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<br />"::1" <br />...-j <br />CJ <br />~ In addition to the 80,000 acres of irrigated land, there are about 750,000 <br />~ aCres of upland dry land that drain to the Colorado River in the Grand <br />~ Valley area. Based on the estimated sediment delivery of 1.8 million tons <br />from this area and the salt content of the eroding material about 90,000 <br />tons of salt annually are delivered to the river from surface sources. <br />Another 50,000 tons are estimated to come from subsurface flow from the up- <br />land area. These contributions of salt are highly variable from year to <br />year and depend on climatic ~onditions. <br /> <br />The averaqe annual water budqet for the Grand Valley area for the period <br />1 964 -71 is given in Tab 1 e 2. <br /> <br /> TABLE 2 <br /> In flow Outflow :Depletion <br />Colo. R. Ungaged Co 1 o. R. <br />near Plateau Gunnison Tributaries Total at State Grand <br />Cameo Creek Ri ver . In flow Line Valley <br />. <br /> (1 ,000 acre-feet) <br />2,600 120 1,71 0 40 4,470 4,200 270 <br /> <br />About 20 percent of the available flow of the Colorado River and tributaries <br />are diverted for irrigation in the Grand Valley. The Grand Valley irrigated <br />area has an abundant water supply. <br /> <br />The average annual salt budget for the Grand Valley is estimated as shown in <br />Tabl e 3. <br /> <br />, <br /> <br />TABLE 3 <br /> <br />Inflow : Outflow: <br />:Colo. R.: :Colo. R.: <br />near :Platea~:Gunnison: :at State: <br />Cameo Creek River: Total: Line <br />(million tons) <br /> <br />Resultant Pick Up <br />Irri-:Upland: <br />gated:Drain-: <br />Area: age Total <br /> <br />Ave. 1964-70 1.40 <br />Range 1964-70 1.2-1.6 <br /> <br />0.07 <br /> <br />1.43 <br /> <br />2.9 <br /> <br />3.54 <br /> <br />0.50 0.14 <br /> <br />0.64 <br />0.6-0.8 <br /> <br />1.2-1.7 2.4-3.3 3.2-4.14 <br /> <br />An analysis of USGS water quality records (1964-70) indicates an average of <br />about 640,000 tons of salt are added to the Colorado River in the Grand <br />Valley reach. As previously stated about 140,000 tons annually of the <br /> <br />- 4 - <br />