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<br /> <br />Mr. Richard Flills - 3 - April 17, 1986 <br />land uses exist on the stream segments in question. If such crop production <br />exists, formal AVF determinations may need to be completed. <br />If AVF's exist on the affected drainages, an inventory of the types of crops <br />grown will have to be made. Depending on the type of crops we find, CYCC and <br />MLRD can develop a precise EC standard to ensure the protection of the <br />specific crops grown in the basin. The Division will use the material damage <br />criteria specified in the AVF Rules (Section 2.06.8(5)(c)(i)) in determining a <br />crop salt tolerance standard. <br />If it appears that water quality is approaching or exceeding this standard, <br />CYCC may need to measure actual soil extract electrical conductivity for <br />various soil types throughout one growing season on the potentially affected <br />AVF's. This will establish a site specific relationship between irrigation <br />water salinity and soil solution salinity. <br />CYCC will also need to make predictions on what the water quality levels will <br />be for 10 year 7 day low flows, during the remainder of the 5 year permit <br />term, for the life of mine term, and for post-mining conditions. <br />If it appears that damage is occurring or is projected to occur, CYCC will <br />need to measure the crop productivity and composition on the affected lands in <br />order for MLRD to make a significance determination. (Alternatively, CYCC <br />could request a change in the standard based on appropriate site specific <br />studies as provided for in 2.06.8(5)(c).) <br />CYCC is reminded that Sections 34-33-114(2)(e) and 34-33-114(2)(c) of the <br />Colorado Surface Coal Mining Reclamation Act prohibit material damage to <br />Alluvial Valley Floors. A significant degradation of water quality supplying <br />alluvial valley floors would be considered material damage. Compensation to <br />farmers through financial means or actual replacement of hay does not relieve <br />CYCC of the Act's requirement to prevent material damage. CYCC is also <br />reminded that the law requires AYF's to be restored to their original <br />productivity, even those lands owned by the operation. <br />If damage to crops were to occur it would probably be manifested during the <br />summer irrigation season June to September. Since the consequences for <br />causing material damage are significant, it is necessary that CYCC resolve <br />this issue prior to the irrigation season. <br />We would like CYCC's preliminary written opinion on the source of elevated TDS <br />in the affected drainages and an identification of where the irrigated and <br />subirrigated crop lands exist in the basin by April 30, 1986. CYCC should <br />concurrently submit a written plan with timetables to complete the <br />investigation and ensure that no material damage will occur. <br />In conclusion, existing CYCC monitoring data raises concerns as to the <br />seriousness of the effect the operation is affecting the hydrologic balance <br />and agricultural water uses in the river basin. With limited information on <br />adjacent land uses it is difficult for MLRD to assess how significant this <br />