5 Colo. Code Regs. § 1002-32.40
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
Fountain Creek Segment 1b was created for Severy Creek and all tributaries from the source to a point just upstream of where US Forest Service Road 330 crosses the stream.
Fountain Creek Segment 3b was created for Bear Creek and all tributaries from the source to a point upstream of GPS coordinates N3847682, W 10454917 (this location is at elevation 8,200 feet above sea level at a 250° angle and 3,000 feet from the trailhead of the Mount Buckhorn Trail off High Drive).
Some renumbering and/or creation of new segments in the basin was made due to information which showed that:
- Middle Arkansas basin segment 4e to include Golf Course Wash.
- Lower Arkansas basin segment 8 to include the Canadian River.
The March 11, 2003 Rulemaking noted concerns relative to re-segmentation of several waters from Lower Arkansas segment 3a to segment 3b. These include Frio Canyon Creek, Borrego Canyon Creek, Munoz Canyon Creek, Williams Canyon Creek, and Castro Canyon Creek. The effect of this action was to move these drainages from a segment that was assigned a full suite of Aquatic Life Use-based numeric standards into segment 3b, which, although still assigned an Aquatic Life Use classification, is assigned Agricultural Use and Water Supply Use-based numeric criteria for inorganic and metal parameters. Noting that these tributaries to the Apishapa River exhibited ephemeral flow regimes at that time, EPA questioned whether the cumulative discharges of production water from Coal Bed Methane production wells might alter instream flows such that an aquatic community might be supported. The Division, at the permittee's request, has inactivated the CDPS permit that had been issued for production water discharge to segment 3b. In the absence of discharge, the Commission has determined that there is not adequate potential for aquatic life use to justify the adoption of Aquatic Life Use-based numeric standards for Lower Arkansas segment 3b.
A "Water + Fish" qualifier was added for Lower Arkansas segment 1c. The qualifier was added based upon the presence of the tail-water fishery below John Martin Reservoir at the upper terminus of the segment.
As part of the Basic Standards hearing of 2005, recreation classifications were revised into four new classifications. The Commission reviewed the previous segment classifications (1a, 1b and 2) and determined the appropriate new classification based on classification 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 those segments previously classified as Recreation Class1a to Recreation Class E with a 126/100 ml E. coli standard. Those segments currently classified as Recreation Class 1b were converted to Recreation Class P with a 205/100 ml E. coli standard. 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:
Upper Arkansas segments 6, 22a and 22b
Lower Arkansas segments 2a and 3b
Cimarron segment 1
Based on review of information regarding the location of public water supplies, WS classification and standards were not added to any segments in this rulemaking hearing.
Numeric standards to protect the Agricultural Uses in Upper Arkansas, segment 6 were considered by parties at this rulemaking hearing. The Commission chose not to adopt these standards at this time because they are not attainable and there are no current agriculture uses present on this segment. The Commission anticipates that this issue will be revisited in 2012 if the current uses change.
Outstanding Waters: The Outstanding Water (OW) designation was added to the newly defined Severy Creek (Fountain Creek segment 1b) and the new Bear Creek (Fountain Creek segment 3b) segments based upon information developed by Trout Unlimited documenting the presence of genetically isolated populations of cutthroat trout in both streams.
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:
Upper Arkansas River segments 8a, 17b, 21a and 21b
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 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 segments are now reviewable:
Upper Arkansas River segment 26
Fountain Creek segments 2a, 2b, 4, and 6
There are several segments in the Basins 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 adopted ambient-based standards for selenium for the following segments:
Middle Arkansas segment 3,
Middle Arkansas, segment 4a
The Commission deleted ambient-based standards for the following segments:
Upper Arkansas segment 8b, Iowa Gulch: This standard, Zn(ch)=430, was previously disapproved by EPA and the Commission did not feel that the ambient standard was appropriate. An investigation of the causes and sources should be conducted through the TMDL Program.
