Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-35 - REGULATION NO. 35 - CLASSIFICATIONS AND NUMERIC STANDARDS FOR GUNNISON AND LOWER DOLORES RIVER BASINS
Section 5 CCR 1002-35.34 - STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; SEPTEMBER 10, 2012 RULEMAKING; FINAL ACTION NOVEMBER 5, 2012; EFFECTIVE DATE MARCH 30, 2012
Current through Register Vol. 47, No. 17, September 10, 2024
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:
A. Waterbody Segmentation
The Commission split lakes and reservoirs from segments tinat also contained streams, so that new temperature standards could be adopted. Lakes and reservoirs were deleted from the following segments that previously encompassed streams and lakes and reservoirs:
Upper Gunnison River segments: 1 -5, 6b, 9-10, 15-17, 19, 21, 23, 25-26, 29a-b and 32
North Fork of the Gunnison River segments: 1, 4-5, 6a and 6b
Uncompahgre River segments: 1-2, 3b, 5, 10-12 and 14
Lower Gunnison River segments: 3, 4b, 8, 1 la-b and 12
San Miguel River segments: 1-2, 6a-b, 7a-b, 9-11 and 12
Lower Dolores River segments: 3a and 3b
The following segments were created for lakes and reservoirs:
Upper Gunnison River segments: 33-38
North Fork of the Gunnison River segments: 8-11
Uncompahgre River segments: 16-21
Lower Gunnison River segments: 14-19
San Miguel River segments: 13-20
Lower Dolores River segments: 7-8
The following segments were deleted when the constituent waterbodies were merged with other segments:
Upper Gunnison River segments: 3 and 13b
San Miguel River segments: 7b
Some renumbering and/or creation of new segments was made due to information which showed that:
Upper Gunnison River 1-3: The segment description was amended to include all tributaries to the Gunnison within the West Elk, Collegiate Peaks, Maroon Bells, Raggeds, Fossil Ridge, or Uncompahgre Wilderness areas. The streams in these wilderness areas were formerly split into Segments 1-3. These waters were combined into one segment because they had the same use classifications, and are all designated Outstanding Waters. The lakes and reservoirs within Segments 1, 2, and 3 were moved to a new Segment 33 to facilitate the adoption of appropriate temperature standards. A new segment description was created for Segment 2: All tributaries and wetlands from North Beaver Creek to Meyers Gulch, from the West Elk Wilderness boundary to their confluences with Blue Mesa Reservoir, Morrow Point Reservoir, or the Gunnison River, excluding Steuben Creek, North Willow Creek, and Soap Creek. These tributaries were moved from Segment 26 to facilitate an outstanding waters designation.
Upper Gunnison River 4: The lakes and reservoirs in this segment were moved to a new Segment 34, with the exception of Taylor Park Reservoir, which was moved to Segment 37 with other coldwater lakes larger than 100 acres surface area. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 5a-5b: Tine mainstem of tine East River from tine confluence witin tine Slate River to the confluence with the Gunnison River was moved to a new Segment 5b. The lakes and reservoirs in Segment 5 were moved to a new Segment 34. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 6b-6c: The lower portion of Cement Creek, including tributaries and wetlands, from the Horse Basin Creek confluence to the East River were moved to a new Segment 6c. The lakes and reservoirs in Segment 6b were moved to a new Segment 34. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 9: The lakes and reservoirs in this segment were moved to a new Segment 34. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 10a-10b: The tributaries and wetlands in Redwell basin were moved to a new Segment 10b. Redwell basin was split from the rest of the Oh-Be-Joyful watershed because the water quality in Redwell basin is significantly different than the rest of the segment, and the ambient lead concentration is higher. The lakes and reservoirs in Redwell Basin were moved to a new Segment 35, and the remaining lakes and reservoirs in Segment 10 were moved to a new Segment 34 to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 13: Segments 13a and 13b were combined to create one segment for Woods Creek. The Commission determined that the Recreation P Use classification should be upgraded to Recreation E. These waters were combined into one segment because they now have the same use classifications, antidegradation designation, and standards.
Upper Gunnison River 15a-15b: South Beaver Creek, including tributaries and wetlands, from the source to the Saguache/Gunnison County line was moved to a new Segment 15b. The downstream boundary of Segment 15a was changed from the inlet of Blue Mesa Reservoir to the County Road 32 crossing. This boundary was changed because the water levels in Blue Mesa Reservoir fluctuate, and the location of the inlet changes with these fluctuations. The lakes and reservoirs in Segment 15 were moved to a new Segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature standards, and to refine the application of ambient iron standards, which now apply only to Segment 15a.
Upper Gunnison River 16a-16b: The mainstem of Ohio Creek from a point immediately below 7 Road to the confluence with the Gunnison River was moved to a new Segment 16b. The lakes and reservoirs in this segment were moved to a new Segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 17a-17b: Antelope Creek, including all tributaries and wetlands, except for West Antelope Creek, was moved to a new Segment 17b. The lakes and reservoirs in this segment were moved to a new Segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 18a-18b: The mainstem of Tomichi Creek from the confluence with Porphyry Creek to the confluence with the Gunnison River was moved to a new Segment 18b. This segment was split to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 19: The lakes and reservoirs in this segment were moved to a new Segment 36 to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 21: The lakes and reservoirs in this segment were moved to a new Segment 36 to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 23: Tine lakes and reservoirs in tinis segment were moved to a new Segment 36 to facilitate tine adoption of appropriate temperature standards.
