9568

• UCREFRP Catalog Number: 9568
• Author: Resource Consultants Inc.
• Title: Sediment Transport Studies of the Little Snake, Yampa, and Green River Systems.
• USFW Year: 1991.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

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from telemetry data (T) of the stream flow. Total suspended concentration (CoI3) uses the results from
the DH-48 and DH-49 sampling. The percent silt/clay (Col 2) was established by wet sieving the
suspended sample. Wash load fractions (Col 4, 7) and suspended sand load fractions (Col 5,8) were
determined by the percent silt/clay.

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A comparative plot of the measured wash load (Col 7) and suspended sand load (CoI8) at seven
sites is shown in Fig. 3.6. This plot indicates that in the Yampa River the wash load is greater than the
suspended sand load, while in the Little Snake River the opposite is true (suspended sand load greater than
wash load).

The Helley-Smith data, which may be considered indicative of bed load, is reported in Col 9, and a
corresponding concentration (CollO) computed for comparison. The ratio of the HeIley-Smith load to
total suspended sand (Colll) was found to vary widely due to the local characteristics of the flow at the
various sites.

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Fig. 3.7 shows the estimated bed material load (CoI12). This plot demonstrates the recognized
importance of the lower Little Snake River as a sediment source area for sand sized material. During
higher flows the sediment discharge in the upper Little Snake (Dixon and Baggs) and in the Yampa River
above the Little Snake confluence (Juniper Hot Spring and the site immediately above the confluence) are
insignificant compared to the discharge in the lower Little Snake (Route 4, Highway 318 and Lily).

Helley Smith samples were dry sieved, providing the gradation curves shown in Fig. 3.8. The
material in transport for the various sites is very consistent over time.

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Note that the Little Snake results reported above compare favorably with USGS data collected in
1983 at the Lily gage (Table 3.2). In both cases, sand load transport reaches values as high as 10,000 to
15,000 tons/day. The similarity of these results conftrms the data collection and analysis procedures.
28.000

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26.000
24.000
}:'
<{ 22.000
0
"-
lJl 20.000
z
0
t, 18.000

Y AMPA RIVER

LITTLE SNAKE
RIVER

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Ul,-..
O.:g 16.000
w ~
() Ul 14.000
a:: ::J
<{ 0
is ~ 12.000
lJl~
o 10.000

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f-
Z 8.000
w
:;?
0 6.000
w
lJl
4.000
2.00d
0.000

HWY 3

LILY G

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1 2 3

123

123

123

123

123

1 2 3

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1989 FIELD SEASON
[ZZ] WASH LOAD IS:sJ SUS SAND LOAD
Figure 3.6 Comparison of 1989 measured wash load and suspended sand load.

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