Fountain Creek segment 2a: The Commission deleted the ambient-based total recoverable iron standard for this segment because the current ambient concentrations of iron are meeting table value standards even though they are close to exceeding the table value standard. This segment had an ambient standard for iron previously, and the Commission acknowledges that an ambient standard may be appropriate in the future, based on updated monitoring information.
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 32.6(3) were modified to conform to Regulation No. 31.
For arsenic, each use (except recreation) has 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) |
The previous basin-wide Uranium standard of 30 pCi/l was changed to 30 ug/l in order to conform with June 2005 changes to Regulation No. 31. Available water quality data indicates that several segments in the Middle and Lower Arkansas basin exceed the newly assigned standard. Although no temporary modifications for Uranium were assigned in these basins, due to the absence of dischargers who might be expected to discharge significant concentrations of Uranium, the Commission expects the Division to include any such waters in its proposed 2008 List of Impaired Waters and Monitoring and Evaluation Lists, as appropriate.
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 segments had temporary modifications that are being removed because current ambient conditions are meeting the applicable underlying standards:
Upper Arkansas Segment 1b: Pb(ch)=6.5 and Zn(ch)=137, Expiration date of 12/31/07.
Upper Arkansas Segment 3: Pb(ch)=1.8 and Zn(ch)=101, Expiration date of 12/31/07.
Upper Arkansas Segment 5: Zn(ch)=78, Expiration date of 12/31/07
Upper Arkansas Segment 7: Zn(ch)=115, Expiration date of 12/31/07.
Upper Arkansas Segment 22a: pH=5.6-9.0, Expiration date of 12/31/07.
Fountain Creek Segment 1a: F.Coli=229/100 mL, Expiration date of 12/31/07.
Fountain Creek Segment 2b: Se(ch)=23, Expiration date of 12/31/07.
Fountain Creek Segment 6: Se(ch)=10, Expiration date of 12/31/07.
Middle Arkansas Segment 2: E. coli=349/100 mL, Expiration date of 12/31/07.
Middle Arkansas Segment 3: Se(ch)=11.7, Expiration date of 12/31/07.
Middle Arkansas Segment 4a: Se(ch)=710, Expiration date of 12/31/07.
Middle Arkansas Segment 14: Se(ch)=6, Expiration date of 12/31/07.
Middle Arkansas Segment 18a: Zn(ch)=542, Expiration date of 12/31/07.
Middle Arkansas Segment 13: F. coliform=336, Expiration date of 12/31/07.
Lower Arkansas Segment 2a: Fe(ch)=2179, Expiration date of 12/31/07
Lower Arkansas Segment 3a: Fe(ch)=2500 and Se(ch)=52, Expiration date of 12/31/07
Lower Arkansas Segment 9c: Fe(ch)=4875, Expiration date of 12/31/07.
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.
Upper Arkansas segment 2b: Seasonal type (i) temporary modifications were adopted: Cd(ch)=1.34 and Zn(ch)=649, expiration date = 12/31/2012. These type (i) temporary modifications are intended to allow time to see if the remediation at the California Gulch Superfund Site improves water quality. The need for these temporary modifications will be reviewed in 2010 and 2011.
Upper Arkansas segment 2c: Seasonal type (i) temporary modifications were adopted: Cd(ch)=0.79 and Zn(ch)=225, expiration date = 12/31/2012. These type (i) temporary modifications are intended to allow time to see if the remediation at the California Gulch Superfund Site improves water quality. The need for these temporary modifications will be reviewed in 2010 and 2011.
Upper Arkansas segment 3: Cd(ch)=0.48, expiration date = 12/31/2012. This type (iii) temporary modification is intended to allow remediation. The need for these temporary modifications will be reviewed in 2010 and 2011.
Upper Arkansas segment 8b: Cd(ch)=1.2, Pb(ch)=6, and Zn(ch)=295, expiration date = 12/31/2012. This temporary modification is intended to allow Res-ASARCO JV, Black Cloud Mine, adequate time to assess any potential changes to its discharge permit. The need for these temporary modifications will be reviewed in 2010 and 2011.
