5 Colo. Code Regs. § 1002-42.14
The provisions of C.R.S. 25-8-202; 25-8-203; 25-8204 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
With this hearing, the Commission continues its efforts to protect the ground water used by 18 select public water systems for domestic and agricultural uses. Protection is provided through the assignment of use classifications and the corresponding water quality standards found in Tables 1-4 of the "Basic Standards for Ground Water" 3.11.0 (5 CCR 1002-8) to all confined and unconfined ground water underlying or influencing the wells serving the public water systems cited in the public notice and the rule.
The public water systems (PWSs) that are the subject of the hearing all rely exclusively on ground water as a source of drinking water. The Division's original proposal for this hearing included 22 public water systems. Four systems were dropped from consideration at this hearing, these were Cottonwood and Parker Water and Sanitation Districts (Douglas County), the Town of Meeker (Rio Blanco County), and Winter Park West Water and Sanitation District (Grand County).
At the request of Lincoln Park Metropolitan District, the proposed classification and standards setting of the ground water underlying the Cottonwood and Parker Water and Sanitation Districts' wellfields was postponed until December, 1995. The postponement was granted by Commissioner Laura Davis, the hearing chair, to allow for a ground water quality study which is expected to better define the ambient quality of the ground water proposed for classification.
Commissioner Davis also agreed to the request for postponement submitted by the Town of Meeker. Classification of the Town's wellfield was rescheduled for November, 1994 to allow for additional time to review and evaluate the proposed classified area for the town's wellfield. Winter Park West Water and Sanitation District was dropped from consideration at the June 7, 1994 hearing due to an error in calculating the resident population served by the District. Had the correct number been used, the District would not have been included in this round of classifications.
Modifications to the boundaries proposed by the Division for Denver Southeast Suburban Water and Sanitation District, Morgan County Quality Water District, Northern Colorado Water Association and the City of Glendale and Cherry Creek Valley Water and Sanitation District were made at the request of the systems, with the concurrence of the interested parties.
The name of the specified area for the City of Glendale's wellfield was changed to "City of Glendale and Cherry Creek Valley Water and Sanitation District Ground Water Classification Area" at the request of the Cherry Creek Valley, with the concurrence of Glendale and the Division.
Records maintained by the Drinking Water Section of the Water Quality Control Division indicate that in 1993, collectively, the 18 PWSs provided drinking water to 66,839 Colorado residents. Compliance records indicate that most of the systems consistently meet the Safe Drinking Water Act requirements for the delivery of potable water at the tap with chlorination as the sole means of disinfection. This is an indication that the water source is of good quality. The Commission concluded that classification and the assignment of standards would help to ensure long term protection of the ground water as a drinking water source.
The aquifer settings included in the proposal cover all examples found in Colorado, i.e. confined, unconfined and fracture-flow. By assigning the use classifications and standards to those portions of the aquifers with documented drinking water and agricultural uses, the Commission sought to protect the uses from undue pollution.
Site-specific classification of ground water begins with the identification of the use of the water. In this instance, and that of the previous site-specific hearing in May, 1993, the identified uses are domestic and agricultural. The agricultural use-quality classification was included in the proposal based on information that irrigation and stock watering wells were frequently identified within the specified areas. The corresponding water quality standards, found in Tables 1 through 4 of the "Basic Standards for Ground Water" 3.1..0 (5 CCR-1002-8), are designed to protect the uses.
The agricultural use classification was dropped for the Park Center Water District in Fremont County when formal verification of the uses indicated that there was no actual or potential agricultural use in the vicinity of the wellfield.
The specified areas to which the use classifications and standards apply were determined through the use of a semi-analytical ground water flow model (WHPA Model 2.1) developed for use in the wellhead protection program. The specified areas represent the zone of influence from which the water is drawn for beneficial use and are determined by assembling information on the well(s) and the aquifer. Examples of data used to generate the specified areas include the location and pumping rate of the wells, hydraulic conductivity and saturated thickness of the aquifers, the direction of flow and recharge or discharge areas. The areas delineated by the computer as influencing the wells are then projected to the surface and parameters are drawn on 7.5 minute maps to outline the specified areas earmarked for classification. The configurations vary and depend on the hydrologic factors present.
The use classifications and standards adopted by the Commission for the specified areas around the 18 public water systems addressed in the hearing serve as the basis for permitting and remedial actions undertaken by various local, state and federal regulatory agencies responsible for protecting ground water. Application of the classifications and standards is triggered by these actions; the regulation in and of itself is not self-implementing.
The classification and standards regulation serves as a means of protecting the ground water and by law, cannot interfere with the exercise of water rights (Colorado Water Quality Control Act, C.R.S. 25-8-104(1).
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-42.14