Upper Gunnison River 25: Blue Mesa, Morrow Point, and Crystal Reservoirs were moved to a new Segment 38 with other coldwater lakes larger than 100 acres surface area to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 26: The lakes and reservoirs in this segment were moved to a new Segment 37 to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 29a-29b: Cebolla Creek, including tributaries and wetlands, from the source to the County Road 29 crossing near Powderhorn was moved from Segment 26 to Segment 29a. Powderhorn Creek, including tributaries and wetlands, from the source to the confluence with Cebolla Creek was also moved from Segment 26 to Segment 29a. The Lake Fork, including tributaries and wetlands, from the confluence with Eaton Creek to Blue Mesa Reservoir was moved from Segment 29a to a new Segment 29b. Lake San Cristobal was moved from Segment 29b to a new Segment 38 with other coldwater lakes larger than 100 acres surface area. The remaining lakes and reservoirs in Segment 29a were moved to a new Segment 37. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 32: The lakes and reservoirs in this segment were moved to a new Segment 37 to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 33: This segment was created to encompass the lakes and reservoirs in the La Garita, Powderhorn, West Elk, Collegiate Peaks, Maroon Bells, Raggeds, Fossil Ridge, and Uncompahgre Wilderness areas. This segment was created to facilitate the adoption of appropriate temperature standards formerly in Segments 1, 2 and 3.
Upper Gunnison River 34: This segment was created to encompass the lakes and reservoirs tributary to the Taylor River and the East River formerly in Segments 4, 5a, 6b, 9 and 10. This segment was created to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 35: This segment was created to encompass the lakes and reservoirs tributary to Redwell Basin, formerly in Segment 10. This segment was created to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 36: This segment was created to encompass the lakes and reservoirs tributary to the Gunnison River from its inception at the confluence of the East River and Taylor River, to the inlet of Blue Mesa Reservoir. These lakes and reservoirs were formerly in Segments 15, 16, 17, 19, 21 and 23. This segment was created to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 37: This segment was created to encompass the lakes and reservoirs tributary to Blue Mesa Reservoir, Morrow Point Reservoir, Crystal Reservoir, and the interconnecting segments of the Gunnison River, which were formerly in Segments 26, 29a and 32. This segment was created to facilitate the adoption of appropriate temperature standards.
Upper Gunnison River 38: This segment was created to encompass the coldwater lakes and reservoirs in the Upper Gunnison Basin that are larger than 100 acres in surface area. These reservoirs were formerly in Segments 4, 25 and 29b.
North Fork of the Gunnison River 1: The lakes and reservoirs in this segment were moved to a new Segment 8 to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 4: The lakes and reservoirs in this segment were moved to a new Segment 9 to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 5a-5b: Roatcap Creek, including all tributaries and wetlands, from the national forest boundary to the confluence with the North Fork of the Gunnison was moved to a new Segment 5b. The lakes and reservoirs in Segment 5 were moved to a new Segment 10. These waters were split to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 6a-6b: Segment 6a encompasses the tributaries to the North Fork of the Gunnison below the confluence with Coal Creek that are not within national forest boundaries, and do not have a Water Supply Use. The tributaries within the same area, but with a Water Supply Use are described in Segment 6b.
Multiple alluvial wells that were being used as a drinking water source were discovered on unnamed tributaries described within Segment 6a. Rather than try to describe the locations of these unnamed tributaries and move them to Segment 6b, larger swaths of tributaries were moved to Segment 6b. On the north side of the North Fork of the Gunnison, all tributaries and wetlands from the confluence with Roatcap Creek to confluence with the Gunnison River were moved from Segment 6a to 6b. Love Gulch, Dover Creek, Cow Creek, Stingley Gulch and Big Gulch were formerly described individually, but were deleted from the Segment 6b segment description, since they are included in this northern swath of tributaries. On the south side of the North Fork of the Gunnison, all tributaries that flow into the North Fork of the Gunnison River from the confluence with Minnesota Creek to the confluence with the Gunnison River were moved to Segment 6b. Miller Creek, German Creek, Reynolds Creek, Bell Creek, McDonald Creek, Cottonwood Creek and Alum Gulch were formerly described individually, but were deleted from the Segment 6b segment description, since they are all included in this southern swath of tributaries.
The lakes and reservoirs in Segments 6a and 6b were moved to a new Segment 11 to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 7: This segment was created to encompass coldwater lakes tributary to the North Fork of the Gunnison River that are greater than 100 acres in surface area. Overland Reservoir was moved to this segment with Paonia Reservoir to facilitate the adoption of appropriate temperature standards. Although Lake Irwin is large enough to qualify for this segment, it contains cutthroat trout and requires the lower temperature standard applied to smaller coldwater lakes to protect that species.
North Fork of the Gunnison River 8: This segment was created to encompass the lakes and reservoirs within the West Elk or Raggeds Wilderness areas, which were formerly in Segment 1. This segment was created to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 9: This segment was created to encompass all the lakes and reservoirs tributary to Muddy Creek, Paonia Reservoir, Coal Creek, or the North Fork of the Gunnison from its inception at the confluence of Muddy Creek and Coal Creek to the confluence with the Gunnison River. This segment also includes lakes that are tributary to the North Fork of the Gunnison and within national forest boundaries. These lakes and reservoirs were formerly in Segment 4. This segment was created to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 10: This segment was created to encompass the lakes and reservoirs tributary to Roatcap Creek and Jay Creek (in their entirety), and lakes and reservoirs tributary to Hubbard Creek, Terror Creek, Minnesota Creek, and Leroux Creek from the national forest boundary to the confluence with the North Fork of the Gunnison. The lakes and reservoirs in this segment were formerly in Segment 5. This segment was created to facilitate the adoption of appropriate temperature standards.
North Fork of the Gunnison River 11: This segment was created to encompass the lakes and reservoirs that are tributary to the North Fork of the Gunnison from its inception at the confluence of Muddy Creek and Coal Creek to the confluence with the Gunnison River, and are not within national forest boundaries. The lakes and reservoirs in this segment were formerly in Segments 6a and 6b. This segment was created to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 1: The lakes and reservoirs in tinis segment were moved to a new Segment 16 to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 2: Como Lake was moved to a new Segment 17 to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 3a-3f: The mainstem of the Uncompahgre River from the confluence with Cascade Creek to the Hwy 90 bridge in Montrose was broken into four new Segments: 3b, 3c, 3d, 3e, and 3f. These waters were split into several segments to facilitate the adoption of appropriate temperature standards, to reflect large changes in water quality, and to better describe the ambient iron conditions. Ridgway Reservoir was moved from Segment 3b to a new Segment 19. Segment 3b now encompasses the mainstem of the Uncompahgre River from the confluence with Cascade Creek to the confluence with Dexter Creek. Segment 3c was created to encompass the mainstem of the Uncompahgre River from the confluence with Dexter Creek to the confluence with Dallas Creek. Segment 3d was created to encompass the mainstem of the Uncompahgre River from the confluence with Dallas Creek to the inlet of Ridgway Reservoir. Segment 3e was created to encompass the mainstem of the Uncompahgre River from the outlet of Ridgway Reservoir to the outlet of the South Canal near Uncompahgre. Segment 3f was created to encompass the mainstem of the Uncompahgre River from the outlet of the South Canal to the Highway 90 bridge in Montrose.
