Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-34 - REGULATION NO. 34 - CLASSIFICATIONS AND NUMERIC STANDARDS FOR SAN JUAN AND DOLORES RIVER BASINS
Section 5 CCR 1002-34.48 - STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JUNE 12, 2017 RULEMAKING; FINAL ACTION AUGUST, 2017; EFFECTIVE DATE DECEMBER 31, 2017
Current through Register Vol. 47, No. 5, March 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. Water Body Segmentation
Some segments were renumbered, combined, or new segments were created to facilitate appropriate organization of water bodies in this regulation. Renumbering and/or creation of new segments was made based on information that showed:
Animas Florida Segments 2 and 3a: The boundary between Segments 2 and 3a was moved upstream from Maggie Gulch to Minnie Gulch, in order to facilitate a change in use classifications and standards on this portion of the mainstem of the Animas River.
Animas Florida Segments 5b through 5d: Segment 5b was divided into Segments 5b through 5d. The proposed boundaries were developed in consultation with the Southern Ute Indian Tribe, and the resegmentation provides a framework for working toward common water quality standards on waters where there is a jurisdictional dispute.
Animas and Florida Segment 11c: All tributaries to the Florida River formerly in Segment 13c were moved to Segment 11c to improve the organization of waters in this basin.
Animas Florida Segment 13c: The unnamed tributary to Coal Gulch was moved to Segment 13c to facilitate a change in the water supply use classification and standards. All water bodies formerly included in Segment 13c were moved to the new Segment 13e, 13f or 11c to improve the organization of waters in this basin.
Animas Florida Segment 13e and 13f: Tributaries to the Animas River were moved to the new Segment 13e (above Basin Creek) and 13f (Basin Creek to New Mexico Border).The proposed boundaries were developed in consultation with the Southern Ute Indian Tribe, and the resegmentation provides a framework for working toward common water quality standards on waters where there is a jurisdictional dispute.
Dolores River Segments 5a: Beaver Creek and Plateau Creek were moved from Segment 5a to a new Segment 11c to facilitate a change in the use classifications and temperature standards.
Dolores River Segments 10a and 10b: Segment 10 was split into Segments 10a and 10b to change the temperature standards on the West Dolores River below Fish Creek from CS-I to CS-II.
Dolores River Segments 11a, 11b and 11c: Segment 11 was split into Segments 11a, 11b and 11c to facilitate changes to the aquatic life use classifications and temperature standards on tributaries to the Dolores River.
La Plata Segment 2b, 2c and 2d: The mainstem of the La Plata River from the Southern Ute Indian Reservation to the Colorado/New Mexico border was split into Segments 2b, 2c and 2d. The proposed boundaries were developed in consultation with the Southern Ute Indian Tribe, and the resegmentation provides a framework for working toward common water quality standards on waters where there is a jurisdictional dispute.
La Plata Segment 3a and 3e: East Alkali Gulch and Hay Gulch were moved from Segment 3a to Segment 3e to facilitate changes to the water supply and aquatic life use classifications and standards.
La Plata Segments 3c and 3d: East Cherry Creek moved from Segment 3c to a new Segment 3d to facilitate changing the temperature standard from CS-II to CS-I.
La Plata Segments 5, 6a, 7b, 8, 10 and 17: Segments 5, 6a, 7b, 8, 10 and 17 were revised and/or renumbered to facilitate the exclusion of water bodies inside the Ute Mountain Ute Indian Reservation. Former Segments 5b, 6b, 7b, 8b, 9, 10b, 20, 21 and 22 were deleted entirely, as these contained water bodies entirely within the Ute Mountain Ute Indian Reservation.
La Plata Segment 6b: The East Fork of Muddy Creek and East Canyon were moved to a new Segment 6b to facilitate a change in the water supply use classification and standards.
La Plata Segment 7b: A portion of the mainstem of McElmo Creek moved to a new Segment 7b to facilitate a change in the water supply use classification and standards.
Los Pinos Segments 2b, 2c and 2d and 4b: Segment 2b was split into 2b, 2c, and 2d. All of the water bodies previously included in Segment 4b were moved either to Segment 2c (Beaver Creek) or Segment 2d (Ute Creek and Spring Creek). The proposed boundaries were developed in consultation with the Southern Ute Indian Tribe, and the resegmentation provides a framework for working toward common water quality standards on waters where there is a jurisdictional dispute.
