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• III IIIIIIIIIIIIIIII ~ <br />DEPARTMENT OF NATURAL RESOURCES <br />Davitl H. Getches. Executive Director <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SH ElTO N, Director <br />Richartl D. Lamm <br />Governor <br />April 17, 1986 <br />Mr. Larry Damrau <br />Twentymile Coal Company <br />29515 Routt County Road 27 <br />Oak Creek, Colorado 80467 <br />Re: Water Quality Issues at the Foidel Creek Mine - File No. C-056-82 <br />Dear Mr. Damrau: <br />Recently the Division completed a review of your 1985 Annual Hydrologic <br />Report. Our comments on the report were forwarded to you by letter on. As we <br />indicated in that letter the Division has identified several additional water <br />quality items that need to be addressed. The items pertain to water quality <br />standards applicable to Foidel Creek, Middle Creek, and Trout Creek. This <br />letter will provide you with the specifics of our concerns and discuss how <br />these issues might be resolved. <br />Our review of your 1985 hydrologic monitoring data reveals that segments of <br />Foidel and Middle Creek contained high levels of Total Dissolved Solids <br />(TDS). The TDS is attributed primarily to elevated sulfate, calcium, and <br />magnesium levels. The Division has compared the TDS levels to known crop salt <br />tolerance levels for irrigated crops grown in the region to ascerain the <br />seriousness of the situation. <br />As you know, the Water Quality Control Division has not adopted any receiving <br />stream standards for TDS. However, the Mined Land Reclamation Division (MLRD) <br />Alluvial Valley Floor (AVF) regulations do specify crop salt tolerance <br />standards for assessing material damage in Rule 2.Ob.8(5)(c)(i). This Rule <br />references threshold electrical conductivity (EC) levels for various crops <br />contained in "Crop Salt Tolerance - Current Assessment" by E. V. Maas and <br />G. J. Hoffman, Journal of the Irrigation and Drainage Division, A.S.C.E., <br />1977. This reference was also in the original Federal Permanent Program <br />Regulations. <br />The Division has made affirmative findings for the existance of alluvial <br />valley floors (AVF) along portions of Foidel Creek, lower Fish Creek, lower <br />Middle Creek, and lower Trout Creek. Although AVF determinations and <br />vegetation inventories have not been made for all areas downstream from your <br />mine, the Division examined salt tolerance levels for various crops which are <br />typically grown in the Yampa River Basin, such as alfalfa, smooth brome, <br />timothy and orchard grass. For the purposes of the assessment we utilized a <br />soil extract EC suspect level of ]500 umhos/cm. This corresponds to a ],000 <br />umhos/cm irrigation water suspect level based on a 1.5 conversion factor <br />(literature values ranged from 1.5-3 ). <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567 <br />