Uncompahgre River 4a-4b: The boundary between Segment 4a and Segment 4b was moved downstream from La Salle Road to Gunnison Road. The Recreation and Aquatic Life Uses in the Uncompahgre River between La Salle Road and Gunnison Road are more similar to Segment 4a than to Segment 4b.
Uncompahgre River 5: The lakes and reservoirs in this segment were moved to a new Segment 17 to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 9: The segment description was amended to give a latitude and longitude location of "1.5 miles above the confluence with Imogene Creek", which is a somewhat indefinite boundary depending on how the stream length is measured.
Uncompahgre River 10: The lakes and reservoirs in this segment were moved to a new Segment 18 to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 11: The lakes and reservoirs in this segment were moved to a new Segment 18 to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 12 and 14: The lakes and reservoirs in this Segment 12 were moved to a new Segment 21 to facilitate the adoption of appropriate temperature standards. Sweitzer Lake was moved from Segment 14 to a new Segment 20. The East and West Forks of Horsefly Creek, including all tributaries and wetlands, and Happy Canyon Creek, including all tributaries and wetlands, from the source to the most downstream national forest boundary were moved from Segment 12 to a new Segment 14. These waters were split to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 16: This segment was created to encompass the lakes and reservoirs in the Mt. Sneffels or Uncompahgre Wilderness areas, which were formerly in Segment 1. This segment was created to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 17: This segment was created to encompass the lakes and reservoirs tributary to the Uncompahgre River from the source to the confluence with Dexter Creek, which were formerly in Segments 2 and 5. This segment was created to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 18: This segment was created to encompass tine lakes and reservoirs tributary to tine Uncompalngre River from tine confluence witin Dexter Creek to tine Soutin Canal near Uncompahgre, which were formerly in Segments 10 and 11. This segment was created to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 19: This segment was created to encompass Ridgway Reservoir, which was formerly in Segment 3b. This segment was moved to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 20: This segment was created to encompass Sweitzer Reservoir, which was formerly in Segment 14. This segment was moved to facilitate the adoption of appropriate temperature standards.
Uncompahgre River 21: This segment was created to encompass all the lakes and reservoirs tributary to the Uncompahgre River from the South Canal to the confluence with the Gunnison River, which were formerly in segment 12. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 3: Island Lake, Eggleston Lake, and Trickle Park Reservoir were moved from this segment to a new Segment 15. The remaining lakes and reservoirs in this segment were moved to a new Segment 14 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 4b: The lakes and reservoirs in this segment were moved to a new Segment 16 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 7a-7b: Segment 7 was split in Segments 7a and 7b to facilitate the adoption of appropriate temperature standards. The mainstem of Ward Creek, from the national forest boundary to the confluence with Dirty George Creek was split and moved to new Segment 7a.
Lower Gunnison River 8: The Fruita Water Supply Reservoirs I and II were moved to a new Segment 14 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 11 a: The lakes and reservoirs in the segment were moved to a new Segment 17 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 11 b: The lakes and reservoirs in this segment were moved to a new Segment 18 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 12: The lakes and reservoirs in this segment were moved to a new Segment 19 to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 14: This segment was created to encompass lakes and reservoirs tributary to the Gunnison River, from the outlet of Crystal Reservoir, to the confluence with the Colorado River, and that are within national forest boundaries. These lakes and reservoirs were formerly in Segments 3 and 8. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 15: This segment was created to encompass large cold lakes and reservoirs tributary to the Gunnison River, from the outlet of Crystal Reservoir, to the confluence with the Colorado River. This segment includes Island Lake, Eggleston Lake, and Trickle Park Reservoir, which were formerly in Segment 3. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 16: This segment was created to encompass the lakes and reservoirs tributary to the Gunnison River from the outlet of Crystal Reservoir, to the confluence with the Colorado River, and not within national forest service boundaries. These lakes and reservoirs were formerly in Segment 4b. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 17: TInis segment was created to encompass tine lakes and reservoirs tributary to tine Smitin Fork, and witlnin national forest boundaries, and all lakes and reservoirs tributary to Doug Creek. These lakes and reservoirs were formerly in Segment 11a. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 18: This segment was created to encompass the lakes and reservoirs tributary to the Smith Fork, and within the West Elk Wilderness area, which were formerly in Segment 11 b. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Gunnison River 19: This segment was created to encompass the lakes and reservoirs tributary to the Smith Fork, and not with national forest boundaries, which were formerly in Segment 12. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 1: The lakes and reservoirs in this segment were moved to a new Segment 13 to facilitate the adoption of appropriate temperature standards.
San Miguel River 2: Trout Lakes was moved to a new Segment 20 with other coldwater lakes larger than 100 acres in surface area. The remaining lakes and reservoirs in this segment were moved to a new Segment 14 to facilitate the adoption of appropriate temperature standards.
San Miguel River 6a: The lakes and reservoirs in this segment were moved to a new Segment 15 to facilitate the adoption of appropriate temperature standards.
San Miguel River 6b: The lakes and reservoirs in this segment were moved to a new Segment 16 to facilitate the adoption of appropriate temperature standards.
San Miguel River 7: The lakes and reservoirs in this segment were moved to a new Segment 17 to facilitate the adoption of appropriate temperature standards. Waterfall Creek was moved into this segment from 7b, and this segment was renumbered as Segment 7.
San Miguel River 9: The lakes and reservoirs in this segment were moved to a new Segment 18 to facilitate the adoption of appropriate temperature standards.
