5 Colo. Code Regs. § 1002-36.34
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 and reservoirs from segments that also contained streams, so that new temperature and nutrients standards could be adopted. Lakes and reservoirs were deleted from the following segments that previously encompassed both streams, and lakes and reservoirs:
Rio Grande segments: 1- 3, 5, 9-11, 14, 18, 19, 21, 23, 25, 28 and 30
Alamosa River/La Jara Creek/Conejos River segments: 1, 2, 11, 14, 17, 19, 20 and 22
Closed Basin - San Luis Valley segments: 1, 2, 4, 8 and 12
The following segments were created for lakes and reservoirs:
Rio Grande segments: 32-38
Alamosa River/La Jara Creek/Conejos River segments: 23-30
Closed Basin - San Luis Valley segments: 15-20
The following segments were deleted when the constituent waterbodies were moved or merged with other segments:
Rio Grande segment: 27
Closed Basin - San Luis Valley segments: 6, 7 and 13b
Some renumbering and/or creation of new segments was made based on information that showed:
Rio Grande segment 1: The lakes and reservoirs within the Weminuche Wilderness Area were moved to a new segment 32. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 2: Lakes and reservoirs tributary to the Rio Grande from the source to Willow Creek were moved to a new segment 33, with the exception of Continental Reservoir, Upper Brown Lake, and Road Canyon Reservoir, which were moved to a new segment 38 with other coldwater lakes and reservoirs larger than 100 acres surface area. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 3: Rio Grande Reservoir and Santa Maria Reservoir were moved from this segment to a new segment 38 with other coldwater lakes and reservoirs larger than 100 acres surface area. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segments 4a-c: Segment 4, which previously encompassed the mainstem of the Rio Grande from Willow Creek to the Rio Grande/Alamosa County Line, was split into three segments to recognize changes in water quality, aquatic life, and to facilitate the adoption of appropriate temperature standards. Segment 4a now encompasses the mainstem of the Rio Grande from the confluence with Willow Creek to the confluence with South Fork Rio Grande. Segment 4b encompasses the Rio Grande from the confluence with South Fork Rio Grande to the Highway 285 crossing near Monte Vista. Segment 4c encompasses the Rio Grande from the Highway 285 crossing near Monte Vista to the Rio Grande/Alamosa County line. This segment was split at the confluence with South Fork Rio Grande to recognize an improvement in water quality, and was split at Highway 285 to recognize a change in the Aquatic Life use from Cold 1 to Warm 1.
Rio Grande segment 5: Lakes and reservoirs tributary to the Rio Grande from Willow Creek to the Highway 112 bridge near Del Norte were moved to a new segment 33. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segments 6 and 7: The East Fork of Willow Creek from the confluence with Whited Creek to the confluence with West Willow Creek was moved from segment 7 to segment 6. Macroinvertebrate data showed that the Aquatic Life use in the East Fork of Willow Creek was much better than West Willow Creek or Willow Creek in segment 7. Segment 6 has an Aquatic Life Cold 1 use classification and standards, which now apply to the East Fork of Willow Creek, which previously had no Aquatic Life use classification or standards.
Rio Grande segment 9: Lakes and reservoirs tributary to the South Fork Rio Grande were moved to a new segment 33, with the exception of Big Meadows Reservoir and Beaver Creek Reservoir, which were moved to segment 38 with other coldwater lakes and reservoirs larger than 100 acres surface area. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 10: Lakes and reservoirs tributary to Pinos Creek were moved to a new segment 33. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 11: The segment description was clarified by specifying that Spring Branch is included in the segment. The lakes and reservoirs tributary to San Francisco Creek were moved to a new segment 33. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 14: The existing segment description referenced all tributaries to the Rio Grande from the Highway 112 bridge near Del Norte to the confluence with Rock Creek, and within the Rio Grande National Forest. Rock Creek breaks into multiple channels when it reaches the San Luis Valley floor, and most of the water is intercepted by the Monte Vista Canal. The Commission adopted a new segment description that encompasses the portions of Dry Pole Creek, Limekiln Creek, Nicomodes Gulch, Raton Creek and Dry Creek within the boundaries of the Rio Grande National Forest, which more clearly describe the tributaries in the original segment description. The lakes and reservoirs tributary to these streams, and within Rio Grande National Forest boundaries, were moved to a new segment 34. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 15: Segments 11, 14 and 31 were added to the list of waters specifically excluded from this segment. The wetlands and tributaries to Cat Creek from the source to the Rio Grande National Forest boundary were moved from this segment to segment 20a. Upper Cat Creek has a historic population of cutthroat trout. By moving these wetlands and tributaries to segment 20a, an Aquatic Life use and standards were added to these waters.
Rio Grande segment 16: Lakes and reservoirs within the Alamosa National Wildlife Refuge were moved to a new segment 35. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 17: Lakes and reservoirs within the Monte Vista National Wildlife Refuge were moved to a new segment 35. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 18: Lakes and reservoirs tributary to the Rio Grande from Highway 112 bridge near Del Norte to the Colorado/New Mexico border were moved to a new segment 35. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards. The list of waters specifically excluded from this segment was updated to only include those segments that have wetlands, and segments 16 and 19 were added to this list.
Rio Grande segment 19: Lakes and reservoirs tributary to Rock Creek were moved to a new segment 34. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segments 20a-b: Cat Creek was split at the Rio Grande National Forest boundary to facilitate the adoption of appropriate temperature standards and Aquatic Life use classification. Segment 20a encompasses Cat Creek, including all tributaries and wetlands, from the source to the Rio Grande National Forest boundary. The tributaries and wetlands to upper Cat Creek were moved to segment 20a from segment 15, which has no Aquatic Life use, since upper Cat Creek has a historic population of Rio Grande cutthroat trout. Segment 20b encompasses Cat Creek from the Rio Grande National Forest boundary to the Terrace Main Canal. The lower portion of Cat Creek is dewatered by two diversions near the Forest Service boundary, and was downgraded from Aquatic Life Cold 1 to Aquatic Life Cold 2.
