5 Colo. Code Regs. § 1002-36.27
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:
Some renumbering and/or creation of new segments in the basin was made due to information which showed that the original reason for segmentation no longer applied. The following changes were made:
Closed Basin-San Luis Valley segment 13b: This segment was created for the North Branch of Saguache Creek and its tributaries. This segment was formerly included in Closed Basin-San Luis Valley segment 3 (All tributaries to the Closed Basin except for segment 2, segments 4-13). The Town of Saguache WWTF discharges to the North Branch of Saguache Creek, and intends to propose site-specific standards for this segment.
Closed Basin-San Luis Valley segment 13a: Segment 13 was changed to segment 13a to reflect the creation of segment 13b.
The Commission reviewed information regarding existing aquatic communities, and made the following change.
Rio Grande River Basin segment 20: The Aquatic Life Use classification was changed from Cold 2 to Cold 1 based on the presence of Rio Grande cutthroat trout, a DOW species of special concern. Appropriate Aquatic-Life based standards were adopted to reflect the change in Use Classification.
As part of the Basic Standards hearing of 2005, recreation classifications were revised into four new classifications. The Commission reviewed the previous classifications (1a, 1b and 2) and determined the appropriate new classifications based on criteria presented as part of the Basic Standards Hearing, use attainability analyses or other basis. In addition, during the 2005 Basic Standards Hearing, the transition from the use of the fecal coliform standard to E.coli standard was completed. Fecal coliform criteria were deleted from the numeric standards.
Based on the information that showed existing primary contact recreation use is in place in at least a portion of the segment, the Commission converted the following segments from Recreation Class 1a to Recreation Class E with a 126/100 ml E.coli standard:
Rio Grande segments: 1-14, and 16-30.
Alamosa River/La Jara Creek/Conejos River segments: 1-2, 3a-3d, 4a-4b, 5-20, and 22.
Closed Basin- San Luis Valley segments: 1-8, 9a-9b, and 10-14.
Based on review of existing Use Attainability Analyses showing that primary contact recreation is not attainable, the following segments were converted to Recreation Class N classification with 630/100 ml E. coli standard:
Rio Grande segment: 15.
Alamosa River/La Jara Creek/Conejos River segment: 21.
Based on review of information regarding the location of public water supplies, no additional WS classifications and standards were added to Regulation No. 36.
Outstanding Waters Designation: Based on evidence that shows the water quality meets the requirements of 31.8(2)a, the OW designation was added to Closed Basin-San Luis Valley segment 10, which includes Sand and Medano Creeks located in the Great Sand Dunes National Park and Preserve. Outstanding waters designation was supported by the National Park Service.
Decoupling Cold 2 and UP: As part of the Basic Standards hearing of 2005, the Commission eliminated the direct linkage between cold-water Aquatic Life Class 2 and the Use-Protected designation. Therefore, all cold-water Aquatic Life Class 2 segments that are Use-Protected were reviewed to determine if that designation is still warranted. The following segments are now Reviewable:
Rio Grande segments: 3, 20, 22, 24, 26, and 29. Alamosa River/La Jara Creek/Conejos River segment: 15. Closed Basin - San Luis Valley segments: 5 and 7.
Decoupling Aquatic Life Warm 2 and UP Also as part of the Basic Standards hearing of 2005, the Commission decided that the presence of a warm-water Aquatic Life Class 2 classification would still be a presumptive basis for applying a Use-Protected designation; however, that presumption can be overcome if there is data showing that the water is of high quality. Therefore, the Commission reviewed all warm water class 2 segments to determine if the use protected designation is still warranted. The following segment(s) are now Reviewable:
Alamosa River/La Jara Creek/Conejos River segments: 12 and 18
There are several segments in the Rio Grande Basin that are assigned ambient standards. Ambient standards are adopted where natural or irreversible man-induced conditions result in exceedances of table value standards. The Commission reviewed the information that is the basis for these standards as well as any new information that would indicate whether they are still appropriate, need to be modified, or should be dropped. The Commission did not adopt any changes to the ambient quality-based standards. The following segments have ambient based standards:
Alamosa segment 3a: pH and Fe
Alamosa segment 3b: Cu and Fe
Alamosa segment 3c: Fe
Alamosa segment 3d: Fe
Alamosa segment 7: Ag, Cd, Cu, Fe, Mn, Ni, Pb, and Zn
New Table Value Standards: As part of the Basic Standards hearing of 2005, new zinc and cadmium table values were adopted. The acute and chronic zinc and cadmium equations in 36.6(3) were modified to conform to Regulation No. 31.
