8269

• UCREFRP Catalog Number: 8269
• Author: U.S. Geological Survey.
• Title: Chemical Characteristics of Bottom Sediments in the Colorado River Upstream from the Price-Stubb Diversion Dam near Palisade, Colorado, October-November 1998.
• USFW Year: 2000.
• USFW - Doc Type: USGS OFR 99-601,
• Copyright Material: NO

material sediments were collected at four sites-two along
the left bank and two along the right bank-during October
and November 1998 (fig. 2). The core samples were taken
from depths between 2.4 and 9.8 inches.

It is possible that other layers of fines exist below
the streambed, but due to the composition of most of the
streambed material (coarse cobbles and boulders) it was not
possible to sample at greater depths. Chemical characteris-
tics of fine material that may be present between the
existing streambed and pre-dam streambed are unknown.
Attempts to sample interstitial water from the bottom sedi-
ments were unsuccessful because of the fine-grained mate-
rial present.

Site PSDG 1 is about 50 feet upstream from the end of
the diversion wall on the right bank and 10 feet stream ward.
Site PSDG2 is on the right bank about 200 feet upstream
from the end of the diversion wall and about 8 feet stream-
ward. Site PSDG3 is on the left bank about 200 feet
upstream from the diversion dam and about 10 feet stream-
ward. Site PSDG4 is along the left bank about 150 feet
upstream from PSDG3 and about 6 feet streamward. An
additional sample, PSDG4a, was collected near site PSDG4
and analyzed for quality-control purposes.

CHEMICAL CHARACTERISTICS OF BOTTOM
SEDIMENTS

Each core sample was analyzed at incremental depths
for 28 constituents at the USGS sediment partitioning labor-

tory. Results of the analyses are listed in table 1. As a
quality-control procedure, duplicate analyses were
performed on parts of the samples at sites PSDG 1 and
PSDG3. Results of the chemical analyses were compared to
data for reference samples that have been collected across
the United States. These reference samples were selected
for comparison because they were about the same sediment
size and chemical composition as the core samples.
The reference sample from the Cody Shale (SCO-l)
is from a site in Wyoming. It is typical of Upper Cretaceous
silty marine shales, intermediate between fine-grained
offshore marine shales and coarser nearshore marine
siltstone and sandstone. The reference sample for shale
(SDO-l) is from the Huron Member of the Ohio Shale in
Kentucky. It can be used to establish analytical accuracy in
the analysis of organic- and sulphur-rich sedimentary rocks.
The reference sample for marine sediment (MAG-I) is a
fine-grained, gray-brown, clayey mud from the Gulf of
Maine. The reference sample NIST 2709 is agricultural soil
from the San Joaquin Valley in California.
The reference samples can be used to establish back-
ground values of different constituents. The comparison of
concentrations between the reference samples and the core
samples indicated that the bottom sediments upstream from
the Price-Stubb diversion dam are at the same level or less
than the reported values of the reference samples. No
unusually high concentrations were determined.

Figure 2. Location of sampling sites upstream from the Price-Stubb Diversion Dam near Palisade,
Colorado. Flow is right to left.