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

Table 6. Selected annual monotonic-trend-analysis results-Grand region
[Sites having less than 10 years of dissolved-solids data are not reported; n, number of years of dissolved-solids data; acre-ft/yr, acre-feet per year;
mg/L, milligrams per liter; tons/yr, tons per year; HS, highly significant (p 4 0.01); S, significant (0.01 < p < 0.05); MS, marginally significant
(0.05 < p < 0.10); - -, not significant (p > 0.10)]

Site Period
(table of
3, record
plate (water
1) years)

n
Annual trend'
in streamflow
Signif- Trend Per-
icance (acre- 1
level ft/yr) cent Annual

Concentration
Signif- Trend Per-
icance '
level (mg/L) cent trend in

Signif-
icance
level dissolved solids
Flow-adjusted
Load concentration
Trend Per- Signif- Trend Per-
(tons/ 1 icance
yr) cent level (mg/L) cents
2 1947-83 37 -- -- -- S 0.4 22 -- -- -- --
3 1947-83 37 -- -- -- S -1.9 21 HS -1,250 26 HS -2.1 23
4 1959-83 25 -- -- -- S -2.4 24 -- -- -- HS -1.0 11
5 1950-83 34 -- -- -- -- -- -- -- -- -- --
6 1959-83 25 -- -- -- -- -- -- -- -- -- -- -- --
8 1973-82 10 -- -- -- -- -- -- -- -- -- -- -- --
10 1934-49 16 -- -- -- MS -5.8 21 -- -- -- -- -- --
10 1950-83 34 --
11 1969-79 11 -- -- -- -- -- -- -- -- -- --
12 1959-80 22 -- -- -- HS -20.4 30 S -3,810 22 HS -19.3 28
13 1934-65 32 -- -- -- -- -- -- -- -- -- S -2.8 13
13 1966-83 18 -- -- -- S -16.1 39 -- -- -- HS -9.9 26
15 1974-83 10 S 1,620 26 S -38.4 25 MS -2,770 19 MS -37.0 25
17 1974-83 10 S 2,220 40 --
18 1962-83 .22 -- -- -- MS -11.2 34 -- -- -- HS -4.8 16
20 1952-83 32 -- -- -- -- -- -- HS 4,990 46 HS 4.7 24
21 1929-49 21 --
21 1950-65 16 -- -- - -- -- -- -- -- " --
21 1966-83 18 -- -- -- -- -- -- -- -- -- MS -2.9 9
'Percent change during period of record.
a 22-percent increase in median annual concentration dur-
ing the 37-year period. The monotonic trend in median
annual streamflow since 1947 was not statistically signifi-
cant, perhaps because of the large annual variability and the
large streamflow volume during 1983.
Eagle River at Gypsum, Colo. (site 3)
Although the streamflow at site 3 (table 3, pl. 1) is com-
parable to the Colorado River preintervention streamflow at
site 2, the dissolved-solids concentration is much higher. The
mean annual flow-weighted dissolved-solids concentration
is 288 mg/L, and the mean annual streamflow is about
410,000 acre-ft (table 5). Sources of dissolved solids include
mining operations and surface outcrops of Pennsylvanian
sedimentary formations. Outcrops of the Eagle Valley
Evaporite contain thick salt beds (Warner and others, 1985).
During the snowmelt season (May-July), calcium and bicar-
bonate are the predominant ions. Calcium and sulfate
predominate during the remainder of the year. The Home-
stake Tunnel has only slightly affected the streamflow of the
Eagle River (fig. 8B).
Although streatnflow has not changed significantly,
dissolved solids decreased during 1947-83. Annual
monotonic-trend analyses indicated a significant decrease in
median annual dissolved-solids concentrations of 1.9 mg/L
per year, and highly significant decreases in values of median
annual dissolved-solids load of 1,250 tons/yr and flow-
adjusted concentration of 2.1 mg/L per year (table 6). Dur-
ing the 37-year period, these trends represent a 21-percent
decrease in median annual concentration, a 26-percent
decrease in median annual load, and a 23-percent decrease
in median annual flow-adjusted concentration. Median annual
flow-adjusted concentrations of all major constituents also
decreased. The cause of the decrease is unknown, but may
be related to the change from mining and agricultural land
uses to recreational land use.
Colorado River near Dotsero, Colo. (site 4)
Streamflow at site 4 averages approximately 1.4 million
acre-ft/yr, and the mean annual, flow-weighted dissolved-
solids concentration is about 213 mg/L (table 5). Calcium
and bicarbonate are the predominant ions throughout the
year. Sulfate also is a predominant ion during the low-flow
season because of the large load contributed by the Eagle
River. During 1959-83, annual monotonic-trend analyses
indicated a significant decrease in median annual dissolved-
solids concentration of 2.4 mg/L per year and a highly signifi-
cant decrease in median annual flow-adjusted concentration
Upper Colorado Subregion 23