Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />1357 <br /> <br />areas in the Upper Basin. This amount will increase in the future as <br />additional ~ater is used on projects now being developed. It has been <br />found that irrigated areas in the Upper nasin have salt-pickup rates <br />that vary from as little as 0.1 ton ner acre per year to as much as <br />n.5 tons per acre per year. Many projects, where irrigation has been <br />practiced continuously for over 80 years, still have pickup rates in <br />excess of six tons per acre per year; and we have concluced that, in <br />the absence of any corrective measures, irrigation salt pickup will <br />continue at approximately the same levels. <br />!1unicipal and industrial uses in the Upper Basin consumptiveJ.y <br />use approximately 50,000 acre-feet annually and add approximately <br />130,000 tons of dissolved salts to the river each year, a minor <br />amount compared with contributions from irrigated agriculture. Other <br />sources of increased salinity in the Upper Basin ~e: (1) the export <br />of approximately 500,000 acre-feet a year of low salinity water from <br />the headwaters of the Colorado River system to adjoining basins in <br />the states of Utah, Colorado, and New 11exico, which further depletes <br />the flow do~mstream but diminishes only slightly the salt loac, and <br />(2) evaporation from storage reservoirs of approximately 300,000 <br />acre-feet per year. Both of these items are expected to increase in <br />the future. <br />In recent years, the salinity at Lee Ferry has averaged about <br />610 npm, which is much hieher than the 250 ppm that prevailed prior <br />to the advent of modern man. Figure 1 shows recent salinity of the <br />river at a number of points in the Colorado River Basin. As the <br />figure indicates, salinity is lowest close ~n the hpA~wa~crs of ~he <br /> <br />-~- <br />