Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-36 - REGULATION NO. 36 - CLASSIFICATIONS AND NUMERIC STANDARDS FOR RIO GRANDE BASIN
Section 5 CCR 1002-36.20 - STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JUNE, 1998 HEARING
Current through Register Vol. 47, No. 5, March 10, 2024
The provisions of 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for the 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. Overview
As part of the CERCLA activities at the Summitville Mine site, the Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division (HMWMD) was tasked by EPA to perform a Use Attainability Assessment (UAA) on the Alamosa River system. The HMWMD entered into a contractual arrangement with the Colorado Department of Natural Resources, Division of Minerals and Geology (DMG) and Division of Wildlife (DOW) for services to perform the UAA with the goal to determine the ambient conditions of the river system for two periods:
The notice for this rulemaking included several proposals by the HMWMD and DMG that were later withdrawn from consideration. In particular, proposals for less stringent water quality classifications, standards and temporary modifications for several segments downstream of the Wightman Fork were withdrawn pending further analysis and discussion of the Summitville cleanup options. In this rulemaking, the Alamosa River Joint Objectors Group requested that the Commission take formal action to direct that a cooperative partnership be established for the future evaluation of issues related to water quality classifications and standards for the Alamosa River. While the Commission does not believe that it is necessary or appropriate for it to take formal action in this regard as a result of this rulemaking, the Commission does wish to encourage an open and inclusive public process for the further assessment of future water quality conditions in the Alamosa River basin. Such cooperative efforts can hopefully include data sharing and an opportunity for public input into the evaluation of Summitville cleanup alternatives. Interested parties are encouraged to request an opportunity to brief the Commission on the progress of these future efforts at appropriate intervals, perhaps annually. The Commission also is encouraged that the Governor's Office has established a task force of state, federal and local interests to address broader Alamosa River watershed initiatives.
Finally, the Commission notes that during this proceeding parties raised potential revisions to water quality classifications and standards for Alamosa River segments 6 and 7. However, it was determined that revisions to the water quality classifications and standards for these segments were not within the scope of the notice for this rulemaking, and therefore could not be considered in this proceeding. Any proposed revisions to these segments can be raised in the next triennial review of Rio Grande classifications and standards.
B. Segment 3a
During this rulemaking it became apparent that there were errors in the water quality classifications and standards currently published in the Colorado Code of Regulations for Alamosa River segment 3a. Segment 3a was first established in its current configuration as the result of a November, 1993 rulemaking hearing. At that time, a class 1 aquatic life classification was adopted for this segment, along with a combination of table value and ambient quality-based numerical standards. That version of the classifications and standards for segment 3a carried through copies of the Rio Grande Basin classifications and standards regulation that reflected revisions adopted in 1995. However, it appears that when this regulation was refiled in 1997 as a part of an overall renumbering of Water Quality Control Commission regulations, an incorrect version of classifications and standards for segment 3a was included.
As a result of the current rulemaking, the Commission has decided to adopt a class 2 aquatic life classification for segment 3a. This classification is based on biological and chemical data indicating that this segment is not capable of sustaining a wide variety of cold water biota, including sensitive species, due to uncorrectable water quality conditions. The UAA indicates that prior to any mining in this area, the natural water quality for a number of pollutants would have exceeded concentrations needed to fully support an aquatic life class 1 use, due to the erosion of naturally exposed, mineralized rock and aggregate. There was very limited mining in the segment 3a watershed, which is upstream of any significant influence of the Summitville Mine. The biological assessment conducted as part of the UAA indicates that the aquatic life present in segment 3a consists only of limited numbers of macroinvertebrate taxa.
The Commission does not believe that the Alamosa River Joint Objectors Group proposal to adopt a seasonal class 1 aquatic life classification for this segment is appropriate. Even though water quality generally improves for the summer months, due to water quality conditions in other months this segment is not "capable of sustaining a wide variety of cold water biota."
Data collected for the UAA were sufficient to determine the 85th percentile value of in-stream water quality levels for each of the four seasons of the year. The chemical analysis indicates that the pre-mining 85th percentile concentration for aluminum is chronically and acutely toxic to trout in each of the seasons. Therefore, the Commission has retained the Al(ac) =750 standard for all seasons. The lower 15th percentile for pH ranges from 3.52 in the winter to a pH of 4.73 in the summer. The Commission has adopted seasonal pH standards reflecting the current data. Finally, revised manganese standards have been adopted (Mn(ac/ch)=TVS) based on revised aquatic life table values for manganese adopted in the Basic Standards and Methodologies for Surface Water in a November, 1997 rulemaking hearing.