Upper Arkansas segment 12a: Zn(ch)=120, expiration date = 12/31/2012. This temporary modification is intended to allow Young Life Frontier Ranch, DOW-Chalk Cliffs Fish Hatchery, Christian Mission and Mt. Princeton Hot Springs adequate time to assess any potential changes to discharge permits. The need for these temporary modifications will be reviewed in 2010 and 2011.
Fountain Creek segment 1a: Se(ch)=8.7, expiration date = 12/31/2012. This temporary modification is intended to allow City of Colorado Springs, Castle Concrete Co., Colorado Springs Utility and Manitou Springs adequate time to assess any potential changes to discharge permits. The need for this temporary modification will be reviewed in 2010 and 2011.
Fountain Creek segment 2a: Cu(ac/ch)=current condition, expiration date = 12/31/2009. This temporary modification is intended to allow the Security Sanitation District adequate time to assess any potential changes to its discharge permit. The need for this temporary modification will be reviewed in 2007 and 2008.
Fountain Creek segment 3a: Pb(ch)=2.1, expiration date = 12/31/2012. This temporary modification is intended to allow Cherokee WSD adequate time to assess any potential changes to its discharge permit. The need for this temporary modification will be reviewed in 2010 and 2011.
Fountain Creek segment 6: Cu(ac/ch)=current condition, expiration date = 12/31/2009. This temporary modification is intended to allow CSU, Coperstone, City of Colorado Springs, Sun Construction and Tri-Lakes WWTF adequate time to assess any potential changes to discharge permits. The need for this temporary modification will be reviewed in 2007 and 2008.
Middle Arkansas segment 4b: Se(ch)=5.6, expiration date of 12/31/2012.
Middle Arkansas segment 5: Se(ch) =18.7, expiration date of 12/31/2012.
Middle Arkansas segment 6: Se(ch)=39.0, expiration date of 12/31/2012.
Middle Arkansas segment 9: Se(ch)=8.6 expiration date of 12/31/2012.
Middle Arkansas segment 10: Se(ch)=15.0, expiration date of 12/31/2012.
Middle Arkansas segment 12: Se(ch)=29.5, expiration date of 12/31/2012.
Middle Arkansas segment 18a: Se(ch)=179.0, expiration date of 12/31/2012.
Lower Arkansas segment 1a: Se(ch) =existing quality (type i), SO4 =existing quality (type i) expiration date of 12/31/2012.
Lower Arkansas segment 1b: Se(ch) =17, expiration date of 12/31/2012.
Lower Arkansas segment 1c: Se(ch) =22.5, expiration date of 12/31/2012.
Lower Arkansas segment 2a: Fe(Trec)=2179, expiration date of 12/31/2012.
Lower Arkansas segment 4: Se(ch) =27, expiration date of 12/31/2012.
Lower Arkansas segment 5a: Se(ch) =11.2, expiration date of 12/31/2012.
Lower Arkansas segment 6: Se(ch) =21.3, expiration date of 12/31/2012.
Lower Arkansas segment 7: Se(ch) =6.4, expiration date of 12/31/2012.
Lower Arkansas segment 9a: Se(ch) =17.8, expiration date of 12/31/2012.
Lower Arkansas segment 9b: Se(ch) =52.4, expiration date of 12/31/2012.
Lower Arkansas segment 9c: Se(ch) =15, expiration date of 12/31/2012.
Lower Arkansas segment 11: Se(ch) =17, expiration date of 12/31/2012.
Upper Arkansas Segment 20 - In the 2002 Basin hearing, the Division proposed to add the water supply classification and associated water quality standards to segment 20. CC&V presented testimony at that hearing which showed that naturally elevated levels of manganese and sulfate were of concern and suggested a resegmentation. In response, the Division suggested that a footnote be adopted stating that the manganese standard should apply at the point of intake. This was done for manganese but sulfate was inadvertently omitted. The Commission revised the existing footnote to include sulfate.
