Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-93 - REGULATION NO. 93 - COLORADO'S SECTION 303(D) LIST OF IMPAIRED WATERS AND MONITORING AND EVALUATION LIST
Section 5 CCR 1002-93.15 - STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; DECEMBER 2015 RULEMAKING, FINAL ACTION JANUARY 11, 2016, EFFECTIVE DATE OF MARCH 1, 2016
Current through Register Vol. 47, No. 5, March 10, 2024
The provisions of C.R.S. 25-8-202(1)(a), (b) and (i), (2) and (6); 25-8-203; 25-8-204; and 25-8-401; 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. Revisions to 303(d) List
This regulation updates Colorado's List of Water-Quality-Limited Segments Requiring Total Maximum Daily Loads (TMDLs) to reflect additional water quality information available since the Regulation was promulgated in 2006. This list was prepared to fulfill section 303(d) of the federal Clean Water Act (Act) which requires that states submit to the U.S. Environmental Protection Agency (EPA) a list of those waters for which technology-based effluent limitations and other required controls are not stringent enough to implement water quality standards.
This regulation also updates Colorado's Monitoring and Evaluation List (M&E List) to reflect additional water quality information available since the Regulation was last promulgated in 2012.
The Section 303(d) Listing Methodology - 2016 Listing Cycle ("Listing Methodology") provides the listing process, the criteria for listing, and the criteria for determination of TMDL priority. The Listing Methodology was developed through a public process and finalized as a policy at a Water Quality Control Commission (Commission) administrative action hearing in March 2015.
This Listing Methodology sets forth the criteria that generally were used to make decisions regarding which waters to include on the 2016 Section 303(d) List and the 2016 M&E List. However, this methodology was not adopted by the Commission as a rule. The Commission therefore has the flexibility to take into account other appropriate factors in making site-specific listing decisions.
To determine the final segments and parameters that would be included on the 303(d) list and M&E list, the Commission considered all existing and readily available information that relates to the segments included in the Notice of Rulemaking (published August 10, 2015).The Commission considered existing and readily available data, which includes the data used to prepare the identification processes, calculations and models referenced in 40 CFR § 130.7(a)(5)(i), (ii) and (iv), and data that was presented in a readily usable format and submitted in conformance with 40 CFR § 130.7(a)(5)(iii). In addition, the Commission accepted credible data and information that was submitted in accordance with the listing process schedule. The Division will continue to independently collect and analyze new data on a rotating basin basis as part of its triennial review efforts, and the Commission will utilize such data and information in making future listing determinations. Existing data which was not brought forward through one of these mechanisms or otherwise presented to the Commission in accordance with the schedule was not treated as "readily available" for purposes of making the 2016 listing decisions. Such information will be considered in the next listing cycle if the information is provided through a proper mechanism.
In the Division's Quality Management Plan 2011 for the Collection and Utilization of Environmental Data, the Division states that "[i]t is the expressed goal of the Division to use only those analytical data that are both reliable and have a defined level of quality."
The objective of prioritization is to identify those segments where the Division and the public should concentrate their resources. Priorities of High, Medium and Low were established according to section IV of the 2016 Section 303(d) Listing Methodology.
The Division remains committed to establishing a plan for monitoring and evaluating water bodies on the M&E List prior to the list submission date for the subsequent listing cycle. Further, the Commission has committed to determining their appropriate status (as either impaired or fully supporting) within ten years of their placement on the M&E List.
In the 2016 listing cycle, the Commission has added a list of impaired waters where a TMDL is not required. There are three primary reasons why the Commission did not require a TMDL for an impaired segment:
The 303(d) Listing Methodology was revised in 2014 for the assessment of Fish Mercury (Hg). The methods compare the weighted average fish Hg for each waterbody and species (and size class, where appropriate) to a 0.3 ppm threshold. The sample size must meet or exceed 30 fish tissue samples per waterbody/species to list new waterbodies for Fish Hg. Waterbodies can also be listed if there is overwhelming evidence of impairment (>0.45 ppm Hg) and a sample size of at least 10 fish tissue samples.
The Commission retained the following 15 lakes on the 303(d) List:
* Lower Arkansas segment 15, Trinidad Reservoir (COARLA15)
* Middle Arkansas segment 26, Horseshoe Lake (COARMA26)
* Upper Arkansas segment 40, Brush Hollow Reservoir (COARUA40)
* Lower Colorado segment 20, Rifle Gap Reservoir (COLCLC20)
* Dolores River segment 4b, McPhee Reservoir (COSJDO04b)
* La Plata segment 11, Narraguinnep Reservoir (COSJLP11)
* La Plata segment 11, Totten Reservoir (COSJLP11)
* Los Pinos segment 3, Vallecito Reservoir (COSJPN03)
* San Juan segment 8, Echo Canyon Reservoir (COSJSJ08)
* Big Thompson segment 11, Carter Lake (COSPBT11)
* Cache la Poudre segment 14, Horsetooth Reservoir (COSPCP14)
* Upper South Platte segment 17a, Berkeley Lake (COSPUS17a)
* Upper South Platte segment 17a, Rocky Mountain Lake (COSPUS17a)
* Yampa River segment 23, Catamount Reservoir (COUCYA22)
* Yampa River segment 22, Elkhead Reservoir (COUCYA23)
The Commission retained the following 3 lakes on the M&E List:
* Middle Arkansas segment 27, Teller Reservoir (COARMA27)
* San Juan segment 8, Navajo Reservoir (COSJSJ08)
* Boulder Creek segment 18, Gross Reservoir (COSPBO18)
The Commission moved the following lake from the M&E List to the 303(d) List:
* North Platte segment 9, Big Creek Reservoir (COUCNP09)
The Commission added the following lake to the M&E List:
* Upper South Platte segment 19, Cheesman Reservoir (COSPUS19)
The Commission removed the following lakes from the 303(d) List or the M&E List:
* Big Thompson segment 12, Boyd Lake (COSPBT12)
* Big Thompson segment 14, Lonetree Reservoir (COSPBT14)
* Upper Colorado segment 12, Lake Granby (COUCUC12)
In October 2010, the Commission adopted Policy 10-1, Aquatic Life Use Attainment Commission's Policy ("Policy 10-1"), which established that the Colorado multi-metric index ("MMI") is an appropriate tool for the quantitative bioassessment of the health of aquatic communities. Utilizing the Commission Policy 10-1, the Division calculated over 750 MMI scores for the 2016 listing cycle. Based on this assessment, the Commission determined that 53 new segments were not attaining, with an additional 14 new segments included on the M&E List. These segments are in addition to 23 segments that were previously included on the 2012 303(d) List, and 5 segments that were previously included on the 2012 M&E List. For 50 of these segments that are not attaining for aquatic life a specific pollutant could not be identified as the cause of non-attainment, accordingly these 50 segments were listed as provisional.
Several segments had data outside of the standard index period for data collection. The Commission included these segments on the M&E List in 2012 to allow the Division and parties to gather additional information within the standard index period. The 2016 Listing Methodology allowed additional flexibility to include additional data that was collected four weeks after the October deadline to be considered in the index period. This resulted in the Commission moving some segments from the M&E List to the 303(d) List. Any data collected outside of the standard index period was not used for the 2016 listing cycle.
