: 4a, 4d-e, 8, 1 la-g, and 12a.
Newly created segments had the same Recreation use classification as the segment they were split from, unless there was insufficient evidence to support keeping that classification or evidence to show that the use classification was inappropriate. The following newly created segments are classified Recreation Class U with a 126/100 ml E. coli standard:
Lower Yampa/Green River segments: 23, 25, 26, 27, 30, 31, and 33.
White River segments: 26 and 27.
Lower Colorado segment: 21.
The following segment was upgraded from a Recreation Class 2 to a Recreation E:
Lower Colorado segment 9a.
Based on review of information regarding the location of public water supplies. Water Supply use classifications and standards were added to the following segment:
White River segment 11.
A review of the standards associated with the Agriculture use classification showed that many segments were missing a nitrate standard protective of the use. A nitrate standard, NO3 =100, was added to the following segments classified for Agriculture use:
Lower Yampa/Green River segments: 3d, 5, 7, 16, and 22a.
White River segments: 14a and 20.
Lower Colorado segments: 3, 9a, 11 d, 11 h, 13b, 13c, and 19.
Decoupling Cold 2 and UP: As part of the Basic Standards hearing of 2005, the Commission eliminated the direct linkage between cold-water aquatic life class 2 and the use-protected designation. Therefore, all cold-water aquatic life class 2 segments that are use-protected were reviewed to determine if that designation is still warranted. The following segments are now reviewable:
Lower Yampa/Green River segments: 13a, and 20.
White River segments: 9a, 9c, 17, and 19.
Lower Colorado segments: 6, lib, 11c, and 11 e.
Decoupling Aquatic Life Warm 2 and UP: As part of the Basic Standards hearing of 2005, the Commission decided that the presence of a warm water class 2 use classification would still be a presumptive basis for applying a use-protected designation; however, that presumption can be overcome if there is data showing that the water is of high quality. Therefore, the Commission reviewed all warm water class 2 segments to determine if the use protected designation is still warranted. The following segment(s) are now reviewable:
Lower Yampa/Green River segments: 3e and 13b.
White River segments: 13b, 13c, 13d, 16, and 22.
Lower Colorado segment: 13d.
Outstanding Waters: Outstanding waters designation was added to the following segments (see Sections O. and R.):
Lower Colorado segments: 8, 9c, and 17a.
Ambient standards are adopted where natural or irreversible man-induced conditions result in exceedances of table value standards. The Commission reviewed the information that is the basis for these standards as well as any new information that would indicate whether they are still appropriate, need to be modified, or should be dropped. The following segments have ambient based standards:
Lower Yampa/Green River segment 16: Fe(ch)=6221(Trec).
White River segment 13b: Se(ch)=7.3 (see Section P.).
White River segment 13c: Fe(ch)=1425(Trec) (see Section P.).
Ambient-based summer temperature standards were adopted for many cold large lakes. The WAT standard is not attainable in the majority of large lakes (> 100 acres in surface area) including many lakes with apparently healthy cold-water fish populations. Summertime temperature for large lakes and reservoirs (collectively referred to as lakes) is well correlated to the lake's elevation. Since the thermal properties are natural or man induced irreversible (in the case of reservoirs) the Commission adopted ambient temperature standards for large lakes wherever data were available to characterize a WAT. For lakes, the WAT is assumed to be equivalent to the average temperature of the mixed layer. If there were less than three years of data, the highest observed WAT was selected for the summertime ambient standard. If three to five years of data were available, the second highest observed WAT was used as the ambient standard. Where temperature data from multiple stations in the same reservoir were collected on the same date, the Division used an average of those stations to calculate the WAT.
White River segment 25: Apr.-Dec. T(wat) =20.7 °C.
Lower Colorado segment 20: Rifle Gap Reservoir Apr.-Sept. T(wat)=23.0 °C.
Lower Colorado segment 20: Vega Reservoir Apr.-Sept. T(wat) =21.5 °C.