Wildhorse Creek, Middle Arkansas River segment 4a - The Commission adopted a site-specific ambient-based selenium standard for this segment based upon information documenting both the natural sources of selenium in the basin and the lack of anthropogenic activity that might potentially exacerbate instream selenium loads.
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.
The reference to "Fish Organics" was corrected to "Fish Ingestion Standards" to incorporate the appropriate standards from both the organics table and the metal parameter table in Regulation No. 31.
The segment description for Upper Arkansas, segment 5 was changed from "except for specific listings in Segments 6 through 12" to "except for specific listings in Segments 6 through 12b"
The segment description for Upper Arkansas, segment 12b was changed from "from the sources" to "from the source".
The segment description was changed for Upper Arkansas, segment 16a to exclude the reference to Section 9 to T17S, R73W.
The segment description was changed for Upper Arkansas, segment 17b to exclude the reference to Section 1 to T17S, R72W.
The Footnote to Table one in connection to Upper Arkansas, segment 20 was corrected to include sulfate in addition to dissolved manganese.
The segment description was changed for Lower Arkansas, segment 3a to exclude Lower Arkansas segment 3c.
The segment description was changed for Lower Arkansas, segment 5a to clarify the segment description.
The previously appl icable temporary modifications of Pb(ch) = 6.5 µg/L and Zn(ch) = 137 µg/L are deleted and an ambient based standard of Zn(ac) = 150 µg/L is adopted. A TMDL was cooperatively developed for Segment 1b by the Division and Climax in 2003 and subsequently approved by EPA. Climax took voluntary action in 2005 to remove and reclaim tailings identified in the TMDL that contributed to lead and zinc loadings in Segment 1b. The Commission found that this remedial action, together with the previous reclamation of the Climax property, resulted in an irreversible man-induced ambient water quality level for acute zinc that is higher than TVS but is adequate to protect the classified uses. Therefore, pursuant to Regulation 31.7(1)(b)(ii), the Commission adopted a site-specific acute standard for zinc based on the 95th percentile of the available data for the last three-year period of record.
Historic mining activities in and around the California Gulch basin have significantly impacted water quality in segments 2b, 2c, and 6 of the Upper Arkansas River. Environmental remediation of mine wastes within the California Gulch Superfund Site has resulted in significant improvement of the water quality within these segments. Additional water quality improvements are expected as Site remediation is completed. Accordingly, the Commission is adopting revised numeric standards for cadmium and zinc for segments 2b and 2c. The revised numeric standards will serve as future remediation goals for the Site. Furthermore, the Commission has reclassified the tributaries of California Gulch from segment 5 to segment 6 to more accurately reflect the use and characteristics of those tributaries.
Upper Arkansas segments 2b and 2c of the Arkansas River Basin Revised Numeric Standards for Cadmium and Zinc - The revised cadmium and zinc numeric standards for segments 2b and 2c are based on the application of the EPA approved recalculation methodology. GEI Consultants Inc./Chadwick Ecological Division completed the recalculation on behalf of Resurrection Mining Company, one of the PRPs implementing portions of the Superfund remediation. The recalculation methodology provides new numeric standards for cadmium and zinc that are protective of the aquatic communities found in segments 2b and 2c of the Arkansas River Basin. The cadmium and zinc numeric standards derived from the recalculation methodology are intended to guide additional remediation work within the Site. Because remediation work at the site is ongoing, the Commission is aware actual water quality within segments 2b and 2c will occasionally exceed the revised cadmium and zinc numeric standards over the next three to five years, especially during spring run-off conditions. For this reason, the Commission also adopted a seasonal temporary modification for the months of April and May for both segments 2b and 2c. The Commission rejected a proposal by Trout Unlimited that the temporary modification period be extended to June, since the data shows that the standards are attained during the month of June.