The Commission added the following segments to the 303(d) List for non-attainment of their Aquatic Life Use based on Policy 10-1:
* White River segment 7 (COLCWH07)
* White River segment 23, East Douglas Creek (COLCWH23)
* Closed Basin segment 2a, North Fork Carnero Creek (CORGCB02a)
* Closed Basin segment 2b, La Garita Creek (CORGCB02b)
* Rio Grande segment 11 (CORGRG11)
* Rio Grande segment 20a (CORGRG20a)
* Big Thompson segment 2 (COSPBT02)
* Upper Gunnison segment 01, Stewart Creek (COGUUG01)
* Upper Gunnison segment 4, Taylor River (COGUUG04
The Commission provisionally added the following segments to the 303(d) List for non-attainment of their Aquatic Life Use based on Policy 10-1:
* Fountain Creek segment 3a, West Monument Creek (COARFO03a)
* Fountain Creek segment 6 (COARFO06)
* Lower Arkansas segment 6a, Apache Canyon (COARLA06a)
* San Miguel segment 12a, MaKenzie Creek (COGUSM12a)
* Upper Gunnison segment 2, Willow Creek (COGUUG02)
* Upper Gunnison segment 18b (COGUUG18b)
* Upper Gunnison segment 19, Razor Creek (COGUUG19)
* Upper Gunnison segment 26, Crystal Creek (COGUUG26)
* Closed Basin/San Luis Valley segment 9b, Kerber Creek from U S Gulch to the confluence with San Luis Creek (CORGCB09b)
* La Plata segment 5a (COSJLP05a)
* La Plata segment 6a (COSJLP06a)
* Piedra River segment 6a (COSJPI06a)
* Bear Creek segment 2 (COSPBE02)
* Boulder Creek segment 7a (COSPBO07a)
* Cache la Poudre segment 2a (COSPCP02a)
* Lower South Platte segment 2b, Kiowa Creek (COSPLS02b)
* Upper South Platte segment 3, Pine Creek, Fourmile Creek and West Creek (COSPUS03)
* Upper South Platte segment 10a, East Plum Creek (COSPUS10a)
* Upper South Platte segment 11b, Spring Creek (COSPUS11b)
* Blue River segment 1 (COUCBL01)
* Blue River segment 2b, Blue River to the confluence with Swan River (COUCBL02b)
* Blue River segment 2c (COUCBL02c)
* Blue River segment 5 (COUCBL05)
* North Platte segment 4a, Little Grizzly Creek (COUCNP04a)
* Yampa segment 12, Wolf Creek (COUCYA12)
The Commission retained the following segments on the 303(d) List for non-attainment of their Aquatic Life Use:
* White River segment 13c, Yellow Creek from Barcus Creek to the White River (COLCWH13c)
* Clear Creek segment 14b (COSPCL14b)
* Clear Creek segment 15 (COSPCL15)
* Big Thompson segment 9, Little Thompson River (COSPBT09)
The Commission retained the following segments provisionally on the 303(d) List for non-attainment of their Aquatic Life Use:
* Upper Arkansas segment 21a, Squaw Gulch to a point 1.5 miles upstream of the confluence with Fourmile Creek (COARUA21a)
* San Miguel segment 12a, Maverick Draw (COGUSM12a)
* Upper Gunnison segment 24, Cochetopa Creek from Forest Rd 43 to Tomichi Creek (COGUUG24)
* Uncompahgre segment 11, Deer Creek (COGUUN11)
* Lower Yampa/Green River segment 22a, Talamantes Creek (COLCLY22a)
* White River segment 15, Piceance Creek (COLCWH15)
* White River segment 20, Black Sulphur Creek (COLCWH20)
* Rio Grande segment 12 (CORGRG12)
* Boulder Creek segment 9, From 107th Street to the confluence with Coal Creek (COSPBO09)
* Upper South Platte segment 10a, West Plum Creek (COSPUS10a)
* Upper South Platte segment 11a, Cook Creek (COSPUS11a)
* Eagle River segment 6, Mainstem of Lake Creek from confluence with East and West Lake Creek to the mouth (COUCEA06)
* Eagle River segment 6, Red Sandstone Creek to confluence with Gore Creek (COUCEA06)
* Eagle River segment 8 (COUCEA08)
* Roaring Fork segment 3a, Roaring Fork from Hunter Creek to Trentaz Gulch (COUCRF03a)
* Roaring Fork segment 3a, West Sopris Creek (COUCRF03a)
* Roaring Fork segment 3d, Cattle Creek from Bowers Gulch (COUCRF03d)
* Roaring Fork segment 7, South Fork of Frying Pan River from diversion to unnamed tributary (COUCRF07)
* Upper Colorado segment 10a, Fraser River and Vasquez Creek (COUCUC10a)
The Commission added the following segments to the M&E List for possible non-attainment of their Aquatic Life Use:
* Upper Arkansas segment 14c, North Hardscrabble Creek (COARUA14c)
* Upper Arkansas segment 15 (COARUA15)
* Rio Grande segment 7 (CORGRG07)
* Lower Yampa/Green River segment 3i (COLCLY03i)
* La Plata/Mancos/McElmo/San Juan segment 4a (COSJLP04a)
* San Juan segment 5, Mainstem San Juan River (COSJSJ05)
* Clear Creek segment 2c (COSPCL02c)
The Commission retained the following segments on the M&E List for possible non-attainment of their Aquatic Life Use:
* Upper Arkansas segment 5, Lake Fork below Sugarloaf Dam (COARUA05)
* White River segment 13b, Duck Creek (COLCWH13b)
* Boulder Creek segment 7b (COSPBO07b)
* Clear Creek segment 1, Kearney Gulch and Grizzly Gulch (COSPCL01)
* Upper South Platte segment 2a, South Fork of South Platte below Antero Reservoir (COSPUS02a)
* Upper South Platte segment 3, Trout Creek (COSPUS03)
* Blue River segment 17 (COUCBL17)
* Eagle River segment 6, Black Gore Creek (COUCEA06)
* Eagle River segment 6, Red Sand Stone Creek from USFS Boundary to northside of I-70 frontage road (COUCEA06)
* Upper Colorado segment 3, Colorado River from Windy Gap Reservoir to Derby Creek (COUCUC03)
The Commission expanded the portion of Upper Colorado segment 3 that is on the M&E List to include the portion from the outlet of Windy Gap Reservoir to Derby Creek. Despite improving MMI scores in the upper reach, the Commission was concerned about declining taxa in the upper reach, and feels the stream would benefit from additional investigation.
The Commission removed the following segments from the 303(d) List for attainment of their Aquatic Life Use:
* Upper Arkansas segment 21a, Cripple Creek from source to above Squaw Gulch (COARUA21a)
* Upper Gunnison segment 6b, Cement Creek (COGUUG06b)
* Upper Gunnison segment 29a, Lake Fork of the Gunnison River between Cooper and Silver Creek (COGUUG29a)
* White River segment 23, West Douglas Creek (COLCWH23)
* Bear Creek segment 1a, Bear Creek (COSPBE01a)
* St. Vrain segment 3, From the confluence with Left Hand Creek to the confluence with Boulder Creek (COSPSV03)
* Roaring Fork segment 4, Mainstem Brush Creek (COUCRF04)
* Yampa River segment 15, Elkhead Creek (COUCYA15)
The Commission removed the following segments from the M&E List for attainment of the Aquatic Life Use standard:
* Fountain Creek segment 4, Sand Creek (COARFO04)
* Upper Gunnison segment 8, Slate River (COGUUG08)
* Bear Creek segment 1e, All (COSPBE01e)
* Bear Creek segment 2, Below Kipling Parkway (CO 391) (COSPBE02)
* Boulder Creek segment 10 (COSPBO10)
* Lower South Platte segment 1 (COSPLS01)
* St. Vrain segment 3, From Hover Road to the confluence of Left Hand Creek (COSPSV03)
* Upper South Platte segment 11b, Bear Creek (COSPUS11b)
* North Platte segment 4a, Grizzly Creek (COUCNP04a)
The Commission moved the following segments from the M&E List to the 303(d) List, provisionally:
* Upper South Platte segment 6a, South Platte from Cheeseman Reservoir to Lazy Gulch (COSPUS06a)
* Upper South Platte segment 01a, South Platte River from the outlet of Elevenmile Reservoir to the Idlewilde picnic area (COSPUS01a)
* Upper South Platte segment 11b, Spring Creek (COSPUS11b)
* Eagle River segment 6, Beaver Creek from Wayne Creek to mouth (COUCEA06)
* Eagle River segment 9a, Eagle River from confluence with Berry Creek to confluence with Squaw Creek (COUCEA09a)
* North Platte segment 4a, Little Grizzly Creek (COUCNP04a)
The Commission removed the provisional qualifier for the non-attainment of the Aquatic Life Use standard for the following segments:
* Upper Gunnison segment 15a, South Beaver Creek (COGUUG15a)
* Clear Creek segment 14a, Clear Creek from Croke Canal to McIntyre Street (COSPCL14a)
* Upper South Platte segment 3, Horse Creek (COSPUS03)
The Commission adopted a new approach in the 2016 Listing Methodology to evaluate impairment of the narrative sediment standard. This methodology, which is described in the Commission's Policy 98-1, Guidance for the Implementation of Colorado's Narrative Stream Standard Regulation #31, Section 31.11 , includes assessment of the macroinvertebrate population using a sediment tolerance indicator score and the percent fines as compared to a regional threshold. An impairment listing is further supported by a review of the watershed for differences of the sampling site from the range of conditions used to establish the expected condition for the sediment region, as well as the presence of likely anthropogenic sources of sediment.
The Commission added the following segments to the 303(d) List for non-attainment of the narrative sediment standard:
* White River segment 13b (COLCWH13b)
* White River segment 23, East Douglas Creek from just below Tommy's Draw to the confluence with Douglas Creek (COLCWH23)
* Closed Basin segment 12a, East Pass Creek (CORGCB12a)
The Commission added the following segments to the M&E List for potential non-attainment of the narrative sediment standard:
* Yampa River segment 13b (COUCYA13b)
* North Platte segment 4a, Sand Creek (COUCNP04a)
The Commission removed the following segment from the 303(d) List for attainment of the narrative sediment standard:
* Upper South Platte segment 3, Trout Creek and its tributaries on USFS land (COSPUS03)
The Commission removed the following segments from the M&E List for attainment of the narrative sediment standard:
* Lower Yampa segment 2 (COLCLY02)
* Upper South Platte segment 3, Sugar Creek on USFS land (COSPUS03)
* Upper South Platte segment 3, Pine Creek on USFS land (COSPUS03)
The Commission retained these segments on the 303(d) List for non-attainment of the narrative sediment standard as no new data was available:
* Lower Colorado segment 13b, Salt Creek (COLCLC13b)
* White River segment 22, West Evacuation Wash, Douglas Creek (COLCWH22)
* Eagle River segment 6, Black Gore Creek, adjacent to I-70 (COUCEA06)
* Eagle River segment 9a, Eagle River from confluence with Berry Creek to confluence with Squaw Creek (COUCEA09a)
* Yampa River segment 3, Bushy Creek (COUCYA03)
* Clear Creek segment 14b (COSPCL14b)
* Clear Creek segment 15 (COSPCL15)
The Commission retained these segments on the M&E List for non-attainment of the narrative sediment standard as no new data was available:
* Lower Arkansas segment 7 (COARLA07)
* Lower Gunnison segment 2 (COGULG02)
* Lower Gunnison segment 11b, Lunch Creek (COGULG11b)
* Uncompahgre River segment 4a (COGUUN04a)
* Uncompahgre River segment 4b (COGUUN04b)
* Uncompahgre River segment 4c (COGUUN04c)
* Uncompahgre River segment 15b, Dry Creek Watershed (COGUUN15b)
* Lower Colorado segment 1 (COLCLC01)
* Lower Colorado segment 2a (COLCLC02a)
* Lower Colorado segment 2b (COLCLC02b)
* Lower Yampa segment 16 (COLCLY16)
* Rio Grande segment 13 (CORGRG13)
* Los Pinos segment 6a, Stollsteimer Creek above Southern Ute boundary (COSJPI06a)
* Eagle River segment 9a, Eagle River from Gore Creek to confluence with Berry Creek (COUCEA09a)
The 2016 Listing Methodology requires that the party proposing a temperature listing is responsible for investigating the temperature excursions as defined in Regulation No. 31, Footnote 5c, Table 1. This footnote includes four allowable excursions to exceedances of the temperature standard. These include an air temperature excursion, a low flow excursion, an excursion for the upper portion of a lake or reservoir and a winter shoulder season excursion. For the 2016 listing cycle the Division analyzed water temperature data from more than 240 stations in more than 100 segments. In cases where the excursions were evaluated and exceedances of the temperature standards remained, the Commission included these segments on the 303(d) List. In cases where the excursions were not fully evaluated and exceedances of the temperature standards remained, the Commission included these segments on the M&E List.
