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<br />n~!178 <br /> <br />derived from sandstones and have low salt loading potential. The exact amount of salinity <br />loading to the Colorado River cannot be determined at this time, but the salt loading from the <br />Dolores Project's use of 54,000 acre-feet of water on similar lands was estimated to be very low <br />for planning studies. Planning studies actually predicted a slight net decrease in salt loading to <br />the Colorado River system as salts would be precipitated in the soils. <br /> <br />oweD does plan to use a loan from the State of eo lor ado to assist in funding development of <br />the irrigation facilities. <br /> <br />Comment 8-. New lands would add to salt loading, perhaps negating the salinity control <br />measures. Increased salt loading and salinity concentration should be quantified. The EA gives <br />only a cursory analysis. This is serious omission because of national and international concern <br />with salinity. <br />Response 8- The potential for salt loading is very low and thus was not discussed in detail in the <br />draft EA. More information is provided in the final because of questions raised in the draft <br />review. <br /> <br />It has long been recognized that irrigation, reservoir evaporation, and municipal and industrial <br />use of water in the Colorado River Basin increases the salinity of the Colorado River. The <br />objective of the Colorado River Basin Salinity Control Program is the maintenance of salinity <br />levels at or below levels found in the main stem of the Colorado River as of April 1972 while <br />allowing the Upper Basin States (Utah, Wyoming, Colorado, New Mexico, and a portion of <br />Arizona) to develop full use of their Colorado River Compact apportioned water. The proposed <br />action is consistent with this objective. <br /> <br />The salinity content of the soils identified for irrigation under the proposed action are among the <br />lowest in the eolorado portion of the Colorado River Basin and substantially lower than the <br />marine shale derived soils of the Montezuma Valley where the water was previously used. <br />The new irrigation lands are "red soils" with lower salt content. Salt loading to the San Juan <br />, River would be lowered, but not to a significant extent due to the relatively small amount of <br />water involved in the Carriage Contract. There would be no salt loading to the Dolores/Colorado <br />river system; however, the continued diversion of the historically diverted 8,000 acre-feet of <br />relatively high quality water would continue to concentrate salts in the rivers. In terms of <br />concentrations, this amounts to approximately an 0.8 mg/l increase as measured on the Colorado <br />River at Imperial Dam. For comparison purposes, observed concentrations at Imperial Dam were <br />669 mgll in 1999 (numeric criteria for salinity standards at that point is 879 mg/l, which was the <br />1972 level). <br /> <br />Comment 9- The carriage agreement will help the salinity problem in McElmo Creek because <br />the water shares will be moved from lower salty soils to non-salty soils. <br />Response 9- The salinity content of the soils identified for irrigation under the proposed action <br />are substantially lower than the marine shale derived soils of the Montezuma Valley where the <br />water was previously used. <br /> <br />23 <br />