Seasonal Type (i) Temporary Modifications - For Segment 2b, the Commission adopted 649 µg/l as the temporary zinc numeric standard and adopted 1.34 µg/l as the temporary cadmium numeric standard. For segment 2c, the Commission adopted 225 µg/l as the temporary zinc numeric standard and adopted 0.79 µg/l as the temporary cadmium numeric standard. These were calculated as seasonal temporary modifications by using 85th percentile of all available water quality data and average hardness data collected during the months of April and May from 2001-2006. In adopting the seasonal temporary modifications, the Commission acknowledged the uncertainty regarding long-term water quality conditions following completion of remediation activities at the Site. This uncertainty arises because water quality improvements resulting from source remediation projects will not be known for a period of time following the completion of the activities because the source control will not always immediately impact water quality within segments 2b and 2c.
Upper Arkansas segments 2b and 2c of the Arkansas River Basin Revised Antidegradation Baseline -Based on continued remediation activities at the Site, the Commission determined that the default baseline for antidegradation established in the September 30, 2000 Basic Standards no longer applies to segments 2b and 2c. Accordingly, the Commission adopted a revised anti-degradation baseline for segments 2b and 2c, including a note in the designation column in the Stream Classifications and Water Quality Standards tables to indicate that the September 30, 2000 default baseline date does not apply to these specific segments. In accordance with the Basic Standards (5 CCR 31.8), the Commission found that the appropriate baseline date and baseline water quality should be determined at the time that any new activity triggers an anti-degradation review. Thus, the Commission adopted a revised anti-degradation baseline for segments 2b and 2c whereby the anti-degradation review and collection of water quality data shall commence upon the same date any new activity occurs in either segment 2b or 2c.
Upper Arkansas segments 5 and 6 of the Arkansas River Basin - The Commission determined that California Gulch tributaries, previously classified within segment 5 as Aquatic Life Cold 1, Recreation 1a, Water Supply, and Agriculture, were inappropriately classified. This determination is based on the use, physical characteristics, and water quality characteristics of the California Gulch tributaries, which include Malta, Airport, Pawnee, Georgia, Oregon, Nugget, White, Stray Horse and Little Stray Horse Gulch. Specifically, the Commission's review of evidence presented during the 2007 rulemaking hearing, and re-evaluation of the 1990 Use Attainability Analysis ("UAA") of California Gulch performed by the Colorado Division of Wildlife ("CDOW"), indicated that the California Gulch tributaries lacked qualities to appropriately identify them as Aquatic Life Cold 1, Recreation 1a, and Water Supply. In an earlier rulemaking, the Commission relied on CDOW's 1990 UAA to establish that segment 6 should not contain numeric water quality standards. While current evidence indicates that California Gulch water quality has improved since the 1990 UAA, the conditions outlined in the 1990 UAA continue to limit potential aquatic communities in California Gulch and its tributaries. Therefore, the Commission determined it is inappropriate to maintain numeric water quality standards for those tributaries, and concluded that those California Gulch tributaries located in segment 5 should be reclassified as part of segment 6 as Recreation 2, Agriculture.
CC&V originally proposed that a qualifier be added to Segment 21 noting that fish were present only in the lower 1.5 miles of Cripple Creek, based on study results from long-term monitoring of the aquatic community in Cripple Creek showing that fish existed only in the lower 1.5 miles of Cripple Creek because of physical barriers, flow constraints, and habitat conditions. The Division's alternate proposal was to resegment Cripple Creek into Segments 21a and 21b. Regulation 31.6(4)(c) provides that segments will generally be delineated according to points where the use, physical characteristics or water quality characteristics change significantly enough to require a change in use classifications or water quality standards. The Commission accordingly resegmented Segment 21. The water quality standards of Segment 21a are based on protection of aquatic life without fish and the water quality standards of Segment 21b are based on full protection of aquatic life, including trout.