For arsenic, each use (except recreation) has a different arsenic ("As") value, including Fish Ingestion (FI) and Water Plus Fish (W+F). In different combinations of uses, different values become the most limiting. In order to eliminate the confusion, the Commission added the operative value to the individual segments. The following matrix displays the most limiting arsenic criteria.
Most Limiting Arsenic Criteria Depending on the Possible Combinations of Uses and Qualifiers
If the Use Classifications were: | These Arsenic Standards were Applied (dissolved unless otherwise noted) |
Class 1 aquatic life, water supply | As(ac) = 340, As(ch) = 0.02(Trec) |
Class 2 aquatic life (water + fish standards), water supply | As(ac) = 340, As(ch) = 0.02(Trec) |
Class 2 aquatic life (no fish ingestion standards), water supply | As(ac) = 340, As(ch) = 0.02 - 10(Trec) |
Class 1 aquatic life | As(ac) = 340, As(ch) = 7.6(Trec) |
Class 2 aquatic life (fish ingestion standards) | As(ac) = 340, As(ch) = 7.6(Trec) |
Class 2 aquatic life (no fish ingestion standards), agriculture | As(ac) = 340, As(ch) = 100(Trec) |
Agriculture only | As(ch) = 100 (Trec) |
Water supply only | As(ch) = 0.02 - 10(Trec) |
At the 2005 Basic Standards rulemaking hearing, the Commission changed the drinking water supply table value for uranium from 40 pCi/L to 30 µg/L.
Language was added to subsection 32.6 [or 36.6(2)] to explain the terms "type i" and "type iii" temporary modifications.
All temporary modifications were re-examined to determine whether to delete the temporary modification or to extend them, either as existing or with modifications of the numeric standards. Because of the June 2005 changes to Regulation No. 31, temporary modifications were not automatically extended if non-attainment persisted.
The following segment had temporary modifications removed because current ambient conditions meet the underlying standards:
Rio Grande segment 7
The following segments had temporary modifications removed because there are no permitted discharges on this segment:
Closed Basin-San Luis Valley segments 9a and 9b
The following segments have new or extended temporary modifications. As specified in 61.8(2)(c)(iii) (the Permit Rules, Regulation No 61), where a temporary modification has been adopted, limits in permits are to be set based on the temporary modification and the provision strictly limiting the loading from the facility does not apply. These temporary modifications will be subject to review and rulemaking for the two years before their scheduled expiration in order to track progress towards the full attainment of water body standards and uses.
Rio Grande segment 4: As(ch)=existing quality, Cd(ch)=existing quality, Cu(ch)=existing quality, Pb(ch)=existing quality, Zn(ch)=existing quality, expiration date of 12/31/2012. Exceedances of the arsenic, cadmium, copper, lead and zinc standards were measured in this segment. A type iii Temporary Modification was adopted based on section 31.7 which states that the Commission may grant a temporary modification "where there is significant uncertainty regarding the appropriate long-term underlying standard - e.g. due to the need for additional information regarding the extent to which existing quality is the result of natural or irreversible human-induced conditions or regarding the level of water quality necessary to protect current and/or future uses -and the adoption of a temporary modification recognizes current conditions while providing an opportunity to resolve the uncertainty". The Willow Creek Reclamation Committee has ongoing projects to reduce metal pollution from Willow Creek to the Rio Grande, and the final effect of these projects is currently unknown. Natural sources also need to be identified and characterized before appropriate underlying standards can be determined. The need for this temporary modification will be reviewed in 2010 and 2011. Where temporary modifications are in effect, the Division is to include effluent limits and (potentially) compliance schedules in discharge permits, consistent with Section 31.14(15).
Alamosa/La Jara/Conejos segment 3b: Se(ch)=existing quality, expiration date of 12/31/2012. Until a revised national criteria is promulgated for selenium, these Temporary Modifications should be based on section 31.7 . The need for this temporary modification will be reviewed in 2010 and 2011. Where temporary modifications are in effect, the Division is to include effluent limits and (potentially) compliance schedules in discharge permits, consistent with Section 31.14(15).
