5 Colo. Code Regs. § 1002-31.6
Current through Register Vol. 47, No. 20, October 25, 2024
Section 5 CCR 1002-31.6 - PROCESS FOR ASSIGNING CLASSIFICATIONSThe Commission is responsible for classifying state waters as set forth in sections 25-8-202(1)(a), and 25-8-203, C.R.S. All state surface waters may be classified in one or more of the use classifications as set forth in section 31.13.
Waters shall be classified for the present beneficial uses of the water, or the beneficial uses that may be reasonably expected in the future for which the water is suitable in its present condition or the beneficial uses for which it is to become suitable as a goal. The assignment of one or more classifications to a portion of the state surface waters is based upon its current suitability for the designated uses or goals for future uses. Where the use classification is based upon a future use for which the waters are to become suitable, the numeric standards assigned to such waters to protect the use classification may require a temporary modification to the underlying numeric standard and an implementation plan for eliminating the temporary modification.
When assigning classifications to waters of a given area, the Commission will consider the goals, objectives, and requirements of federal and state statutes and regulations, recommendations of the regional wastewater management plans (208 plans); 208 plans of adjoining regions; testimony, comments, and documents presented at public hearings on the issue; and other relevant information.
(1)Considerations in Assigning ClassificationsThe following will serve to guide the Commission in assigning classifications:
(a) Classifications should be directed towards the realization of the water quality goals as set forth in the federal and state Acts.(b) It is state law and policy to prevent any water quality degradation that can interfere with present uses.(c) Upstream classifications must not jeopardize downstream classifications or actual uses.(d) Classification must protect all current classified and actual uses, unless it is determined after a public hearing that downgrading is justifiable. (See section 31.6(2)(b)).(e) Classifications should be for the highest water quality attainable. Attainability is to be judged by whether or not the use classification can be attained in approximately twenty (20) years by any recognized control techniques that are environmentally, economically, and socially acceptable as determined by the Commission after public hearings. At a minimum, uses are deemed attainable if they can be achieved by the imposition of effluent limits required under the federal Act for point sources and cost-effective and reasonable best management practices for nonpoint source control, in accordance with duly adopted regulations.(f) Relevant physical, chemical and biological characteristics are valid water quality concerns that may be taken into account in the classification process.(2)Upgrading and Downgrading(a)UpgradingThe state shall maintain those water use classifications which are currently being attained. Where existing classifications specify fewer designated water uses than those which are presently being attained, the Commission shall upgrade the designated classification to reflect the uses actually being attained.
(b)DowngradingAt a minimum, the state shall maintain those water use classifications currently designated, unless it can be demonstrated that the existing classification is not presently being attained and cannot be attained within a twenty (20) year time period. Nonattainability must be due to at least one or more of the following conditions:
(i) Naturally occurring pollutant concentrations prevent the attainment of the use within a twenty (20) year period; or(ii) Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the use, unless these conditions may be compensated for by the discharge of sufficient volume of effluent discharges without violating state water conservation requirements to enable uses to be met; or(iii) Human caused conditions or sources of pollution prevent the attainment of the use and cannot be remedied within a twenty (20) year period or would cause more environmental damage to correct than to leave in place; or(iv) Dams, diversions or other types of hydrologic modifications preclude the attainment of the use, and it is not feasible to restore the waterbody to its original condition or to operate such modification in a way that would result in the attainment of the use; or(v) Physical conditions related to the natural features of the waterbody, such as the lack of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses; or(vi) Controls more stringent than those required by section 301(b) and 306 of the federal Act would result in substantial and widespread economic and social impact; or(vii) Agricultural practices which are considered satisfactory for the locality. It must be demonstrated that these agricultural practices preclude the present classifications. Satisfactory practices will be approved by the Commission based on evidence from areawide 208 agencies, soil conservation districts, agricultural extension services and other public input. An additional reason for revising classifications will be where previous classifications had no basis in fact and did not reflect actual beneficial uses. Such corrections to classifications shall not be considered downgrading. See e.g., section 31.6 regarding hearings pursuant to section 25-8-207, C.R.S.