San Miguel River 10: Gurley Reservoir was moved to a new Segment 20 with other coldwater lakes larger than 100 acres in surface area to facilitate the adoption of appropriate temperature standards.
San Miguel River 11 a-11 b: Miramonte Reservoir was moved from Segment 11 to a new Segment 20 with other coldwater lakes larger than 100 acres in surface area. The remaining lakes and reservoirs were moved to a new Segment 19. Saltado Creek, from the national forest boundary to the confluence with the San Miguel River, was split to a new Segment 11 b. These waters were split to facilitate the adoption of appropriate temperature standards.
San Miguel River 12a-12b: The lakes and reservoirs in Segment 12 were moved to a new Segment 19. The tributaries to the San Miguel from the confluence with Naturita Creek to the confluence with the Dolores River were moved to a new Segment 12b. These waters were split to facilitate the adoption of appropriate temperature standards.
San Miguel River 13: This segment was created to encompass the lakes and reservoirs within the Lizard Head or Mount Sneffels Wilderness areas, which were formerly in Segment 1. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 14: This segment was created to encompass the lakes and reservoirs tributary to the San Miguel River from it source to the confluence with Leopard Creek, which were formerly in Segment 2. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 15: TInis segment was created to encompass tine lakes and reservoirs tributary to Ingram Creek, which were formerly in Segment 6a. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 16: This segment was created to encompass the lakes and reservoirs tributary to Marshall Creek, which were formerly in Segment 6b. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 17: This segment was created to encompass the lakes and reservoirs tributary to the Howard Fork from the confluence with Swamp Gulch to the confluence with the San Miguel River. These lakes and reservoirs were formerly in Segment 7a. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 18: This segment was created to encompass the lakes and reservoirs tributary to the San Miguel River from the confluence with Leopard Creek to the confluence with the Dolores River that are within national forest boundaries. These lakes and reservoirs were formerly in Segment 9. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 19: This segment was created to encompass the lakes and reservoirs tributary to the San Miguel from the confluence with Leopard Creek to the confluence with the Dolores River that are not within national forest boundaries. These lakes and reservoirs were formerly in Segments 11 and 12. This segment was created to facilitate the adoption of appropriate temperature standards.
San Miguel River 20: This segment was created to encompass the coldwater reservoirs tributary to the San Miguel River that are greater than 100 acres surface area. These reservoirs were formerly in Segments 2, 10 and 11. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Dolores River la, lb and 2: Segment 1 was split into Segments la and lb, and the Dolores River from the Highway 141 road crossing to the Little Gypsum Valley Bridge was moved to Segment 2. Segment la encompasses the Dolores River from the bridge at Bradfield Ranch to the confluence with Big Canyon Creek, and is a coldwater segment. Segment lb encompasses the Dolores River from the confluence with Big Canyon Creek to the Highway 141 road crossing near Slick Rock, and this coldwater segment has an ambient-based MWAT temperature standard. The upstream boundary of Segment 2 was moved from the Little Gypsum Valley Bridge at the San Miguel/Montrose County line to the Highway 141 road crossing near Slick Rock. The Commission determined that the Dolores River from the Highway 141 road crossing to the Little Gypsum Valley Bridge had been misclassified as a coldwater river. These segment boundaries were moved to facilitate the adoption of appropriate temperature standards.
Lower Dolores River 3a-3c, 4-6: The lakes and reservoirs in Segment 3a were moved to new Segments 7 and 8. Segment 3a was split, and the tributaries to the Dolores River within national forest boundaries (excluding a small area of Uncompahgre National Forest in the Disappointment Valley) were moved to Segment 3b. Additionally, the North Fork of West Creek, including all tributaries and wetlands, and Granite Creek from the source to the Colorado/Utah border were moved from Segment 3a to a new Segment 6. Segment 3b, which formerly encompassed Salt Creek was renumbered 3c, and the lakes and reservoirs in that segment were moved to new Segment 8. These waters were split to facilitate the adoption of appropriate temperature standards.
Lower Dolores River 4: The mainstem of West Paradox Creek from the source to the Manti-La Sal National Forest boundary, and Blue Creek from the source to the Uncompahgre National Forest boundary were moved from Segment 4 to a new Segment 3b.
Lower Dolores River 5: Multiple changes were made to the new Segment 3b. Roc Creek, La Sal Creek, and Mesa Creek from the source to the national forest boundary were moved from Segment 5 to Segment 3b.
Lower Dolores River 6: This segment was created to encompass tine Nortin Forkof West Creek, including all tributaries and wetlands, from the source to the confluence with West Creek, and Granite Creek, including all tributaries and wetlands, from the source to the Colorado/Utah border. This segment was created to facilitate the adoption of appropriate temperature standards.
Lower Dolores River 7: This segment was created to encompass the lakes and reservoirs tributary to the Dolores River, and within national forest boundaries. These lakes and reservoirs were formerly in Segments 3a and 3b. This segment was created to facilitate the adoption of appropriate Aquatic Life Use classifications, and temperature standards.
Lower Dolores River 8: This segment was created to encompass the lakes and reservoirs tributary to the Dolores River, and not within national forest boundaries. The lakes and reservoirs in this segment were formerly in Segments 3a and 3b. This segment was created to facilitate the adoption of appropriate temperature standards.
The following segment descriptions were edited to improve clarity, correct typographical errors, and correct spelling errors:
Upper Gunnison River segments: 6a, 14, 15a, 19, 22 and 26
North Fork of the Gunnison River segments: 1, 2, 4, 5a and 6a
Uncompahgre River segments: 1,4c, 5, 9, 11 and 15a
Lower Gunnison River segments: 3, 4a, 4b, 5, 6, 7b, 8, 1 la and 12
San Miguel River segments: 1, 3a, 5, 6a, 6b, 7, 8, 10 and 11a
Lower Dolores River segments: 3c and 5
B. Revised Aquatic-Life Use Classifications
The Commission reviewed information regarding the existing aquatic communities. Class 2 segments with exceptionally high MMI scores, or fish data showing the presence of a wide variety of species, were upgraded from Class 2 to Class 1.
The following segments were upgraded from Warm 2 to Warm 1.
