9521

• UCREFRP Catalog Number: 9521
• Author: Liebermann, T. D., D. K. Mueller, J. E. Kircher and A. F. Choquette.
• Title: Characteristics and Trends of Streamflow and Dissolved Solids in the Upper Colorado River Basin, Arizona, Colorado, New Mexico, Utah, and Wyoming.
• USFW Year: 1989.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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WATER YEAR
1980
Figure 28. Monthly, change in Lake Powell volume that is not explained by inflow-outflow mass balance.
fore, the mixing-tank concept seems appropriate for assess-
ing the long-term effect of Lake Powell on dissolved-solids
loads. Inflow volumes and loads are mixed in the reservoir,
and the variability of the outflow dissolved-solids concen-
tration has decreased. The loss or gain of dissolved solids
within the reservoir could not be detected.
SUMMARY
Annual and monthly concentrations and loads of
dissolved-solids and major constituents were estimated for
70 streamflow-gaging stations in the Upper Colorado River
Basin. Trends in streamflow, dissolved-solids concentrations,
and dissolved-solids loads were identified. Nonparametric
trend-analysis techniques were used to determine long-term,
monotonic trends and step trends that resulted from human
activities upstream. Results were compared with physical
characteristics of the basin and historical water-resource
development in the basin to determine source areas of dis-
solved solids and possible cause of trends.
The mean annual dissolved-solids concentration of the
Colorado River increases from less than 100 mg/L in the
headwater streams to more than 500 mg/L at Lees Ferry,
1985
Ariz., downstream from Lake Powell. For the 70 sites
analyzed in this report, mean annual flow-weighted concen-
tration ranged from 29 mg/L near the headwaters of the Colo-
rado River to 6,740 mg/L in Bitter Creek near Bonanza,
Utah. In headwater streams, calcium and bicarbonate are the
predominant dissolved constituents. Lower in the basin, in
areas underlain by sedimentary rocks, large quantities of
sulfate, sodium, and calcium are transported into the stream
system. In many streams in the Colorado Plateau province,
dissolved sulfate constitutes about 60 percent of the dissolved-
solids load.
For sites on streams that have a mean annual stream-
flow greater than 25,000 acre-ft, the maximum dissolved-
solids concentrations occurred downstream from areas where
irrigated agriculture has major effects on streamflow and
dissolved solids. Streams affected by irrigation return flow
include the Big Sandy, Price, San Rafael, Uncompahgre, and
Dirty Devil Rivers, McElmo and Salt Creeks, and Reed
Wash. In the basins of these streams (except the Big Sandy
River), large tracts of irrigated land are underlain by Mancos
Shale. At sites downstream from these areas, sulfate is the
predominant anion. Calcium or magnesium usually is the
predominant cation in streams in the Grand region and the
eastern side of the San Juan region. Sodium is the predomi-
60 Characteristics and Trends of Streamflow and Dissolved Solids in the Colorado River Basin