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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A Mean
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Period of record 1950-83 -
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- Mean Period of record 1950-83 -
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OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT
Figure 25. Mean daily streamflow at selected sites in main-stem subregion of San Juan region. A, Site 58,
Dirty Devil River above Poison Spring Wash, near Hanksville, Utah. B, Site 69, Colorado River at Lees
Ferry, Ariz. C, Site 69, Colorado River at Lees Ferry, Ariz., showing selected non-exceedance probabilities
during the principal filling period (1966-80). D, Site 70, Paria River at Lees Ferry, Ariz.).
low-flow months, but did not change annually. A significant
decrease of 27 mg/L in median annual bicarbonate concen-
tration was indicated between the two periods. Although not
statistically significant, the mean annual concentration of
calcium decreased and all other constituents increased.
Upstream changes in water use probably would not decrease
the concentration of calcium and bicarbonate, and the
estimated loss may be from precipitation of calcite in the
reservoir.
Annual monotonic-trend analyses of the preinterven-
tion period indicated a significant increase in median annual
dissolved-solids concentration of 7.3 mg/L per year (table
10). This represents a 33-percent change in median annual
concentration during the 21-year period. Median annual flow-
adjusted concentration also increased significantly by 3.3
mg/L per year, which represents a 14-percent change dur-
ing the period of record. These increases result from increas-
ing development and decreasing streamflow upstream in the
Upper Colorado River Basin. No statistically significant
annual monotonic trends were indicated for the principal fill-
ing period, except that concentrations of calcium and bicar-
bonate decreased by 1.04 mg/L per year, which _may result
from increasing calcite precipitation as the reservoir filled.
Paria River at Lees Ferry, Ariz. (site 70)
Site 70 (table 3, pl. 1) is near the confluence of the
Colorado River, about 1 mi downstream from site 69.
Although streamflow of the Paria River averages less than
0.5 percent of the streamflow of the Colorado River at site
69, flows at the two sites normally are added together to result
in the official flow leaving the Upper Colorado River Basin
at Lee Ferry, Ariz. Water-quality analyses for the Paria River
are few, and dissolved-solids data are reported only to
generally indicate dissolved-solids concentrations in the Paria
River. Although streamflow and dissolved-solids load are
less than those for site 58, areal runoff is comparable at both
sites (table 9). The pattern of seasonal streamflow is similar
at both sites, except that runoff from thunderstorms is a
greater part of the total streamflow in the Paria River (fig.
25D). Mean annual flow-weighted dissolved-solids concen-
Main-Stem Subregion 57