5 Colo. Code Regs. § 1002-31.27
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 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:
The Commission considers the existing definition of "state waters" broad enough to include wetlands. Therefore, the definition has not been modified.
To add further clarity in this regard, a definition of "wetlands" has been added to the regulation. This definition is the same as that used by both EPA and the U.S. Army Corps of Engineers, except that the list of examples included in the federal definition has been omitted. These examples do not appear to be generally relevant to the types of wetlands most likely to be found in Colorado. The Commission believes that use of this definition is appropriate for consistency with Clean Water Act programs. The Commission recognizes that the site-specific application of this definition has led to considerable controversy, for example with respect to the Federal Interagency Delineation Manual. That controversy addresses a level of detail that is beyond the scope of this hearing. The Commission generally anticipates that implementation of this definition in Colorado will be consistent with the federal delineation manual once it is finalized, taking any relevant regional differences into account. However, the Commission will await resolution of the issues pertaining to the federal delineation manual and, depending on how such issues are resolved, may elect to provide further clarification or refinement regarding the appropriate delineation of wetlands in Colorado.
A definition of "constructed wetlands" has also been added to the regulation. This definition is intended to provide further clarification as to which wetlands will be subject to water quality classifications and standards. Consistent with the definition of "state waters" , those wetlands that are designed, constructed and operated for the purpose of treatment of wastewater or storm water, including wetlands designed, constructed, and operated as a system or part of a system for control, storage, or retention of wastewater or storm water, are excluded from coverage. Wetlands constructed as a part of environmental remediation provided under CERCLA or RCRA and section 319 of the Clean Water Act are also excluded since they also serve primarily a treatment function. The Commission has used the term "primary purpose" rather than "sole purpose" because it recognizes that some wetlands created for the purpose of treatment may, as a secondary matter, provide other beneficial functions. These secondary benefits should not be discouraged by an overly restrictive definition of constructed wetlands.
There was considerable debate in the hearing regarding whether wetlands constructed for treatment on previously existing wetlands sites should qualify as constructed wetlands, and thereby be excluded from state waters. The Commission believes that such wetlands should be considered constructed wetlands where approval or authorization has been obtained under section 404 of the Federal Act for filling in the previous wetlands. In other words, if a judgment is made in the 404 program that previously existing wetlands may appropriately be eliminated by or transformed into new constructed wetlands for treatment purposes, the water quality standards system should be applied in a manner that is consistent with that determination. Moreover, the existence of the water quality standards adopted by the Commission for wetlands is not intended to affect section 404 permit determinations regarding the permanent filling of areas of state waters. Rather, the standards are intended to govern activities potentially impacting wetlands that will continue to exist as (other than constructed) wetlands after any fill occurs. The Commission recognizes that some flood control, urban drainage improvement and stormwater management activities may have been conducted without prior 404 approval, but such activities may have resulted in the creation of wetlands which could be useful for purposes of complying with the new stormwater discharge requirements. If 404 requirements are demonstrated to be no longer applicable or enforceable, or after-the-fact authorization can be obtained from the Corps of Engineers, such created wetlands shall be considered constructed wetlands. Constructed wetlands are required to be permitted under the CDPS system if they are designed to provide treatment for wastewater or stormwater point sources and discharge to state waters. However, there is nothing in the regulation that interferes with the Corps of Engineers' responsibility to negotiate mitigation for wetlands lost in a project for which a section 404 permit is required.
Next, a definition of "compensatory wetlands" has been added which includes wetlands created to mitigate for adverse impacts to other wetlands. The definition of constructed wetlands includes a provision clarifying that wetlands created to provide mitigation for adverse impacts to other wetlands will not qualify as "constructed wetlands". If new wetlands are created essentially to replace other wetlands which were state waters, such new wetlands should also be protected as state waters.
Next, a definition of "created wetlands" has been added. Many wetlands today are not natural, but rather created as a result of human actions. In many instances, such wetlands are the unintentional result of topographic or hydrologic modifications undertaken for other purposes. Examples would include wetlands resulting from highway construction or from irrigation tailwaters. These wetlands satisfy the statutory definition of "state waters". However, they have been separately defined because the Commission believes that their varied nature warrants separate treatment under the water quality classification and standards system, as discussed further below.