Rio Grande segments 21a-b: Ute Creek was split at latitude 37.50°N to facilitate the adoption of appropriate temperature standards. Segment 21a encompasses Ute Creek including all tributaries and wetlands, from the source to 37.50°N latitude. Segment 21b encompasses Ute Creek from 37.50°N latitude to Highway 160. Lakes and reservoirs tributary to Ute Creek from the source to Highway 160 were moved to a new segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 23a-b: Sangre de Cristo Creek was split to facilitate the adoption of appropriate temperature and nutrients standards. Segment 23a encompasses Sangre de Cristo Creek, including all tributaries and wetlands, from the source to Highway 159, excluding the mainstem from Placer Creek to Highway 159. Segment 23b encompasses the mainstem of Sangre de Cristo Creek from Placer Creek to Highway 159. Lakes and reservoirs tributary to Sangre de Cristo Creek from the source to Highway 159 were moved to a new segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature standards.
Rio Grande segment 25: Lakes and reservoirs tributary to Trinchera Creek from the source to Mountain Home Reservoir were moved to a new segment 36, with the exception of Mountain Home Reservoir, which was moved to a new segment 38 with other coldwater lakes and reservoirs larger than 100 acres surface area. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 26: The exclusion of segment 27 was deleted since the segment description did not overlap with Smith Reservoir.
Rio Grande segment 27: Smith Reservoir was moved from this segment to a new segment 38 with other coldwater lakes and reservoirs larger than 100 acres surface area.
Rio Grande segment 28: Lakes and reservoirs tributary to Rito Seco from the source to the outlet of Salzar Reservoir were moved to a new segment 36. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segments 30-31: The tributaries to Culebra Creek were split to facilitate the adoption of appropriate temperature and nutrients standards. The mainstem of Ventero Creek was moved to a new segment 31 to facilitate the adoption of appropriate temperature and nutrients standards. Additionally, Costilla Creek, including all tributaries and wetlands within Colorado, but excluding the East Fork and West Fork, were moved to segment 31 to facilitate appropriate temperature and nutrients standards. The lakes and reservoirs tributary to Culebra Creek from the source to State Highway 159 were moved to a new segment 36, with the exception of Sanchez Reservoir. Sanchez Reservoir was moved to a new segment 37, and downgraded from Aquatic Life Cold 1 to Aquatic Life Warm 1. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards and Aquatic Life use classification.
Rio Grande segment 32: This segment was created to encompass the lakes and reservoirs within the Weminuche Wilderness Area. The lakes and reservoirs in this segment were previously in segment 1. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 33: This segment was created to encompass the lakes and reservoirs tributary to the Rio Grande River from the source to the Highway 112 bridge near Del Norte, and all lakes and reservoirs tributary to San Francisco Creek from the source to Spring Branch. This segment excludes lakes and reservoirs in the Weminuche Wilderness Area, and coldwater lakes larger than 100 acres surface area. The lakes and reservoirs in this segment were previously in segments 2, 5, 9, 10 and 11. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 34: This segment was created to encompass the lakes and reservoirs tributary to Dry Pole Creek, Limekiln Creek, Nicomodes Gulch, Raton Creek, or Dry Creek, and within the Rio Grande National Forest boundaries. This segment also includes all lakes and reservoirs tributary to Rock Creek from the source to the Monte Vista Canal. The lakes and reservoirs in this segment were previously in segments 14 and 19. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 35: This segment was created to encompass the lakes and reservoirs tributary to the Rio Grande River from the Highway 112 bridge near Del Norte to the Colorado/New Mexico border, excluding lakes and reservoirs within the boundaries of the Rio Grande National Forest, and excluding lakes and reservoirs tributary to portions of Rock Creek, Ute Creek, Sangre de Cristo Creek, Trinchera Creek, Rito Seco, Culebra Creek and Costilla Creek. The lakes and reservoirs in this segment were previously in segments 16, 17 and 18. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 36: This segment was created to encompass lakes and reservoirs tributary to portions of Ute Creek, Sangre de Cristo Creek, Trinchera Creek, Rito Seco, Culebra Creek, and Costilla Creek. The lakes and reservoirs in this segment were previously in segments 21, 23, 25, 28 and 30. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Rio Grande segment 37: This segment was created to encompass Sanchez Reservoir, which was previously in segment 30. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards, and Aquatic Life use classification. Sanchez Reservoir was downgraded from Aquatic Life Cold 1 to Aquatic Life Warm 1.
Rio Grande segment 38: This segment was created to encompass cold lakes and reservoirs larger than 100 acres in surface area. The lakes and reservoirs in this segment were previously in segments 2, 3, 9, 25 and 27. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 1: Lakes and reservoirs within the South San Juan Wilderness Area were moved to a new segment 23. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards. The segment description was clarified by replacing the reference to the Rio Grande River with the Alamosa River and Conejos Creek.
Alamosa River/La Jara Creek/Conejos River segment 2: Lakes and reservoirs tributary to the Alamosa River from the source to Alum Creek were moved to a new segment 24. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards. Segments 4a and 4b were added as specific exclusions to this segment.
Alamosa River/La Jara Creek/Conejos River segment 3c: The description of the upper segment boundary was changed from immediately below Fern Creek to immediately above Fern Creek to match the lower segment boundary described in segment 3b.
Alamosa River/La Jara Creek/Conejos River segment 4a: Tributaries and wetlands to Iron Creek, Alum Creek, Bitter Creek and Burnt Creek were added to this segment. These tributaries were added to the mainstem listings since they have similarly poor water-quality as the mainstems listed in this segment.
