Laserfiche WebLink
<br />Introduction 13 <br /> <br />N <br />en <br />CD <br />f\;' <br /> <br />TDS in mglI. <br />under 50 <br />186 <br /> <br />200 <br /> <br />250 <br /> <br />334 <br /> <br />349 <br />500 <br /> <br />537 <br /> <br />539 <br /> <br />542 <br />678 <br />747 <br /> <br />825 <br /> <br />Table 1. - TDS levels considered <br />for baseline and current condnlon assumptions <br /> <br />Remarks <br /> <br />DistiUed water, may be chemically aggressive. <br /> <br />Average TDS of water supply to 100 largest cities in the <br />United States (1982). <br /> <br />Typical of water supplies in Upper Basin above Glenwood <br />Springs, Colorado. Some household damages begin to be documented. <br /> <br />Rounded TDS of alternate water supply to Southern California from <br />state project sources (1986); and probable virgin flow of Colorado <br />River measured at Lee Ferry (based on CRSS natural flow data, <br />1906 - 1983). <br /> <br />Natural TDS of the Colorado River at Hoover Dam based on the <br />1942-1961 hydrologic record, as developed in EPA's 1971 The Milleral <br />Quality Problem in the Colorado River Basill. <br /> <br />Maximum TDS of Upper Basin conditions at Cisco, Utah. <br /> <br />EP A secondary drinking water standard, a recommended but not <br />mandatory standard, apparently selected on the basis of estimated <br />health and taste aspects. <br /> <br />1986 reported level of water deliveries by the Metropolitan Water <br />District of Southern California [MWD] (lowest TDS level in 42 years). <br /> <br />Estimated TDS of Colorado River in the Lower Basin with no dams, <br />based on earliest water quality measurements (1926-1934) at <br />Yuma, Arizona. <br /> <br />Current 1986 level at Parker Dam (provisional data). <br /> <br />Ten year average (1976-1985 at Parker Dam). <br /> <br />Salinity criterion below Parker Dam established by the <br />Colorado River Basin Salinity Control Forum. <br /> <br />Maximum TDS projected for Parker Dam in 2010 (1987 CRSS <br />study) without further controls. <br /> <br />'1 <br /> <br />I <br /> <br />The A WW A policy stated that hardness of 80- <br />100 mg/L is not objectionable to most con- <br />sUlllcrs. The 200 mgiL baseline also appeared to <br />be similar to the annual average salinity of State <br />project water delivered to MWD from the <br />California Aqueduct (219 mgiL TDS in 1985) <br />and to a recently reported level of TDS in the <br />Colorado River near G\enwood Springs, <br />Colorado. <br /> <br />The case that can be made for a baseline <br />TDS level around 250 mgiL includes, with some <br />accuracy, the possibility that it represents the <br /> <br />level of salinity that a Colorado River completely <br />untouched by man might have. With no dams, <br />no irrigation projects, no diversion for any <br />human uses, a free-flowing river with an annual <br />average virgin flow of approximately 15 maf with <br />a natural salt load of about 5.2 million tons at <br />Lee Ferry (based on CRSS natural flow data, <br />1906-1983) represents a TDS level of 255 mgiL.4 <br />It is arguable that such a figure could represent <br />the natural state for the entire length of a free- <br />flowing river (even including the salt input from <br />Blue Springs). <br /> <br />:1 <br />, <br /> <br />4.n,csc numbers were developed by David Merritt, Senior Water Resources Engineer, Colorado River Wafer <br />Conservation District, based on his work devel.oping the CRSS data base wh\1c at the Bureau of Reclama\ion. <br /> <br />j <br />