The final revision to the Definitions section is the addition of a definition of "tributary wetlands" . The Commission has added this term to the definitions because it is used in section 3.1.13 to identify certain wetlands that are subject to existing surface water classifications, and some of the associated standards, on an interim basis. Tributary wetlands either serve as the headwaters of surface waters or are wetlands within the floodplain. Tributary wetlands have been defined in this manner because there is a strong hydrologic connection characterized by rapid permeabilities between surface and ground water in the floodplain. This is because at some point during the past a river has occupied each and every position within its floodplain resulting in deposition of porous cobble material and sand and gravel throughout the floodplain. Waters and tributary wetlands may directly influence water quality in downgradient stream segments and, waters in streams may directly affect water quality in hydrologically downgradient wetlands.
To summarize, the result of this set of definitions, as further elaborated below, is as follows:
The Commission has decided as a matter of policy that the approach to water quality classifications and standards for wetlands in Colorado that will result in the most appropriate protection of the resource with the least disruption to the current system is a two-step process. The initial step is a clarification that for wetlands that are tributary to other surface waters (except for created wetlands), the classifications adopted for the segment into which the wetlands fall will apply on an interim basis. This is consistent with the Commission's approach to classifying all tributaries of a segment. This approach will also ensure that the use of the streams to which the wetland is tributary is not impacted. The Commission recognizes, however, that the use of wetlands as drinking water supply sources is highly unlikely. For that reason, the Commission's rule exempts tributary wetlands from the drinking water supply classification, even if the segment to which they are hydrologically connected is subject to such classification. This does not mean that drinking water supply cannot be considered a water quality dependant function of wetlands, but only that such a determination must be made on a case-by-case basis. The Commission intends that in the next round of basin-specific rulemaking hearings appropriate language will be added for each basin to further clarify the application of existing classifications as interim classifications for wetlands that are tributary to other surface waters in the basin.
The Commission has provided that existing surface water classifications will not be considered to apply to created wetlands, which have been defined as described above. Rather, these wetlands will initially be subject only to the narrative standards set forth in new subsection 3.1.11 . The Commission has determined this distinction to be appropriate because of the varied nature of these wetlands. Because these wetlands are not natural, their functions may in many instances be more limited than those of other wetlands. Moreover, a blanket application of classifications and standards to these wetlands may create a counter-productive incentive for the elimination (e.g. through draining) or prevention of such wetlands in the future. Given the already apparent disagreements regarding the proper implementation of the wetland narrative standards and the inherent difficulties in distinguishing between tributary and created wetlands, the adopted approach to regulation of created wetlands (i.e., initially applying narrative standards only) is likely to be more resource intensive and more difficult to implement than the approach to regulation of tributary wetlands. Some parties at the hearing expressed concern with the potential abuse of this approach and the burdens faced by the Division if required to make a demonstration that a wetland is not created. In the created versus tributary wetlands determination, the Commission expects that wetlands that otherwise meet the definition of tributary wetlands, will be presumed to be tributary until shown to be created by human activity as specified in the created wetlands definition. Finally, it should be noted that if it is determined that specific wetlands of this type warrant additional or more precisely defined protection, the wetlands classification described below, along with associated site-specific standards, can be adopted.
The second step in the process established by the Commission is the application of the new wetlands classification established in section 3.1.13 , which can be applied on a site-specific basis. The protection resulting from such a site-specific classification could be more or less stringent than that provided by the interim classifications. Some wetlands may have unique functions that are not adequately protected by the interim classifications and standards. In other instances, the interim classifications and standards may protect uses, e.g. sensitive aquatic species, that are not present in particular wetlands and therefore do not require site-specific protection. Because the initial adoption of the wetlands classification, and associated site-specific standards, to replace the interim classifications would provide the first opportunity for review of the site-specific factual circumstances of the wetlands in question, the Commission has provided that such a revision would not be considered a downgrading. This provision is intended to apply only the first time a wetland-specific classification and associated standards are adopted to replace the interim standards established by this rulemaking action.
The new wetlands classification also can be applied to any wetlands that are not tributary to other surface waters. These wetlands, sometimes referred to as isolated wetlands, would initially be protected by the statewide narrative standards in new subsection (1)(b) (discussed below), which apply to all state surface waters. In addition, since these wetlands would generally be associated with the ground water table, they would receive some protection from the statewide, regional, and site-specific ground water quality standards that the Commission has adopted.