C. New Segments 3b and 3c
Observational data collected in the 1970s and presented in the UAA indicates that a reproducing fish population may have been present in the portion of the Alamosa River below Fern Creek to the inlet of Terrace Reservoir. Based on this information and other data presented in the UAA, the Commission has split segment 3b into two segments, an upstream segment 3b and a downstream segment 3c. Segment 3b includes the Alamosa River reach between Wightman Fork and Fern Creek. Segment 3c includes the Alamosa River from a point just above the confluence with Fern Creek to the inlet of Terrace Reservoir. It is expected that improved water quality following the Summitville cleanup will again support a fishery, and a reestablished, reproducing fishery is the remediation goal for segment 3c.
In view of the HMWMD and DMG withdrawal of their proposal for a revised classification for segment 3b, and considering the input from other parties and interested persons, the Commission has not made any changes to the water quality classifications for this segment. The numerical water quality standards for segment 3b are also being left unchanged at this time, with two exceptions. The Commission has adopted Mn(ac/ch) = TVS standards, based on the aquatic life table value criteria for manganese recently adopted in the Basic Standards, as noted above. In addition, corrections were made to the arsenic standards for segment 3b, to reflect the fact that no water supply classification exists for this segment.
The Commission has also retained the existing aquatic life class 1 use for the new segment 3c. This classification is supported by the UAA's chemical data and geochemical modeling of pre-mining (pre-1870) conditions. These data and the modeling indicate that, with the exception of iron, the long-term water quality in segment 3c will be better than table value standards. Therefore, the Commission has adopted table value standards for this new segment, with the exception of iron, for which the previous 12000 ug/l standard has been retained. The information presented in this hearing does not demonstrate that the 1000 ug/l table value for iron is attainable in this segment.
Finally, the Commission was not persuaded by the Alamosa River Joint Objectors Group argument that a 200 ug/l manganese standard should be adopted for segments 3b and 3c, since the downstream agricultural use is protected by the manganese standards in effect for segments 8, 9 and 10.
D. New Segments 4a and 4b
The Commission has adopted the proposed resegmentation of segment 4 into two segments, 4a and 4b. With the exception of segment 4b described below, the remaining parts of the previous segment 4 are renamed as segment 4a and will retain the current water quality classifications and standards. The Commission was not persuaded by the Alamosa River Group Objectors Group argument that numerical standards for metals and more restrictive pH standards should be adopted for segment 4a, since this segment is not classified to support aquatic life.
The new segment 4b consist of that portion of Iron Creek from its source to immediately above the confluence with Tributary G. The Commission has adopted an aquatic life class 1 use for this new segment with table value standards. The classification and standards are based on the UAA biological and chemical assessment, which demonstrates that the upper reaches of Iron Creek supported a reproducing fishery.
E. Segments 8, 9 and 10
The Commission has retained the existing water quality classifications for segments 8, 9 and 10. The Commission declined to adopt the Alamosa River Joint Objectors Group proposal to upgrade segment 8 (Terrace Reservoir) to aquatic life class 1. There was insufficient evidence submitted that a class 1 use is attainable for Terrace Reservoir, in view of fluctuations in the reservoir level due to irrigation use.
Only limited revisions to the numerical standards for these segments have been adopted by the Commission. Corrections were made to the arsenic standards for segments 8 and 10, to reflect the fact that no water supply classification exists for those segments. In addition, acute and chronic table value standards for aluminum were adopted for these segments, based on chemical and modeling information indicating that they should be attainable following Summitville cleanup.
F. Other Issues
The Alamosa River Joint Objectors Group also proposed in this rulemaking that the Commission take action to direct completion Alamosa River total maximum daily loads (TMDLs) by a specified date. Issues concerning priorities for and timing of completion of TMDLs are beyond the scope of this rulemaking, and the Commission is therefore taking no formal action with respect to TMDLs at this time. However, in view of the obvious importance of these issues to the downstream community, the Commission encourages the completion of Alamosa River TMDLs by those agencies involved with Alamosa River cleanup and water quality standards attainment issues.
Finally, in this hearing the Commission has corrected typographical errors in the chemical symbols for NH3, Cl2, NO2, NO3, and SO4 in the tables for segments throughout the basin.
PARTIES/MAILING LIST STATUS FOR THE JUNE 10, 1998 RULEMAKING HEARING