Alamosa River/La Jara Creek/Conejos River segment 4b: Tributaries and wetlands to Iron Creek above the confluence with South Mountain Creek were moved to this segment from segment 2 to clarify that the tributaries to upper Iron Creek were not also being moved to segment 4a. The Water Supply use classification and standards were removed from these tributaries.
Alamosa River/La Jara Creek/Conejos River segment 11a-b: Lakes and reservoirs tributary to La Jara Creek from the source to Hot Creek were moved to a new segment 25. Although La Jara Reservoir is large enough to qualify the Cold Large Lake temperature tier, brook trout and cutthroat trout are present, and would not be adequately protected by that standard. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards. La Jara Creek was split into two segments to facilitate the adoption of appropriate temperature standards and Water Supply use classification. Segment 11a encompasses all tributaries to La Jara Reservoir, and La Jara Creek tributaries and wetlands from the outlet of La Jara Reservoir to Jarosa Creek. Segment 11b encompasses the mainstem of La Jara Creek from the outlet of La Jara Reservoir to Hot Creek, and the tributaries to La Jara Creek from Jarosa Creek to Hot Creek. A Water Supply use classification and standards were added to new segment 11b.
Alamosa River/La Jara Creek/Conejos River segment 14a-b: Lakes and reservoirs tributary to the Conejos River from the source to Fox Creek were moved to a new segment 26, with the exception of Platoro Reservoir, which was moved to segment 30. The mainstem of Conejos Creek from Elk Creek to Fox Creek, including all tributaries and wetlands, were moved to a new segment 14b. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 17a-b: Lakes and reservoirs tributary to Rio de Los Pinos from the source to the Colorado/New Mexico border were moved to a new segment 27. The Rio San Antonio from the Colorado/New Mexico border to Highway 285 was moved to a new segment 17b. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 19: Lakes and reservoirs tributary to the Rio Chama from the source to the Colorado/New Mexico border were moved to a new segment 27. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 20: Lakes and reservoirs tributary to the Alamosa River, La Jara Creek, or the Conejos River from their sources to their confluences with the Rio Grande, within the boundaries of the Rio Grande National Forest, and not within another segment, were moved to a new segment 28. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards. The segment description was clarified by replacing the reference to tributaries to the Rio Grande with tributaries to the Alamosa River, La Jara Creek, and the Conejos River. The list of waters specifically excluded from this segment was updated to reflect segment splits for segments 11, 14, and 17.
Alamosa River/La Jara Creek/Conejos River segment 21: The segment description was clarified by replacing the reference to tributaries to the Alamosa River, La Jara Creek, and the Conejos River, to tributaries to the Conejos River only. The segment references Fox Creek, which is a tributary to the Conejos River. The exclusion for the listings in segment 22 was removed.
Alamosa River/La Jara Creek/Conejos River segment 22: The segment description was clarified by replacing the reference to tributaries to the Rio Grande with tributaries to the Alamosa River and La Jara Creek. Many of the tributaries to the Alamosa River and La Jara Creek were previously unclassified (it appears they were intended to be included in segment 21), and were added to this segment. Segment 21 was added to the list of exclusions. The lakes and reservoirs tributary to the Alamosa River or La Jara Creek and not listed elsewhere, were moved to a new segment 29. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 23: This segment was created to encompass the lakes and reservoirs tributary to Alamosa River or Conejos Creek, and with the South San Juan Wilderness Area. The lakes and reservoirs in this segment were previously in segment 1. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 24: This segment was created to encompass the lakes and reservoirs tributary to Alamosa River from the source to Alum Creek, excluding lakes and reservoirs in the South San Juan Wilderness Area. The lakes and reservoirs in this segment were previously in segment 2. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 25: This segment was created to encompass the lakes and reservoirs tributary to La Jara Creek from the source to Hot Creek. The lakes and reservoirs in this segment were previously in segment 11. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 26: This segment was created to encompass the lakes and reservoirs tributary to the Conejos River from the source to Fox Creek, excluding lakes and reservoirs in the South San Juan Wilderness Area and Platoro Reservoir. The lakes and reservoirs in this segment were previously in segment 14. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 27: This segment was created to encompass the lakes and reservoirs tributary to the Rio de Los Pinos and Rio Chama, excluding lakes and reservoirs in the South San Juan Wilderness Area. The lakes and reservoirs in this segment were previously in segments 17 and 19. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 28: This segment was created to encompass the lakes and reservoirs tributary to the Alamosa River, La Jara Creek, or the Conejos River, and with the Rio Grande National Forest, and not listed in another segment. The lakes and reservoirs in this segment were previously in segment 20. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 29: This segment was created to encompass the lakes and reservoirs tributary to the Alamosa River, La Jara Creek, or the Conejos River, and not listed in another segment. The lakes and reservoirs in this segment were previously in segment 20. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Alamosa River/La Jara Creek/Conejos River segment 30: This segment was created to encompass coldwater lakes and reservoirs larger than 100 acres in surface area, and that have no brook or cutthroat trout. The reservoir in this segment was previously in segments 14. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 1: Lakes and reservoirs tributary to the Closed Basin and within the La Garita Wilderness Area were moved to a new segment 15. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 2a-c: Lakes and reservoirs tributary to La Garita Creek and Carnero Creek were moved to a new segment 16. Segment 2, which previously encompassed La Garita Creek and Carnero Creek was split into three segments to facilitate the adoption of appropriate temperature standards. Segment 2a now encompasses La Garita Creek from the source to Geronimo Creek, and the North, Middle, and South Forks of Carnero Creek from their sources to their confluence. Segment 2b encompasses La Garita Creek from Geronimo Creek to 38 Road, and all tributaries to the mainstem of Carnero Creek from its inception at the confluence of the North, Middle and South Forks of Carnero Creek to 42 Road. Segment 2c encompasses the mainstem of Carnero Creek from its inception at the confluence of the North, Middle and South Forks to 42 Road.