Ambient-based DM temperature standards were also adopted for the Little Dolores River where cutthroat and brook trout are present, but the DM temperature standards exceed the default table values associated with those species. Additionally, a site-specific adjustment of the season was adopted. The summer season was expanded to include May. The area is remote and the exceedances of the temperature standard could not be attributed to anthropogenic effects, abnormally high air temperatures, or abnormally low flows. The need for ambient-based temperature standards should be re-examined or recalculated if additional data or other information becomes available.
Lower Colorado segment 18: May-Sept. T(DM) =24.4 °C, T(mwat) =CS-I °C.
Oct-Apr T(DM) =13.9 °C, T(mwat) =CS-I °C.
New Table Value Standards: As part of the Basic Standards hearing of 2005, new zinc and cadmium table values were adopted. The acute and chronic zinc and cadmium equations in 37.6(3) were modified to conform to Regulation No. 31.
Site-Specific Zinc Standards for Mottled Sculpin: In low hardness situations (hardness below 113 mg/L) the new chronic zinc equation is not protective of mottled sculpin {Cottus bairdi), a native west-slope fish species. The Commission adopted a sculpin-specific chronic zinc equation as site-specific standards for the following segments that are inhabited by mottled sculpin and also have low hardness:
Lower Yampa/Green River segments: 2, 4, 7, 10, 12a, 13b, 15, and 18.
White River segments: 1, 3, and 6.
Lower Colorado segments: 7a and 15.
Chromium III Standards: A review of chromium III standards showed that the standard associated with the Water Supply use classification was not protective of aquatic life where the average hardness was less than 61 mg/l. A chromium standard, Crlll(ch)=TVS was added to following segments with an Aquatic Life use classification and average hardness values less than 61 mg/l.
Lower Yampa/Green River segments: 4, 8, 15, and 18.
For arsenic, each use (except recreation) has a different arsenic ("As") value, including Fish Ingestion (Fl) and Water Plus Fish (W+F). In different combinations of uses, different values become the most limiting. In order to eliminate the confusion, the Commission added the operative value to the individual segments. The following matrix displays the most limiting arsenic criteria.
Most Limiting Arsenic Criteria Depending on the Possibie Combinations of Uses and Quaiifiers
if the Use Classifications were: | These Arsenic Standards were applied (dissolved unless otherwise noted) |
Class 1 aquatic life, water supply | As(ac) = 340, As(ch) = 0.02(Trec) |
Class 2 aquatic life (water + fish standards), water supply | As(ac) = 340, As(ch) = 0.02(Trec) |
Class 2 aquatic life (no fish ingestion standards), water supply | As(ac) = 340, As(ch) = 0.02 - lO(Trec) |
Class 1 aquatic life | As(ac) = 340, As(ch) = 7.6(Trec) |
Class 2 aquatic life (fish ingestion standards) | As(ac) = 340, As(ch) = 7.6(Trec) |
Class 2 aquatic life (no fish ingestion standards), agriculture | As(ac) = 340, As(ch) = lOO(Trec) |
Agriculture only | As(ch) = lOO(Trec) |
Water supply only | As(ch) = 0.02 - lO(Trec) |
At the 2005 Basic Standards rulemaking hearing, the Commission changed the drinking water supply table value for uranium from 40 pCi/L to 30 µg/l.
All temporary modifications were re-examined to determine whether to delete or extend them, either as existing or with modifications of the numeric standards. Because of the June 2005 changes to Regulation No. 31, temporary modifications were not automatically extended if non-attainment persisted.
The following segments had temporary modifications that were not renewed:
White River segment: 13c.
Lower Colorado segment: 13b.
The following segments have temporary modifications for ammonia that were amended to clarify the chronic standard as 0.06, rather than just "TVS old". As specified in 61.8(2)(c)(iii) (the Permit Rules, Regulation No 61), where a temporary modification has been adopted, limits in permits are to be set based on the temporary modification and the provision strictly limiting the loading from the facility does not apply. These temporary modifications will be subject to review and rulemaking for the two years before their scheduled expiration in order to track progress towards the full attainment of water body standards and uses.
Lower Yampa/Green River segment: 2.
White River segment: 21.
Lower Colorado segments: 2a and 13b.
A new type i temporary modification for ammonia NHs (ac)=TVS(old) and NHs (ch)=0.06 was adopted for the following segment:
Lower Colorado segment 2b.
