5 Colo. Code Regs. § 1002-42.13
The provisions of C.R.S. 25-8-202(1)(b)(2) and (7) and 25-8-204 provide the specific statutory authority for adoption of these regulatory provisions. The Commission has also adopted, in compliance with C.R.S. 24-4-103(4), the following statement of basis and purpose.
BASIS AND PURPOSE
In the continuing effort to ensure that the state's ground-water reserves remain viable for beneficial use, the Water Quality Control Commission has expanded application of the interim narrative standard, adopted in September, 1991 and applied to five select aquifer systems, to all ground waters of the state to which standards have not previously been assigned. In taking this action, the Commission has exempted those aquifers in which the total dissolved solids (TDS) are equal to or exceed 10,000 mg/l. The Commission does not intend to preempt any agency's independent statutory authority to protect ground water. In those areas where the TDS equal or exceed 10,000 mg/l, the statewide standards for radioactive materials and organic pollutants established in section 3.11.5 C of the basic standards for ground water shall apply.
The exemption for high levels of TDS was included in recognition of the fact that currently, these waters could not be recovered for beneficial use within reasonable economic cost.
At the time the interim narrative standard was adopted in September, 1991, application was limited to the five regional aquifer systems due to the constraints of the public notice which had specified the aquifer systems to which the Division's original proposal (May 1991) would apply. In the Basis and Purpose Statement developed for the interim narrative standard, the Commission recognized that it may be appropriate to consider adoption of the interim narrative standard for ground water elsewhere in the state at a subsequent time (Subsection 3.12.11 B.1.). As a result of this rule, the unconfined ground water in the five regional aquifer systems continues to enjoy the protection of the INS. In addition, the INS will also apply to the confined ground waters in those aquifers as well as other ground waters in the state. January 31, 1994, the effective date for statewide application of the INS replaces October 30, 1991, and applies to all confined and unconfined ground water in the state including the five regional aquifers addressed in the original INS hearing. With statewide application of the INS, the five figures depicting the regional aquifers to which the INS applied prior to statewide application, has been deleted from the regulation as they are no longer needed.
In the two years since its adoption, the interim narrative standard has been very effective in protecting the ambient quality of the state's ground-water reserves and preventing further deterioration. Expansion of the concept statewide will ensure that the remainder of the state's ground-water supplies are similarly protected until more appropriate site-specific use classifications and standards can be adopted.
The interim narrative standard (INS), adopted by the Commission in September, 1991, established a process to arrive at numeric standards for five (5) specific aquifer systems within the state. The intent of the regulation was to maintain ground-water quality in aquifers not yet contaminated, and to prevent further deterioration from human-induced pollution where contamination has occurred. It is important to note that it was not designed to prevent or control naturally occurring pollution.
In adopting the INS, the Commission made clear that the intent was to foster clean up of ground water contaminated by human activities to the maximum degree technically feasible within reasonable economic limits. The stated goal of clean up is to make the ground water useable for all existing and potential beneficial uses. The Commission further indicated that the intent of the INS is not to define the limits of remediation, but instead to ensure that a contaminated area will be stabilized or will improve (Subsection 3.12.5 . The INS defines the protection provided unless and until replaced by site-specific use classifications and numerical standards at another time.
The growing number of people in the state who rely on ground water as a source of drinking water and for other beneficial uses prompted the Commission to consider expanding the application to all ground waters of the state. The statistics maintained by the Drinking Water Section of the WQCD indicate that there are currently 532 public water systems in the state relying entirely on ground water serving approximately 428,000 residents.
The numbers of people at risk are one indication of the need to protect ground water as a drinking water source. The growing incidences of ground water contamination are another. Expansion of the interim narrative standard allows the Commission to meet its statutory responsibility to protect ground water until more complete information is available to establish site-specific standards.
Implementation of the interim narrative standard statewide will essentially be the same as it has been on a regional basis. The appropriate implementing state or local agency will use the best information available to determine or "estimate" existing ambient quality to make determinations regarding points of compliance, issuing permits, and taking remedial actions. Where this information is inadequate or unavailable, these agencies will rely on best professional judgment to determine existing ambient quality.
The interim narrative standard provides for a default standard that applies if there is inadequate information to determine or estimate existing ambient quality. The default standard is that quality which meets the most stringent criteria set forth in Tables 1 through 4 of the "Basic Standards for Ground Water". As stated in the 1991 statement of basis and purpose, and restated here for clarity, "the Commission has determined as a matter of policy, that where existing information is limited, the interim narrative standard should resolve any uncertainty in favor of protection. For this statement, the Commission fully incorporates this policy as well as all other applicable information contained in the 1991 statement of basis and purpose for the interim narrative standard."
A potentially regulated entity can avoid application of the default standard by generating site-specific data, even subsequent to the effective date of the regulation. The ambient quality established then becomes the standard for all appropriate regulatory purposes through the implementing agencies. If the regulated entity feels that an implementing agency is improperly determining or applying ambient quality-based standards, it can petition the Commission for a site-specific rulemaking hearing.
As with regional application, statewide expansion of the interim narrative standard does not address the issues of when remediation of existing ground water quality contamination is necessary, or how much remediation is appropriate for any site-specific situations. These determinations are established in state and federal law, and are made by the appropriate regulatory agencies responsible for implementing these laws. In expanding the INS to all ground waters of the state, the Commission provides the implementing agencies with guidelines to make regulatory decisions.
Although the INS is not self-implementing, and does not in and of itself require remediation of polluted ground water, it is important to reiterate that the Commission's stated intent is to foster and encourage clean up of contaminated ground water to the maximum degree technically feasible and economically reasonable. (The exemption of ground water equal to or in excess of 10,000 mg/l is compatible with this position).
The statutory prohibitions regarding impairment to water rights contained in 25-8-104 are not compromised with this rule. Any lawful right to withdraw and beneficially use ground water will not be affected by this narrative standard because its purpose is to provide a foundation for controlling discharges to the ground water, not withdrawals. Recharge or augmentation plans will have to consider the quality of the recharge water similar to the current requirements of the State Engineer's Office, so this rule does not change that previous requirement. Ultimately, this rule should protect and enhance the value of water rights since its purpose is to maintain a level of quality that supports the beneficial uses to which the water will be applied.
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-42.13