Where the Commission applies the new wetlands classification on a site-specific basis, the intent of establishing the classification will be to maintain or restore appropriate wetland characteristics and functions, within the range of natural variation of the affected wetland. Thus, where the site-specific wetlands classification includes the "sediment or other pollutant retention" function, the intent of including this function within the classification is to promote the maintenance or restoration of the natural wetlands characteristics. The classification should not be viewed as authorizing or promoting the use of the wetlands for treatment or retention of sediments or other pollutants from human sources. Rather, the Commission intends that this classification be interpreted and applied in a manner consistent with section 131.10 of the federal water quality standards regulation, which prohibits adoption of waste transport or waste assimilation as a designated use for any waters of the United States. The wetlands functions to be protected should be related to water quality and determined on a site-specific basis.
All wetlands that are state waters (i.e. not constructed wetlands) are subject to the statewide basic standards for all state waters contained in section 3.1.11 . Concerns were raised in the hearing regarding the appropriateness of the previous narrative standards (section 3.1.11 -(f)) for waters in wetlands. The Commission believes that not all of these standards are appropriate for wetlands.
Accordingly, section 3.1.11 has been amended and new subsections (a) and (b) have been created. Subsection (a) continues to apply all narratives to all surface waters, except wetlands. Subsection (b) specifies the narrative standards which are specifically applicable to wetlands.
A number of parties expressed concern regarding the potential use of the regulation and, in particular, the narrative standards, to create or expand other agencies' jurisdiction over wetlands. The Commission does not have the authority to create or expand the authority of other agencies and, therefore, this regulation cannot have such an effect. Neither the narrative standards nor the numeric standards proposed in this rule are self-implementing. Rather, implementation occurs only through discharge permits or other independent regulatory programs specifically designed to include water quality standards implementation as one of their purposes. It is the intent of the Commission that, to the extent these regulations are utilized by other agencies under independent statutory authority, the Division's interpretation thereof, as reflected in Division implementation guidance or otherwise, must be followed by such agencies. For example, the Commission intends that compliance with the water quality standards developed in this proceeding be determined using the techniques, methodologies and policies used by the Division for determining compliance with the adopted standards.
Subsection (1)(b)(i) incorporates a new narrative standard which addresses discharges that would be harmful to water quality dependent functions of wetlands. Each wetland function outlined in section 3.1.13 may be considered to be a water quality function of the wetland, depending on the facts of each case. The Commission intends that implementation of this narrative standard only address activities with adverse water quality impacts. This provision is not intended for example, to be applied as a biological criterion for wetlands that would more broadly mandate preservation of wetlands functions. Any such regulatory provisions should be addressed as part of the broader biological criteria issue, on which the Commission has chosen to defer the adoption of binding standards at this time. The new narrative standard in subsection (1)(b)(i) also addresses the potential impact of discharges which affect the pH of the wetland in such a manner as to harm the water quality dependent functions of the wetland. Considerable testimony about the need to protect wetlands from discharges of substances that could cause significant changes in pH was provided by EDF. Based on this testimony, the Commission has elected to adopt a specific prohibition against the discharge of pollutants in amounts that produce changes in pH to such degree as to harm the water quality dependent function of the wetland.
In addition, all wetlands would receive the protection offered by the applicable portions of the antidegradation rule contained in section 3.1.8 . A provision has been included in section 3.1.7 to provide that all created wetlands will initially be considered to have a "use-protected" designation. For the same reasons that the Commission has decided to initially apply only narrative standards to these wetlands, the Commission believes that a blanket subjection of such wetlands to antidegradation review requirements is not appropriate at this time. To the extent that specific wetlands do warrant such review, that can be addressed in the site-specific classification and standard-setting process.
The need to apply the narrative standards to created wetlands is not expected to arise very frequently. If this need does arise, e.g. due to a proposed point source discharge into such a wetland, the Commission intends that the water quality dependent functions of the particular wetland would be considered by the Division in applying the standards. In many circumstances, those functions may already be limited by the quality of the inflow that has led to the, sometimes unintentional, creation of the wetland in the first place. In such instances, the discharge of additional flows of similar quality may not interfere with those functions. The Commission recognizes that created wetlands can provide beneficial storm retention and cleansing functions, and intends with these provisions to allow enough flexibility so that such functions can be protected without imposing a degree of regulation likely to result in unreasonable treatment costs or a disincentive to the preservation or future creation of such wetlands.
Consistent with the Commission's two-step approach discussed above, wetlands subject to the interim classifications described in section 3.1.13 (i.e., tributary wetlands) shall be initially subject to the numeric standards adopted for the applicable segment, unless it is demonstrated that said standards are not being met in the wetland in question. To the extent that such a standard is not met for any given parameter, the applicable interim standard shall be the ambient levels for that parameter. The determination of ambient quality shall be made by, or in consultation with the Division, on a case-by-case basis based on available data and information. The Commission expects that ambient conditions, for purposes of subsection 3.1.7 (b(iv)(A), will be determined in accordance with the past Division practice in recommending ambient water quality standards for adoption by the Commission.
