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<br />Q~:'{S5 <br /> <br />efficiency improvements in the area have been made, is the maintenance of salinity levels at or <br />below that found in the mainstem of the Colorado River as of April 1972. This while allowing <br />the Upper Basin States (Utah, Wyoming, Colorado, New Mexico, and a portion of Arizona) to <br />develop full use of their Colorado River Compact apportioned water. The proposed action is <br />consistent with this objective. <br /> <br />The salinity content of the soils identified for irrigation under the proposed action is among the <br />lowest in the Colorado 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 />Salt loading to the San Juan River would be lowered or not materially increased. Modeling <br />performed for similar lands for the Dolores Project predicted essentially no net salt loading from <br />irrigation of new lands in the red soil area (Reclamation, I 977b). Project planning studies <br />actually predicted a slight net decrease in salt loading to the Colorado River system as salts <br />would be precipitated in the soils. There would also be no salt loading to the Dolores/eolorado <br />River-Lake Powell river segment; however, the continued diversion of the historically diverted <br />6,000-8,000 acre-feet of relatively high quality water (low salinity) would continue to concentrate <br />salts in the rivers. In terms of concentrations, this amounts to approximately an 0.6-0.8 <br />milligram/liter (mg/l) increase as measured in the Colorado River at Imperial Dam. For <br />comparison purposes, observed concentrations at that point were 669 mg/I in 1999 (numeric <br />criteria for salinity standards at that point is 879 mg/l, [Department of the Interior, 1999]). <br /> <br />Initial monitoring of return flows from new lands in the Dove Creek area under the Dolores <br />Project recorded samples with selenium concentrations that exceeded the Environmental <br />Protection Agency criterion of 5 microgramsll, despite soil studies that showed low selenium <br />concentrations in the areas' soils. Despite these low concentrations, there is apparently sufficient <br />soluble or oxidizable selenium in the red soils to produce detectable selenium concentrations in <br />irrigation drainage, at least under initial leaching conditions (Butler et ai, 1997). Total selenium <br />loads to the San Juan River system from the Dove ereek area irrigation returns are very low <br />because stream discharges are low (Butler et ai, 1995). Monitoring drainage from new lands for <br />selenium is being continued; selenium trends seem to indicate an overall slight average decline <br />(Bureau of Reclamation, 2000). Monitoring is difficult because return flows are very low; wet <br />and dry periods may affect short-term results; and farming efficiencies improve in the early years <br />of new irrigation. Return flows from new lands under the Carriage Contract would be monitored <br />also in coordination with the Fish and Wildlife Service (Service) as indicated in the Biological <br />Opinion. Overall, selenium loading from new lands is expected to be low because of soil quality, <br />irrigation efficiencies, and relatively small acreage. <br /> <br />Al?ficulture and Land Use <br /> <br />Montezuma County has a total land area of approximately 1.4 million acres of which roughly <br />one-third are private land, one-third Ute Mountain Ute Tribal land, and one-third state and <br />Federal lands. The population of the county is around 23,000 people. Around 45,000 acres of <br />farmland in the county have adequate irrigation water and many qualify as prime farmland. <br /> <br />10 <br />