Closed Basin-San Luis Valley segment 13b: NH3 (ac/ch)=existing quality, expiration date of 12/31/2011. There is uncertainty as to what the appropriate underlying standard for ammonia should be in this segment, because the North Branch is frequently dry, and the extent that this segment supports aquatic life is unknown. A type iii Temporary Modification was adopted based on section 31.7 . This Temporary Modification has been adopted to allow the Town of Saguache adequate time to determine the appropriate ammonia standards for this segment by completing an aquatic life survey particularly for the presence of fish and early life stages. The need for this temporary modification will be reviewed in 2010 and 2011. Where temporary modifications are in effect, the Division is to include effluent limits and (potentially) compliance schedules in discharge permits, consistent with Section 31.14(15).
Rio Grande segment 16: The Mn=WS was removed because there is no Water Supply use classification for this segment. Mn(ac/ch)=TVS was added to reflect the Aquatic Life use classification for this segment.
Alamosa River/La Jara Creek/Conejos River segment 5: The pH=6.0-9.0 standard was changed to pH=6.5-9.0 to reflect the Aquatic Life use classification. D.O.=6.0 mg/l and D.O.(sp)=7.0 mg/L were added to reflect the Aquatic Life use classification.
Alamosa River/La Jara Creek/Conejos River segment 12: The E. coli=630/100ml was changed to E. coli=126/100ml to reflect the Recreation 1a use classification.
Alamosa River/La Jara Creek/Conejos River segment 18: The E. coli=630/100ml was changed to E. coli=126/100ml to reflect the Recreation 1a use classification.
The Commission corrected several typographical and spelling errors, and clarified segment descriptions.
The reference to "Water+Fish Organics" was corrected to "Water+Fish Standards" to incorporate the appropriate standards from both the organics table and the metal parameter table in Regulation No. 31.
Rio Grande segment 18: The segment description was amended to reference segment 30 instead of segment 31. There is currently no segment designated as 31.
Rio Grande segment 30: The segment description was amended to correct an inaccurate reference to Road 7 which crosses the mainstem of Costilla Creek instead of West Fork Costilla Creek. The reference to the New Mexico/Colorado border was removed since this creek crosses the state-line three times, and was reworded to include only those portions within Colorado.
Alamosa River/La Jara Creek/Conejos River segment 4b: In the site description, the reference to Tributary G was changed to South Mountain Creek, because the name Tributary G does not appear on USGS or commercial maps readily available to the public.
Alamosa River/La Jara Creek/Conejos River segment 3c: In the site description, the reference to the confluence with Ranger Creek was changed to "below the confluence with Ranger Creek" so that the segment description is consistent with the segment description of Alamosa segment 3d.
Alamosa River/La Jara Creek/Conejos River segments 8-12: The Mn(ch)=200 standard was changed to Mn(ch)=200(Trec) to clarify that the standard refers to total recoverable manganese.
Alamosa River/La Jara Creek/Conejos River segment 19: A typographical error was corrected such that NO2 = 0.0 was changed to NO2 = 0.05.
HMWMD prepared a Use Attainability Assessment (UAA, updated from the 1998 UAA) on the Alamosa River system, specifically assessing the aluminum sources and resulting levels in segments 3a, 3b, 3c, 3d and 8. The goal of the updated UAA was to evaluate the current and attainable conditions of the river system with respect to aluminum for snowmelt and non-snow-melt periods from 1999 to 2006. This time frame was chosen because it exhibits improved water quality, compared to the preceding years. The improved conditions are attributable to a significant decline in metal concentrations in Wightman Fork due to stability of the chemistry and the effectiveness of remedial activities at the Summitville Mine Superfund Site ("SMSS").
The 2007 UAA Update identified the natural, irreversible man-induced and reversible sources of aluminum. Three conditions were modeled that differ by the amount of human-induced sources that are removed in the calculation. In addition, three remedial scenarios were then modeled which investigated the resulting aluminum concentrations based on water treatment scenarios at the SMSS.
The Commission agrees with the conclusions of the 2007 UAA Update that even if all reversible and irreversible human-induced aluminum sources were completely removed from the Alamosa River basin (Updated Condition 2), attainment of the current aluminum standards in the Alamosa River would not be achieved (2007 UAA Update Table 28). Loading from natural sources located in the Stunner, Summitville and Jasper Hydrothermal Altered Areas is of a large enough magnitude to result in elevated aluminum concentrations in the Alamosa River segments considered in this UAA. These natural aluminum loading sources have existed since well before mining in the basin and will continue to negatively impact the Alamosa River in the foreseeable future (i.e., longer than 20 years).
