5 Colo. Code Regs. § 1002-39.7
A review of the water quality standard for salinity in the Colorado River and the plan of implementation has been held in accordance with the Colorado Water Quality Control Act and the Clean Water Act. The same water quality standard is adopted for salinity-the water characteristics within the Colorado River basin in Colorado appropriate to maintain the numeric levels established at the three downstream checkpoints. The purpose of water quality standards is to protect the uses of the waters. The narrative criteria adopted by Colorado will adequately protect the uses. It has been the consensus of EPA and the Forum for some time that the numeric levels are appropriate.
The standard rests upon the dual considerations that salinity levels shall be maintained in the lower Colorado River while the upper basin states continue to develop their compact-apportioned share of the Colorado River. These were recognized as necessary companion considerations even before the 1972 amendments to the Federal Water Pollution Control Act were adopted. See, for example, the Conclusions and Recommendations of the Conferees at the Reconvened Seventh Session of the Conference in the Matter of Pollution of the Interstate Waters of the Colorado River, page 3 of Exhibit C to the 1975 Forum proposed Water Quality Standard for Salinity and Plan of Implementation. The 1975 document was Exhibit A at the hearing.
The points chosen as appropriate for establishing numeric criteria are three key locations in the lower mainstem. The 1975 document affords a clear explanation for the choice of the three locations at pages 55 and 56:
In order to provide for sound water quality objectives, numeric criteria are to be established at three key stations (i.e., below Hoover, below Parker and at Imperial Dams). The State of Nevada diverts Colorado River mainstem water from Lake Mead for use in the Las Vegas area, and the returns enter the lake just upstream from Hoover Dam. The gaging station below Parker Dam is immediately downstream of the major Lake Havasu diversion for the Metropolitan Water District of Southern California. Also, the Central Arizona Project now under construction will divert from Lake Havasu. The large agricultural areas in the Imperial and Coachella Valleys in California and Yuma area in California are served by diversions at Imperial Dam.
This action repeals the May 1976 adoption of the "Water Quality Standards for Salinity Including Numeric Criteria and Plan of Implementation for Salinity Control, Colorado River System" , dated June 1975 and the "Supplement Including Modifications" to the above-referenced document, August 26, 1975.
The standard adopted reflects the basinwide approach for controlling salinity which has been endorsed by Congress, affected federal agencies, and the Colorado River basin states for several years. The rationale for using the basinwide approach is thoroughly documented in the record.
This approach has been developed by the Colorado River basin states through the Colorado River Salinity Control Forum ("Forum").
Colorado has consistently participated in the basinwide approach for controlling salinity. It continues to do so through the Forum which is now preparing its proposed 1981 update. That will be before the Commission within a few years. Furthermore, the standards continue to be met, and will certainly be achieved for the next several years. Questions or concerns regarding the approach taken can be raised again, if appropriate, as a part of the next update review.
The basinwide approach is followed through the adoption of the water quality standard as a regulation with separate adoption of the 1978 proposed revision by the Forum, the supplement thereto, and the Third Annual Progress Report as statements of the Commission's policy. The linkage between the standard and the policy is found in Section 3.9.5 Separating these two actions better meets the requirements of the Colorado Water Quality Control Act and the Clean Water Act. This approach is the best method to follow to comply with the established water quality management programs of the two acts. While the Commission recognizes the continuing importance of a plan of implementation, applicable federal law does not require such a plan as part of the standard. Also, the form and substance of that document is appropriate as a policy statement rather than as a regulation.
Should any aspect of the plan be amenable for adoption as a regulation, a regulatory hearing may be held to consider adopting such a regulation. The only aspect of the plan of implementation which is now amenable to adoption in a regulatory format is the NPDES policy. That was adopted as a regulation sometine ago by the Commission.
5 CCR 1002-39.7