Uncompahgre River segments: 4a, 4c, 12 and 15a
Lower Gunnison River segment: 16
Lower Dolores River segment: 4
The following segments were upgraded from Cold 2 to Cold 1:
Uncompahgre River segment: 10
Lower Gunnison River segment: 7b
The following segment was upgraded from Warm 2 to Cold 1 based on biological data showing that the segment has a wide variety of cold-water species:
Lower Dolores River segment: 7
Fish Ingestion qualifiers were deleted for the following segment that was upgraded from Class 2 to Class 1, since fish ingestion is presumed for all Class 1 waters:
Lower Gunnison River segment: 7b
The following segments were upgraded from Warm 2 to Cold 2 based on biological data showing that cold-water species are present:
Uncompahgre River segments: 14 and 15b
A Use Attainability Analysis was prepared to downgrade the following segments, or portions of these segments, from Cold 1 to Warm 1.
Lower Gunnison River segment:
13 Lower Dolores River segment: 1
C. Recreation Classifications and Standards
Newly created segments were given the same Recreation Use classification as the segment from which they were split, unless there was insufficient evidence to support keeping that classification, or evidence to show that the use classification was inappropriate.
The following segments with year-round or seasonal Recreation N standards were upgraded to Recreation P:
North Fork of the Gunnison River segment: 3
Uncompahgre River segments: 2, 4b, 7, 8, 10, 11, 12 and 15a
Lower Gunnison River segments: 4a and 9
The Towns of Hotchkiss and Olathe provided testimony expressing concerns about the potential cost of complying with new effluent limitations that could result from the adoption of revised Recreation standards for North Fork segment 3 and Uncompahgre segment 4b, respectively. The Commission notes that should compliance with such effluent limitations become an issue, several options may be available to help address the compliance burden, including the possibility of compliance schedules. Temporary Modifications or discharger-specific variances, if necessary and appropriate.
The following segment with year-round or seasonal Recreation N standards was upgraded to Recreation E.
Uncompahgre River segment: 17
D. Water Supply Use Classification and Standards
Based on review of information regarding the location of alluvial wells, where the evidence demonstrates a reasonable potential for a hydrological connection between the surface water and the wells, the Water Supply Use classifications and standards were added to the following segments:
Upper Gunnison River segment: 12
North Fork of the Gunnison River segments: 3 and 11
Uncompahgre River segments: 4a and 4b
Lower Gunnison River segments: 7b, 10 and 12
San Miguel River segments: 3b and 7a
Lower Dolores River segments: 2, 3a and 4
The Commission found that the information submitted by U.S. Energy is insufficient to demonstrate the lack of a hydrological connection between Upper Gunnison segment 12 and the existing wells located adjacent to that section of the stream.
The following segment with Fish Ingestion standards was upgraded to Water+Fish when the Water Supply Use was added:
Uncompahgre River segment: 9
A review of the segments with an existing Water Supply Use classification showed that some segments were missing one or more standards to protect that use. The full suite of Water Supply standards were added to the following segments:
Upper Gunnison River segment: 13 Uncompahgre River segments: 3a and 10 Lower Gunnison River segment: 4a San Miguel River segment: 12a
E. Agriculture Standards
A review of the standards associated with the Agriculture Use classification showed that many segments were missing a chronic chromium III standard to protect the use. The chronic chromium III standard to protect the Aquatic Life Use classification may be not be protective of the Agriculture Use in some high hardness situations. A chromium III standard of Crlll(ch)=100(Trec), was added to the following segments classified for Agriculture Use, but not for Water Supply, which has a more restrictive chromium III standard:
Upper Gunnison River segments: 6a, lOa-b, 20, and 31
Uncompahgre River segments: 4c, 6a, 15b, 19-20 and 21
Lower Gunnison River segment: 13
San Miguel River segments: 3a, 5, 6a-b, lla-b, 16 and 17
Lower Dolores River segments: 3c and 8
Molybdenum: In 2010, the Commission adopted a new standard for molybdenum to protect cattle from the effects of molybdenosis. The table value adopted at that time was 300 ug/l, but included an assumption of 48 mg/day of copper supplementation to ameliorate the effects of molybdenosis. State and local experts on cattle nutrition indicated that copper supplementation in region is common, but is not universal. Therefore, copper supplementation assumption was removed from the equation, which yields a standard of 160 ug/l. The Commission expects that this value may be revised when data on the copper and molybdenum content of local forage becomes available. The Commission also notes that in view of EPAs disapproval of the 300 ug/l table value in the Basic Standards and Methodologies for Surface Water, the Commission intends to review this value during the next Basic Standards triennial review.
The Agriculture table value assumes that the safe copper:molybdenum ratio is 4:1. Food and water intake is based on a 273 kg (600 lb) feeder steer consuming 6.8 kg/day of dry matter and 20% of its body weight in water per day. Total copper and molybdenum intakes are calculated from the following equations:
Cu intake mg/day = [([Cu] forage, mg/kg) x (forage intake, kg/day)] + [([Cu] water, mg/l) x (water intake, L/day)] + (Cu supplementation, mg/day)
Mo intake mg/day = [([Mo] forage, mg/kg) x (forage intake, kg/day)] + [([Mo] water, mg/l) x (water intake, L/day)] + (Mo supplementation, mg/day)
The assumed values for these equations are as follows:
[Cu] forage = 7 mg/kg, [Mo] forage = 0.5 mg/kg, forage intake = 6.8 kg/day, [Cu] water = 0.008 mg/L, [Mo] water = 0.375 mg/L, water intake = 54.6 L/day, Cu supplementation = 0 mg/day. Mo supplementation = 0 mg/day.
A molybdenum standard of 160 ug/l was adopted for the following segments in Regulation 35 that have an Agriculture Use classification, and where livestock or irrigated forage are present or expected to be present.