The following segment has a type ill temporary modification for temperature to allow the Mesa County / City of Grand Junction Persigo Wastewater Treatment Facility time to address areas of uncertainty with regards to the appropriate underlying winter temperature standard. The primary uncertainty relates to the winter temperature requirements of species expected to be present in Persigo Wash. In addition, since Persigo Wash is designated as Endangered Species Act critical aquatic habitat there are additional mixing zone restrictions that must be considered. The temporary modification of the winter temperature standard is Dec-Feb T(dm) = 18.0 °C, T(mwat) = 18.0 °C, expiration date of 12/31/2011. The temporary modification will be subject to review and rulemaking for the two years before their scheduled expiration in order to track progress towards the full attainment of water body standards and uses.
Lower Colorado segment 13b.
In some cases the Commission adopted temporary modifications of underlying standards with the notation of "existing quality" rather than a numeric. This was done where it was not possible to derive an appropriate characterization of current instream concentrations or temperature conditions. The Commission's intent of using the notation "existing quality" is to preserve the status quo during the term of the temporary modification. Dischargers to those segments shall maintain the existing water quality or pollutant loading characteristics of their effluent with respect to the parameter that has the temporary modification. The Commission does not intend the temporary modifications to apply to new facilities or in Preliminary Effluent Limitations. The Commission adopted type ill temporary modifications equal to "existing quality," for the following segments:
Lower Colorado segment 4e: temperature, dissolved copper, and total recoverable iron; expiration 5/31/2011 (see Section Q.).
Lower Colorado segment 13d: dissolved selenium; expiration 5/31/2011 (see Section S.).
As part of the Basic Standards hearing of 2007, new table values were adopted for temperature. Temperature standards were applied to individual segments based upon the distribution offish species, as provided by the CDOW, temperature data, and other available evidence.
The following segments are cold stream tier one (CS-I):
Lower Yampa/Green River segments: 4, 8, 9, 10, 12a, 18, 21, and 22a.
White River segments: 1, 3, 4, 6, 8, 9a, 9c, 10b, 14a, 17, 19, 20, and 23.
Lower Colorado segments: 5, 6, 7a, 8, 9a, 9c, lla-g, 12a, 14a, 15, and 18.
The following segments are cold stream tier two (CS-II):
Lower Yampa/Green River segments: 7, 12b, 13a, 15, 17a, 19a, and 20.
White River segments: 7, 9b, 9d, 14b, and 18.
Lower Colorado segments: 1, 4a, 4d, 4e, 7b, 10, 11h, 12b, 14b, 16, 17a, and 17b.
The following segments are warm stream tier two (WS-II):
Lower Yampa/Green River segments: 2, 3c, 3d, 3e, 3f, 5, 13b, and 19b.
White River segments: 12, 13c, 15, and 21.
Lower Colorado segments: 2a, 2b, 3, 13b, 13d, and 14c.
The following segments are warm stream tier four (WS-IV):
Lower Yampa/Green River segments: 3a, 3b, 3g, 6a, 16, 17b, 22b, and 22c.
White River segments: 13a, 13b, 16, and 22.
Lower Colorado segments: 4c and 13a.
The following segments are cold lakes (CL):
Lower Yampa/Green River segments: 24, 25, 28-31, and 33.
White River segments: 10a, 13d, 24, and 26
Lower Colorado segments: 9b and 21.
The following segments are cold lakes larger than 100 acres surface area (CLL):
White River segment 25.
Lower Colorado segment 20.
The following segments are warm lakes (WL):
Lower Yampa/Green River segments: 23, 26, 27, and 32.
White River segments: 11 and 27.
Lower Colorado segments: 13c and 19.
A temperature standard was not adopted for Lower Colorado segment 4b, which encompasses the South Canyon Hot Springs.
Seasonal ambient-based temperature standards were adopted for the following segments (see Section G.):
White River segment 25.
Lower Colorado segments: 18 and 20.
The Commission recognizes that in some cases tinere is uncertainty about the temperature standards adopted in this Inearing. The uncertainty stems from a lacl< of data about temperature or the aquatic community or winere tinere is a conflict between the lines of evidence. It is the Commission's intent that the Division and interested parties work to resolve the uncertainty for the following segments by the next basin-wide review.
