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<br />w <br /><:::) <br />I-'" <br />w::.. <br /> <br />CHAPTER I. <br /> <br />SCOPE OF PROBLEM <br /> <br />The increase of salinity in the Colorado River is not a <br />new or unique ,situation in the history of western water <br />resources. Water quality changes in the river were <br />recognized as early as 1903. Today, the salinity <br />problem of the Colorado River is viewed as the <br />forerunner of similar problems of other western rivers <br />such as the Rio Grande, Arkansas, and Platte which are <br />all affected in different degrees by increasing salinity <br />levels, <br /> <br />In geographical terms, the majestic Colorado River is <br />one of the most diverse river basins in the world. The <br />1,4DO-mile-long river originates in the Rocky <br />Mountains and flows through scenic canyons and <br />desert vistas to accommodate drainage from parts of <br />seven western states and Mexico. <br /> <br />In its journey to the Gulf of California, the river carries <br />a salinity burden of about 10 million tons annually. <br />About one-half of the salt concentration arises from <br />natural sources, the other half from man's use. <br /> <br />The river water is used and reused several times during <br />its journey, reducing the available water supply and <br />increasing salinity along the way. In overall terms, the <br />high salinity levels in the lower river reaches adversely <br />affect nearly 10,000,000 people and about a million <br />acres of fertile, irrigated farmland. Salinity <br />concentrations are expected to have little adverse <br />impact on instream uses such as recreation, <br />hydroelectric power generation, and fish and wildlife. <br />Serious economic impacts, however, are expected in <br />the municipal, lhdustrial, and agricultural sectors. <br />Recent studies by the Bureau of Reclamation have <br />shown annual economic losses ranging froin $194,000 <br />to $395,000 per mg/I increase in salinity at Imperial <br />Dam. Using an annual economic loss value of $230,000 <br />per mg/I increase, the total damages attributable to <br />salinity in the Colorado River system for 1973 are <br />about $53 million. By the year 2000, using the same <br />criteria, these damages to the total regional economy <br />could reach about $124 million per year if water <br />resource development continues and no salinity <br />reduction meaS4Jres are instituted. <br /> <br />Salinity levels in the: Colorado River now range from <br />less than 50 mg/I at the headwaters to average <br />concentrations of about 850 mg/I at Imperial Dam. <br />Projected concentrations of total dissolved solids at <br />Imperial Dam for the year 2{)OO range from 1,160 mg/I <br />to about 1,300 mg/I if no salinity control measures are <br />undertaken. <br /> <br />SUMMARY <br /> <br /> <br />The salinity problem in the Colorado River has been <br />the object of several past studies and investigations. <br />Various aspects of the problem and control measures <br />have been pursued by the Bureau of Reclamation, U.S. <br />Geological Survey, Environmental Protection Agency <br />(and its predecessor agencies), Water Resources <br />Council, Colorado River Board of California, and <br />several universities. Studies spanning several years have <br />traced historic salinity levels and flows, sources of salt <br />loading, and the nature and magnitude of damages and <br />potential control measures. The largest portion of the <br />mineral burden and water supply is found to originate <br />in the Upper Basin. <br /> <br />The 1972 EPA Enforcement Conference on the <br />Pollution of Interstate Waters of the Colorado River <br />initiated new efforts to establish an overall salinity <br />control policy for the river. The seven basin state <br />conferees and Federal agency representatives <br />concluded that such a policy would have as its <br />objective the maintenance of salinity concentrations at <br />or below levels presently found in the lower main stem <br />while the Upper Basin continues to develop its <br />compact-apportioned waters. <br /> <br />Another related matter highlighting the need for <br />basinwide salinity controls is a recently executed <br />agreement with Mexico in an effort to find a <br />permanent, definitive, and just solution to the <br />international salinity problem with Mexico. Under the <br />agreement, water delivered to Mexico shall have an <br />average annual salinity of no more than 115 mg/I (plus <br />or minus 30 mg/J) over the average annual salinity of <br />waters arriving at Imperial Dam. This requirement is to <br />become effective upon the authorization of Federal <br />funds to construct works necessary to achieve the <br />limited differential in salinity. Should the river salinity <br />further increase as forecasted, the salinity level of <br />water delivered to Mexico would increase in <br />corresponding amounts. <br /> <br />Another recent institutional consideration in salinity <br />control is recognized in Public Law 92-500. The 1972 <br />"Federal Water Pollution Control Act Amendments" <br />have been interpreted by the EPA to require numerical <br />salinity standards on the Colorado River. Accordingly, <br />the seven basin states have been requested to undertake <br />studies and negotiations to develop such standards and <br />detailed plans of implementation. Moreover, the law <br />provides that by 1977, the "best practicable" water <br />pollution control technology shall be appl ied to carry <br />out proposed control measures on the river. <br /> <br />5 <br />