These interim standards will apply until the Commission adopts site-specific standards for the tributary wetlands in question. The Commission expects to review any interim ambient standard established pursuant to subsection iv(A), during the Commission's triennial review of the basin in which the wetlands subject to such interim standards are located. Upon triennial review, where ambient based interim standards have been developed by the Division, the Commission will establish site-specific standards such as: permanent ambient quality based standards, table value standards, temporary modifications or alternative numeric standards when the "wetlands" classification is adopted. The Commission may determine, however, that insufficient data exists to adopt the interim ambient based standard(s) developed by the Division on a permanent basis. Such standards will be based on very limited data in many cases. A trial and error period and an iterative approach will typically be needed to address stormwater discharges and nonpoint sources impacting wetlands water quality. While the Commission recognizes that the issue of an appropriate numeric standard, which is demonstrated to protect the use(s) of state waters, needs to be resolved through rulemaking as quickly as possible, it may be necessary to allow time to gain implementation experience, acquire field data and to evaluate the effectiveness of various BMPs. When additional data is necessary to establish appropriate numeric standards or additional time is needed to achieve the numeric standards for which adequate supporting data has been collected, the Commission may adopt the interim values as temporary modifications. A temporary modification is generally appropriate in such cases because it will allow time to evaluate options for establishing or achieving the underlying standards or for development and adoption of more appropriate site-specific standards be they basin standards or ambient based standards.
In many cases, the stream standards on which the tributary wetland's standards are based are expressed as a function of the total hardness of the stream in question (i.e., table-value standards for protection of aquatic life for certain metals found in Table III, Section 3.1.16). The Commission expects the interim numeric standards for protection of aquatic life in tributary wetlands to be expressed as a function of total hardness as well. In addition, the Commission finds that the concept of water effect ratio, as developed by EPA in its recently adopted toxics criteria for aquatic life (57 Fed. Reg. 60,848 (12-22-92)), is appropriate in the development of numeric criteria for protection of aquatic life in wetlands. Accordingly, the Commission has adopted language that allows the Division or agencies implementing these standards and classifications for wetlands to express the appropriate numeric standard as a function of both hardness and water effect ratio of the pollutant in question. The Commission expects such adjustments to be made at the time of permitting, certification, or other action by the Division or other agency implementing these standards and classifications for wetlands, in a manner consistent with EPA's criteria. The water effect ratio of a pollutant shall be assigned a value of 1.0, except where the implementing authority assigns a different value that protects the designated uses of the water body.
Altemative numeric standards, to apply when the "wetlands" classification is adopted to replace the interim classifications, or for specific created wetlands, will need to be developed on a case-by-case basis, taking into account the functions of the wetlands in question. In making this determination, the Commission will take into account all relevant and available information. This information may include, e.g., whether the wetlands are natural or created, or, in the case of the latter, the reason for their creation. Given the diversity of functions of individual wetlands, the Commission does not believe that an effort to develop general "table values" for this new classification would be feasible or constructive at this time.
The Commission has decided not to adopt biological criteria as water quality standards for wetlands at this time. Very little is known at present about the structure and function of aquatic communities within wetlands. Concerns that have been raised regarding the lack of standardized, field-tested biological evaluation techniques are much more significant with respect to wetlands than for other surface waters.
Considerable concern was expressed in the hearing regarding the potential impact of wetlands water quality standards on activities involving the exercise of water rights. As in all other areas of Colorado's water quality program, the potential for application of these standards in a manner detrimental to water rights is constrained by the provisions of section 25-8-104, C.R.S. However, in an effort to more directly alleviate concerns in this regard, the Commission has adopted new subsection 3.1.7 , to clarify that wetlands water quality standards shall not be interpreted or applied in a manner that restricts the lawful exercise of water rights.
The Commission expects that in permitting the discharge of pollutants into the state's streams, the Division will ensure the protection of the downstream wetland uses. However, where the downstream, tributary wetland is upgradient of the stream, there may be no pathway from the stream to the wetland. In such circumstances, the discharge to the stream need not be regulated for the protection of the wetland use.
PARTIES TO THE RULEMAKING HEARING MARCH 2, 1993
5 CCR 1002-31.27