Closed Basin - San Luis Valley segment 3: The specific exclusions from this segment were updated to reflect changes in segmentation.
Closed Basin - San Luis Valley segment 4: Lakes and reservoirs tributary to San Luis Creek from the source to Piney Creek were moved to a new segment 16. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 6: San Luis Lake was deleted from this segment and moved to a new segment 19. This segment was moved to group lake segments together.
Closed Basin - San Luis Valley segment 7: Head Lake was deleted from this segment and moved to a new segment 20. This segment was moved to group lake segments together.
Closed Basin - San Luis Valley segment 8: Lakes and reservoirs tributary to Kerber Creek from the source to the Cocomongo Mill were moved to a new segment 16. These waters were split into different segments to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 9b: The segment description was clarified by specifying that the segment begins at a point immediately above Brewery Creek, which matches the lower boundary of segment 9a.
Closed Basin - San Luis Valley segment 11: The specific exclusions from this segment were updated to reflect changes in segmentation.
Closed Basin - San Luis Valley segment 12a-b: Lakes and reservoirs tributary to Saguache Creek from the source to Highway 285 were moved to a new segment 16. Segment 12 was split to facilitate the adoption of appropriate temperature and nutrients standards. Segment 12a encompasses Saguache Creek, including all tributaries and wetlands, from the source to Ford Creek, excluding the listings in the La Garita Wilderness Area. Segment 12b encompasses the mainstem of Saguache Creek, including all tributaries and wetlands, from Ford Creek to Highway 285. The tributaries and wetlands to Saguache Creek in segment 12a were moved to this segment from segments 11 and 3. The tributaries and wetlands to Saguache Creek in segment 12b were moved to this segment from segment 3. The tributaries from segment 3 were upgraded from Aquatic Life Warm 2 to Aquatic Life Cold 1 and have a "Reviewable" instead of Use Protected antidegradation designation. The tributaries and wetlands to the portion of Saguache Creek in segment 12a and 12b are expected to have coldwater fish species.
Closed Basin - San Luis Valley segment 13: Segments 13a and 13b were combined. The North Branch of Saguache Creek was split to segment 13b in the last basin hearing in preparation for a site-specific proposal. Since that proposal is no longer being pursued, all of Saguache Creek below Highway 285 was re-combined into segment 13.
Closed Basin - San Luis Valley segment 15: This segment was created to encompass the lakes and reservoirs within the La Garita Wilderness Area. The lakes and reservoirs in this segment were previously in segment 1. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 16: This segment was created to encompass the lakes and reservoirs tributary to portions of La Garita Creek, Carnero Creek, San Luis Creek, Kerber Creek and Saguache Creek. The lakes and reservoirs in this segment were previously in segments 2, 4, 8 and 12. This segment was created to facilitate the adoption of appropriate temperature and nutrients standards.
Closed Basin - San Luis Valley segment 17: This segment was created to encompass the lakes and reservoirs within the Rio Grande National Forest boundaries, excluding lakes and reservoirs tributary to portions of La Garita Creek, Carnero Creek, San Luis Creek, Kerber Creek, Saguache Creek, or within the La Garita Wilderness Area. The lakes and reservoirs in this segment were not previously identified by the Commission in any segment descriptions.
Closed Basin - San Luis Valley segment 18: This segment was created to encompass the lakes and reservoirs within the Closed Basin, excluding lakes and reservoirs within the Rio Grande National Forest boundaries, or tributary to portions of La Garita Creek, Carnero Creek, San Luis Creek or Saguache Creek. The lakes and reservoirs in this segment were not previously identified by the Commission in any segment descriptions.
Closed Basin - San Luis Valley segment 19: This segment was created to encompass San Luis Lake, which was previously in segment 6. This segment was created to group lake and reservoir segments together.
Closed Basin - San Luis Valley segment 20: This segment was created to encompass Head Lake, which was previously in segment 7. This segment was created to group lake and reservoir segments together.
The following segment descriptions were edited to improve clarity, improve consistency, correct typographical errors, and/or correct spelling errors:
Rio Grande segments: 1- 3, 5, 8-11, 15, 16, 18, 19, 21a, 22, 23a, 24, 25, 28 and 30
Alamosa River/La Jara Creek/Conejos River segments: 1- 3a, 3d, 4a- 7, 9, 10, 13, 14a, 15, 17a,
18, 19, 20, 21 and 22
Closed Basin - San Luis Valley segments: 1, 2a, 3, 4, 8, 9a-10, 13 and 14
The Commission reviewed information regarding the existing aquatic communities. Class 2 segments with exceptionally high MMI scores or a wide variety of fish species, were upgraded from Class 2 to Class 1.
The following segments were upgraded from Warm 2 to Warm 1.
Closed Basin - San Luis Valley segment: 3
Alamosa River/La Jara Creek/Conejos River segment: 16
The following segments were upgraded from Cold 2 to Cold 1:
Rio Grande segment: 38
Alamosa River/La Jara Creek/Conejos River segment: 15
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:
Rio Grande segment: 38
Alamosa River/La Jara Creek/Conejos River segments: 15 and 16
A fish ingestion qualifier was added to the following segment since Terrace Reservoir is now open for fishing:
Alamosa River/La Jara Creek/Conejos River segment: 8
The following segment previously had no Aquatic Life use classification, but was upgraded to Cold 2:
Rio Grande segment: 7
A portion of the following segment, which previously had no Aquatic Life use classification, was moved to Rio Grande segment 20a and upgraded to Cold 1:
Rio Grande segment: 15
The lakes and reservoirs in the following segment were not previously identified by the Commission in any segment descriptions. This segment is now classified Cold 1:
Closed Basin - San Luis Valley segment: 17
The lakes and reservoirs in the following segment were not previously identified by the Commission in any segment descriptions. This segment is now classified Warm 2:
Closed Basin - San Luis Valley segment: 18
A portion of the following segment previously had no Aquatic Life use classification, but was upgraded to Cold 1:
Rio Grande segment: 6
A Use Attainability Analysis was prepared to downgrade the following segments, or portions of these segments, from Cold 1 to Warm 1.