The Commission added the following segments to the 303(d) List for exceedances of the temperature standards (portions are indicated where appropriate):
* Fountain Creek segment 6 (COARFO06)
* Lower Arkansas segment 3a (COARLA03a)
* Middle Arkansas segment 2 (COARMA02)
* Lower Dolores segment 2 (COGULD02)
* Upper Gunnison segment 8 (COGUUG08)
* Lower Colorado segment 1 (COLCLC01)
* White River segment 7 (COLCWH07)
* White River segment 13c, Yellow Creek below Greasewood Creek (COLCWH13c)
* White River segment 15, Piceance Creek from 3 miles above the confluence with the White River, to the confluence with the White River. (COLCWH15)
* White River segment 23 (COLCWH23)
* Rio Grande segment 4b (CORGRG04b)
* Bear Creek segment 1b (COSPBE01b)
* Bear Creek segment 1e (COSPBE01e)
* Bear Creek segment 3 (COSPBE03), Vance Creek
* Big Thompson segment 2, From Cedar Creek to Home Supply Canal (COSPBT02)
* Clear Creek segment 11 (COSPCL11)
* Clear Creek segment 13b, Mainstem of North Clear Creek (COSPCL13b)
* Clear Creek segment 14a (COSPCL14a)
* Clear Creek segment 15 (COSPCL15)
* Upper South Platte segment 3, Goose Creek (COSPUS03)
* Blue River segment 17, Blue River downstream of Green Mtn Reservoir (COUCBL17)
* Roaring Fork segment 3c (COUCRF03c)
* Upper Colorado segment 2, Colorado River from Shadow Mountain Reservoir to Granby Reservoir (COUCUC02)
* Upper Colorado segment 2, Willow Creek, Stillwater Creek and Arapaho Creek (COUCUC02)
* Upper Colorado segment 7a, mainstem of Muddy Creek (COUCUC07a)
* Yampa River segment 2a, Yampa River below Stagecoach Reservoir (COUCYA02a)
* Yampa River segment 2b (COUCYA02b)
The Commission added the following segments to the M&E List for exceedances of the temperature standards (where portions are not indicated the entire segment was listed):
* Lower Arkansas segment 5b (COARLA05b)
* Lower Arkansas segment 6a, Reilly Canyon and Sarcillo Canyon(COARLA06a)
* Lower Arkansas segment 6b (COARLA06b)
* Middle Arkansas segment 7b (COARMA07b)
* Upper Arkansas segment 4a (COARUA04a)
* Lower Gunnison segment 8 (COGULG08)
* Closed Basin segment 12a (CORGCB12a)
* San Miguel segment 10, Naturita Creek (COGUSM10)
* San Miguel segment 12b (COGUSM12b)
* Lower Colorado segment 4a (COLCLC04a)
* Alamosa River segment 11b (CORGAL11b)
* Los Pinos River segment 4a, East Mancos River (COSJLP04a)
* Piedra River segment 5 (COSJPI05)
* San Juan River segment 6a (COSJSJ06a)
* San Juan River segment 10 (COSJSJ10)
* Bear Creek segment 6a, Turkey Creek below Parmelee Gulch (COSPBE06a)
* Bear Creek segment 6b (COSPBE06b)
* Clear Creek segment 14b (COSPCL14b)
* Clear Creek segment 17b (COSPCL17b)
* Upper South Platte segment 3, Trout Creek and tributaries on USFS property (COSPUS03)
* Upper South Platte segment 10a, Plum Creek (COSPUS10a)
* Upper South Platte segment 15 (COSPUS15)
* Upper South Platte segment 16g (COSPUS16g)
* Yampa River segment 13e (COUCYA13e)
The Commission retained the following segments on the 303(d) List for exceedances of the temperature standards:
* Bear Creek segment 1a, Bear Creek below the confluence with Yankee Creek (COSPBE01a)
* Cache la Poudre segment 10a (COSPCP10a)
* Saint Vrain segment 2b (COSPSV02b)
* Upper Colorado segment 3, From 578 Road Bridge (COUCUC03)
* Upper Colorado segment 7b, Muddy Creek and tributaries (COUCUC07b)
* Upper Colorado segment 10a, Ranch Creek (COUCUC10a)
The Commission retained the following segment on the M&E List for exceedances of the temperature standards:
* Upper South Platte segment 2a, Twin Creek, on USFS Land (COSPUS02a)
The Commission delisted the following segments from the 303(d) List or the M&E List for exceedances of the temperature standards:
* Bear Creek segment 1e, Bear Creek from the outlet of Evergreen Lake to Kerr/Swede Gulch (COSPBE01e)
* Upper South Platte segment 2a, Salt Creek (COSPUS02a)
* Eagle River segment 9a, Eagle River from Berry Creek to confluence with Ute Creek (COUCEA09a)
* Eagle River segment 9a, Eagle River from Ute Creek to confluence with Rube Creek (COUCEA09a)
* Upper Colorado segment 10c (COUCUC10c)
* Yampa River segment 2c (COUCYA02c)
* Bear Creek segment 1a, Bear Creek from Witter Gulch to Evergreen Lake (COSPBE01a)
The Commission moved the following segment from the 303(d) List to the M&E List for exceedances of the temperature standards:
* Big Thompson segment 8 (COSPBT08)
For the secondary water supply standards of dissolved iron, manganese and sulfate, the less restrictive of the following two options apply as the numeric standard: existing quality as of January 1, 2000 or the table value criteria in Regulation No. 31, Tables II and III. For dissolved iron, the table value standard (TVS) is 300 ug/l. For dissolved manganese, the TVS is 50 ug/l. For sulfate, the TVS is 250 mg/l.
In the 2016 303(d) Listing Methodology, the Commission included additional language regarding the determination of existing quality from the year 2000. This included a minimum data requirement of ten data points, and the ability to use data collected after the year 2000 when characterizing existing quality from 2000. However, pursuant to section 31.11 of Regulation 31, the use of data collected after 2000 may only be used upon a showing that there are no new or increased sources of these pollutants in the segment being assessed since 2000.
Some issues were raised regarding whether the data should be assessed station by station when comparing concentrations from 2000 to current conditions or can data be aggregated for the entire segment (or a portion of the segment). The Commission determined that unless a good reason was presented to assess station to station, data should be combined and assessed to characterize water quality as of 2000 and current conditions for manganese, dissolved iron and sulfate.