Based on review of the UAA and other information in the record, the Commission agrees that the only feasible reduction in aluminum that can be expected in the next 20 years will result from elimination of the loading from legacy mines identified in the UAA as reversible, control of the SMSS SDI seepage and construction of a new single stage plant at the SMSS. Consequently, the Commission has adopted site-specific standards.
Dissolved and Total Recoverable Aluminum Standards
In ambient waters, aluminum can exist in different forms and particle size as a function of pH. In addition, the aquatic toxicology of aluminum is complex. It is likely that total recoverable versus the dissolved forms of aluminum have dissimilar potentials to adversely affect aquatic life. In this situation where attainability-based standards have been adopted, the Commission established standards in both the dissolved and total recoverable form. These dual standards more completely characterize the different forms and particle size in which aluminum currently exists in the Alamosa River. This dual standard will be useful in maintaining and protecting the existing condition while also mandating controls that are feasible to achieve. The Commission has adopted the following site-specific changes:
Segment 3a Alamosa River above Wightman Fork: The Commission has adopted a seasonal aluminum ambient-based standard for segment 3a, which is above the influence of the SMSS. The 85th percentile ambient standards for Al(Trec) = 3,100 µg/L(5/1 to 6/30) and 6,200 µg/L (7/1 to 4/30) and 95th percentile ambient standards for Al(Trec) = 4,000 µg/L(5/1 to 6/30) and 19,900 µg/L (7/1 to 4/30). The 85th percentile ambient standards for Al(Dis) = 98 µg/L(5/1 to 6/30) and 903 µg/L (7/1 to 4/30) and 95th percentile ambient standards for Al(Dis) = 161 µg/L(5/1 to 6/30) and 6,005 µg/L (7/1 to 4/30). These standards were derived from the 85th and 95th percentile concentration of aluminum (Trec and Dis), chronic and acute respectively, of the data collected from 1981 through 2006.
Segment 3b Alamosa River from Wightman Fork to Fern Creek: The Commission adopted a seasonal aluminum technology-based standard for segment 3b. This is derived from monitoring and modeling of chemical data. The 85th percentile 1999-2006 conditions indicate that aluminum, due to naturally occurring conditions, will exceed the existing aluminum acute standard. The Commission has adopted 85th percentile seasonal technology-based standards for Al(Trec) = 3,000 µg/L(5/1 to 6/30) and 3,000 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Trec) = 4,300 µg/L(5/1 to 6/30) and 3,100 µg/L (7/1 to 4/30). The 85th percentile seasonal technology-based standards for Al(Dis) = 41 µg/L(5/1 to 6/30) and 317 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based for Al(Dis) = 41 µg/L(5/1 to 6/30) and 756 µg/L (7/1 to 4/30). These standards represent the expected 85th and 95th percentile concentration of aluminum (Trec and Dis), chronic and acute respectively, once the new single stage plant is installed and operating at the SMSS.
Segment 3c Alamosa River from Fern Creek to Ranger Creek: The Commission has adopted a seasonal aluminum technology-based standard for segment 3c. This is derived from monitoring and modeling of chemical data. The 85th percentile 1999-2006 conditions indicate that aluminum, due to naturally occurring conditions, will exceed the existing aluminum acute standard. The Commission has adopted 85th percentile seasonal technology-based standards for Al(Trec) = 4,600 µg/L(5/1 to 6/30) and 3,700 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Trec) = 6,200 µg/L(5/1 to 6/30) and 6,700 µg/L (7/1 to 4/30). The 85th percentile seasonal technology-based standards for Al(Dis) = 42 µg/L(5/1 to 6/30) and 137 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Dis) = 87 µg/L(5/1 to 6/30) and 645 µg/L (7/1 to 4/30). These standards represent the expected 85th and 95th percentile concentration of aluminum (Trec and Dis), chronic and acute respectively, once the new single stage plant is installed and operating at the SMSS.