Lower Yampa/Green Rivers segment: 3b
White River segments: 14a, 14b, and 15.
Lower Colorado segments: 4d, 4e, and 16.
Lower Yampa/Green River 3b: The erroneous reference to temporary modifications and associated expiration date were deleted since all temporary modifications were previously deleted from this segment.
Lower Yampa/Green River 3d: To reflect the Aquatic-Life Warm 2 use classification the standard for chromium III was changed from Crlll(ac)=TVS to Crlll(ac/ch)=TVS.
Lower Yampa/Green River 5: To reflect the Aquatic Life Warm 1 use classification, D.O.=6.0 mg/l was changed to D.O.=5.0 mg/l.
Lower Yampa/Green River 12a: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
Lower Yampa/Green River 17a: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
Lower Yampa/Green River 17b: To reflect the change in Aquatic Life use classification from Cold 2 to Warm 2, D.O.=6.0 mg/l was changed to D.O.=5.0 mg/l, and D.O.(sp)=7.0 mg/l was deleted.
Lower Yampa/Green River 20: To reflect the change in Aquatic Life use classification from Warm 2 to Cold 2, D.O.=5.0 mg/l was changed to D.O.=6.0 mg/l, and D.O.(sp)=7.0 mg/l was added.
Lower Yampa/Green River 22a: The reflect the changed in Aquatic Life use classification from Warm 2 to Cold 1, D.O.=5.0 mg/l was changed to D.O.=6.0 mg/l, and D.O.(sp)=7.0 mg/l was added. The Colorado Division of Wildlife provided evidence that trout were present, so trout standards were added to cadmium and silver: Cd(ac/ch)=TVS was changed to Cd(ac)=TVS(tr) and Cd(ch)=TVS, and Ag(ac/ch)=TVS was changed to Ag(ac)=TVS and Ag(ch)=TVS(tr).
Lower Yampa/Green River 22c: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
White River 11: To reflect the addition of the Water Supply use classification, NO3 =10, Cl=250, SO4 =WS, Fe(ch)=WS(dis), Mn(ch)=WS(dis) were added, and Crlll(ac/ch)=50 was changed to Crlll(ac)=50(Trec).
White River 15: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
White River 16: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
White River 17: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
White River 19: To reflect the Agriculture use classification and absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100.
White River 21: To reflect the Water Supply use classification Crlll(ac)=TVS was changed to Crlll(ac)=50(Trec).
Lower Colorado 3: To reflect the Aquatic Life Warm 1 use classification for this segment, D.O.=6.0 mg/l was changed to D.O.=5.0 mg/l, and D.O.(sp)= 7.0 mg/l was deleted.
Lower Colorado 4b: To reflect the Aquatic Life Warm 2 use classification and the absence of a Water Supply use classification, the Crlll(ac)=50(Trec) was changed the Crlll(ac/ch)=TVS.
Lower Colorado 9a: The Recreation use classification was changed from Recreation 2 to Recreation E. All of the streams and wetlands within Rifle Gap State Park, Rifle Falls State Park, and Rifle Creek State Wildlife Area are encompassed within this segment. Fishing, hunting, camping, and hiking are allowed, and numerous public roads and trails allow access to Rifle Creek and its tributaries.
Lower Colorado 11d: To reflect the Aquatic Life use classification and absence of the Water Supply use classification the chromium III standard was changed from Crlll(ac/ch)=50 to Cr(ac/ch)=TVS.
Lower Colorado 11e: To reflect the Water Supply use classification for this segment, NO2 (ac)=10 was changed to NO2 =1.0, NO3 (ac)=100 was changed to NO3 =10, and the following standards were added: S=0.002, Cl=250, SO4 =WS, Crlll(ac)=50(Trec), Fe(ch)=WS(dis), Mn(ch)=WS(dis), and Hg(ch)=0.01(tot).
Lower Colorado 12a: To reflect the Agriculture use classification, and the absence of a Water Supply use classification, NO3 =10 was changed to NO3 =100, and the chloride standard Cl=250 was deleted.