Los Pinos Segment 6: Los Pinos Segment 6 was revised to exclude Segment 4b. The Segment number was revised from 6a to 6, since the number for 6b was no longer needed.
Los Pinos Segment 7a: Los Pinos Segment 6b was changed to 7a and the segment description was revised to exclude Segments 2b, 2c and 2d.
Los Pinos Segment 7b: The segment description for Segment 7b was revised to include only Trail Canyon and its tributaries. Other tributaries formerly included in Los Pinos Segment 7b were moved to San Juan Segment 11b (direct tributaries to Navajo Reservoir), as it is a more appropriate sub-basin for the geographic location of these tributaries.
Piedra Segment 4a: A portion of Devil Creek was moved from Segment 5 to 4a to facilitate changes to the temperature standards.
Piedra Segment 4b and 4c: Segment 4b was split into Segments 4b and 4c to facilitate changes to the temperature standards.
Piedra Segment 5a and 5b: Segment 5 was split into Segments 5a and 5b to facilitate changing the temperature standard from CS-I to CS-II on some of the tributaries to the Piedra River.
Piedra Segment 6c: Stollsteimer Creek was moved from Segment 6b to 6c to facilitate a change in the temperature standards.
Piedra Segment 6d: Steven's Draw was moved from Segment 6a to a new Segment 6d to facilitate a change in the water supply use classification and standards.
San Juan Segments 5 and 6a: The segment description for Segments 5 and 6a was revised in order to facilitate changing the temperature standard on the mainstem of the San Juan River from CS-I to CS-II for the portion between the West Fork and Fourmile Creek.
San Juan Segments 6a through 6f: Segments 6a was divided into two segments, Segments 6a and 6b. The former Segment 6b was renumbered as Segment 6c, and waters from this segment were divided into four Segments 6c through 6f. These changes in segmentation were made to facilitate changes to temperature standards on the mainstem of the San Juan River below Pagosa Springs.
San Juan Segment 11c: A new Segment 11c was created to facilitate changes to the aquatic life use classifications and standards for McCabe Creek.
Segment descriptions were also edited to improve clarity, correct typographical errors, and correct spelling errors. These changes are listed in Section Q
B. Aquatic Life Use Classifications and Standards
The commission reviewed information regarding the existing aquatic communities. For segments lacking an Aquatic Life use classification, a use was added where biological information demonstrated that these waters are capable of sustaining aquatic biota. Additionally, Class 2 segments with high MMI scores or a wide variety of fish species were upgraded from Class 2 to Class 1.
The following segments were upgraded from no Aquatic Life use to Aquatic Life Cold 1:
Animas Florida segment: 2 (a portion was moved from Segment 3a, resulting in the upgrade)
The following segments were upgraded from Cold 2 to Cold 1:
Dolores River segment: 9
For segments where the existing aquatic communities are not aligned with the Aquatic Life use, the following segments were upgraded from Warm to Cold:
San Juan River segment 11c
For segments where the existing aquatic communities are not aligned with the Aquatic Life use, the following segments were downgraded from Cold to Warm:
San Juan River segment: 2
Dolores River segment: 11c
The commission reviewed all Class 2 segments that have fish that are "of a catchable size and which are normally consumed and where there is evidence that fishing takes places on a recurring basis." Water + Fish or Fish Ingestion standards were applied to the following segments:
San Juan River segment: 19
Los Pinos River segment: 6
Animas Florida River segment: 11c
La Plata River segments: 3b, 19
C. Recreation Use Classifications and Standards
The commission reviewed information regarding the current Recreation use classifications and evidence pertaining to actual or potential primary contact recreation, and no changes were adopted at this time. In addition, 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.
D. Water Supply Use Classification and Standards
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:
San Juan River segment: 11b
La Plata River segments: 3e, 7b
Los Pinos River segments: 6, 7
The commission removed the Water Supply use classification and standards where the evidence demonstrated that a Water Supply use does not currently exist due to flow or other conditions, and that such a use is not reasonably expected in the future due to water rights, source water options, or other conditions. The water supply standard for chloride was retained for these segments, given concerns regarding the protection of aquatic life by the existing Water Supply standard. The Water Supply use classification and standards, except for chloride, were removed from the following segments:
Animas Florida segment: 13c
Piedra River segment: 6d
For the segments where the Water Supply use classification and standards were removed, the commission adopted the division's proposal to retain the 250 mg/L chronic (30-day average) standards for chloride as an interim step, based on evidence presented demonstrating the toxic effects of chloride on aquatic life. Retaining the current chloride standard is necessary to protect the assigned Aquatic Life uses and to ensure that these waters are free from substances toxic to aquatic life in accordance with 31.11(1)(a)(iv). The commission retained the numeric standard for chloride because narrative standards have often proved challenging to implement, and interim numeric standards will provide implementable interim standards while allowing time for development of robust replacement criteria based on the latest scientific information.