Segment 3d Alamosa River from Ranger Creek to Terrace Reservoir: The Commission has adopted a seasonal aluminum technology-based standard for segment 3d. This is derived from monitoring and modeling of chemical data. The 85th percentile 1999-2006 conditions indicate that aluminum, due to naturally occurring conditions, will exceed the existing aluminum acute standard. The Commission has adopted 85th percentile seasonal technology-based standards for Al(Trec) = 3,500 µg/L(5/1 to 6/30) and 3,100 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Trec) = 5,200 µg/L(5/1 to 6/30) and 3,700 µg/L (7/1 to 4/30). The 85th percentile seasonal technology-based standards for Al(Dis) = 87 µg/L(5/1 to 6/30) and 56 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Dis) = 90 µg/L(5/1 to 6/30) and 559 µg/L (7/1 to 4/30). These standards represent the expected 85th and 95th percentile concentration of aluminum (Trec and Dis), chronic and acute respectively, once the new single stage plant is installed and operating at the SMSS.
Segment 8 Terrace Reservoir: The Commission has adopted a seasonal aluminum technology-based standard for segment 8. This is derived from monitoring and modeling of chemical data. The 85th percentile 1999-2006 conditions indicate that aluminum, due to naturally occurring conditions, will exceed the existing aluminum acute standard. The Commission has adopted 85th percentile seasonal technology-based standards near surface/near bottom for Al(Trec) = 1,800/4,800 µg/L (5/1 to 6/30) and 200/400 µg/L (7/1 to 4/30) and 95th percentile seasonal technology-based standards for Al(Trec) = 1,800/5,600 µg/L(5/1 to 6/30) and 200/600 µg/L (7/1 to 4/30). The Commission has adopted 85th percentile technology-based standards for Al(Dis) = 28 µg/L and 95th percentile technology-based standards for Al(Dis) = 77 µg/L. These standards represent the expected 85th and 95th percentile concentration of aluminum (Trec and Dis), chronic and acute respectively, once the new single stage plant is installed and operating at the SMSS.
The "near surface" layer represents that part of the reservoir that is well mixed by wind action and can be expected to have relatively homogenous physical and chemical conditions. Prior to sample collection, a vertical thermal profile is gathered from the reservoir. When the reservoir is thermally stratified during the summer months, the "near surface" layer corresponds to the epilimnion and the "near bottom"corresponds to the hypolimnion. When the reservoir is unstratified, the "near surface" of Terrace Reservoir is defined as the upper 10 feet of the water column and the "near bottom" is defined as lower 20 feet of the water column. Because the Terrace Reservoir serves as a settling basin for particulates, and thus there is a gradient from near surface to near bottom, the stratified sampling technique will be used to collect total recoverable aluminum data. A single standard for the entire reservoir is proposed for dissolved aluminum because based on current data, there is no such stratification of dissolved aluminum concentrations.
Future Monitoring and Review of the Standards
The Alamosa Riverkeeper, Colorado Trout Unlimited, the Water Quality Control Division and EPA expressed concern regarding the size of the water quality dataset for aluminum and whether it accurately characterizes existing conditions from which the attainable conditions are calculated. Therefore, it is the intent of the Commission that these proposed 85th and 95th percentile standards shall be reassessed for each segment during each triennial review for the Rio Grande Basin, Regulation 36. The monitoring data that has been collected in the interim will be used to recalculate the standards for segments 3a, 3b, 3c, 3d and 8 as the database increases in size. In this way, the attainability - based numeric standards for aluminum can be refined.
The HMWMD has agreed to be responsible for collecting and analyzing samples during the snowmelt (generally May of each year) and non-snowmelt (generally September of each year) periods at the currently established monitoring stations for Alamosa River segments 3a, 3b, 3c, 3d and 8. In addition, the Alamosa Riverkeepers, community based groups, or other entities may collect and analyze additional samples data (in accordance with the Field Sampling Plan and Quality Assurance Project Plan for the Summitville Mine Superfund Site, prepared by Tetra Tech RMC and dated May 2003) for the accessible monitoring stations during other portions of the year such as mid-summer and mid-winter. These data shall become part of the master database and will be evaluated during future WQCC hearings on Regulation 36.
In the 2012 hearing, the calculations for the 2007 UAA conditions and remedial scenarios will be updated for the purpose of reviewing the aluminum concentrations that are feasible to achieve in each segment using the 1999 through 2011 data. The 85th and 95th percentile standards will be re-calculated for both the total recoverable and dissolved forms of aluminum. If it is determined that revisions to the standards adopted in this rulemaking are appropriate; that is, there are changes from the current values, then the Commission expects that a proposal shall be presented for inclusion in the public notice for the 2012 rulemaking hearing and a revision to Regulation 36, Alamosa River segment 3a, 3b, 3c, 3d and 8.
PARTIES TO THE RULEMAKING
5 CCR 1002-36.27