Lower Colorado 14c: To reflect the Water Supply use classification, Crlll(ac)=50(Trec) was added and Crlll(ac/ch)=TVS was deleted.
Lower Colorado 17a: To reflect the Recreation P use classification, E.coli=126/100 ml was changed to E.coli=205/100 ml. To reflect the Cold 1 use classification, D.O. = 5.0 mg/l was changed to D.O.=6.0 mg/l, and D.O.(sp)= 7.0 mg/l was added.
The Commission corrected several typographical and spelling errors, and clarified segment descriptions. The abbreviation for chlorine was changed from CI2 to CI2, and the (ac) and (ch) designations were removed from the inorganic standards where that designation was not appropriately applied.
The reference to "Water+Fish Organics" was corrected to "Water+Fish Standards" to incorporate the appropriate standards from both the organics table and the metal parameter table in Regulation No. 31.
Based on evidence that shows that water quality meets the requirements of 31.8(2)a and the presence of Colorado River cutthroat trout, the Outstanding Water (OW) designation was added to the following segments:
Lower Colorado segments: 8 and 9c.
The Commission understands that existing land uses are in place in these watersheds. The evidence demonstrates that these existing land uses are compatible with the OW designation since the current high level of water quality has been attained with these uses in place. It is the Commission's intent that this OW designation should not be used to establish additional permit requirements for existing uses within this area.
Shell Frontier Oil and Gas (Shell) has proposed resegmentation of the Yellow Creek watershed in the White River basin. Shell proposed revised classifications and standards for the new segments.
The Commission determined that the Yellow Creek basin warranted resegmentation in order to appropriately apply ambient-based site-specific criteria for total recoverable iron and dissolved selenium. It also recognizes the absence of fish in the upper Yellow Creek basin and the presence in the lower basin. The Commission notes that a hydrologically disconnected waterbody, Violett Springs Ponds , has characteristics unlike Yellow Creek and its tributaries. Ponds or lakes exhibit different physical biological and chemical characteristics than streams. Furthermore, these ponds are managed by Colorado Division of Wildlife as a stocked recreational fishery for brook trout. As a result, the Commission determined this segment met the definitions of Class 2 aquatic life use.
Continued application of the existing agricultural standards for livestock watering adopted for the Yellow Creek basin by the Commission in 2003 was supported by the UAA and Shell's rebuttal statement. These standards were retained for all three segments. Segments 13b and 13c retained the Recreation N classification (previously Recreational Class 2) currently applied to Yellow Creek. A Recreation P classification was applied to Segment 13d to acknowledge the CDOW management activities in the Little Hills State Wildlife Area. Segments 13b and c were assigned undesignated antidegradation designation because although they are classified as warm 2, the existing water quality meets the 12 parameter test of 31.8.(2)(b). Segment 13d is undesignated because it is cold 2.
The current Aquatic Life Warm 2 classification was retained for Segments 13b and 13c. Segment 13d was classified as Aquatic Life Cold 2, reflecting CDOW management strategies for the Violett Springs Ponds.
Site-specific chronic aquatic life standards based on ambient conditions were adopted for iron for Segment 13c [Fe(ch), 50th percentile = 1425 µg/L] and selenium [Se(ch), 85th percentile = 7.3 µg/L] for Segment 13b. The Commission determined that these reflected natural or man-induced irreversible conditions for these segments and would be protective of the attainable aquatic life use. The ambient selenium standard for Segment 13b recognizes the spatial variability of monitoring locations in this segment. It was developed from data collected from four separate monitoring sites (Corral Gulch upstream of Water Gulch, Corral Gulch upstream of Stake Springs, Duck Creek near the mouth, and Yellow Creek immediately downstream of Duck Creek). Future evaluation of attainment of the ambient selenium standard for Segment 13c will apply to the four sites used to develop the ambient standard. Current water quality will be maintained at the remaining sites in the segment where TVS for selenium were met.
For Segment 13d, the Commission determined that certain standards specific to the Cold 2 Aquatic Life Use classification would be applied. Dissolved oxygen was set at 6.0 mg/L, but the Commission did not adopt a spawning dissolved oxygen standard because spawning habitat is not present. The cold water ammonia TVS includes the present acute "salmonids" value but is not intended to include the "early life stages present" standard.