In this rulemaking the Commission considered two separate proposals to add a water supply classification to segments immediately upstream of segments with existing water supplies. (Upper Arkansas segment 21 and Middle Arkansas segment 4e). The Commission has determined that it is not appropriate to add a water supply classification to either of these segments at this time. The evidence submitted does not demonstrate an immediate threat to either water supply that is not adequately addressed by existing water supply classifications for the segments from which the water supplies are withdrawn.
However, with the evolution of source water planning and protection efforts under the State's drinking water program, the Commission believes that the relationship between surface water use classifications and source water protection efforts should be explored further. In general, the Commission believes that the water quality classification and standards system should be consistent with and supportive of source water protection efforts. The Commission requests that the Division work with interested stakeholders to develop a proposed approach to this issue for consideration in future rulemaking actions.
Depending upon the results of such discussions, it may be appropriate to revisit either or both of the water supply classification proposals advanced in this rulemaking during a future review of this basin.
The Division proposed that the use-protected designation be removed from Segment 21, since the presumption that such a designation is appropriate for aquatic life class 2 cold water streams has been eliminated. CC&V argued that the use-protected designation should be retained, based on an argument that Segment 21 is an effluent dominated stream. The Commission has determined that the data and analysis submitted by CC&V is not adequate to demonstrate that Segments 21a and 21b meet the effluent dominated definition, because using average conditions in a comparison does not appropriately characterize what occurs in a year that is wetter or drier than average. It is inappropriate to extrapolate from a comparison of the average condition to that which occurs eight out of ten years.
Pueblo West Metropolitan District proposed resegmentation of Golf Course Wash, a tributary to Pueblo Reservoir, from Middle Arkansas Segment 4d to a new Segment 4e. They proposed this new segment be classified as aquatic life warm class 2, recreation class E and agriculture with a use-protected designation. Numeric standards would be applied only for recreation and agriculture uses with the addition of ammonia. A temporary modification of the ammonia standards of NH3 (ac/ch)=TVS old was also proposed. The Commission declined to adopt this temporary modification because the evidence submitted did not demonstrate a need for the temporary modification. Rather, the evidence demonstrated that Pueblo West may be able to comply with the new ammonia standard. Should further investigation demonstrate that additional time will be required to comply with the ammonia standard, the Commission assumes that a discharge permit compliance schedule may be available. If it should be determined that a compliance schedule is not available or not adequate for Pueblo West to comply with the ammonia standard, a temporary modification can be reconsidered at a later date.
Pueblo Board of Water Works provided an alternative proposal to add a water supply classification or at least a full suite of numeric standards to protect aquatic life, because the downstream segment (Pueblo Reservoir) serves as the City's water supply. The Commission has determined that the adoption of a water supply classification or additional standards to protect this use is not appropriate at this time, as explained above in section P of this statement of basis and purpose,
Tri-Lakes Wastewater Treatment Facility proposed a site-specific copper water effects ratio for segment 6 of Monument Creek using a combination of the streamlined water effects ratio (WER) and the Biotic Ligand Model (BLM). In response to EPA's February 2007 Copper Criteria, Tri-Lakes revised their proposal to a temporary modification based on uncertainty. The Commission adopted Tri-Lakes revised proposal.
This temporary modification recognizes the uncertainty created by the evolving guidance regarding use of the WER, BLM, or other appropriate copper standard to protect the aquatic life use, as well as uncertainty about whether protective levels can feasibly be attained in the effluent of the Tri-Lakes WWTF. An additional source of uncertainty is whether or not a translator study will provide adequate relief for the WWTF.
The temporary modification has been set to expire on December 31, 2009. During the term of the temporary modification Tri-Lakes will investigate the efficacy of a translator from dissolved criterion to a potentially dissolved (or total recoverable) permit limit. In addition, the Commission anticipates that there will be an expanded dialogue between EPA, the Division and interested parties regarding the appropriate methods for setting site-specific copper stream standards.