Rio Grande segments: 4c, 13 and 37
A Use Attainability Analysis was prepared to downgrade the following segment from Cold 1 to Cold 2.
Rio Grande segment: 20b
A Use Attainability Analysis was prepared to remove the Aquatic Life use classification for portions of the following segment, which were moved to segment 4a:
Alamosa River/La Jara Creek/Conejos River segment: 2
During the hearing, public comment was offered questioning the appropriateness of Aquatic Life use classifications for Rio Grande segments 24, 26 and 29. The Commission does not believe that removal of the Aquatic Life use classifications would be appropriate based upon the limited information received in this hearing.
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 existing use classification was inappropriate.
All segments with a Recreation N use classification were reviewed. No new information was found to support a change in classification.
The Commission added a Water Supply use classification and standards where the evidence demonstrated a reasonable potential for a hydrological connection between surface water and alluvial wells used for drinking water. The Water Supply use classification and standards were added to the following segments:
Rio Grande segments: 15 and 20b
Alamosa River/La Jara Creek/Conejos River segments: 11b and 21
A Water Supply use classification and standards were added to some lakes and reservoirs when they were split from stream segments and combined with similar lakes and reservoirs that previously had that use:
Rio Grande segment: 38
Alamosa River/La Jara Creek/Conejos River segment: 30
Closed Basin - San Luis Valley segment: 16
The following segments did not have a Water Supply use classification, but had a chromium III standard associated with that use. The acute total recoverable chromium III standard of 50 ug/l was deleted from the following segments:
Rio Grande segments: 6, 20a, 20b, 23a, 23b, 24 and 26
Alamosa River/La Jara Creek/Conejos River segments: 3a-3d, 4b, 5, 8-10 and 11a
Chromium III: 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 CrIII(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:
Rio Grande segments: 3, 16-18, 20a, 23a-24, 26 and 35
Alamosa River/La Jara Creek/Conejos River segments: 3a-3d, 4b, 5, 8-11a, 12, 16, 18, 22, 25 and 29
Closed Basin - San Luis Valley segments: 5, 8, 14, 19 and 20
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, the 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 EPA's 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 of160 ug/l was adopted for the following segments in Regulation 36 that have an Agriculture use classification and standards, and where livestock or irrigated forage are present or expected to be present.
Rio Grande segments: 1-5 and 7-38
Alamosa River/La Jara Creek/Conejos River segments: 1-3d, 4b, 5 and 7-30
Closed Basin - San Luis Valley segments: 1-5, 8-9b and 11-20
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:
Closed Basin - San Luis Valley segment: 10
Nitrate: A review of the standards associated with the Agriculture use classification showed that many segments were missing a nitrate standard to protect the use. A nitrate standard of NO3 =100, was added to the following segments with an Agriculture use and standards, but no Water Supply use, which has a more restrictive nitrate standard:
Rio Grande segments: 3, 12, 13, 16-18, 20a, 23a-24, 26 and 35
Alamosa River/La Jara Creek/Conejos River segments: 3a-3d, 4b, 5, 7, 8, 9-11a, 12, 16, 18 and 22
Closed Basin - San Luis Valley segments: 5, 8, 14, 19 and 20
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. No Aquatic Life Cold 2 segments were changed to Reviewable.
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. No Aquatic Life Warm 2 segments were changed to Reviewable.
The Use Protected designation was removed from the following segments that were upgraded from Aquatic Life Class 2 to Class 1. The following segments are now Reviewable:
Alamosa River/La Jara Creek/Conejos River segment: 16
Closed Basin - San Luis Valley segment: 3
Rio Grande segment 4a: The Commission decided to retain the "Reviewable" designation for Rio Grande segment 4a based on the exceptional recreational significance of its fishery, despite the fact that existing concentrations of chronic cadmium, lead and zinc are higher than those specified in Table III for the protection of Aquatic Life Class I (31.8(2)(b)(i)).
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:
Rio Grande segments: 20a, 21b and 23b
Alamosa River/La Jara Creek/Conejos River segments: 3a-4a, 7, 8 and 16
Closed Basin - San Luis Valley segments: 2c and 19
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 36.6(3) were modified to conform to Regulation No. 31. The footnotes to the table values in 36.6(3) were renumbered to match the appropriate references. Footnote (4 old) was deleted, and footnotes 5 through 7 were renumbered 4 through 6.
Aluminum: The following segments had old numeric TVS values that were replaced with "TVS(Trec)" to reflect the new hardness and pH based standards:
Alamosa River/La Jara Creek/Conejos River segments: 9 and 10
Seasonal TVS aluminum standards were added to the following segments:
Alamosa River/La Jara Creek/Conejos River segments: 3b-3d and 8
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, CrIII(ch)=TVS was added to following segments with Aquatic Life and Water Supply use classifications that did not previously include this standard:
Rio Grande segments: 1, 2, 4a-4c, 8-10, 19, 21a-22, 25, 28-34 and 36-38
Alamosa River/La Jara Creek/Conejos River segments: 1-2, 13-15, 17a-17b, 19, 20, 23, 24, 26-28 and 30
Closed Basin: San Luis Valley segments: 1-4, 9b-13 and 15-18
Some segments had an acute chromium III standard of 50 ug/l associated with the Water Supply use, but did not have a Water Supply use classification. The Water Supply standard was deleted and replaced with acute and/or acute and chronic chromium III TVS for the following segments:
Rio Grande segments: 6, 14, 20a, 23a, 23b, 24 and 26
Alamosa River/La Jara Creek/Conejos River segments: 3a-3d, 4b, 5, 8-11a and 22
Chromium VI standards: An extra parenthesis was removed from the chromium VI standards in the following segments:
Rio Grande segments: 2, 6, 11, 22, 25, 28, 29, 30 and 31
Alamosa River/La Jara Creek/Conejos River segments: 1, 2, 3a-3d, 8-10, 14a and 17a
Closed Basin: San Luis Valley segments: 11 and 13
At the 2010 Basic Standards rulemaking hearing, the Commission changed the 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 36.5(3)(c) to reflect the change to the basin-wide standard. A new section 36.5 was added to explain the hyphenated standard. Subsection 36.5 was deleted because it was redundant with 36.5(3)(c).
