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<br />. <br /> <br />. <br /> <br />. <br /> <br />r.... <br />(,0 <br />~\) <br />o <br /> <br />PRESENT SURFACE WATER QUALITY <br /> <br />This section will discuss present baseline water quality conditions <br />in those subbasins of the Upper Colorado River Region most likely to be <br />influenced by EET development. Only those pollution parameters which <br />have been designated as problems, or for which water quality standards <br />violations have occurred, will be reported. Tables showing individual <br />state water quality standards and present monitoring data are not given. <br />Reports by the EPA, USGS, and state 208 planning agencies were consulted <br />in the preparation of this brief discussion, as well as detailed develop- <br />ment plans and environmental baseline reports. Few footnotes are given, <br />but the references listed at the end of this section may be consulted <br />for further information and documentation. Also, at the end of this <br />section is a brief discussion on present water quality planning efforts <br />in the Upper Basin. <br /> <br />Problem Parameters <br /> <br />Total dissolved solids (TDS) , or salt concentration and loading, has <br />long been recognized as the most prevalent water quality problem in the <br />Upper Colorado River Basin. The following description of the problem <br />and of the institutional arrangements adopted by the Upper Basin states <br />is from the U.S. Water Resources Council's '75 Water Assessment, Upper <br />Colorado Region Technical Memorandum No.2,. State/Regional Future, <br />August, 1976, pp. 28-29. <br /> <br />Of all man's activities, irrigation is responsible for the <br />largest increase in salinity. Water is removed through <br />evaporation and consumption by plants, but nearly all of <br />the salt is returned to the river, concentrating the salts <br />in a smaller volume of water. At the same time the return <br />flows leach salts from the soils and rocks which add to the <br />River's salt load. <br /> <br />Reservoir evaporation also contributes to increasing <br />salinity because evaporation removes water but leaves the <br />salts to be concentrated in a smaller volume of water. <br />Out-of-basin exports and in-basin uses that do not return <br />salt to the system ordinarily cause higher salt concentrations <br />down stream. Salt loads contributed by municipal and indus- <br />trial use are of minor significance in this Region. <br /> <br />I <br /> <br />The Federal Water Pollution Control Act Amendments of 1972 <br />(P.L. 92-500) require the adoption of water quality standards <br />for the Colorado River System. The seven Colorado River <br />Basin States have adopted an objective that calls for main- <br />tenance of salinity in the lower mainstem of the river at or <br />below the average value found during 1972 while the Basin <br />States continue to develop their compact-apportioned waters. <br /> <br />3-7 <br />