The commission recognizes that there is scientific uncertainty about the appropriate standards for chloride and/or sulfate to protect the Aquatic Life use, and that appropriate standards may need to recognize that toxicity is affected by site water characteristics (similar to the influence of hardness on the toxicity of dissolved metals). The commission's intention is that future revisions to the numeric standards assigned to these segments, and also to Regulation No. 31 (i.e., aquatic life-based table values chloride and/or sulfate), can be considered if:
E. Agriculture Use Classification and Standards
A review of the segments with an existing Agriculture use classification showed that some segments were missing one or more standards to protect that use. The full suite of Agriculture standards was added to the following segments:
Dolores River segment: 9
The commission reviewed all segments with lacking an Agriculture use. Based on an evaluation of the available data and information, no changes were adopted at this time.
F. Other Standards to Protect Agriculture, Aquatic Life, and Water Supply Uses
In the 2015 Regulation No. 38 hearing, the commission adopted a standard of 150 µg/L, based on an improved understanding of the dietary- and water-intake rates for various life-stages of cattle. This standard is protective of all life-stages of cattle (including lactating cows and growing heifers, steers and bulls) at all times of year.
The Agriculture table value assumes that the safe copper:molybdenum ratio is 4:1. Food and water intake is based on growing heifers, steers, and bulls consuming 6.7 kg/day of dry matter and 56.8 liters of 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 = 6.7 kg/day, [Cu] water = 0.008 mg/L, water intake = 56.8 L/day, Cu supplementation = 0 mg/day, Mo supplementation = 0 mg/day.
In 2010, the commission also adopted a new standard for molybdenum to protect the Water Supply use that was calculated in accordance with Policy 96-2.
A molybdenum standard of 150 µg/L was adopted for all segments in Regulation No. 34 that have an Agriculture use classification, and where livestock or irrigated forage are present or expected to be present. The following segments do not have an Agriculture or a Water Supply use classification. No molybdenum standard was applied to these segments:
Animas Florida Segment 3b
Acute = e(0.9789*ln(hardness) - 3.866)*(1.136672-(ln (hardness)*(0.041838))
Chronic = e(0.7977*ln(hardness) - 3.909)*(1.101672-(ln (hardness)*(0.041838))
EPA's updated cadmium criteria are less stringent than Colorado's current cadmium standards when water hardness is greater than 45 mg/L CaCO3. Although the criteria are less stringent, they were developed using the latest science and are protective of aquatic life, and it is expected that Colorado's state-wide cadmium standards will likely be updated using the 2016 EPA cadmium criteria at a later date. Therefore, the commission determined it was appropriate to adopt the new criteria for waters known to be impaired for cadmium to ensure forthcoming clean-up goal development and Total Maximum Daily Load (TMDL) evaluations are based on the most relevant water quality standards available. The updated cadmium standards were adopted for the following segments:
Animas Florida segments: 3a, 3c, 4a, 4b, 6 and 9
Dolores River segment: 9
The cadmium Water Supply standard was added because the acute Aquatic Life standard is not protective when the hardness was greater than 200 mg/L in non-trout streams and 345 mg/L in trout streams; the lead Water Supply standard was added because the acute Aquatic Life standard is not protective when hardness is greater than 79 mg/L; and the nickel Water Supply standard was added because the chronic Aquatic Life standard is not protective when hardness is greater than 216 mg/L. Cadmium, lead, and nickel Water Supply standards were added to the following segments:
San Juan segments: 1a, 1b, 2, 4, 5, 6a, 6b, 6c, 6d, 6e, 6f, 7, 8, 9a, 9b, 10, 11a, 11b, 11c, 13, 15a, 15b, 16, 17
Piedra River segments: 1, 2a, 2b, 3, 4a, 4b, 4c, 5a, 5b, 6a, 6b, 6c, 7, 8, 9, 10, 11a, 11b
Los Pinos segments: 1, 2a, 2b, 2c, 2d, 3, 4, 5, 6, 7a, 8, 9, 10
Animas Florida segments: 1, 4b, 5a, 5b, 5c, 5d, 5e, 6, 9, 10a, 10b, 11a, 11b, 11c, 12a, 12b, 12c, 12d, 13a, 13b, 13e, 13f, 14a, 14b, 15, 16, 18, 21, 22, 23, 24