Warm water temperature standards (Warm Stream Tier II) were applied for Segment 13c, based on CDOW's recommendation in consideration of the presence of the flannelmouth sucker. Warm Stream Tier IV temperature standards were applied to Segment 13b. Default temperature standards for cold lakes (also known as CL) were applied for Segment 13d based on the size of the ponds.
The Commission resegmented Dry Creek and its tributaries and wetlands from the source to the confluence with the Colorado River into new segment 4e. This segment is undesignated and classified as Aquatic Life Cold 2, Recreation N, and Agriculture. Water quality standards normally associated with these uses are adopted with the exception of boron which is based on livestock watering instead of irrigated agriculture. The Commission adopted a CS-II temperature standard.
The Commission adopted type (iii) temporary modifications of "existing quality" to expire on May 31, 2011 based on uncertainty for temperature, copper, and iron. It is the intention of the parties to preserve the status quo during the term of the temporary modification. Tri-State shall maintain the existing quality or pollutant loading of its effluent with respect to temperature, copper, and iron. The Commission does not intend the temporary modifications to apply to new facilities or in Preliminary Effluent Limitations. During the term of the temporary modification, Tri-State will evaluate the relevant factors associated with the antidegradation designation, aquatic life use, monitor its discharge for priority pollutants and determine what numeric criteria are appropriate to protect the aquatic life use. The Division and EPA will work with Tri-State to develop a work plan to evaluate the relevant factors remaining from the 2008 UAA submitted by Tri-State. Tri-State will submit the additional information collected to the Commission as part of either the December, 2009 or 2010 temporary modification hearings. The Commission expects to review these issues as well as the temporary modifications in December, 2009 or 2010.
The Town of Palisade proposed resegmentation of Rapid Creek and designation of the upper portion, which is the source water area for the Town's water supply, as outstanding waters (OW). The Commission resegmented Rapid Creek and its tributaries and wetlands into two segments: segment 17a from its source to a point immediately below the confluence with Cottonwood Creek including Kruzen Springs, and segment 17b from a point immediately below the confluence with Cottonwood Creek to the confluence with the Colorado River. Based on evidence that shows that water quality in segment 17a meets the requirements of 31.8(2)(a) and the presence of Colorado River cutthroat trout within this segment, the OW designation was added to the new segment 17a. The evidence demonstrates that the existing land uses are compatible with the new OW designation since the current high level of water quality has been attained with these uses in place. It is the Commission's intent that this OW designation should not be used to establish additional permit requirements for existing uses within this area.
The Commission determined that a new segment 13d was warranted to separate lower Coal Canyon Creek, downgradient of the Government Highline Canal, from the rest of the stream reaches in segment 13b. This new segment 13d is undesignated based on the ecological significance of the stream as habitat for juvenile roundtail chub and flannelmouth sucker as indicated in Regulation 31.8(2)(b)(i)(C). Aquatic Life Warm 2, Recreation P, and Agriculture use classifications were assigned. Evidence submitted at the hearing showed this small stream lacks diverse habitat due to low base-flows, yet still supports an aquatic community comprised of multiple species of juvenile fish and benthic invertebrates as well as two amphibian species. Given the use classification and attainable aquatic community, the Commission adopted a WS-II temperature standard and determined that site-specific standards for copper were appropriate, based on Regulation 31.7(1)(b)(iii). The recalculation procedure was used to derive the site-specific copper standards, with Ephoron (mayfly), Tubifex (worm), Bufo (amphibian), and Physa (snail) as the four most sensitive genera.
In addition, a type ill temporary modification of existing quality was adopted for selenium with an expiration date of 5/31/2011, based on uncertainty regarding the current effluent and stream quality as well as the appropriate standard for protection of aquatic life. It is the intention of the parties to preserve the status quo during the term of the temporary modification. Public Service shall maintain the existing quality or pollutant loading of its effluent with respect to selenium. The Commission does not intend the temporary modification to apply to new facilities or in Preliminary Effluent Limitations.
PARTIES TO THE RULEMAKING
5 CCR 1002-37.25