(3)Procedures for Assigning or Changing Classifications(a)General(i) Assigning or changing a classification shall be accomplished by rule after a rulemaking hearing. Rulemaking hearings to consider a classification will be conducted according to the Procedural Regulations of the Commission. At a minimum, the Commission shall review classifications once every three years. Any interested person have shall have the right to petition the Commission to assign or change a stream classification. Such petition shall be open to the public inspection. Except as provided below, pursuant to section 24-4-103(7), C.R.S., action on such petition shall be within the discretion of the Commission. The Commission may also decide to consider a classification on its own motion.(ii) In making a decision regarding a proposed classification, the Commission will consider the principles set forth in this regulation. The decision will be made by the Commission applying its expertise after analyzing the evidence presented at public hearing and considering the requirements of law, its own policies, and all other matters deemed pertinent in the discretion of the Commission.(iii) Where the classifications of a waterbody segment do not include an aquatic life classification or recreation class E, P, or U, as a part of the triennial review of the segment the Division shall review any prior use attainability analyses or other basis for omission of one or more of the above classified uses. If the justification for the omission is determined not to be consistent with accepted use attainability procedures, the Division or other party, if any, advocating the omission shall perform a supplemental analysis to provide a basis for a Commission determination whether such uses are attainable. When the Commission wishes to remove an aquatic life class 1 or 2 or recreation class E, P, or U classification, the Division shall conduct or the Commission shall require the petitioner to conduct, in consultation with the Division, a use attainability analysis to justify the proposed change.(b)Section 25-8-207(i) Procedural requirements relating to reviews pursuant to section 25-8-207, C.R.S., are set forth in the Procedural Regulations, Regulation No. 21, 5 CCR 1002-21.(ii) The Commission shall, upon petition, or upon its own motion, review existing stream standards, classifications or water quality designations in subsection (iii) below. The Commission may revise stream standards, classifications and designations pursuant to the criteria listed in subsection (iv) below.(iii) The Commission shall make a finding of inconsistency, taking into account sections 25-8-102 and 25-8-104, C.R.S., if a water quality designation does not conform with the provisions of section 25-8-209 or if the existing use classification(s) or water quality standards: (A) are more stringent than is necessary to protect fish life, shellfish life, and wildlife in waterbody segments which are reasonably capable of sustaining such fish life, shellfish life, and wildlife from the standpoint of physical, streambed, flow, habitat, climatic and other pertinent characteristics. Where such characteristics are adequate to support the use, use classifications shall be adopted or retained to protect aquatic life which constitutes a significant source of food supply for the fish, shellfish, or wildlife that is the basis for the classified use; or(B) were adopted based upon material assumptions that were in error or no longer apply.(iv) As a result of any hearing held pursuant to this section, the Commission may revise or change use classifications, water quality standard(s) or water quality designations in accordance with the criteria contained in the Act or whenever necessary to insure compliance with the other provisions of this regulation.(v) Where the Commission determines that an inconsistency exists, it shall declare the inconsistent classification, standards or designations void ab initio and shall simultaneously establish appropriate classifications, standards or designations.(4)Segmentation(a) For purposes of adopting site-specific classifications and water quality standards, the streams and other surface water bodies shall be identified according to river basin and/or subbasin and specific water segments.(b) Segments may constitute a specified stretch of a river mainstem, a specific tributary, a specific lake or reservoir, or a generally defined grouping of waters within the basin (e.g., a specific mainstem segment and all tributaries flowing into that mainstem segment).(c) Segments shall generally be delineated according to the points at which the use, physical characteristics or water quality characteristics of a watercourse are determined to change significantly enough to require a change in use classifications and/or water quality standards. In many cases, such transition points can be specifically identified from available water quality data. In other cases, however, the delineation of segments shall be based upon best judgments of where instream changes in uses, physical characteristics or water quality occur, based upon upstream and downstream data.(d) Segment descriptions, unless specified by the Commission, are to mean that any boundary reference other than those that begin at the "source" means to be "immediately above" that reference.39 CR 11, June 10, 2016, effective 6/30/201639 CR 17, September 10, 2016, effective 12/31/201640 CR 03, February 10, 2017, effective 3/2/201740 CR 23, December 10, 2017, effective 12/30/201741 CR 01, January 10, 2018, effective 1/31/201843 CR 03, February 10, 2020, effective 6/30/202043 CR 11, June 10, 2020, effective 6/30/202044 CR 17, September 10, 2021, effective 12/31/2021Renumbered from 5 CCR 1002-31.57 44 CR 17, September 10, 2021, effective 12/31/2021Renumbered to 5 CCR 1002-31.5844 CR 17, September 10, 2021, effective 12/31/202146 CR 10, May 25, 2023, effective 6/14/2023