2 Colo. Code Regs. § 402-6-6
Current through Register Vol. 48, No. 1, January 10, 2025
Rule 2 CCR 402-6-6 - Determination Of Specific Yield For Wells In The Denver BasinA. In determining the allowed average annual amount of withdrawal from a well in one of the Denver Basin Aquifers, the State Engineer shall apply the following specific yield values, unless the applicant or permittee submits site specific data acceptable to the State Engineer that support a different value pursuant to paragraph B below: Aquifer | Specific Yield |
1. Upper Dawson | - | 20.0% |
2. Lower Dawson | - | 20.0% |
3. Denver | - | 17.0% |
4. Upper Arapahoe | - | 17.0% |
5. Lower Arapahoe | - | 17.0% |
6. Laramie-Fox Hills | - | 15.0% |
B. If a specific yield test or tests meeting the requirements of the Statewide Nontributary Ground Water Rules are done at the location of a permitted well or wells, the value derived therefrom shall be used as the specific yield for determining the allowed average annual amount of withdrawal from the well or wells. If the requirements of a specific yield test are not set forth in the Statewide Nontributary Ground Water Rules or those rules are not in effect, the State Engineer shall consider site specific data for specific yield presented by an applicant or permittee and vary the specific yield value for determining the allowed average annual amount of withdrawal from a well if such data rebut the presumptive value set forth in Rule 6.A. Such use of site specific data shall not be deemed to be a modification of these rules. In determining whether an applicant or permittee has rebutted a presumptive specific yield value set forth in paragraph A above, nothing in this rule shall preclude the State Engineer from considering any other site specific data available to him.