WSP03032

• File Number: 8272.600.60
• Description: Colorado River Basin Salinity Control Program - Basin Member State Info - Utah
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/7/1975
• Author: Utah State Univ
• Title: Colorado Regional Assessment Study - Phase One Report for the National Commission on Water Quality - Part 1 of 2 -- Title Page - end Chapter V
• Water Supply Pro - Doc Type: Report/Study

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affect downstream uses, For example, it is reported that within the

Lake Powell and Lake Mead storage reservoirs the concentrating effects

due to evaporation from these water surfaces are essentially offset by

the precipitation of dissolved salts from the impounded waters. However,

the precipitating salts tend to be predominantly calcium compounds so

that the resulting ionic content of the waters is shifted towards the sodium

ion. This change (increased sodium adsorption ratio) may be regarded

as beneficial by domestic users, but the water quality is less desirable

for irrigation purposes farther downstream.

Salinity and Irrigation Practice. Over the years, irrigation techn-

ology has been primarily concerned with management and application of

water to the land} andcontrol.of salinity levels~ indhe soils. . Through

irrigation practices man diverts salts already dissolved within the stream-

flow and applies them to agricultural lands. If these salts are permitted

to accumulate within the soil root zone, the lands quickly become saline

and plant growth is either retarded or stifled, This condition is. pre-

vented by applying an excess of irrigati.on water such that the salts are

carried back to the streams with the irrigation return flows. The net

effect oHhts process is that water now rates in the streams are reduced

by crop evapotranspiration, while salt loads either remain fixed or

increase by additional pickup of salts from within the soils of the

irrigated area,unless the soil is used as a salt sink.

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