In the following segments, the TVS was less restrictive than water quality as of the year 2000. Therefore, the TVS was used as the standard for these listing decisions. The Commission added the following segments to the 303(d) List:
* Middle Arkansas segment 2, mainstem of the Arkansas River from Pueblo Reservoir to Blue Ribbon Creek: manganese (COARMA02)
* Lower Yampa/Green River segment 3c, Wilson Creek: sulfate (COLCLY03c)
* Boulder Creek segment 2a, Como Creek to the confluence of North Boulder Creek: dissolved iron (COSPBO02a)
* Big Thompson segment 8, From source to St Vrain Supply Canal: sulfate (COSPBT08)
* Cache la Poudre segment 7: manganese (COSPCP07)
* Cache la Poudre segment 13a, Dry Creek: manganese and sulfate (COSPCP13a)
* Middle South Platte segment 1b: manganese (COSPMS01b)
* Upper Colorado segment 7a, Alkali Slough: sulfate (COUCUC07a)
In the following segments, the existing quality as of 2000 was greater (less restrictive) than the TVS. Therefore, the water quality representative of 2000 was used as the standard for these listing decisions. The Commission added the following segments to the 303(d) List:
* Fountain Creek segment 1a, Mainstem: manganese (COARFO01a)
* Lower Arkansas segment 1b: manganese (COARLA01b)
* Lower Arkansas segment 1c: manganese (COARLA01c)
* Lower Arkansas segment 4a: sulfate (COARLA04a)
* Middle Arkansas segment 6b: manganese and sulfate (COARMA06b)
* Lower Colorado segment 14c: manganese (COLCLC14c)
* Lower Yampa segment 3c, Stinking Gulch: sulfate (COLCLY03c)
* Clear Creek segment 2c, Turkey Gulch below Rockford Tunnel: manganese and dissolved iron (COSPCL02c)
* Upper South Platte segment 3, Trout Creek and tributaries on USFS property: manganese (COSPUS03)
* Upper South Platte segment 5b, Geneva Creek: manganese (COSPUS05b)
* Blue River segment 06a: manganese (COUCBL06a)
* Eagle River segment 5c: dissolved iron (COUCEA05c)
* North Platte segment 4a, Snyder Creek: manganese and dissolved iron (COUCNP04a)
* Upper Colorado segment 10c, below Fraser Canyon: dissolved iron (COUCUC10c)
In the following segments, the TVS was less restrictive than water quality as of the year 2000. Therefore, the TVS was used as the standard for these listing decisions. The Commission added the following segments to the M&E List:
* Middle Arkansas segment 6a: manganese (COARMA06a)
* Upper Arkansas segment 38, Skagway Reservoir: dissolved iron (COARUA38)
* Upper Gunnison segment 29a, Lake Fork of the Gunnison upstream of Cottonwood Creek: manganese (COGUUG29a)
* Lower Colorado segment 4a: sulfate (COLCLC04a)
* Lower Yampa/Green River segment 3c, Wilson Creek: manganese (COLCLY03c)
* Lower Yampa/Green River segment 6: sulfate (COLCLY06)
* Lower White segment 9b: manganese (COLCWH09b)
* Lower White segment 13b, Corral Gulch: manganese (COLCWH13b)
* Alamosa River segment 20: dissolved iron (CORGAL20)
* Closed Basin segment 12a, Ford Creek: manganese (CORGCB12a)
* Rio Grande segment 2, South Clear Creek: dissolved iron (CORGRG02)
* Rio Grande segment 38, Big Meadows Reservoir: dissolved iron and manganese (CORGRG38)
* Rio Grande segment 38, Road Canyon Reservoir: dissolved iron (CORGRG38)
* Boulder Creek segment 2a, North Boulder Creek from Caribou Creek to the confluence with Como Creek: dissolved iron (COSPBO02a)
* Big Thompson segment 7, Buckhorn Creek: manganese (COSPBT07)
* Boulder Creek segment 2a, from the outlet of Barker Reservoir to Longitude: 105.475577°Latitude: 39.971275°: manganese (COSPBO02a)
* Cherry Creek segment 1: manganese (COSPCH01)
* Clear Creek segment 3b, Leavenworth Creek: manganese (COSPCL03b)
* Clear Creek segment 6, North Empire Creek: sulfate (COSPCL06)
* Clear Creek segment 12a, Gilson Gulch and tributaries: dissolved iron, manganese, and sulfate (COSPCL12a)
* Cache la Poudre segment 7: dissolved iron (COSPCP07)
* Laramie River segment 2a: manganese (COSPLA02a)
* St. Vrain segment 4a, (Hwy 72 to James Creek): manganese (COSPSV04a)
* North Platte segment 3: dissolved iron (COUCNP03)
* Yampa River segment 18, South Fork Little Snake River: dissolved iron (COUCYA18)
In the following segments, the existing quality as of 2000 was greater (less restrictive) than the TVS. Therefore, the water quality representative of 2000 was used as the standard for these listing decisions. The Commission added the following segments to the M&E List:
* Lower Arkansas segment 2a: manganese and sulfate (COARLA02a)
* Middle Arkansas segment 6b: sulfate (COARMA06b)
* Upper Arkansas segment 5, Lake Fork below Sugarloaf Dam to the confluence with the Arkansas River and Colorado Gulch: manganese (COARUA05)
* Upper Arkansas segment 38, Skagway Reservoir: manganese (COARUA38)
* Lower Colorado segment 2b, Humphrey Backwater area: manganese and sulfate (COLCLC02b)
* Lower Yampa/Green River segment 3e: sulfate (COLCLY03e)
* Lower Yampa/Green River segment 6: manganese (COLCLY06)
* White River segment 13b, Stake Springs: sulfate (COLCWH13b)
* Alamosa River segment 2: dissolved iron and manganese (CORGAL02)
* Closed Basin segment 9a, Squirrel Creek: manganese (CORGCB09a)
* Rio Grande segment 4c: manganese (CORGRG04c)
* Clear Creek segment 6, North Empire Creek: dissolved iron (COSPCL06)
* Lower South Platte segment 1: sulfate (COSPLS01)
* Middle South Platte segment 1a: manganese (COSPMS01a)
* Blue River segment 12: manganese (COUCBL12)
* North Platte segment 4a, Canadian River: manganese (COUCNP04a)
* North Platte segment 4a, Illinois River: dissolved iron (COUCNP04a)
* North Platte segment 4b, Illinois River: manganese (COUCNP04b)
* North Platte segment 5b: dissolved iron and manganese (COUCNP05b)
In the following segments, there was not enough data available to characterize the water quality representative of the year 2000. Until additional information can be gathered to make a determination on the water quality as a 2000, the Commission added the following segments to the M&E List:
* Middle Arkansas segment 6a: sulfate (COARMA06a)
* Middle Arkansas segment 9: manganese (COARMA09)
* Middle Arkansas segment 11b: manganese (COARMA11b)
* Closed Basin segment 2a, North Fork Carnero Creek: manganese (CORGCB02a)
* Closed Basin segment 2a, South Fork Carnero Creek: dissolved iron and manganese (CORGCB02a)
* Closed Basin segment 2b, La Garita Creek: dissolved iron and manganese (CORGCB02b)
* Closed Basin segment 2c: manganese (CORGCB02c)
* Clear Creek segment 14b: dissolved iron (COSPCL14b)
* Boulder Creek segment 14, Barker Reservoir: dissolved iron, manganese (COSPBO14)
* Blue River segment 20, Spruce Creek: dissolved iron (COUCBL20)
* Upper Colorado segment 7a, Alkali Slough: manganese (COUCUC07a)
* Yampa River segment 3, Little Morrison Creek: manganese (COUCYA03)
For the following segments, existing 303(d) and M&E listings for exceedances of the secondary water supply standards were retained:
* Coal Creek segment 11: manganese (COGUUG11)
* Clear Creek segment 14b: manganese (COSPCL14b)
* Lower South Platte segment 1: manganese (COSPLS01)
* St. Vrain segment 5, Left Hand Creek below US 36 to a point above the Lefthand Feeder Canal: manganese (COSPSV05)
* North Platte segment 4a, Canadian River: dissolved iron (COUCNP04a)
* Yampa segment 2a, Yampa River below Stagecoach: manganese (COUCYA02a)
The 2016 303(d) Listing Methodology was modified to reflect changes in Regulation #31 for the assessment of arsenic, nitrite and nitrate. Previously, the assessment of arsenic, nitrite and nitrate water supply standards was solely conducted at the point of intake for a water supply. This provision was removed in the Regulation #31, resulting in the assessment of these standards throughout the entire segment.
Based on comments received from parties regarding the arsenic listings the Commission reiterates the following Commission decisions. The source of a pollutant is not considered during the listing analysis, and the Commission recommends that parties who believe that impairments are the result of high background levels of arsenic consider site-specific regulatory changes, such as site-specific standards or removal of a classified use through a use attainability analysis. Attainment is assessed against the underlying standard, not against a temporary modification. Data for dissolved arsenic may be used in determining attainment of total arsenic.
For arsenic listings the Commission determined that the Division may use "j data" in its assessment. "J data" is an analytical result that falls between the method detection limit ("MDL") and the minimum level ("ML"). The arsenic water supply standard (0.02µg/L) is below the MDL for arsenic (with the lowest MDL in data assessed for this rulemaking hearing at 0.022 µg/L). J data may be used in assessing arsenic because a j data result means that the lab is 99% certain arsenic is present in the sample at a level higher than the MDL, which is higher than the standard for arsenic.