Upper Gunnison River segments: 1-4, 5a-b, 6a-b, 7-8, 10a-b, 12, 13a-b, 14, 15a-b, 16a-b, 17a-b, 6a, 18a-
b, 19-26, 29a-b, and 30-36
Nortin Forkof tine Gunnison River segments: 1-4, 5a-b, 6a-b, and 7-11
Uncompalngre River segments: 1, 2, 3a-f, 4a-c, 5, 6a-b, 7-14, 15a-b, and 16-21
Lower Gunnison River segments: 1-3, 4a-c, 5, 6, 7a-b, 8-10, lla-b, and 12-19
San Miguel River segments: 1,2, 3a-b, 4a-b, 5, 6a-b, 7-10, lla-b, 12a-b, and 13-20
Lower Dolores River segments: la-b, 2, 3a-c, and 4-8
The following segments have an Agriculture Use classification, but neither livestock nor irrigated forage are present, nor are they expected to be present. A molybdenum standard of 210 ug/L was applied to these segments to protect the Water Supply Use classification:
Upper Gunnison River segments: 9 and 11
F. Changes to Antidegradation Designation
Decoupling Cold 2 and Use-Protected designations: 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. The Commission reviewed all Cold 2 segments that were Use-Protected to determine if that designation was still warranted. The following segments are now Reviewable:
Uncompahgre River segments: Sand 15b
Decoupling Aquatic Life Warm 2 and Use-Protected designations: As part of the Basic Standards hearing of 2005, the Commission decided that the presence of a Warm Water Class 2 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. The Commission reviewed all Warm 2 segments to determine if the Use-Protected designation is still warranted. The following segment(s) are now Reviewable:
North Fork of the Gunnison River segments: 6a and 6b
Uncompahgre River segments: 4a, 4c and 15a
Lower Gunnison River segments: 4b-c and 12
Lower Dolores River segment: 3c
The Commission adopted an Outstanding Waters designation for Upper Gunnison Segment 2 based on ample evidence that water quality in Segment 2 meets the requirements of 31.8(2)(a). The Commission also notes that the outreach undertaken by the Park Service as proponent of this designation helps to demonstrate broad support for the conclusion that these waters constitute an outstanding natural resource and that the additional protection provided by this designation is appropriate.
The evidence demonstrates that existing uses such as cattle grazing/agriculture, recreation, forest practices, and year-round and seasonal residences, on public and private land are compatible with the new Outstanding Waters 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 Outstanding Waters designation should not be the basis upon which federal, state or local agencies place more onerous or costly conditions upon permits or approvals existing at the time of the designation, or upon any renewals thereof.
Further, acknowledging that the adoption of the Outstanding Waters designation for identified segments is a discretionary undertaking by the Commission, with such designations not being subject to federal approval or disapproval, the Commission may, in the future, remove the Outstanding Waters designation from any such segment in accordance with the state substantive and procedural rules then in effect.
The Commission Inas not adopted tine Outstanding Waters designations proposed by WildEartln Guardians for multiple segments. The Commission is not persuaded that the fact of being located within an area identified as a "roadless area" is sufficient to demonstrate that the waters in question constitute an outstanding natural resource. Moreover, the proponents did not provide adequate data to persuasively demonstrate the current quality of the waters in question. Finally, the Commission notes that the proponents did not demonstrate a substantial level of public outreach that might have helped to demonstrate a consensus that the criteria in section 31.8(2)(a) are met.
G. Ambient Standards
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. In some cases, new ambient standards were adopted. The following segments have ambient-based standards:
Upper Gunnison River segments: 10a-b, 12, 15a, 16b and 20
Uncompahgre River segments: 1, 3a-b, 4b-c, 7 and 12
Lower Gunnison River segments: 2 and 8
San Miguel River segments: 3a-b, 4b, 6b, 8, 10 and 16
Lower Dolores River segment: la, lb and 3c
H. Aquatic Life Metals Standards
New Table Value Standards: The zinc, zinc sculpin, and aluminum table values were revised in the 2010 Basic Standards hearing. The acute and chronic zinc, zinc sculpin, and aluminum equations in 35.6(3) were modified to conform to Regulation No. 31.
Site-Specific Zinc Standards for Mottled Sculpin: In low-hardness situations (hardness below 102 mg/L), the zinc equation is not protective of mottled sculpin {Cottus bairdi), a native west-slope fish species. The Commission added a sculpin-specific zinc equation as site-specific standard to the following segments where mottled sculpin are expected to be present, and hardness is low:
North Fork of the Gunnison River segment: 5a
Uncompahgre River segment: 10
Lower Gunnison River segments: 1 and 10
The Commission deleted the zinc scuplin standards from the following segments where mottled sculpin are not expected to be present:
Upper Gunnison River segments: 4, 6a, 7, 15a, 16a-b, 19, 22, 23, 29a, 30, 32-36 and 37 Uncompahgre River segments: 5, 6a, 16 and 17
Chromium III Standards: A review of chromium III standards showed that the standard associated with the Water Supply Use classification is not protective of aquatic life where the average hardness is low (less than 61 mg/l). A chromium III standard, Crlll(ch)=TVS was added to following segments with Aquatic Life and Water Supply Use classifications that did not previously include this standard:
Upper Gunnison River segments: 1, 4, 5a-b, 6a-c, 7-9, 11, 14, 15a-b, 16a-b, 17a-b, 18a-b, 19, 21-26,
29a-b, 30, 32, 33-36 and 37
North Fork of the Gunnison River segments: 1-2, 4, 5a-b, 6b, 7-10 and 11
Uncompahgre River segments: 1-2, 5, 7-8, 11, 16-17 and 18
Lower Gunnison River segments: 1-3, 5, 8, lla-b, 12, 14-15, 17-18 and 19
San Miguel River segments: 1-2, 4a-b, 8-10, 13-14, 17-18 and 20
Lower Dolores River segments: la-b, 2, 3a and 5
I. Uranium Standards
At the 2010 Basic Standards rulemaking Inearing, tine Commission cinanged tine Water Supply table value for uranium from 30 ug/L to a hyphenated standard of 16.8-30 ug/L. The Commission revised the language in 35.5(3)(c) to reflect the change to the basin-wide standard. A new section 35.5 was added to explain the hyphenated standard. Subsection 35.5 was deleted because it was redundant with 35.5(3)(c).
