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

dissolved solids is added annually between sites 4 and 5, 70
percent as dissolved sodium and chloride. Most of this
dissolved-solids load is contributed by very saline, thermal
springs between the towns of Dotsero and Glenwood
Springs (Iorns and others, 1965; Warner and others, 1985).
Dissolved-solids concentration at site 5 averages 18 mg/L
higher in dissolved sodium and 30 mg/L higher in dissolved
chloride than at site 4. Calcium and bicarbonate are the
predominant ions during the snowmelt season. Sodium,
calcium, and chloride are predominant during the low-flow
season. The mean monthly loads of dissolved sodium and
chloride are relatively constant throughout the year.
The period of record was divided into a preintervention
period (1942-49) and a postintervention period (1950-83),
based on the Alva B. Adams Tunnel/Lake Granby exports.
The annual step trend in streamflow was -330,000 acre-ft,
a significant decrease of 18 percent from the preinterven-
tion median streamflow (table 4). The annual step trend in
dissolved-solids concentration was 39 mg/L, a highly sig-
nificant increase of 17 percent from the preintervention
median concentration. Dissolved-solids load did not change
significantly. Monthly step trends indicated a significant
decreasing streamflow and a highly significant increasing
dissolved-solids concentration during the snowmelt season
when water is stored in Lake Granby (fig. 9).
Annual monotonic-trend analysis for the preinter-
vention period indicated increased streamflow and decreased
dissolved-solids concentration during January through
March. No significant annual monotonic trends were
indicated for the postintervention period.
Roaring Fork River at Glenwood Springs, Colo. (site 6)
Site 6 (table 3, pl. 1) has a mean annual flow-weighted
dissolved-solids concentration of 245 mg/L (table 5). The
high mountains that form the headwaters region of the Roar-
ing Fork River are the source of large volumes of water.
The mean annual streamflow of the Roaring Fork River is
about 867,000 acre-ft (table 5). Approximately 35,000 acres
of irrigated farmland is in the downstream reaches of the river
basin, which contain outcrops of Cretaceous sedimentary
rocks. Mancos Shale, which contains relatively soluble
deposits of gypsum (calcium sulfate) and trona (sodium car-
bonate and sodium bicarbonate), is exposed in a large area
along the river and may be responsible for higher dissolved-
solids concentrations. The Eagle Valley Evaporite also is
exposed. The predominant ions are calcium and bicarbonate
during the snowmelt season and calcium and sulfate during
the low-flow season. The Twin Lakes Tunnel and C.H.
Boustead Tunnel/Ruedi Reservoir each have caused
decreases in peak flow at this site (fig. 8C). Large quan-
tities of gypsum were leached from the bank material short-
ly after construction of Ruedi Reservoir (J.W. Yahnke, U.S.
Bureau of Reclamation, written commun., 1982). No
statistically significant annual monotonic trends were detected
for this site.
SITE 5
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SITE 10
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MONTH
EXPLANATION
Highly significant (p 0.01)
® Significant (0.01< P<0.05)
® Marginally significant (0.05<p<_0.10)

ANNUAL
Figure 9. Step trends at site 5 (Colorado River near Glenwood
Springs, Colo.) from 1942-49 to 1950-83 and at site 10 (Co-
lorado River near Cameo, Colo.) from 1934-49 to 1950-83.
Parachute Creek at Parachute, Colo. (site 7)
Site 7 (table 3, pl. 1) has a mean annual flow-weighted
dissolved-solids concentration of 528 mg/L and a mean
annual streamflow of 23,000 acre-ft (table 5). Parachute
Creek drains Roan Mesa located north of the Colorado River.
In the drainage basin, Tertiary sedimentary rocks are ex-

Upper Colorado Subregion 25