With a 2009 expiration date, Tri-Lakes' progress will be reported to the Commission at the December 2007 and December 2008 annual Temporary Modification Review hearing, and the need for the temporary modification will be reviewed at that time. If a translator is inadequate, the Commission recognizes that more time may be needed to develop a site-specific standards proposal.
The temporary modification is set at "current condition." It is the intention of the Commission that when implementing this temporary modification in a CDPS permit, and interpreting the term current condition, the Division will assess the current effluent quality, recognizing that it changes over time due to variability in treatment plant removal efficiency and influent loading from industrial, commercial, and residential sources. One necessary element of an approach to maintain the current condition would be a requirement that the total loading from commercial and industrial contributors be maintained at that level as of the date of adoption of the temporary modification and that neither the concentration nor the frequency of high concentration shall increase over historic levels and frequency.
Based on evidence that shows that water quality meets the requirements of 31.8(2)a, the Outstanding Water (OW) designation was added to the new Fountain Creek Segment 1b: Severy Creek, and all tributaries, from the source to a point immediately upstream to where US Forest Service Road 330 crosses the stream and the new Fountain Creek Segment 3b: Bear Creek, and all tributaries, from the source to a point upstream of GPS coordinates N3847682, W10454917 (this location is at elevation 8,200 feet above sea level at a 250 ° angle and 3,000 feet from the trailhead of the Mount Buckhorn Trail off High Drive). Two new segments were created for these two waters. The Commission understands that there are existing land uses in place in these watersheds. The evidence demonstrates that these existing land uses are compatible with the OW designation since the current high level of water quality has been attained with these uses in place. It is the Commission's intent that this OW designation should not be used to establish additional permit requirements for existing uses within this area.
Security Sanitation District proposed a site-specific copper water effects ratio for segments 2a of Fountain Creek using a combination of the streamlined water effects ratio (WER) and the Biotic Ligand Model (BLM). In response to EPA's February 2007 Copper Criteria, Security revised their proposal to a temporary modification based on uncertainty. The Commission adopted Security's revised proposal.
Similar to the situation on Monument Creek segment 6 (discussed above) this temporary modification recognizes the uncertainty created by the evolving guidance regarding use of the WER, BLM, or other appropriate copper standard to protect the aquatic life use, as well as uncertainty about whether protective levels can feasibly be attained in the effluent of the Security WWTF. An additional source of uncertainty is whether or not a translator study will provide adequate relief for the WWTF.
The temporary modification has been set to expire on December 31, 2009. During the term of the temporary modification Security will investigate the efficacy of a translator from dissolved criterion to a potentially dissolved (or total recoverable) permit limit. In addition, the Commission anticipates that there will be an expanded dialogue between EPA, the Division and interested parties regarding the appropriate methods for setting site-specific copper stream standards.
With a 2009 expiration date, Security's progress will be reported to the Commission at the December 2007 and December 2008 annual Temporary Modification Review hearings, and the need for the temporary modification will be reviewed at that time. If a translator is inadequate, the Commission recognizes that more time may be needed to develop a site-specific standards proposal.
The temporary modification is set at "current condition." It is the intention of the Commission that this term be interpreted as discussed in section R above.
The Commission adopted site-specific ambient- and attainability-based underlying standards for selenium on several segments in the Middle and Lower Arkansas, and Fountain Creek sub-basins. These included Fountain Creek segment 2b, Middle Arkansas segments 3 and 4a, and Lower Arkansas segment 1a. Ambient-based standards were adopted for Middle Arkansas segments 3 and 4a based upon showings by the City of Pueblo and the Division, respectively, that selenium loading to both segments results from natural sources and is not exacerbated by land use or other reversible, anthropogenic factor.
Evidence developed by the City of Pueblo indicates that some degree of selenium and sulfate load reduction is attainable for Fountain Creek segment 2b and Lower Arkansas segment 1a. Reductions of one and six percent respectively are feasible given the current extent of irrigated agriculture within these two sub-basins. The Commission has therefore adopted attainability-based underlying selenium and sulfate standards for these segments, while retaining temporary modifications set at existing levels.