Upper Gunnison Segment 20: The Commission changed the site-specific chronic uranium standard of 2000 ug/l, and the acute uranium standard of TVS, to narrative standards of "lowest practical level".
J. Temporary Modifications
All existing Temporary Modifications were examined to determine if they should be allowed to expire or to extend them. Temporary Modifications were not automatically extended if non-attainment persisted due to revisions made to the Temporary Modification provisions in 2005 and 2010.
The following segments had Temporary Modifications that were not renewed:
Upper Gunnison River segments: 8 and 16
North Fork of the Gunnison River segments: 3, 5a and 6b
Uncompahgre River segments: 3a and 12
Lower Gunnison River segments: 4a and 7b
San Miguel River segments: 2 and 3b
In some cases, the Commission adopted Temporary Modifications with a narrative value of "current conditions". It is the Commission's intent to preserve the status quo during the term of the Temporary Modification. Existing discharges shall continue to be authorized to discharge parameters with a "current conditions" Temporary Modification at their current permitted concentration and flow levels, including a "report only" value. The Commission does not intend that Temporary Modifications set at "current condition" will apply to new or expanded facilities. Implementation of the underlying standard into existing permits is to take place as soon as feasible after the standard becomes effective in accordance with the Basic Standards and Methodologies for Surface Water.
New or extended Temporary Modifications were adopted for the segments below.
Upper Gunnison River Segment 12: The Commission adopted a Type A Temporary Modification for chronic arsenic with a narrative value of "current conditions", and an expiration date of June 30, 2014. U.S. Energy intends to participate in the April 2013 statewide rulemaking hearing on arsenic, which is the basis for a Type A Temporary Modification.
The Commission also adopted Type B Temporary Modifications for chronic cadmium, chronic copper, and chronic zinc with expiration dates of June 30, 2013. The Temporary Modification for cadmium and zinc have numeric values of 2.1 ug/l and 440 ug/l, respectively, based on ambient conditions that were calculated as the 85th percentile of a dataset that had been de-biased due to a preponderance of samples collected in the spring when water quality is poorest. The copper Temporary Modification has a value of current conditions. The Commission expects U.S. Energy to work with the Division and interested parties to develop a sampling plan to determine the natural and man-induced irreversible sources of cadmium, copper, and zinc in the Coal Creek watershed, which is the basis for a Type B Temporary Modification. The sampling plan will be reviewed in the annual Temporary Modification hearing in December 2013. Provided that the sampling plan is adequate, the expiration date will be extended to provide a reasonable amount of time to complete sampling and data analysis to set underlying standards.
Upper Gunnison Segment 20: The Commission adopted Type B Seasonal Temporary Modifications for cinronicand acute uranium standards witin an expiration date of June 30, 2015. Tine Temporary Modifications apply at sampling site SW-33, which is located just below the discharge from Homestake's Pitch Mine. The numeric values for the Temporary Modifications are based on ambient conditions at that sampling location, and are lower than the previous underlying uranium standards of 2000 ug/l for chronic uranium, and TVS for acute uranium. The Pitch Mine is being reclaimed, and this Temporary Modification will provide time to determine the "lowest practical level" of uranium that is achievable for this site. The progress to establish an appropriate underlying uranium standard for this segment will be reviewed in the annual Temporary Modification hearing in December 2013.
North Fork of the Gunnison Segment 2: The Commission adopted a Type B Temporary Modification for chronic arsenic with a narrative value of "current conditions", and an expiration date of July 1, 2015. Mountain Coal submitted evidence of natural sources of arsenic with the watershed, which is the basis for a Type B Temporary Modification. The progress on resolving the uncertainty with the arsenic standard will be reviewed in the annual Temporary Modification hearing in December 2013. During the Temporary Modification, a study will be completed that addresses watershed sources including the company's discharge.
Uncompahqre Segment 4b: The Commission adopted a Type A Temporary Modification for chronic selenium with a narrative value of "current condition", and an expiration date of December 31, 2017. The Town of Olathe wastewater treatment facility is currently discharging selenium at an average concentration of 7.8 ug/l. The Commission expects Olathe to make all reasonable efforts to identify the source of selenium to their wastewater treatment plant, and to make all reasonable efforts to reduce those sources for the duration of the Temporary Modification. There is significant uncertainty concerning the underlying selenium standard. Time is needed to wait for the EPA's new selenium criteria and implementation guidance, and to determine an appropriate underlying selenium standard for Uncompahgre Segment 4b. The progress on resolving the uncertainty with the selenium standard will be reviewed in the annual Temporary Modification hearing in December 2015.
Lower Gunnison Segment 2: The Commission adopted a Type A Temporary Modification for chronic selenium with a narrative value of "current condition", and an expiration date of December 31, 2017. The City of Delta wastewater treatment facility is currently discharging selenium at an average concentration of 8.3 ug/l, and is addressing the inflow and infiltration into their system that is the cause of elevated selenium in their effluent. There is significant uncertainty concerning the underlying selenium standard. Time is needed to wait for the EPA's new selenium criteria and implementation guidance, and to determine an appropriate underlying selenium standard for Lower Gunnison Segment 2. The progress on resolving the uncertainty with the selenium standard will be reviewed in the annual Temporary Modification hearing in December 2015.
K. Temperature
New table values were adopted for temperature in the 2007 Basic Standards hearing, and revised in the 2010 Basic Standards hearing. Temperature standards were applied to individual segments based upon the fish species expected to be present as provided by Parks and Wildlife, temperature data, and other available evidence.
The following segments have a Cold Stream Tier I temperature standard (CS-I):
Upper Gunnison River segments: 1,4, 5a, 6a-b, 7-9, lOa-b, 11-13, 15b, 16a, 17a, 18a, 19-23,26,
29a and 30-32.