The Commission added the following segments to the 303(d) List for exceedances of the arsenic standard:
* Fountain Creek segment 1a, Mainstem (COARFO01a)
* Lower Arkansas segment 1b (COARLA01b)
* Lower Arkansas segment 1c (COARLA01c)
* Lower Arkansas segment 5a (COARLA05a)
* Lower Arkansas segment 5b (COARLA05b)
* Lower Arkansas segment 9a (COARLA09a)
* Middle Arkansas segment 3 (COARMA03)
* Middle Arkansas segment 9 (COARMA09)
* Upper Arkansas segment 2c (COARUA02c)
* Upper Arkansas segment 05, Colorado Gulch (COARUA05)
* Upper Arkansas segment 15 (COARUA15)
* North Fork of the Gunnison segment 4, Ruby Anthracite Creek (COGUNF04)
* Upper Gunnison segment 12, Coal Creek (COGUUG12)
* Lower Colorado segment 1, Colorado River from Roaring Fork confluence to confluence with Paradise Creek (COLCLC01)
* Lower Colorado segment 4c (COLCLC04c)
* Lower Colorado segment 10 (COLCLC10)
* Lower Colorado segment 15a (COLCLC15a)
* Lower Colorado segment 15c (COLCLC15c)
* Lower Yampa segment 3c, Stinking Gulch (COLCLY03c)
* White River segment 7, White River below Meeker (COLCWH07)
* White River segment 12 (COLCWH12)
* White River segment 14a, Piceance Creek (COLCWH14a)
* White River segment 20, Black Sulphur Creek (COLCWH20)
* White River segment 21 (COLCWH21)
* Closed Basin segment 2a, North Fork Carnero Creek and South Fork Carnero Creek (CORGCB02a)
* Closed Basin segment 2b, La Garita Creek (CORGCB02b)
* Closed Basin segment 2c (CORGCB02c)
* Closed Basin segment 4 (CORGCB04)
* Closed Basin segment 9b (CORGCB09b)
* Closed Basin segment 12a (CORGCB12a)
* Rio Grande segment 4b, South Fork Rio Grande to Del Norte (CORGRG04b)
* Rio Grande segment 4c (CORGRG04c)
* Rio Grande segment 09, North Branch of Pass Creek (CORGRG09)
* Rio Grande segment 11 (CORGRG11)
* Rio Grande segment 19 (CORGRG19)
* Bear Creek segment 2 (COSPBE02)
* Boulder Creek segment 2a (COSPBO02a)
* Boulder Creek segment 2b (COSPBO02b)
* Boulder Creek segment 3 (COSPBO03)
* Boulder Creek segment 4b (COSPBO04b)
* Boulder Creek segment 9 (COSPBO09)
* Boulder Creek segment 10 (COSPBO10)
* Boulder Creek segment 14, Barker Reservoir (COSPBO14)
* Big Thompson segment 1 (COSPBT01)
* Big Thompson segment 2 (COSPBT02)
* Big Thompson segment 3 (COSPBT03)
* Big Thompson segment 7, Buckhorn Creek and North Fork of Big Thompson (COSPBT07)
* Big Thompson segment 8 (COSPBT08)
* Cache la Poudre segment 2a (COSPCP02a)
* Cache la Poudre segment 6 (COSPCP06)
* Cache la Poudre segment 9 (COSPCP09)
* Cache la Poudre segment 10a (COSPCP10a)
* Cache la Poudre segment 10b (COSPCP10b)
* Middle South Platte segment 1b (COSPMS01b)
* Republican Basin segment 1 (COSPRE01)
* St. Vrain segment 2b (COSPSV02b)
* Saint Vrain segment 7, Boulder Reservoir (COSPSV07)
* Upper South Platte segment 2c, South Mosquito Creek (COSPUS02c)
* Upper South Platte segment 10a, East Plum Creek (COSPUS10a)
* Blue River segment 2c (COUCBL02c)
* Blue River segment 4a, Gold Run Gulch below Jessie Mine (COUCBL04a)
* Blue River segment 20, Spruce Creek (COUCBL20)
* Eagle River segment 2 (COUCEA02)
* Eagle River segment 5c (COUCEA05c)
* Eagle River segment 6 (COUCEA06)
* Eagle River segment 9a (COUCEA09a)
* Eagle River segment 9c (COUCEA09c)
* North Platte segment 1, South Fork Big Creek (COUCNP01)
* North Platte segment 4a, Illinois River, South Fork Big Creek and Snyder Creek (COUCNP04a)
* North Platte segment 4b, Illinois River (COUCNP04b)
* North Platte segment 5b (COUCNP05b)
* North Platte segment 09, Lake John and North Delaney Lake (COUCNP09)
* Upper Colorado segment 7a, Muddy Creek (COUCUC07a)
* Upper Colorado segment 7b, Muddy Creek (COUCUC07b)
* Upper Colorado segment 10c (COUCUC10c)
* Upper Colorado segment 12, Shadow Mountain Reservoir (COUCUC12)
* Yampa River segment 2a, Yampa River above Stagecoach Reservoir (COUCYA02a)
* Yampa River segment 2b (COUCYA02b)
* Yampa River segment 3, Little Morrison Creek and Gunn Creek (COUCYA03)
* Yampa River segment 15, Elkhead Creek (COUCYA15)
The Commission added the following segments to the M&E List for potential non- attainment of the arsenic standard:
* Middle Arkansas segment 11b (C)OARMA11b)
* Lower Arkansas segment 10, Adobe Creek Reservoir (COARLA10)
* Upper Arkansas segment 35 (COARUA35)
* Upper Arkansas segment 38, Skagway Reservoir (COARUA38)
* Lower Dolores segment 5, Mesa Creek and tributaries (COGULD05)
* Lower Colorado segment 2b, Humphrey Backwater area (COLCLC02b)
* Lower Colorado segment 14c (COLCLC14c)
* Lower Colorado segment 20, Rifle Gap Reservoir (COLCLC20)
* Bear Creek segment 11, Harriman Reservoir (COSPBE11)
* Cache la Poudre segment 7 (COSPCP07)
* Laramie segment 2a (COSPLA02a)
* Laramie segment 2b (COSPLA02b)
* Alamosa River segment 20 (CORGAL20)
* Rio Grande segment 37 (CORGRG37)
* Upper South Platte segment 12, Jackson Creek (COSPUS12)
* Blue River segment 12 (COUCBL12)
* Eagle River segment 9b (COUSEA09b)
* North Platte segment 4a, Grizzly Creek and Little Grizzly Creek (COUSNP04a)
* Upper Colorado segment 3, Lake Granby to Gore Canyon (COUCUC03)
* Upper Colorado segment 12, Willow Creek Reservoir (COUCUC12)
* Yampa River segment 18, South Fork of the Little Snake River (COUCYA18)
* Upper Gunnison segment 29a, Lake Fork of the Gunnison River Upstream of Cotonwood Creek (COGUUG29a)
* Yampa River segment 8, Lost Dog Creek (COUCYA08)
The Commission retained the following segments on the 303(d) List for exceedances of the arsenic standard:
* Upper Gunnison segment 09, Coal Creek (COGUUG09)
* Upper Gunnison segment 11, Elk Creek (COGUUG11)
* Upper Gunnison segment 11, Coal Creek (COGUUG11)
* Big Thompson segment 11 (COSPBT11)
* Cache la Poudre segment 14 (COSPCP14)
* Upper South Platte segment 3, Fourmile Creek (COSPUS03)
* Upper South Platte segment 3, Pine Creek (COSPUS03)
* Upper South Platte segment 14 (COSPUS14)
* Upper South Platte segment 17a, Berkeley Lake (COSPUS17a)
The Commission retained the following segment on the M&E List for exceedances of the arsenic standard:
* Upper South Platte segment 03, West Creek (COSPUS03)
The Commission retained the following segment on the M&E List for exceedances of the nitrite standard:
* Middle Arkansas segment 4a (COARMA04a)
The Commission added the following segment to the M&E List for exceedances of the nitrite standard:
* Lower Colorado segment 2b, Humphrey Backwater Area (COLCLC02b)
The Commission delisted the following segments as they are attaining the arsenic standard:
* Upper Arkansas segment 20, North Fork Wilson Creek below Independence Mine (COARUA20)
* Saint Vrain segment 4c (COSPSV04c)
In May 2012, the Commission adopted nutrient control management regulations, as detailed in Regulation 85 and Regulation 31. Interim total nitrogen and total phosphorus values were included in Regulation 31, and as the Commission revises basin regulations, the interim value for total phosphorus is adopted as a numeric standard in waters upstream of domestic wastewater treatment facilities. A list of such dischargers has been included in each of the basin regulations. At the time of this hearing, the total phosphorus standard has been adopted in the upstream waters of the following basins: Upper Colorado, Lower Colorado, Arkansas, and Rio Grande.
For the 2016 303(d) Listing Methodology, the Commission outlined the assessment methodology for numeric nutrient standards. The ambient annual median is assessed against the numeric standard, with an allowable exceedance frequency of one in five years. If the annual median nutrient concentration exceeds the standard but fewer than five samples are available for a specific year, the segment should be included on the M&E until additional data can be collected.
The following segments have been included on the M&E list for exceeding the numeric total phosphorus standard but not meeting sample size requirements.
* Lower Colorado segment 4a (COLCLC04a)
* Closed Basin segment 2a, North Fork Carnero Creek (CORGCB02a)
* Closed Basin segment 2a, South Fork Carnero Creek (CORGCB02a)
* Closed Basin segment 2b, La Garita Creek (CORGCB02b)
* Closed Basin segment 2c (CORGCB02c)
* Closed Basin segment 12a (CORGCB12a)
* Rio Grande segment 11 (CORGRG11)
* Rio Grande segment 19 (CORGRG19)
* Rio Grande segment 20a (CORGRG20a)
* Rio Grande segment 20b (CORGRG20b)
The Division submitted 11 TMDLs to EPA since the approval of the 2012 303(d) List that have been approved. The Commission has removed the following segments from the 303(d) List:
* Upper Arkansas segment 8b, Iowa Gulch: cadmium, lead, and zinc (COARUA08b)
* Lower Gunnison segment 9, Fruitgrowers Reservoir: dissolved oxygen (COGULG09)
* Alamosa segment 8, Terrace Reservoir: total recoverable iron (CORGAL08)
* La Plata segment 4a, East Mancos: copper and manganese (COSJLP04a)
* Middle South Platte segment 4, Barr Lake and Milton reservoir: pH and DO (COSPMS04)