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 for one or more parameters that were not renewed:
Rio Grande segments: 4a, 4b and 4c
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. 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. Temporary Modifications were adopted or extended for the segments below.
Rio Grande segment 4a: The Commission extended the existing Temporary Modifications for chronic cadmium, lead, and zinc in segment 4a to June 30, 2015. The existing copper temporary modification was allowed to expire. The arsenic temporary modification adopted in April 2013 was left unchanged. The Temporary Modification narrative value of "existing quality" for cadmium, lead and zinc was changed to "current conditions." The Temporary Modifications meet condition B of Regulation 31.7(3)(a)(ii), since there is significant uncertainty as to whether existing quality is the result of natural or irreversible human induced conditions. Rio Grande Silver, Inc. submitted evidence of natural and human-induced sources of cadmium and zinc in segment 4a as well as potentially irreversible human induced conditions for arsenic, cadmium, lead, and zinc. Rio Grande Silver, Inc. demonstrated that Willow Creek, Rio Grande segment 7, contributes heavy metals loads to segment 4a. EPA has initiated a Remedial Investigation (RI) and Feasibility Study (FS) concerning these metal loads under CERCLA for the Nelson Tunnel/Commodore Waste Rock Pile Superfund Site. The RI identified major sources of metal loading to the Rio Grande, but did not include a detailed study of loading sources below the confluence of East and West Willow Creek. Further, as noted above, the EPA FS is investigating potential remedial actions to address major metals sources attributable to the Nelson Tunnel/Commodore Waste Rock Pile, the primary source of the metal loads in segment 4a. Rio Grande Silver submitted a Plan for Site Specific Standards Analysis for Willow Creek Segment 7 and Rio Grande Segment 4a to resolve the uncertainty with the underlying Table Value Standards to use all available data of acceptable quality from EPA and other sources to determine the extent to which water quality is the result of natural and human induced sources, and the extent to which the human included sources are reversible. The progress on resolving the uncertainty concerning the cadmium, lead, and zinc standards will be reviewed at the annual temporary modification hearing held in December 2013.
Rio Grande segment 7: The Commission adopted Type B Temporary Modifications for, acute and chronic cadmium, acute and chronic copper, acute and chronic lead, acute silver, and acute and chronic zinc with expiration dates of June 30, 2015. The Temporary Modifications are based on ambient conditions that were calculated as the 85th percentile (chronic) or 95th percentile (acute) of a dataset that had been de-biased by calculating the median of all samples taken within a 7-day period. Numeric values were calculated for three different portions of segment 7, which have very different water quality: West Willow Creek, Windy Gulch, and mainstem Willow Creek. Rio Grande Silver submitted a plan to use all available data of acceptable quality from EPA and other sources to determine the extent to which water quality is the result of natural and human induced sources, and the extent to which the human induced sources are reversible. The progress on resolving the uncertainty concerning the cadmium, copper, lead, silver and zinc standards will be reviewed at the annual Temporary Modification hearing held in December 2013. The Commission decided not to adopt a temporary modification for ammonia because there was no evidence of a water-quality based effluent-limit compliance problem.
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):
Rio Grande segments: 1-3, 5, 6, 8-11, 19, 21a, 23a, 25 and 30
Alamosa River/La Jara Creek/Conejos River segments: 1, 2, 3a-3d, 4b, 5, 7, 11a, 14a, 17a, 19 and 20
Closed Basin - San Luis Valley segments: 1, 2a, 4, 8 and 9b-12a
The following segments have a Cold Stream Tier II temperature standard (CS-II):
Rio Grande segments: 4a, 4b, 7, 14, 20b, 22, 24, 26, 28, 29 and 31
Alamosa River/La Jara Creek/Conejos River segments: 9, 10, 11b, 13, 14b, 15 and 17b
Closed Basin - San Luis Valley segments: 2b, 5 and 12b
The following segments have a Warm Stream Tier II temperature standard (WS-II):
Rio Grande segments: 4c, 12, 13, 17 and 18
Alamosa River/La Jara Creek/Conejos River segments: 12, 16 and 18
Closed Basin - San Luis Valley segments: 3, 13 and 14
The following segments have a Warm Stream Tier III temperature standard (WS-III):
Rio Grande segment: 16
Alamosa River/La Jara Creek/Conejos River segment: 22
The following segments have a Cold Lakes temperature standard (CL):
Rio Grande segments: 32-34 and 36
Alamosa River/La Jara Creek/Conejos River segments: 23-28
Closed Basin - San Luis Valley segments: 15-17
The following segments have a Large Cold Lakes (greater than 100 acres surface area) temperature standard (CLL):
Rio Grande segment: 38
Alamosa River/La Jara Creek/Conejos River segments: 8 and 30
Closed Basin - San Luis Valley segment: 20
The following segments have a Warm Lakes temperature standard (WL):
Rio Grande segments: 35 and 37
Alamosa River/La Jara Creek/Conejos River segment: 29
Closed Basin - San Luis Valley segment: 18
A temperature standard was not adopted for the following segments, which do not have an Aquatic Life use classification:
Rio Grande segment: 15
Alamosa River/La Jara Creek/Conejos River segments: 4a, 6 and 21
Closed Basin - San Luis Valley segment: 9a
The following segments have ambient-based temperature standards:
Rio Grande segments: 20a, 21b and 23b
Closed Basin - San Luis Valley segments: 2c and 19
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 the lines of evidence conflict. It is the Commission's intent that the Division and interested parties work to resolve the uncertainty for the following segments:
Rio Grande segment: 23a
Alamosa River/La Jara Creek/Conejos River segments: 9, 10 and 16
Closed Basin - San Luis Valley segment: 2a
In March 2012, the Commission adopted interim nutrient values in the Basic Standards (Regulation 31) and created a new statewide control regulation (Regulation 85) to address nutrients in Colorado. Regulation 31.17 includes interim nutrient values for total phosphorus, total nitrogen, and chlorophyll a for both lakes and reservoirs, and rivers and streams. Due to the phased implementation approach adopted with these criteria (31.17(e)), the Commission adopted only total phosphorus and chlorophyll a standards at this time. Nitrogen standards were not considered as part of this rulemaking hearing, but will be considered in the next triennial review, currently scheduled for June, 2018.