North Fork of the Gunnison River segments: 1, 4 and 5a
Uncompahgre River segments: 1-2, 3a-b, 5, 6a, 7-8, 9, 11 and 13
Lower Gunnison River segments: 3, 7a, 11a and lib
San Miguel River segments: 1-2, 3a-b, 6a, 6b, 7, 9 and 11 b
Lower Dolores River segments: 3b and 6
The following segments have a Cold Stream Tier II temperature standard (CS-II):
Upper Gunnison River segments: 5b, 6c, 14, 15a, 17b, 18b, 24, 25 and 29b
Nortin Fork of tine Gunnison River segments: 2, 3 and 5b
Uncompalngre River segments: 3c-e, 10, 14 and 15b
Lower Gunnison River segments: 1, 5, 6, 7b, 8 and 10
San Miguel River segments: 4a, 8, 10, 11a, 12a and 12b
Lower Dolores River segments: la and 5
The following segments have a Warm Stream Tier II temperature standard (WS-II):
North Fork of the Gunnison River segment: 6a
Uncompahgre River segments: 4a-c, 12 and 15a
Lower Gunnison River segments: 2, 4a and 4b
San Miguel River segment: 5
Lower Dolores River segments: 2, 3a and 4
The following segments have a Warm Stream Tier III temperature standard (WS-III):
North Fork of the Gunnison River segment: 6b
Lower Gunnison River segments: 4c and 12
Lower Dolores River segment: 3c
The following segments have a Cold Lakes temperature standard (CL):
Upper Gunnison River segments: 33-37
North Fork of the Gunnison River segments: 8-10
Uncompahgre River segments: 16-18
Lower Gunnison River segments: 14, 17 and 18
San Miguel River segments: 13-18 and 19
Lower Dolores River segment: 7
The following segments have a Large Cold Lakes (greater than 100 acres surface area) temperature standard (CLL):
Upper Gunnison River segment: 38
North Fork of the Gunnison River segment: 7
Uncompahgre River segment: 19
Lower Gunnison River segment: 15
San Miguel River segment: 20
The following segments have a Warm Lakes temperature standard (WL):
North Fork of the Gunnison River segment: 11
Uncompahgre River segments: 20-21
Lower Gunnison River segments: 9, 13, 16 and 19
Lower Dolores River segments: 8 and 13
A temperature standard was not adopted for the following segment, which does not have an Aquatic Life Use classification:
Uncompahgre River segment: 6b
The following segments have ambient-based temperature standards:
Upper Gunnison River segment: 16b Uncompahgre River segment: 3b
San Miguel River segment: 4b
Lower Dolores River segments: 1a and 1b
The Commission recognizes that in some cases there is uncertainty about the temperature standards adopted in this hearing. The uncertainty stems from a lack of data about temperature, the aquatic community, or where there is a conflict between these two lines of evidence. It is the Commission's intent that the Division and interested parties work to resolve the uncertainty for the following segments:
Upper Gunnison River segment: 19
Uncompahgre River segments: 3b, 6, 11 and 13
Lower Gunnison River segments: 4c, 8 and 13
San Miguel River segments: 10 and 12b
Lower Dolores River segments: 3b and 5
L. Other Site-Specific Revisions
Upper Gunnison River 6a: This segment does not have a Water Supply Use, but had an acute chromium III standard associated with that use. The Water Supply standard was deleted and replaced with TVS.
Upper Gunnison River 12: An ambient-based chronic manganese standard of 191 ug/l was adopted to protect the Water Supply Use classification. Adequate data from 2000 were not available to calculate an ambient standard. Ambient conditions were calculated as the 85th percentile of a dataset using the most recent 5-years of data. The dataset was de-biased due to a preponderance of samples collected in the spring when water quality is poorest.
Upper Gunnison River 13a: The Fish Ingestion standards were replaced with Water+Fish since the Water Supply Use applies to this segment.
North Fork of the Gunnison River 6a: This segment does not have a Water Supply Use, but had several standards associated with that use. The nitrate standard was changed from 10 mg/l to 100 mg/l, the chloride standard was deleted, and the acute chromium III standard was replaced with TVS. Acute and chronic TVS lead standards were added.
North Fork of the Gunnison River 6b: This segment was missing acute and chronic lead standards. Acute and chronic TVS lead standards were added. The acute and chronic designations were deleted from the nitrate and chloride standards since those descriptions do not apply to those standards.
Uncompahgre River 8: This segment had outdated Drinking Water standards for cadmium, copper, lead, nickel, selenium, silver and zinc. Recent water quality data showed that the table value standards were exceeded for lead and copper only. Acute and chronic table value standards were added for all metals except for lead and copper, which were left unchanged. A mercury standard was also added to protect the Aquatic Life Use. This segment may be a candidate for ambient-based lead and copper values when more data become available about the sources of metals to Mineral Creek.
Lower Gunnison River 2: The Aquatic Life Use classification for this segment was downgraded from Cold 1 to Warm 1 in 2006. The dissolved oxygen standards were changed to reflect the Warm Use classification.
Lower Gunnison River 3: This segment had a typographical error in the pH standard. The pH standard was changed from 6.4-9.0 to 6.5-9.0.
Lower Gunnison River 9: This segment does not have a Water Supply Use, but had iron and manganese standards associated with that use. The iron and manganese Water Supply standards were deleted from this segment.
San Miguel River 3b: TInis segment was missing an acute lead standard. An acute TVS lead standard was added to this segment.
San Miguel River 4b: This Aquatic Life Use classification for this segment was changed from Cold 2 to Warm 1 in 2010. The dissolved oxygen and nitrite standards were changed to reflect the Warm Use classification.
San Miguel River 6a-b: These segments had the outdated chronic arsenic standards of 150 ug/L. The chronic arsenic standards were changed to 100 ug/L to protect the Agriculture Use classification.
San Miguel River 11a: This segment does not have a Water Supply Use, but had nitrate and chloride standards associated with that use. The nitrate standard was changed from 10 mg/L to 100 mg/L, and the chloride standard was deleted.
Lower Dolores River 3c: This segment had ambient selenium and zinc standards. Recent data showed that the selenium concentrations were lower than the ambient-based standard, so the acute selenium standard was changed from 23.4 ug/L to 18.4 ug/L, and the chronic selenium standard was changed from 21.4 ug/L to 6.6 ug/L. The data showed that Salt Creek was attaining the table value standards for zinc, so the ambient based acute and chronic standards were replaced with TVS.
PARTIES TO THE RULEMAKING HEARING
