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<br />Table 4
<br />
<br />PROJECTED CONCENTRATIONS OF TOTAL
<br />DISSOLVED SOLIDS (mg/J) AT IMPERIAL DAM
<br />(Average annual values)
<br />
<br /> Year
<br />Source 1980 2000 2010 2020 2030
<br />EPA 1,060 - 1,220 - -
<br />CRBC 1,070 1,340 - - 1,390
<br />WRC 1,260 1,290 - 1,350 -
<br />USBR 930 1,160 - - -
<br />
<br />EPA: Environmental Protection Agency, 1972
<br />CRBC: Colorado River Board of California, 1970
<br />WRC: Water Resources Council (Lower Colorado
<br />Region Comprehensive
<br />Framework Study), 1971
<br />USBR: Bureau of Reclamation, 1973
<br />
<br />salinity water were used. Municipal and industrial users
<br />are faced with considerable expense due to water
<br />quality. Allowing the salinity of the river to increase
<br />will result in additional economic impacts.
<br />
<br />ECONOMIC IMPACTS
<br />
<br />Economic detriments can be computed using the
<br />projected increases in salinity, under the assumption
<br />that a control program will not be installed. The
<br />adverse effects would be expressed primarily in the
<br />agricultural, municipal, and industrial uses. Few
<br />adverse impacts on instream uses such as recreation,
<br />hydroelectric power generation, and propagation of
<br />aquatic life are expected. The detriments in agriculture
<br />would arise from one or a combination of the
<br />following: decreased crop yields, increased leaching
<br />requirements, increased management costs, and
<br />application of various adaptive practices such as
<br />changes in crop patterns, improved drainage systems,
<br />and pJantings on sloping beds. In the municipal and
<br />industrial uses, the detriments arise primarily from
<br />increased water treatment costs, accelerated pipe
<br />corrosion and appliance wear, increased use of soap
<br />and detergents, and decreased palatability of drinking
<br />water.
<br />
<br />Based on the foregoing kinds of impacts, the total and
<br />direct damages now being experienced and those
<br />contemplated if no salinity control measures are
<br />installed have been determined and the findings are
<br />presented in Table 5. These figures are the relevant
<br />damages, i.e., those caused by salinity levels in excess
<br />of threshold values. The threshold values assumed for
<br />
<br />M&I and agriculture are 500 and 750 mgl',
<br />respectively.
<br />
<br />Table 5
<br />
<br />TOTAL AND DIRECT DAMAGES
<br />ATTRIBUTABLE TO SALINITY
<br />IN THE COLORADO RIVER SYSTEM
<br />
<br />Year Total Direct
<br />1973 $ 53,000,000 $ 49,000,000
<br />1980 72,000,000 64,000,000
<br />1990 111,000,000 96,000,000
<br />2000 124,000,000 107,000,000
<br />2010 147,000,000 126,000,000
<br />
<br />The total damages reflect the impact on the entire
<br />regional economy while the direct damages affect only
<br />the water users. Damages to water users in Mexico and
<br />recreation and fishing uses in the Salton Sea have not
<br />been estimated.
<br />
<br />Apply i ng present worth factors at 6-7/8 pe rcent to the
<br />values from Table 5 indicates the economic magnitude
<br />of the salinity problem on the Colorado River. The
<br />present value of the future damages amounts to about
<br />$1.1 billion for the direct damages and $1.24 billion
<br />for the total damages.
<br />
<br />PREVIOUS STUDIES AND FINDINGS
<br />
<br />The salinity problem in the Colorado River has been
<br />the object of many studies and investigations,
<br />stemming from the deep concern of the states as
<br />expressed during hearings and negotiations with
<br />Mexico relating to the 1944 Mexican Water Treaty.
<br />California in particular wanted the water quality issue
<br />clearly stated to avoid future misunderstanding. This
<br />was not accomplished as recent events have shown.
<br />
<br />The most relevant studies on salinity in the Colorado
<br />River were made by the U.S. Geological Survey,
<br />Bureau of Reclamation, Environmental Protection
<br />Agency (and its predecessor agencies), Water Resources
<br />Council, Colorado River Board of California, and Utah
<br />State University.
<br />
<br />The USGS studies concentrate on definition of the
<br />salinity problem. They trace historic salinity levels,
<br />estimate salt loading from specific sources, and identify
<br />salt contribution from various river reaches. The
<br />Bureau of Reclamation studies report on the past,
<br />present modified, and future water quality conditions
<br />in the basin. The effects of salinity on water uses and
<br />
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