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<br />ENVIRONMENTAL PROTECTION AGENCY <br /> <br />~ <br />o::!" <br />~ downstream presently exceed U.S. Public Health Service recommended limits <br />~ for drinking water. Project development will cause an increase in these <br />salinity concentrations. The average annual salinity increase is expected <br />to be 4 rog/l in the Gunnison River at Grand Junction and 0.8 rug/l in the <br />Colorado River at Lake Mead. <br /> <br />The estimated 4 rug/l annual increase in TDS concentration in the <br />Gunnison River near Grand Junction, Colorado will have no significant <br />economic impact wi thin and between the project area and Lake Mead because: <br />(1) the quantity of water used in these reaches is small, and (2) the <br />magnitude of the salinity increase in the range of mineral quality exist- <br />ing in these reaches of the rivers will have very little effect on benefi- <br />cial uses. <br /> <br />The estimated 0.8 rug/l increase in the TDS concentration at Lake <br />Mead resulting from use of project water will have a detrimental effect <br />on all Colorado River water users below that point. This estimated annual <br />increase in TDS concentration will result in an average annual direct pen- <br />alty cost of about $49,000. A tabular suroroary of the estimated economic <br />and physical impact by segment of project related salinity increases in <br />the Colorado River below Lake Mead is shown below. This analysis was <br />based on salinity increases attributable to irrigation return flows and <br />depletions of the Colorado River. <br /> <br />Tomichi Creek <br />East River <br />Ohio Creek <br /> <br />Salini ty <br />Increase <br />(mg/l) <br /> <br />0.4 <br />0.1 <br />0.3 <br /> <br />Annual <br />Penalty Cost <br />(1972 Dollars) <br /> <br />$25,000 <br />6,000 <br />l8,000,Y <br /> <br />Segment <br /> <br />Total Upper Gunnison <br />Project <br /> <br />0.8 <br /> <br />$49,000 <br /> <br />It is our belief that the economic analysis of the Upper Gunnison <br />Project should include the econorrdc impact that will result from project <br />induced salinity increases. <br /> <br />11 The figures are for the plan including the irrigation increment, <br />now termed the alternative Ohio Creek Unit. For the Ohio Creek Unit plan <br />whiCh includes only municipal and domestic water service, the increase in <br />salinity is estimated at slightly more than 0.2 rog/l and the annual pen- <br />alty cost at $15,000. <br /> <br />54 <br />