The temporary modifications for selenium and sulfate in Lower Arkansas segment 1a are identified as type i temporary modifications. The expectation is that the Division and stakeholders will identify appropriate Best Management Practices as necessary to achieve the necessary load reductions within a twenty-year period.
The City of La Junta proposed a type iii temporary modification for selenium for Lower Arkansas segment 1b of 27.1 ug/L chronic and 36 ug/L acute, with an expiration date of December 31, 2020. Based on discussion with the Division, La Junta revised its proposal to be "Se = current condition, expiration date 12/31/2009". The Commission has adopted La Junta's revised proposal.
This temporary modification recognizes the uncertainty regarding the relative magnitude of natural sources, irreversible man-induced sources and reversible sources of selenium. There is also uncertainty regarding what levels are appropriate to protect the aquatic life use. In addition, there is uncertainty about whether protective levels can feasibly be attained in the effluent of La Junta's WWTF.
The temporary modification has been set to expire on December 31, 2009. During the term of the temporary modification La Junta will investigate the efficacy of modifying the way RO brine is blended with their traditional wastewater.
With a 2009 expiration date, La Junta's progress will be reported to the Commission at the December 2007 and December 2008 annual Temporary Modification Review hearings, and the need for the temporary modification will be reviewed at that time. During this same time, the Division will continue to support efforts to quantify selenium loading, particularly selenium loads from un-irrigated upland areas, and to begin to implement selenium reductions, which will take longer than two years.
The temporary modification is set at "current condition." It is the intention of the Commission that when implementing this temporary modification in a CDPS permit, and interpreting the term current condition, the Division will assess the current effluent quality, recognizing that it changes over time due to variability in treatment plant removal efficiency and influent loading from industrial, commercial, and residential sources. One necessary element of an approach to maintain the current condition would be a requirement that the total loading from commercial and industrial contributors be maintained at that level as of the date of adoption of the temporary modification and that neither the concentration nor the frequency of high concentration shall increase over historic levels and frequency.
The State of Kansas presented information that salinity and selenium concentrations increase between John Martin Reservoir and the state line (Lower Arkansas segment 1c), and that the concentrations of these constituents has increased over the last decade. Kansas participated in this rulemaking in order to expedite the identification of appropriate water quality endpoints for Lower Arkansas segment 1c, thereby facilitating development of TMDLs addressing these parameters. The Commission decided that, while adequate information is available to characterize irreversible selenium loading on several segments within the Arkansas basin, such is not yet the case in the lowermost portion of the basin. The Commission does, however, acknowledge the efforts undertaken by Kansas to address these pollutants in TMDLs promulgated earlier (sulfate), and planned for later this year (selenium) for the Arkansas River as it enters Kansas. The Commission expects the Division to work closely with the State of Kansas and stakeholders in addressing these issues upstream of the state line. The Division will work on UAAs to support attainable underlying standards, TMDLs where appropriate underlying standards have been adopted and implementation of remedial actions (BMPs) throughout the basin to reduce the loading of selenium.
Kansas asked the Commission to establish a Salinity Task Force that would lay the ground work for evaluating research results, selecting appropriate BMP's and formulating a long-term strategy of salt load reduction to the river. At this time, the Commission cannot commit to such an expenditure of resources. However, the state is supporting a watershed restoration planning effort sponsored by Southeast Colorado Resource Conservation and Development with Clean Water Act Section 319 funding.
Later this fall Colorado will be in a better position to determine whether resources are available that could be allocated towards this issue. The Division will be completing a statewide prioritization of watershed restoration of impaired waters (as required by EPA) and will report the information to the Commission. This information may be used by the Commission to recommend revisions to the proposed priority watersheds.
PARTIES TO THE RULEMAKING
5 CCR 1002-32.40