Total phosphorus and chlorophyll a standards were adopted for waters upstream of all permitted domestic wastewater treatment facilities discharging prior to May 31, 2012 or with preliminary effluent limits requested prior to May 31, 2012, and any non-domestic facilities subject to Regulation 85 effluent limits and discharging prior to May 31, 2012. A new section (4) was added at 36.5 describing implementation of the interim nutrient values into the tables at 36.6, and includes a table which lists these facilities and the segment to which they discharge.
* For segments located entirely above these facilities, nutrient standards apply to the entire segment.
* For segments with portions downstream of these facilities, nutrient standards only apply above these facilities. A footnote "C" was added to the total phosphorus and chlorophyll a standards in these segments. The footnote references the table of qualified facilities at 36.5(4).
* For segments located entirely below these facilities, nutrient standards do not apply.
For rivers and streams segments, total phosphorus standards were adopted for segments with an Aquatic Life use. Chlorophyll a standards were adopted for segments with either an E or P Recreation use classification.
The Commission decided not to adopt nutrients standards at this time for Rio Grande segment 18 and Closed Basin segment 14. These two segments consist solely of wetlands. The Commission believes that further consideration of the appropriateness of the interim nutrients values for the protection of uses in wetlands-only segments is needed, and does not intend that this decision set precedent in other basins but rather that the issue be further explored.
For lakes and reservoirs segments, a footnote "B" was added to total phosphorus and chlorophyll a standards adopted for lakes in the tables at 36.6, as these standards only apply to lakes larger than 25 acres.
31.17(e)(iii) also allows the Commission to adopt numeric nutrient standards for Direct Use Water Supply (DUWS) lakes and reservoirs. No proposals were made to adopt standards based on this provision in this rulemaking.
31.17(e)(iii) also allows the Commission to adopt numeric nutrient standards for circumstances where the provisions of Regulation 85 are not adequate to protect waters from existing or potential nutrient pollution. No proposals were made to adopt standards based on this provision in this rulemaking.
Chlorophyll a standards were adopted for the following segments:
Rio Grande segments: 1-3, 5-11, 14, 16-26 and 28-38
Alamosa River/La Jara Creek/Conejos River segments: 1-15, 17a-20 and 22-30
Closed Basin - San Luis Valley segments: 1-5 and 8-20
Total phosphorus standards were adopted for the following segments:
Rio Grande segments: 1-3, 5-11, 14, 16-26 and 28-38
Alamosa River/La Jara Creek/Conejos River segments: 1-3d, 4b-5, 7-15, 17a-20 and 22-30
Closed Basin - San Luis Valley segments: 1-5, 8 and 9b-18
Also in the March 2012 rulemaking hearing, the Commission adopted a sub-classification of the Domestic Water Supply Use called "Direct Use Water Supply Lakes and Reservoirs Sub-classification (Regulation #31, at 31.13(1)(d)(i)). This sub-classification is for water supply lakes and reservoirs where there is a plant intake location in the lake or reservoir, or a man-made conveyance from the lake or reservoir that is used regularly to provide raw-water directly to a water treatment plant that treats and disinfects raw water. The Commission did not adopt the DUWS sub-classification for any lakes in Regulation 36, because no lakes were identified with a direct water supply use.
Rio Grande segment 15: This segment did not have an Aquatic Life use classification, but had a dissolved oxygen standard of 5.0 mg/l, which is associated with that use. The dissolved oxygen standard was changed to 3.0 mg/l to protect Water Supply and Agriculture uses on this segment.
Alamosa River/La Jara Creek/Conejos River segment 8: This segment did not have a Water Supply use classification, but had chromium III, chloride, nitrate and sulfate standards associated with that use. The chromium III, chloride, and sulfate Water Supply standards were deleted from this segment. The nitrate standard was changed from 10 to 100 to protect the Agriculture use.
Alamosa River/La Jara Creek/Conejos River segment 10: An extra parenthesis was removed from the selenium standard.
Alamosa River/La Jara Creek/Conejos River segment 11a: This segment did not have a Water Supply use classification, but had a dissolved iron standard associated with that use. The dissolved iron Water Supply standard was deleted from this segment.
Alamosa River/La Jara Creek/Conejos River segment 12: The trout qualifier for the chronic silver standard was deleted since this is a warmwater segment.
Alamosa River/La Jara Creek/Conejos River segment 16: The trout qualifier for the chronic silver standard was deleted since this is a warmwater segment.