La Plata River segments: 1, 2a, 2b, 2c, 2d, 3b, 3c, 3d, 3e, 4a, 4b, 4c, 5, 6b, 7b, 8, 11, 12, 15
Dolores River segments: 1, 2, 3, 4a, 4b, 5a, 5b, 6, 7, 8, 10a, 10b, 11a, 11b, 11c, 12, 13, 14, 15
G. Antidegradation Designations
The commission reviewed all Warm 2 segments designated Use Protected to determine if the Use Protected designation was still warranted. Based upon available water quality data that meet the criteria of 31.8(2)b, the Use Protected designation was removed from the following segments:
Piedra River segment: 6a
La Plata River segment: 3b
H. Ambient Quality-Based Standards
Ambient quality-based standards are adopted where a comprehensive analysis has been conducted demonstrating that elevated existing water quality levels are the result of natural conditions or are infeasible to reverse, but are adequate to protect the highest attainable use. [
The commission reviewed all existing site-specific standards. Based on an evaluation of the available data and information, no changes were adopted at this time.
I. Temporary Modifications
All existing Temporary Modifications were examined to determine if they should be allowed to expire or if they should be extended, either unchanged or with changes to the numeric limits.
The commission deleted or allowed to expire on 12/31/2017 certain temporary modifications on the following segments:
Animas Florida River segment: 3b (cadmium and zinc)
The commission revised or extended Temporary Modification on the following segments:
Animas Florida Segments 3b and 4a: Temporary modifications of the copper standards were extended to 12/31/2022 on Segment 3b and adopted on Segment 4a. The Town of Silverton presented evidence that additional time is needed to resolve the uncertainty regarding the underlying copper standards. There is uncertainty regarding the degree to which existing concentrations of copper are irreversible, because the U.S. EPA Superfund Program is evaluating potential remediation projects in the watershed that may reduce loading of copper to the Animas River. There is also uncertainty regarding the degree to which the copper loading from Silverton's effluent is irreversible, and Silverton will complete an alternatives analysis to resolve this uncertainty and determine how much copper reduction is feasible. Therefore, the commission extended the expiration date of the "current conditions" temporary modifications for copper to 12/31/2022.
La Plata Segment 7a and 9: The commission extended the ammonia temporary modifications on La Plata Segment 7a and 9. There is uncertainty regarding the degree to which the ammonia loading from Lee Mobile Home Park's and Vista Verde's effluent discharges is irreversible, and these facilities will complete an alternatives analysis to resolve this uncertainty and determine how much water quality improvement is feasible. Therefore, the commission extended the expiration date of the temporary modifications for copper to 6/30/2020. The commission changed the operative value of the temporary modification from "old TVS" to "current condition" on La Plata Segment 7a to be consistent with the commission's current practice for temporary modifications. Since the "old TVS" is no longer referenced in Appendix 34-1, the old ammonia standard equations and related footnotes were deleted from 34.6.
To remain consistent with the commission's decisions regarding arsenic in section 34.41 , all existing temporary modifications for arsenic of "As(ch)=hybrid" (expiration date of 12/31/21) were retained. An arsenic temporary modification was added to the following segments, which had an existing or newly added chronic arsenic standard 0.02 µg/L and a permitted discharger with a water quality-based effluent limit compliance problem:
Los Pinos River segments: 6
J. Discharger Specific Variances
There is currently one segment in the San Juan and Dolores River Basins (Animas Florida Segment 13c) that has a discharger specific variance (DSV) for ammonia. The commission reviewed the basis for this DSV and the available information regarding progress toward achieving the highest attainable water quality. The commission determined that this DSV is still appropriate and does not require revision at this time.