* Saint Vrain segment 4a, Left Hand Creek from Hwy 72 to James Creek: copper, zinc, and pH (COSPSV04a)
* Saint Vrain segment 4b: copper and lead (COSPSV04b)
* Saint Vrain segment 4c: copper (COSPSV04c)
As additional water quality data is collected and assessed, new data may show attainment of the standards. The Commission removed the following segments and parameters from the 303(d) List due to attainment of current water quality standards:
* Fountain Creek segment 7a, Willow Springs Ponds #1 & #2: Aquatic life use (tetrachloroethylene fish tissue) (COARFO07a)
* Lower Arkansas segment 1a: selenium, sulfate (COARLA01a)
* Lower Arkansas segment 4a, Timpas Creek: total recoverable iron (COARLA04a)
* Lower Arkansas segment 7: selenium (COARLA07)
* Lower Arkansas segment 9b, Chicosa Creek: total recoverable iron, selenium (COARLA09b)
* Middle Arkansas segment 6a: selenium (COARMA06a)
* Middle Arkansas segment 14: selenium (COARMA14)
* Upper Arkansas segment 20, Wilson Creek below Independence Mine: arsenic (COARUA20)
* Upper Arkansas segment 40: dissolved oxygen (COARUA40)
* Lower Gunnison segment 9: dissolved oxygen (COGULG09)
* Upper Gunnison segment 29a, Lake Fork between Cooper and Silver Creeks: aquatic life (provisional) (COGUUG29a)
* Lower Colorado segment 10: selenium (COLCLC10)
* Lower Colorado segment 13b, Adobe Creek, Leach Creek: total recoverable iron (COLCLC13b)
* Lower Yampa segment 2: total recoverable iron (COLCLY02)
* Lower Yampa segment 5: selenium (COLCLY05)
* White River segment 14a, Willow Creek to Hunter Creek: total recoverable iron (COLCWH14a)
* Alamosa segment 3b, Alamosa River above Jasper Creek: cadmium (CORGAL03b)
* Alamosa segment 8, Terrace Reservoir: total recoverable iron (CORGAL08)
* Rio Grande segment 7, Nelson Creek, West Willow Creek below Nelson Creek to East Willow Creek: pH (CORGRG07)
* Rio Grande segment 37: dissolved oxygen (CORGRGR37)
* Big Dry segment 1: selenium (COSPBD01)
* Bear Creek segment 2, below Kipling Parkway: E. coli (COSPBE02)
* Bear Creek segment 5, Swede/Kerr Gulch: E. coli (COSPBE05)
* Big Thompson segment 2: cadmium, zinc, copper (from downstream of the UTSD discharge) (COSPBT02)
* Big Thompson segment 8: dissolved oxygen (COSPBT08)
* Big Thompson segment 9: copper (COSPBT09)
* Big Thompson segment 10, Big Hollow: selenium (COSPBT10)
* Cherry Creek segment 3: selenium (COSPCH03)
* Cherry Creek segment 3, Cherry Creek from Holly Street to the South Platte River: total recoverable iron (COSPCH03)
* Clear Creek segment 2b: cadmium (COSPCL02b)
* Clear Creek segment 6, Mad Creek: zinc (COSPCL06)
* Clear Creek segment 15: manganese (COSPCL15)
* Cache la Poudre segment 8: arsenic (COSPCP08)
* Cache la Poudre segment 10a: copper (COSPCP10a)
* Cache la Poudre segment 11: selenium (COSPCP11)
* Cache la Poudre segment 12: selenium (COSPCP12)
* Cache la Poudre segment 13a: selenium (COSPCP13a)
* Cache la Poudre segment 14: copper (COSPCP14)
* Middle South Platte segment 1b: selenium (COSPMS01b)
* Middle South Platte segment 7, Prospect Lake: dissolved oxygen (COSPMS07)
* Republican River segment 4: E.coli (COSPRE04)
* St. Vrain segment 2a: zinc (COSPSV02a)
* St. Vrain segment 2b: copper (COSPSV02b)
* St. Vrain segment 6: selenium (COSPSV06)
* Upper South Platte segment 17a, Duck Lake: dissolved oxygen (COSPUS17a)
* Upper South Platte segment 17b, Sloan's Lake: dissolved oxygen (COSPUS17b)
* Upper South Platte segment 23, Garfield and Huston Lakes: dissolved oxygen (COSPUS23)
* North Platte segment 4b, Illinois River: total recoverable iron (COUCNP04b)
* North Platte segment 9, Lake John: dissolved oxygen (COUCNP09)
* Upper Colorado segment 3, from 578 Rd Bridge to Blue River: manganese (COUCUC03)
* Yampa River segment 13d, Below Seneca sample location 8 (WSD5): selenium (COUCYA13d)
The Commission removed the following segments and parameters from the M&E List due to attainment of current water quality standards:
* Middle Arkansas segment 6a: uranium (COARMA06a)
* Middle Arkansas segment 6b: uranium (COARMA06b)
* Middle Arkansas segment 7b: copper, zinc (COARMA07b)
* Middle Arkansas segment 9: selenium (COARMA09)
* San Miguel segment 12a, Calamity Draw: dissolved oxygen (COGUSM12a)
* Lower Colorado segment 4a, Alkali Creek: E. coli, copper, total recoverable iron, lead, zinc (COLCLC04a)
* Lower Colorado segment 4c: copper and selenium (COLCLC04c)
* Lower Colorado segment 13b, Indian Wash: total recoverable iron (COLCLC13b)
* Lower Colorado segment 15a, Plateau Creek: selenium (COLCLC15a)
* Lower Yampa segment 3c, Stinking Gulch: copper, zinc (COLCLY03c)
* Lower Yampa segment 3c, Wilson Creek: selenium (COLCLY03c)
* Lower Yampa segment 18: E .coli, total recoverable iron, selenium (COLCLY18)
* White River segment 7, White River below Meeker: copper (COLCWH07)
* White River segment 9a, Strawberry Creek: copper, zinc (COLCWH09a)
* White River segment 23, East Douglas Creek: total recoverable iron (COLCWH23)
* White River segment 10b, Coal Creek below Ninemile Gulch: selenium (COLCWH10b)
* Closed Basin segment 9a, Squirrel Creek: cadmium, copper, zinc, total recoverable iron (CORGCB09a)
* Blue River segment 20, Spruce Creek: total recoverable iron (COUCBL20)
* Boulder Creek segment 1: lead, zinc (COSPBO01)
* Boulder Creek segment 2a: cadmium, copper (COSPBO02a)
* Boulder Creek segment 2b: cadmium, copper (COSPBO02b)
* Boulder Creek segment 3: cadmium, copper (COSPBO03)
* Boulder Creek segment 9: cadmium (COSPBO09)
* Boulder Creek segment 10: cadmium (COSPBO10)
* Boulder Creek segment 14, Boulder Reservoir: cadmium (COSPBO14)
* Big Thompson segment 2: sulfide (COSPBT02)
* Big Thompson segment 6, Dry Creek: E. coli (COSPBT06)
* Cherry Creek segment 6, Lollipop Lake: selenium (COSPCH06)
* Clear Creek segment 6, Mad Creek: pH (COSPCL06)
* Clear Creek segment 6, Hoop Creek: cadmium, lead, zinc (COSPCL06)
* Clear Creek segment 9a, Fall River: zinc, dissolved oxygen (COSPCL09a)
* Clear Creek segment 15: lead (COSPCL15)
* Cache la Poudre segment 6: copper (COSPCP06)
* Cache la Poudre segment 9: cadmium, lead (COSPCP09)
* Lower South Platte segment 3, Jackson Reservoir: selenium (COSPLS03)
* North Platte segment 1, South Fork Big Creek: copper, E. coli (COUCNP01)
* North Platte segment 4a, Little Grizzly Creek: E. coli, total recoverable iron (COUCNP04a)
* North Platte segment 4a, Grizzly Creek, Little Grizzly Creek: Aquatic Life Use (COUCNP04a)
* North Platte segment 4a, Lake Creek: pH (COUCNP04a)
* Roaring Fork segment 3a, Capitol Creek: selenium (COUCRF03a)
* Roaring Fork segment 10, Thompson Creek: total recoverable iron (COUCRF10)
* St. Vrain segment 13, Lake Thomas: dissolved oxygen (COSPSV13)
* Upper Colorado segment 10c, Fraser River: copper, lead (COUCUC10c)
* Upper Colorado segment 10c, from Town of Fraser to Colorado River: copper (COUCUC10c)
* Upper Colorado segment 10c, from Town of Tabernash to Town of Granby: lead (COUCUC10c)
* Upper South Platte segment 12, Jackson Lake: lead (COSPUS12)
* Upper South Platte segment 17a, Rocky Mountain Lake and Grasmere Lake: copper (COSPUS17a)
* Upper South Platte segment 17b, Sloan's Lake: total recoverable iron (COSPUS17b)
* Upper South Platte segment 23, Aqua Golf: total recoverable iron (COSPUS23)
* Yampa segment 2a, Yampa River below Stagecoach: selenium (COUCYA02a)
* Yampa segment 3, Little Morrison Creek: zinc, dissolved iron (COUCYA03)
* Yampa segment 3, Walton Creek: manganese (COUCYA03)
* Yampa River segment 13d, Dry Creek below Routt County Rd 53: lead and E.coli (COUCYA13d)
The Commission adopted a new assessment methodology in the 2016 Listing Methodology to evaluate ambient based standards. This methodology uses a statistical approach based on the concept of the confidence interval to minimize uncertainty of assessment conclusions. The following segments were delisted due to attainment of ambient based standards using the new assessment methodology for ambient based standards:
* Middle Arkansas segment 4a: selenium (COARMA04a)
* Middle Arkansas segment 6a: selenium (COARMA06a)
The following segments or parameters were added to the 303(d) List due to exceedances of water quality standards not identified above:
* Fountain Creek segment 3b: copper (COARFO03b)
* Fountain Creek segment 4, Sand Creek: selenium (COARFO04)
* Lower Arkansas segment 1a, E. coli (COARLA01a)
* Lower Arkansas segment 9b, Big Sandy Creek: total recoverable iron (COARLA09b)
* Lower Arkansas segment 10, Nee Gronda: selenium (COARLA10)
* Lower Arkansas segment 12, Lake Meredith: selenium (COARLA12)
* Middle Arkansas segment 3: selenium (COARMA03)
* Middle Arkansas segment 14: total recoverable iron (COARMA14)
* Upper Arkansas segment 4a: copper (COARUA04a)
* Upper Arkansas segment 5, Lake Fork below Sugarloaf Dam: zinc (COARUA05)
