WSP07738

• File Number: 8281.970
• Description: Colorado River Studies and Investigations -- Great Basin Comprehensive Framework Study
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1971
• Title: Appendix V - Water Resources -- Great Basin Region Comprehensive Framework Study
• Water Supply Pro - Doc Type: Report/Study

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;;; The chemical quality of surface water and ground water is generally
'~) good under natural conditions. Some deterioration occurs in the lower
~ segments of the principal streams and locally elsewhere, especially
to during periods of low flow. Return flows from irrigation and from
~ municipal and industrial uses increase the deterioration of natural
water quality.

Interior drainage, a primary feature of the Region, results in very
high total dissolved-solids concentrations in the major terminal sinks.
Great Salt Lake has concentrations on the order of 290,000 milligrams per
liter. Ground water in the Great Salt Lake Desert, also is highly con-
centrated. Walker Lake has total dissolved-solids concentrations of
8,500 milligrams per liter and Pyramid Lake about 5,000 milligrams per
liter. Ground water is similarly poor in chemical quality in many low-
land areas.

The total nominal water supply of 9.6 MAF comes from several supply
elements. Approximate values for these are: principal streams, 2.9 MAF;
upstream depletion along principal streams, 3.0 MAF; secondary and minor
streams, 1.4 MAF; and natural ground-water discharge, 2.3 MAF.

The principal uses at the 1965 level of development, together with
some related uses, such as nonirrigated meadow and unmanaged fish and
wildlife areas, result in an annual depletion rate of about 6 MAF. This
value does not include depletion from the terminal lakes; Great Salt Lake,
Pyramid Lake, and Walker Lake~ Their .net annual rate of evaporation, though
variable from year to year, was about 2.3 MAF for the 1965 year-end stage.

The residual nominal supply was about 3.6 MAF. Of this total, 40
percent is principal streamflow, 40 percent ground-water discharge, and
20 'percent .is secondary and minor streamflow. Possibly 1. 4 MAF of
principal streamflow goes to the terminal lakes. Part of the residual
secondary and minor streamflow and natural ground water reaches the
terminal lakes, especially Great Salt Lake, but most is widely distributed
in the numerous valleys of the Great Basin Region.

The natural characteristics of the several elements of the residual
water supply place limitations on the availability for development for
general use. Considering these aspects, about 1.8 MAF of the residual
water supply may be available annually for development. This amount
includes about 1.0 MAF from principal streams, 0.2 MAF from secondary
and minor streams, and 0.6 MAF of water intercepted from natural ground-
water discharge. An additional 0.4 MAF of ground water may be available
if treated to improve quality. In the upstream depletion areas about 0.3
MAF may be salvaged by improved management. Reduction of evaporation
from Utah Lake will save about 0.07 MAF of water annually.

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