K. Temperature Standards for Rivers and Streams
The commission revised temperature criteria in Regulation No. 31 in 2007, and again in 2010, based on the development of the Colorado Temperature Database and a lengthy stakeholder process. In 2012, the new temperature standards were adopted for all segments with an Aquatic Life use classification in Regulation No. 34. In June 2016, temperature criteria in Regulation No. 31 were further revised, including changes to the temperature table value standards, revision of warm water winter acute standards, and the addition of footnotes to protect lake trout and mountain whitefish.
Since temperature criteria were revised in Regulation No. 31 in 2007, the division and others have worked to ensure that appropriate temperature standards were adopted for segments throughout the state. At times, this effort to assign temperature standards has also included reevaluation of the existing Aquatic Life use classifications, and use revisions have been proposed and adopted where appropriate. Incremental progress continues as temperature standards are refined based on the experience and data gains that have occurred since initial adoption of temperature standards.
In the 2016 Regulation No. 31 hearing, the commission declined to adopt the division's proposal for statewide solutions for temperature transition zones and shoulder seasons, in favor of a basin-by-basin consideration of temperature standards on a site-specific basis. The basin-by-basin approach was selected as it allows for consideration of temperature attainability and ambient quality-based site-specific temperature standards issues in the context of multiple lines of evidence and site-specific contravening evidence. The sections below describe the considerations and methods used to develop and support the site-specific temperature standards revisions adopted in this basin hearing.
Based upon information regarding the species expected to occur, temperature data, physical habitat, land cover/use, groundwater inputs, flow conditions, and all other available information regarding thermal drivers, the commission adopted revisions of temperature standards for the segments listed below where water quality is not feasible to improve or where the thermal regime is the result of natural conditions, but is sufficient to protect the highest attainable use.
The following segments were changed from CS-I to CS-II:
San Juan River segment: 6a Piedra River segment: 5b Dolores River segment: 10b, 11b
The following segments were changed from CS-II to CS-I:
La Plata River segment: 3d
The following segments were changed from CS-II to WS-II:
San Juan River segment 2 Dolores River segment 11c
The following segments were changed from WS-II to CS-II:
La Plata River segment 3e The following segments were changed from WS-III to WS-II:
Piedra River segment: 6c
Ambient temperature standards were adopted where a use attainability analysis was conducted demonstrating that elevated ambient temperatures are the result of natural conditions or are not feasible to improve to the level required by the current numeric standard, but are adequate to protect the highest attainable use. Ambient temperature standards were adopted for the following segments:
San Juan River segments: 6b, 6c, 6d, 6e, 6f, 11c
Piedra River segments: 4a, 4b, 4c
Adequate data or resources were not always available to support a revision of the use classification or a temperature standards change. In these cases, no change was proposed. It is the commission's intent that the division and interested parties work to resolve the uncertainty. There is uncertainty regarding the appropriate use classifications and temperature standards to protect the highest attainable use still exist for the following segments:
San Juan River segments: 3, 9a and 9b
Los Pinos River segments: 2c, 2d, 4b, 7a and 11b
Animas Florida segment: 4a, 5b - 5e, 11a, 11b, 11c, 13b, 13c, 13f, 14b
La Plata River segments: 2b, 2c, and 2d
Moving forward with this site-specific approach, the commission encourages the division to consider whether any additional information would be appropriate to be included in the use attainability analyses.
L. Ambient Quality-Based Temperature Standards for Lakes
The WAT standard was found to be unattainable for a number of cold large lakes and reservoirs where evidence indicated there are healthy cold water fish populations. Because summertime temperature in the mixed layer for large lakes and reservoirs is very well correlated to the water body's elevation, the commission adopted ambient temperature standards for large lakes wherever data were available to characterize a WAT and the thermal characteristics of the lakes and reservoirs were determined to be the result of natural or irreversible man-induced conditions. Ambient temperature standards were adopted for the following lakes:
Dolores River: 4b (McPhee and Summit Lakes)
M. Nutrients
In March 2012, the commission adopted interim nutrient values in the Basic Standards (Regulation No. 31) and created a new statewide control regulation (Regulation No. 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 considered adoption of 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 2020.
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 No. 85 effluent limits and discharging prior to May 31, 2012. A new section (4) was added at 34.5 describing implementation of the interim nutrient values into the tables at 34.6, 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 note was added to the total phosphorus and chlorophyll a standards in these segments. The note references the table of qualified facilities at 34.5(5).
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.
