RADIOLOGICAL CONTENT OF
COLORADO RIVER BASIN BOTTOM SEDIMENTS
AUGUST 1960 - AUGUST 1961
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service, Region VIII
Denver, Colorado
June 1963
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RADIOLOGICAL CONTENT OF
COLORADO RIVER BASIN BOTTOM SEDIMENTS
August I960 - August 1961
U„ S'. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Burenu of State Services
Division of Water Supply arid Pollution Control
Region VIII
Colorado River Basin Water quality Control Project
June 1963
-------
ACKNOWLEDGMENT
The generous cooperation and assistance of the following
in the conduct of the field sampling are gratefully acknowledged:
U. S. Department of Interior, Bureau of Reclamation, Region 3,
Boulder City, Nevada; National Park Service, Lake Mead National
Recreation Area, Boulder City, Nevada; Fish and Wildlife Service,
Havasu National Wildlife Refuge, Parker, Arizona, and Imperial
National Wildlife Refuge, Yuma, Arizona.
The cooperation of the seven Basin states in all Project
activities is greatly appreciated.
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TABLE I - Uranium Processing Plants - 1961 (1)
2
A.
Company
COLORADO RIVER BASIN
Location of Mill
Figure 1
Code No.
U.S.Atomic Energy Commission_l/
Climax Uranium Co.
Gunnison Mining Co. 1/
Kerr-McGee OJ1 Industries
Rare Metals Corp. of America 1/
Texas-Zinc Minerals Corp.
Trace Elements Co.
Union Carbide Nuclear Co.
Union Carbide Nuclear Co.
Uranium Reduction Co.
Vanadium Corp. of America
Union Carbide Nuclear Co.1»3/
Union Carbide Nuclear Co.I>3/
Vanadium Corp. of America
Vanadium Corp. of America _3/
B. OTHERS
Monticello, U. 1
Grano Junction, Colo. 2
Gunnison, Colo. 3
Shiprock, N. M. 4
Tuba City, Ariz. 5
Mexican Hat, Utah 6
Maybell, Colo. 7
Rifle, Colo. 3
Uravan, Colo. 9
Moab, Utah 10
Durango, Colo. 11
Design Capacity
(Tons of Ore
per Day)
350
330
200
300
300
1,000
300
1,000
1,000
1,500
750
Green River, Utah 12
Slick Rock, Colo. 13
Monument Valley, Utah 14
Naturita, Colo. 15
TOTAL 7,230
Cotter Corp.
Canon City, Colo.
200
Anaconda Co,
Grants, N.M.
3,000
Lie p.e s t a ke - N. M. Partner s_I/
Grants, N. M.
750
Ilomestake-Sapin Partners
Grants, N. M.
1,500
Kevmac Nuclear Fuels Corp.
Grants, N. M.
3,300
'billips Petroleum Co.
Grants, N. M.
1,725
Lrkeview Mining Co._Jt/
Lakeviev?, Ore.
210
Mines Development, Inc.
Edgemont, South Dakota
400
Susquehanna-Uestein, Inc.
Fall City, Texas
200
Vitro Cnemical Co.
Salt Lake City, U.
600
Dax'U Mining Co.
Ford, Washington
400
Federal-Radoroclc-Gas Hills
Partners
Fremont Co., Uyoming
520
Globe Mining Co.
Natrona Co., Wyoming
490
O /
Petrotomics Co. '
Carbon Co., Wyoming
200
Suiquehanna-Uestern, Inc.
Riverton, Wyoming
500
Utah Construction and Mining Co.
Fremont Co., Uyoming
930
Western Nuclear, Inc.
9 -3 /
Wyo. Mining & Milling Corp.i^-i'
Jeffrey City, Wyoming
345
Natrona Co., Wyoming
TOTAL
15,620
1/ Inactive
2/ Under construction
3/ Upgrading plants
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RADIOLOGICAL CONTENT OF
COLORADO RIVER BASIN BOTTOM SEDIMENTS
August 1960 - August 1961
INTRODUCTION AND BACKGROUND
Studies which concern the disposal of and subsequent fate of
radioactive materials in the water environment must consider all phases
of this environment. This includes the water itself, suspended and
bottom sediment material, fish, algae and other aquatic biota. Many
investigators have demonstrated that sediments and aquatic life can
accumulate significant amounts of radioactivity from overlying waters*
The radioactivity contained in these sediments and possibly that from
decaying aquatic life can be leached back to the water phase.
