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COLORADO <br /> . _/ Division of Reclamation, <br /> ® Mining and Safety <br /> Department of Natural Resources <br /> Interoffice Memorandum <br /> Date: November 15, 2021 <br /> From: Rob Zuber RDZ <br /> To: Zach Trujillo and Jason Musick <br /> Subject: Colowyo Coal Mine(Permit No. C-1981-019) <br /> Preliminary adequacy review of TR-150,with focus on the"Salinity <br /> Material Damage Assessment," by Cedar Creek Associates, Inc. <br /> At this time, I have one particular adequacy item regarding the Cedar Creek assessment: <br /> Please justify the use of weighted averages in Table 1 to develop a salinity tolerance for an <br /> entire field,rather than looking at tolerance for individual crop species. It is the opinion of the <br /> Division that if a farmer is using irrigation water with high TDS concentrations it could likely <br /> impact the yield of sensitive crops (or moderately sensitive crops such as alfalfa) regardless of <br /> the other types of crops grown in that field. <br /> I talked to Janet Binns about my issue with Table 1 (she has an agronomy background), and she <br /> agrees with me. After they address that issue, I may have other issues or questions. <br /> A general issue for us to discuss: should we consider potential future uses of the water in <br /> Goodspring Creek? For example, at some point in the future a farmer may want to grow nothing <br /> but alfalfa. In some of the fields shown in Table 1 of the Cedar Creek report(e.g., Cox field 1 I and <br /> Proctor field 6), alfalfa is currently the dominant crop grown. <br /> An authoritative definition of material damage suggests that future uses should be considered. The <br /> 1988 guideline by Fred Banta(former Director of the Mined Land Reclamation Division) includes <br /> the following statement: <br /> Impacts which result in impairment ofpresent water uses which cannot be mitigated or which result <br /> in long term impairment of existing or potential water users shall be considered significant. <br /> If we (DRMS staff and management) decide that we do need to consider potential uses of the water <br /> in the future,then the issue with weighted averages may be irrelevant. <br /> References <br /> Banta, Fred R, "A Description of the Material Damage Assessment Process Pertaining to Alluvial <br /> Valley Floors, Surface Water, Ground Water and Subsidence at Coal Mines," 1988. <br /> pF COl0 <br /> 1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us ' * ** <br /> Jared S. Polis, Governor I Dan Gibbs, Executive Director I Virginia Brannon, Director * 1 * <br />