For lakes and reservoirs segments, a note was added to total phosphorus and chlorophyll standards adopted for lakes in the tables at 34.6, as these standards only apply to lakes larger than 25 acres.
31.17(e)(ii) 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 (see section N).
31.17(e)(iii) also allows the commission to adopt numeric nutrient standards for circumstances where the provisions of Regulation No. 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:
San Juan River segments: 1a, 1b, 2, 3, 4, 5, 6a, 6b, 7, 8, 9a, 9b, 10, 11a, 11b, 11c, 12, 13, 14, 15a, 15b, 16, 17, 18a, 18b, 19
Piedra River segments: 1, 2a, 2b, 3, 4a, 5a, 5b, 6a, 6b, 6c, 6d, 8, 9, 10, 11a, 11b
Los Pinos River segments: 1, 2a, 4, 5, 6, 7a, 7b, 8, 9, 10, 11a, 11b
Animas Florida River segment: 1, 2, 3a, 3b, 3c, 6, 7, 8, 9, 10a, 10b, 11c, 12a, 12b, 12c, 12d, 13a, 13b, 13c, 13d, 13e, 13f, 14a, 14b, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
La Plata River segments: 1, 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d, 3e, 4a, 4b, 4c, 5, 6a, 6b, 6c, 7a, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19
Dolores River segments: 1, 2, 3, 4a, 4b, 5a, 5b, 6, 7, 8, 9, 10a, 10b, 11a, 11b, 11c, 12, 13, 14, 15
Total Phosphorus standards were adopted for the following segments:
San Juan River segments: 1a, 1b, 2, 3, 4, 5, 6a, 6b, 7, 8, 9a, 9b, 10, 11a, 11b, 11c, 12, 13, 14, 15a, 15b, 16, 17, 18a, 18b, 19
Piedra River segments: 1, 2a, 2b, 3, 4a, 5a, 5b, 6a, 6b, 6c, 6d, 8, 9, 10, 11a, 11b
Los Pinos River segments: 1, 2a, 4, 5, 6, 7a, 7b, 8, 9, 10, 11a, 11b
Animas Florida River segment: 1, 3a, 3c, 6, 9, 10a, 10b, 11c, 12a, 12b, 12c, 12d, 13a, 13b, 13c, 13e, 13f, 14a, 14b, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
La Plata River segments: 1, 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d, 3e, 4a, 4b, 4c, 5, 6a, 6b, 6c, 7a, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19
Dolores River segments: 1, 2, 3, 4a, 4b, 5a, 5b, 6, 7, 8, 9, 10a, 10b, 11a, 11b, 11c, 12, 13, 14, 15
N. Direct Use Water Supply Sub-classification
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" (DUWS), in Regulation No. 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 has begun to apply this sub-classification and anticipates that it will take several basin reviews to evaluate all the reservoirs in the basin. The commission adopted the DUWS sub-classification on the following reservoirs and added "DUWS" to the classification column in the standards tables. The public water systems are listed along with the reservoirs and segments.
Piedra River segment: 7 (Hatcher and Stevens Reservoirs)
Animas Florida River segment: 23 (City Reservoir #1 and Lake Durango)
La Plata River segment: 4b (Jackson Gulch Reservoir)
Dolores River segment: 4b (McPhee Reservoir)
31.17(e)(ii) also allows the commission to adopt numeric nutrient standards for DUWS lakes and reservoirs. No proposals were made to adopt standards based on this provision in this rulemaking.
O. Other/Site-Specific Revisions
The commission revised segment descriptions and/or deleted entire segments to exclude all waters within the Ute Mountain Ute Indian Tribe from Regulation No. 34:
La Plata River, Mancos River, McElmo Creek, and San Juan River in Montezuma County and Dolores County: Segments 5, 6a, 7b, 8, 10 and 17
P. Duration of nitrite standard
The commission corrected the duration of the nitrite standard from chronic to acute on all segments. When the commission adopted the new format for tables in 2016, all nitrite standards were incorrectly included in the "chronic" standards column.
Q. Typographical and Other Errors
The following edits were made to segment descriptions to improve clarity and correct typographical errors:
Los Pinos River segments: 4, 6
Animas Florida River segment: 4b, 5a, 6, 10b, 11b, 13b
La Plata River segments: 6a, 9, 14
PARTIES TO THE RULEMAKING HEARING
