WSP03614

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1981
• Author: USDOI
• Title: Quality of Water - Colorado River Basin - Progress Report No. 10 - January 1981 -- Part 1 of 2 -- Title Page through Part IX - page 98
• Water Supply Pro - Doc Type: Report/Study

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PART IV. CAUSES OF SALINITY

A. Increased Concentration from Salt Additions

1. Natural Sources of Salinity

Flow and quality records reveal that along certain reaches of the
Colorado River there are large increases in the dissolved-solids load that
cannot be attributed to irrigation or other man-related activity. This
increase is mainly due to natural di ffused sources and sal ioe springs.

Natural diffused sources are those sources of salt contribution which
occur gradually over long reaches of the river system. Salt pickup occurs
over large areas of surface and underlying soils, from stream channels and
banks, and is difficult to identify, measure, or control. This source
contributes the largest overall share of the salts to the Colorado River.
Natural point sources are mainly saline springs where the contribution of
salt and water is easily identified, issuing from single or concentrated
sources.

Very little information was obtained prior to irrigation, making it
difficult to identify the magnitude of specific natural sources of salinity
in the Colorado River Basin.

Upper Basin. Past records indicate a substantial increase ,LO salt
load in the Lake Powell area above Lees Ferry and below the Green River,
Utah, Cisco, and Bluff stations. Iorns and others (1965, p. 20) presented
estimates of dissolved-solids loads in this river reach based on the period
1914-57 adjusted to 1957 conditions of development.(l) Unaccounted inflow
of dissolved solids in this reach amounted to about 5 percent of the load
at Lees Ferry. Most of this resulted from natural diffused sources "ith
the San Rafael and Dirty Devil areas being fairly heavy contributors.

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Other areas in the Upper Basin with large amounts of natural diffused
sources of salt are the Grand Valley, Uncompahgre, Lower Gunnison, and
McElmo Creek areas in Colorado; Price River and Uinta Basin in Utah; and
Big Sandy River and Blacks Fork area in Wyoming. Although a large amount
of salt pickup in these areas is due to natural runoff, a large amount can
also be attributed to irrigation in some parts of the areas.

Table A summarizes information about the contribution of water and
dissolved salts by point sources, including the springs and wells in the
Upper Colorado River system. Although wells are man-made and not a natural
source, abandoned saline flowing wells are shown with the natural springs.
The largest contributors in the Upper Basin are the Dotsero and Glenwood
Springs which supply the major part of the salts from point sources.

Lower Basin. The inflow to the reach of the Colorado River between
Lees Ferry and Grand Canyon has varied from a low of 18,000 acre-feet
(22 x 106m3) in 1949 to a high of 939,000 acre-feet (1160 x 106m3)in 1941
with an average annual inflow of water for the 1941-7B period of 310,000

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