WSP04684

• File Number: 8272.500
• Description: Colorado River Basin Salinity Control Forum
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1975
• Title: Appendix C - Water Quality Management Plan - Colorado River Basin - Water Quality Standards for Salinity Including Numeric Criteria and Plan of Implementation for Salinity Control
• Water Supply Pro - Doc Type: Report/Study

Diversions from the Upper Colorado River Basin into surrounding

qasins occur at or near the headwaters where the river's water has

~ a very low salt content. This removal of high quality water,
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~ even though some salt is also removed from the ,Basin, results in
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a salt concentrating effect downstream.

Most industrial plants in the last few years, particularly large

coal-fired thermal electric generating plants, have been designed

to eliminate the return of cooling tower blowdown water to the

Colorado River. As water is circulated through the cooling towers,

a part of it evaporates and the dissolved solids in the remaining

water become more and more concentrated. As cooling water must

be maintained at or below specific levels of salinity, a portion

of the concentrated water is removed or "blown down" and replaced

with fresh water. When this blowdoWn is not returned to the river

system, the salt load in the water diverted is removed from the

river. Even though these no-return uses remove salt from the river,

the river's concentration of dissolved 'solids usually increases

below the point of use because of the reduced flow resulting from

the beneficial use. The effects on river salinity of a no-return

consumptive use are similar to those of an out-of-basin export.

Historically, salt loads contributed 'by municipal and industrial

sources have been, minor, totaling about 1 percent of the Basin salt

load for the period 1942-61. With the exception of concentrated

returns from the Las Vegas, Nevada, area most municipal and

industrial wastes in the Basin are relatively low in total salt load.

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