* Upper Arkansas segment 5, Colorado Gulch: cadmium, copper, zinc (COARUA05)
* Upper Arkansas segment 12a: cadmium (COARUA12a)
* Uncompahgre segment 9, Imogene Creek: cadmium and zinc (COGUUN09)
* Lower Colorado segment 4a, Mamm Creek: total recoverable iron (COLCLC04a)
* Lower Colorado segment 4a, South Canyon Creek above Hot Springs: total recoverable iron (COLCLC04a)
* Lower Colorado segment 13b: total recoverable iron (COLCLC13b)
* Lower Colorado segment 14c, Roan Creek: total recoverable iron (COLCLC14c)
* Lower Yampa segment 3c, Wilson Creek: total recoverable iron (COLCLY03c)
* Lower Yampa segment 3c, Stinking Gulch: selenium (COLCLY03c)
* Closed Basin segment 3, Willow Creek: copper (CORGCB03)
* Closed Basin segment 12a: total recoverable iron (CORGCB12a)
* Rio Grande segment 2, South Clear Creek: total recoverable iron (CORGRG02)
* Rio Grande segment 4a: lead (CORGRG04a)
* Rio Grande segment 4c: copper (CORGRG04c)
* Rio Grande segment 7: cadmium, lead, zinc (CORGRG07)
* Rio Grande segment 9, North Branch of Pass Creek: zinc (CORGRG09)
* Big Dry Creek segment 1, Big Dry Creek downstream of Weld County Road 8: total recoverable iron (COSPBD01)
* Boulder Creek segment 2a, North Boulder Creek from Caribou Creek to the confluence with Como Creek: copper (COSPBO02a)
* Boulder Creek segment 2a, Como Creek to the confluence of North Boulder Creek: total recoverable iron (COSPBO02a)
* Boulder Creek segment 2a, North Boulder Creek to confluence of Caribou Creek: copper and lead (COSPBO02a)
* Boulder Creek segment 4a: copper (COSPBO04a)
* Boulder Creek segment 4b: copper (COSPBO04b)
* Boulder Creek segment 7b, below Rock Creek: selenium (COSPBO07b)
* Boulder Creek segment 9: E. coli (COSPBO09)
* Boulder Creek segment 10: pH (COSPBO10)
* Boulder Creek segment 14, Barker Reservoir: copper (COSPBO14)
* Big Thompson segment 2, from RMNP to above UTSD discharge: copper (CPSPBT02)
* Cherry Creek segment 2: chlorophyll and dissolved oxygen (COSPCH02)
* Cherry Creek segment 4a, Goldsmith Gulch: E. coli and selenium (COSPCH04a)
* Cherry Creek segment 4a, McMurdo Gulch: dissolved oxygen (COSPCH04a)
* Cherry Creek segment 4b, Upper Windmill Creek: selenium (COSPCH04b)
* Clear Creek segment 2c, Turkey Gulch below Rockford Tunnel: copper, nickel, total recoverable iron, zinc (COSPCL02c)
* Clear Creek segment 5, from Hoop Creek to confluence with Clear Creek: copper (COSPCL05)
* Clear Creek segment 6, Mad Creek: copper (COSPCL06)
* Clear Creek segment 6, North Empire Creek: copper (COSPCL06)
* Clear Creek segment 12a, Gilson Gulch and tributaries: cadmium, copper, nickel, lead, selenium and zinc (COSPCL12a)
* Clear Creek segment 12a, all tributaries except Gilson Gulch: cadmium, copper, and zinc (COSPCL12a)
* Clear Creek segment 15: ammonia (COSPCL15)
* Cache la Poudre segment 11: E. coli (COSPCP11)
* Cache la Poudre segment 13b: E. coli (COSPCP13b)
* Laramie segment 2b: copper (COSPLA02b)
* Lower South Platte segment 1: uranium (COSPLS01)
* Lower South Platte segment 3, North Sterling: dissolved oxygen and selenium (COSPLS03)
* Middle South Platte segment 1b: E. coli (COSPMS01b)
* St. Vrain segment 3: E. coli (COSPSV03)
* St. Vrain segment 5, Left Hand Creek: pH (COSPSV05)
* St. Vrain segment 6, Dry Creek: selenium (COSPSV06)
* Upper South Platte segment 2c, South Mosquito Creek: cadmium (COSPUS02c)
* Upper South Platte segment 3, Trout Creek and tributaries: dissolved oxygen and pH(COSPUS03)
* Upper South Platte segment 5b, Geneva Creek: pH(COSPUS05b)
* Upper South Platte segment 10a, Plum Creek: E. coli (COSPUS10a)
* Upper South Platte segment 16c: E. coli (COSPUS16c)
* Upper South Platte segment 16i: E. coli (COSPUS16i)
* Upper South Platte segment 16i, Sand Creek from Westerly Creek to the South Platte River: selenium (COSPUS16i)
* Upper South Platte segment 17a, Rocky Mountain Lake: dissolved oxygen (COSPUS17a)
* Upper South Platte segment 17a, Smith Lake: pH (COSPUS17a)
* Upper South Platte segment 17a, Grasmere Lake: ammonia (COSPUS17a)
* Upper South Platte segment 23, Garfield Lake: dissolved oxygen (COSPUS23)
* Upper South Platte segment 23, Aqua Gulf: pH (COSPUS23)
* Upper South Platte segment 23, Parkfield Lake: pH (COSPUS23)
* Blue River segment 2a, above South Barton Gulch: zinc (COUCBL02a)
* Blue River segment 4a, Gold Run Gulch below Jessie Mine: zinc (COUCBL04a)
* Blue River segment 4a, Meadow Creek: copper (COUCBL04a)
* Blue River segment 6a: zinc (COUCBL06a)
* Blue River segment 12: zinc (COUCBL12)
* North Platte segment 4a, Snyder Creek: total recoverable iron (COUCNP04a)
* North Platte segment 9, Lake John: pH (COUCNP09)
* Upper Colorado segment 2, north inlet to Grand Lake: copper (COUCUC02)
* Upper Colorado segment 10a, Vasquez Creek: copper (COUCUC10a)
* Yampa segment 3, Little Morrison Creek: total recoverable iron (COUCYA03)
* Yampa segment 3, Gunn Creek: zinc (COUCYA03)
* Yampa segment 13h: selenium (COUCYA13h)
The following segments or parameters were added to the M&E List due to exceedances of water quality standards not identified above:
* Fountain segment 4, Little Fountain Creek below Deadman Canyon: selenium (COARFO04)
* Lower Arkansas segment 3a: E. coli (COARLA03a)
* Lower Arkansas segment 7: E. coli (COARLA07)
* Lower Arkansas segment 9a, Adobe Creek: total recoverable iron (COARLA09a)
* Lower Arkansas segment 12, Lake Henry: total recoverable iron (COARLA12)
* Middle Arkansas segment 11b: total recoverable iron (COARMA11b)
* Upper Arkansas segment 5, Lake Fork below Sugarloaf Dam: cadmium (COARUA05)
* Upper Arkansas segment 5, Colorado Gulch: silver, lead (COARUA05)
* Upper Gunnison segment 29a, Lake Fork of the Gunnison upstream of Cottonwood Creek: zinc and cadmium (COGUUG29a)
* Uncompahgre segment 9, Imogene Creek: copper (COGUUN09)
* Lower Colorado segment 3: selenium (COLCLC03)
* Lower Colorado segment 4e: total recoverable iron, copper, selenium and cadmium (COLCLC04e)
* Lower Colorado segment 13a, Sulphur Gulch: total recoverable iron, copper and lead (COLCLC13a)
* Lower Colorado segment 16: total recoverable iron (COLCLC16)
* Lower Yampa segment 3c, Wilson Creek: selenium (COLCLY03c)
* Lower Yampa segment 3e: selenium (COLCLY03e)
* White River segment 7, White River below Meeker: total recoverable iron (COLCWH07)
* Alamosa River segment 10: total recoverable iron (CORGAL10)
* Alamosa River segment 12: total recoverable iron (CORGAL12)
* Closed Basin segment 3, Cottonwood Creek: copper (CORGCB03)
* Closed Basin segment 3, Major Creek: total recoverable iron (CORGCB03)
* Closed Basin segment 5: copper (CORGCB05)
* Closed Basin segment 10, Sand Creek: copper (CORGCB10)
* Closed Basin segment 12a, Ford Creek: cadmium and zinc (CORGCB12a)
* Rio Grande segment 3: total recoverable iron (CORGRG03)
* Rio Grande segment 9, North Branch of Pass Creek: copper (CORGRG09)
* Rio Grande segment 25: copper (CORGRG25)
* Rio Grande segment 28, Upper Rito Seco below Battle Mountain: copper (CORGRG28)
* Rio Grande segment 33, Alberta Park: silver (CORGRG33)
* Rio Grande segment 38, Road Canyon: silver (CORGRG38)
* Boulder Creek segment 14, Barker Reservoir: silver (COSPBO14)
* Big Thompson segment 5: E. coli (COSPBT05)
* Big Thompson segment 10: dissolved oxygen (COSPBT10)
* Clear Creek segment 3b: cadmium (COSPCL03b)
* Clear Creek segment 6, North Empire Creek: cadmium, total recoverable iron, zinc (COSPCL06)
* Clear Creek segment 12a, Gilson Gulch and tributaries: pH (COSPCL12a)
* Clear Creek segment 12a, all tributaries except Gilson Gulch: dissolved oxygen (COSPCL12a)
* Clear Creek segment 14b: ammonia (COSPCL14b)
* Clear Creek segment 17b: E. coli (COSPCL17b)
* Cache la Poudre segment 7: silver (COSPCP07)
* Cache la Poudre segment 9: pH (COSPCP09)
* Cache la Poudre segment 12: pH (COSPCP12)
* St. Vrain segment 2b: silver(COSPSV02b)
* Upper South Platte segment 1a, Middle South Platte: pH (COSPUS01a)
* Upper South Platte segment 3, West Creek: total recoverable iron, dissolved oxygen (COSPUS03)
* Upper South Platte segment 23, Aqua Gulf: ammonia (COSPUS23)
* Upper South Platte segment 23, Harvey Lake: total recoverable iron (COSPUS23)
* Blue River segment 4a, Meadow Creek: zinc (COUCBL04a)
* Blue River segment 12: copper (COUCBL12)
* North Platte segment 4a, Illinois River: copper (COUCNP04a)
* North Platte segment 5b: copper (COUCNP05b)
* North Platte segment 6: copper (COUCNP06)
* Roaring Fork segment 2: copper (COUCRF02)
* Upper Colorado segment 8, below Kinney: copper (COUCUC08)
* Yampa segment 13j: selenium (COUCYA13j)
The Arkansas Fountain Coalition for Urban River Evaluation ("AF CURE") raised site-specific issues with listing segments that are within the geographic area that was affected by the Waldo Canyon Fire in 2012 and with using samples that are collected during or soon after storm events.