Alamosa River/La Jara Creek/Conejos River segment 18: The mercury standard of "TVS" was changed to 0.01. The trout qualifier for the chronic silver standard was deleted since this is a warmwater segment.
Alamosa River/La Jara Creek/Conejos River segment 21: The nitrate and nitrite standards were flipped. The nitrite standard was changed from 100 to 10. The nitrate standard was changed from 10 to 100.
Alamosa River/La Jara Creek/Conejos River segment 22: The trout qualifier for the acute cadmium and chronic silver standards were deleted since this is a warmwater segment.
Closed Basin - San Luis Valley segment 9a: A dissolved qualifier was added to the acute arsenic standard.
Closed Basin - San Luis Valley segment 9b: A dissolved qualifier was added to the following standards to protect the Aquatic Life use: acute arsenic, chromium VI, copper, lead, manganese, nickel, selenium, silver, and zinc.
Closed Basin - San Luis Valley segment 13: The trout qualifier for the acute cadmium and chronic silver standards were deleted since this is a warmwater segment.
Closed Basin - San Luis Valley segment 14: A parenthesis was added to the manganese standards.
Alamosa River/La Jara Creek/Conejos River segments 3a, 3b, 3c, 3d and 8:
The Commission adopted revised site-specific aluminum standards for segments in the vicinity of the Summitville Mine Superfund Site (SMSS). These standards were originally developed by the Hazardous Materials and Waste Management Division (HMWMD) based on a Use Attainability Analysis (UAA) update for the upper Alamosa River as part of the 2007 Rio Grande Basin Rulemaking.
The data and modeling results presented in the 2007 UAA update indicated that even if all reversible and irreversible human-caused aluminum sources were completely removed from the Alamosa River basin, attainment of the then applicable aluminum standards in the Alamosa River would not be achieved.
Aluminum loading from natural sources located in the Stunner, Summitville and Jasper Altered Areas results in elevated aluminum concentrations in Alamosa River Segments 3a, 3b, 3c, 3d and 8. These natural sources of aluminum have existed since well before the advent of mining in the basin and will continue to negatively impact the Alamosa River for the foreseeable future (i.e., longer than 20 years).
The HMWMD has completed the implementation of remedial actions at SMSS since 2007 and these actions have led to an increase in the HMWMD's overall ability to manage water at the SMSS. The HMWMD and other entities have collected additional water-quality data since 2007, and have located and used additional data collected before 2007.
HMWMD revised the models developed for the 2007 UAA update to reflect a larger dataset describing background conditions, and advances in water collection, storage and treatment at the SMSS. Additionally, the revised total recoverable aluminum standards were based on the 50th percentile of available data, which is the standard practice for total recoverable metals, rather than the 85th percentile which was used in 2007. The HMWMD used the models to recalculate the attainable aluminum concentrations in the Alamosa River watershed based on the inclusion of additional data collected through 2011.
Segment 3a: Segment 3a aluminum concentrations are naturally elevated and would only be slightly reduced if remediation of abandoned mines occurred. Based on data collected from 1993 through 2012, and assuming 3.6% reduction in aluminum loading from reversible anthropogenic sources, the Commission adopted revised seasonal site-specific standards for total recoverable and dissolved aluminum for segment 3a.
Segment 3b: Segment 3b aluminum concentrations are influenced by loads originating in segment 3a, loads from natural sources and abandoned mines in the Summitville Altered Area, and activities at the SMSS. The existing aluminum concentrations in segment 3b will be reduced through the future operation of the new SDI seepage capture system, the new 1,600 gpm water treatment plant, and optimized water management at the SMSS. Aluminum concentrations could be further reduced by remediation of additional abandoned mines, and this scenario was included in the calculation of the adopted site-specific standards. The Commission adopted seasonal site-specific standards for total recoverable and dissolved aluminum, and acute TVS for total recoverable aluminum in the non-snowmelt period for segment 3b. The segment 3b standards were derived from data collected from 1999 through 2011.
Segment 3c: The aluminum concentrations in segment 3c are influenced by loads from segments 3a and 3b, and from natural sources and abandoned mines in the Jasper Altered Area. The existing aluminum concentrations in segment 3c will be reduced through remedial actions at the SMSS. Aluminum concentrations could be further reduced by remediation of additional abandoned mines, and this reduction was included in the calculation of the adopted site-specific standards. The Commission adopted seasonal site-specific standards for total recoverable and dissolved aluminum, and acute TVS for total recoverable aluminum in the non-snowmelt period for segment 3c. The segment 3c standards were derived from data collected from 1999 through 2011.
Segment 3d: The aluminum concentrations in segment 3d are influenced by loads from segments 3a, 3b and 3c. The existing aluminum concentrations in segment 3d will be reduced through remedial actions at the SMSS. Aluminum concentrations could be further reduced by remediation of additional abandoned mines, and this scenario was included in the calculation of the adopted site-specific standards. The Commission adopted seasonal site-specific standards for total recoverable and dissolved aluminum, and acute TVS for total recoverable aluminum in the snowmelt period for segment 3d. The segment 3d standards were derived from data collected from 1999 through 2011.
Segment 8: The aluminum concentrations in Terrace Reservoir (segment 8) are influenced by loads from segments 3a, 3b and 3c. The existing aluminum concentrations in segment 8 will be reduced through remedial actions at the SMSS. Aluminum concentrations could be further reduced by remediation of additional abandoned mines, and this scenario was included in the calculation of the adopted site-specific standards. The Commission adopted seasonal site-specific standards for total recoverable and dissolved aluminum, and acute TVS for total recoverable aluminum for non-snowmelt in the lower portion and for snowmelt and non-snowmelt in the upper portion of Terrace Reservoir (segment 8). These standards were derived from data collected in Terrace Reservoir from 1999 through 2011.
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-36.34