Laserfiche WebLink
<br /> <br />""'j <br /> <br />. <br /> <br />",...;.~~ <br /> <br />~ <br />'_.- 'a.:.._,~ <br /> <br /> <br />. <br /> <br />Figure 1. - Recreation - one of the many uses of the Colorado River. <br /> <br />The salt loading arises from both natural and manmade sources. The water <br />is used and reused several times along its length, causing the volume of <br />available water to decrease while the salinity increases. The potential <br />demands on the river exceed its dependable supply. The overriding issue on <br />the Co 1 or ado River i nvo 1 ves the i nterre 1 ated matter of inadequacy of the <br />water supply to meet all proposed uses and the deteriorating water quality. <br /> <br />The Colorado River at its headwaters in the mountains of north-central <br />Colorado has a salinity concentration of only about 50 mg/L. The salinity <br />concentrations progressively increase downstream as a result of water <br />diversions and salt contributions from a variety of sources. In 1981, the <br />salinity concentration averaged about 816 m9/L at Imperial Dam, the last <br />major diversion point on the Colorado River in the United States. <br /> <br />The historical salt load fluctuates annually with the overall Basin water <br />supply. Without control measures, and as the Upper Basin States continue m <br />develop their compact-apportioned waters, the salinity at Imperial Dam is <br />expected to increase. As the following graph indicates, since 1949 the <br />general trend of sal inity at Imperial Dam has been upward, although since <br />1970 the salinity has decreased, possibly as a result of the construction <br />of the Colorado River Storage Project reservoirs such as Lake Powell (Glen <br />Canyon Dam). This downtrend is believed to be a temporary phenomenon, and <br />the projected salinity level at Imperial Dam through the year 2010, without <br />water quality improvement proj ects, is expected to follow the over all <br />rising trend as shown in figure 2. <br /> <br />2 <br />