Data collected after the Waldo Canyon Fire was appropriately used to assess segments COARF001a, COARF002a, COARF002b, COARF003a COARF004 and COARF006. Any variability in data was alleviated through application of the nonparametric statistical analysis as included in the Listing Methodology; removal of data that was collected by USGS as part of a special study specifically looking at the effects of the fire; or by comparing attainment of water quality standards before and after the fire event, and where available listing those segments on the 303(d) list that were out of attainment prior to the fire event and out of attainment after the fire event (segments that were in attainment prior to the fire event were listed on the M&E list). Additionally, the Commission was uncertain whether two years is a sufficient period of time for macroinvertebrate communities to recover from the impacts of sedimentation that result from forest fires, and the time may vary based on the proximity to the fire, the amount of water flowing through the waterway, and other factors. The Commission anticipates that the next iteration of the Listing Methodology will address the complexity of listing fire, flood, or other catastrophic event impacts on streams to provide further guidance for these types of decisions, and also acknowledges that there may be many case specific determinations.
| Condition Prior to Fire | Condition After Fire | Recommended Listing |
|
Out of Attainment |
Out of Attainment |
List on 303(d) List |
|
In Attainment |
Out of Attainment |
List on M & E List |
|
Out of Attainment |
In Attainment |
Do not list |
Based on USGS standard operating procedure, the Commission determined that sampling should not be conducted for four weeks following a significant flushing event. However, the data on the record for these segments was collected outside of the four week window, and therefore was appropriately included in the assessment.
Public Service Company of Colorado (PSCo) submitted a Category 4b Demonstration Plan (the Plan) to the Division for Clear Creek segment 3a in the South Platte River Basin, for the portion of the segment of South Clear Creek downstream of Lower Cabin Creek Reservoir to Clear Lake. Category 4b is an alternative to listing an impaired segment on the 303(d) list. A Category 4b Demonstration Plan, when implemented, must ensure attainment of all applicable water quality standards through pollution control mechanisms within a reasonable time period. The Plan was accepted by the U.S. Environmental Protection Agency prior to the rulemaking hearing. The Commission approved Public Service Company of Colorado's Category 4b Plan for segment COSPCL03a (South Clear Creek downstream of Lower Cabin Creek Reservoir to Clear Lake) and as a result, the Commission did not include Clear Creek segment 3a, South Clear Creek downstream of Lower Cabin Creek Reservoir to Clear Lake, on the 303(d) List for the aquatic life use, for which the Category 4b Demonstration Plan was written. PSCo will provide updates on the implementation of the Plan to the Commission in future 303(d) rulemaking hearings. The Commission expects that after a reasonable period of time as defined in the Category 4b Demonstration Plan, the aquatic life use be reexamined on this portion of Clear Creek segment 3a. If the aquatic life use is not attained by this time, the segment will be considered impaired and placed on the 303(d) List.
In 2012, the Commission removed Lower Colorado segment 3 from the 303(d) List for selenium impairment due to attainment of standards. At that time, USFWS opposed its removal from the list because the segment is critical habitat for the endangered Colorado pike minnow and razorback sucker. The Commission acknowledged the significance of this issue and recommended USFWS pursue an alternative standard in the next Colorado basin rulemaking; however, USFWS did not submit a proposal in 2014. In this rulemaking there was consensus that the acute selenium standard was attained; however, there was disagreement among the parties regarding whether the chronic selenium standard is attained due to uncertainty regarding the representativeness of a portion of the data set used in the assessment.
During 2012-2014, EPA and USFWS collected samples in segment 3 targeting critical habitat for the endangered fish. These samples were collected during low-flow periods from August to October. Colorado River Water Conservation District and the Colorado Stone, Sand and Gravel Association disagreed about whether the tributary-influenced sample locations and time periods are representative of conditions in the mainstem. Specifically, these parties argued that the majority of the data comes from poorly mixed sites located downstream of tributaries, and therefore is not representative of the spatial and temporal variability.
When the Commission adopts a standard it applies to the entire segment including areas of the segment that are under the influence of tributaries. The Listing Methodology excludes data collected within the mixing zone of a discharge (as defined by Regulation 31), however it does not exclude data collected at the confluences of tributaries and river mainstems. Because selenium bio-accumulates in fish, the chronic selenium standard is designed to protect fish from cumulative life-long exposure. The default from the Listing Methodology is that data from the entire segment (including data at the confluences) is representative because the data represents the levels of selenium that aquatic food chain is exposed to through the segment.
However, where a sampling study targets a particular constituent in a portion of a segment, the data from that study may be skewed and may not be representative of the spatial and temporal nature of the whole segment. Here the Commission determined that it is unclear whether the data collected in the EPA and USFWS's study was representative of the entire segment, and therefore included segment 3 (COLCLCO3) on the 2016 M&E List for selenium.
The River District and the Colorado Stone Sand and Gravel Association have agreed to work with the Division, the Selenium Task Force, and other stakeholders to evaluate whether an alternative approach to a TMDL may be a more effective approach to achieving load reductions
Segment 5c on the Eagle River is located downstream of the Eagle Mine superfund site with a history of being impacted by the mine. Remedial activities conducted at the Eagle Mine superfund site beginning in the late 1980s resulted in reductions in metals loading and improved water quality in the Eagle River in the vicinity of the superfund site.
At the 2005 Regulation No. 33 rulemaking hearing (Reg. 33 RMH), the Commission adopted resegmentation of Eagle River segment 5 into segments 5a, 5b, and 5c, based on recognized changes in water quality, hardness, and use. In this rulemaking hearing, the Commission placed segment 5c on the 303(d) list for dissolved iron and total recoverable arsenic. Although it was argued that the upstream segments (segments 5a and 5b) should also be included on the 303(d) list as the primary source of contamination in segment 5c, segments 5a and 5b were not included in the Notice for this Rulemaking. The Commission finds that data collected in segment 5c which consisted of 123 total arsenic values with lower detection limits were representative of water quality conditions. The majority of data submitted to assess segments 5a and 5b, however, used a reporting limit of 15 ug/L for the water quality standard of 0.02 ug/L, and all such data were reported as non-detect (43 of the 65 values for segment 5a, and 79 of the 98 values for segment 5b). It is the Commission's intent that TMDLs for this segment 5c will consider upstream sources of loading occurring in the Eagle River as is the division's typical practice for TMDL development.
Jackson County Water Conservancy District (District) proposed to remove the Illinois River (COUCNP04b) from the 303(d) List for total recoverable iron. The division assessed total recoverable iron for the Illinois River portion of the segment. After locational issues with sampling sites were resolved, the division concluded that the segment was in attainment of the total recoverable iron standard. The 50th percentile of the 10 total recoverable iron values for the portion was found to be 746 ug/L, a value less than the aquatic life standard of 1000 ug/L. Therefore, the data supported delisting of this portion and the Commission removed this segment from the 303(d) List for total recoverable iron.
Several parties raised issues with the representative nature of the aquatic life data for Upper South Platte segment 6a. Specifically they state that one data point is not enough to make a listing decision, that the location of the data point collected was not representative of the segments and that the 2003 EPA Standard Operating Procedure (SOP) for collecting benthic macroinvertebrate samples were not used. All of these issues are inconsistent with the Listing Methodology.
The Listing Methodology establishes the standard procedure for collecting macroinvertebrate data, which is the procedure established in Policy 10-1. The Commission reiterates that one data point is sufficient to include or remove a segment on the 303(d) List. Appendix B of the Listing Methodology ensures that samples are collected in stream reaches that are representative but does not necessarily prohibit sampling near areas of human disturbance. The Commission determined that both stations used in the assessment of segment 6a are located at a substantial and sufficient distance upstream from the nearest road or bridge crossing, which in this instance is a highway. Finally, the Commission determined that following the procedures in Policy 10-1 is the appropriate methodology, or standard operating procedure for collecting macroinvertebrate data.
The Commission determined that the data was representative and that segment 6a should be included on the 303(d) List provisionally. The Commission directs the division and interested parties to study this segment to determine the stressors and pollutants that are impacting aquatic life in this segment.
The Commission intends that the list of water quality-limited segments requiring total maximum daily loads shall apply to waters within the external boundaries of the Southern Ute Indian Reservation only to the extent that the state has jurisdiction, and is not attempting to resolve that jurisdictional issue here.
Chatfield Watershed Authority will continue its proactive monitoring program, including current E. coli data collection efforts. The Authority is in the early stages of the data analysis and interpretation. Any potential control measures will be based on data and science.
Toll Gate Creek, East Toll Gate Creek, and West Toll Gate Creek are meeting adopted ambient selenium standards. Toll Gate Creek, East Toll Gate Creek, and West Toll Gate Creek were resegmented from Upper South Platte segment 16c to segment 16h at the 2008 Temporary Modifications RMH but never formally delisted from the 303(d) List.
State Line Ranch submitted a proposal as part of written public comment proposing that Sand Creek be listed as impaired for sediment due to impacts to a beneficial use. While the Commission found the evidence submitted to be persuasive and compelling evidence of impairment, the Commission was reluctant to list the segment as impaired in this hearing for a number of reasons. One reason was that the proposal was made late in the process and therefore the Division had not had an opportunity to thoroughly review and evaluate the proposal. In addition, potentially affected parties, such as the BLM and the affected local community, were not able to participate in the process. Also, because this would be the first time a segment would be listed for sediment impairing a beneficial use, the Commission would like to proceed thoughtfully to establish appropriate precedent about the factors to be considered in such a decision. Therefore, the Commission included the segment on the M&E List. A proposal may be made for a special hearing to consider this proposal, or that it may be proposed to be included on the 303(d) List as part the next 303(d) listing cycle.
PARTIES TO THE RULEMAKING HEARING