In the United States vast deposits of uranium ores are located
in the Colorado Plateau area, central Wyoming, and the Grants-Ambrosia
Lake areas of New Mexico, with lesser deposits in the western Dakotas,
southern Oregon, and northeastern Washington. There were in 1961 twenty-
six operating uranium mills and four upgrading plants in the western
United States. Table I presents a listing of these facilities and their
design capacities. From this table it is seen that, on the basis of
design capacity, about 30 percent of the total national uranium ore
production is milled in the Colorado River Basin. With respect to the
waters of the Colorado River Basin, major sources of radioactive con-
tamination have been those associated with the mining and milling of
these uranium-bearing ores. Figure 1 shows the location of uranium
mills and upgrading plants in the Colorado River Basin.
Uranium-bearing ores generally average about 0.25 percent
uranium as U^Og (2). The milling processes are designed principally
to extract uranium from the ore. The bulk of the ore processed becomes
a waste product containing large amounts of radioactive constituents
other than the uranium originally present in the raw ore. Detailed
descriptions of processing and waste disposal operations at various
uranium mills are given in recent Public Health Service reports. (1)(3)
Radioactive waste products associated with discharges from uranium
milling operations include uranium, radium, thorium, and all of their
decay products in varying amounts. By far the most important of these
radionuclides is Ra-226 because of its extremely low Maximum Permissible
Concentration (MPC) in water (4)(5), its bone-seeking characteristics,
and its long half-life of -1622 years.
Studies of the effects of waste discharges from uranium mills
on the waters of the Colorado River Basin have been carried out by the
Public Health Service since 1950. In 1950 samples of river water were
collected at locations above and below several uranium mills. These
data showed that the dissolved radium content of river water below
uranium mills was increased considerably by waste discharges from the
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\
UNNISON
NCWMEXIC
I VCR
ARIZONA
MEXICO
SCALE IN MILES
(fl U MILL SITES
COLORADO RIVER BASIN
URANIUM MILL LOCATIONS
1961
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
DEPARTMENT OF HEALTH, EDUCATION,8 WELFARE
PUBLIC HEALTH SERVICE
REGION VIII
DENVER,COLORADO
FIGURE
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3
milling operations. In the fall of 1955 a second short-term survey was
performed on streams in the vicinity of eight uranium mills, seven of
which were in the Colorado River Basin (6). At this time, in addition to
river water, bottom muds and biota (algae and insects) were collected.
Although radium analyses were not performed on the river muds, gross
alpha and beta analyses showed accumulation factors of 100 times back-
ground or more in the muds, A detailed survey was conducted in 1956
(7) on two of the most seriously polluted streams in the Colorado River
Basin. The latter study showed that radium content of river muds
immediately below the uranium mills was 1,000 to 2,000 times natural
background concentrations.
The Animas River surveys (8)(9) were the first studies which pro-
vided detailed information concerning the effect of radium-bearing bottom
sediments upon the stream environment. These studies clearly demonstrated
that considerable radium was leached out of the sediments with the result
that the dissolved radium content of the river water was above the Maximum
Permissible Concentration value for radium-226.
One of the questions raised in the Animas River studies was that
of the leachability of radium from uranium mill waste solids and river
sediments, and the factors which influenced such leaching. Accordingly,
detailed laboratory investigations were undertaken along these lines (10).
These studies showed that the major factor controlling leachability of
radium was the liquid-to-solid ratio (volume of liquid per unit weight
of solids). A more detailed discussion of these findings is presented in
Appendix A.
The objectives of the three Basinwide sediment surveys conducted
by the Colorado River Basin Project during August 1960 to August 1961
were to determine: (a) the radioactivity burden of Basin sediments; (b)
distribution of this radioactivity throughout the Basin; (c) the difference
between natural background concentrations of radioactivity, and radio-
activity resulting from waste disposal operations; and (d) effects of river
hydrology on sediment deposition and transport.
GENERAL HYDROLOGY OF BASIN
Within the Colorado River Basin, particularly the upper portions,
most of the annual surface runoff is the result of snow-melt. The first
melts usually begin each year in early or mid-April, with peak streamflow
around the early part of June. Flows subside through the month of July
and reach base-levels in the early part of summer. During late summer and
early fall local intense rainfalls may be frequent and produce brief periods
of somewhat higher flows. From late September until the beginning of snow-
melt the following April, streamflows are fairly constant and maintained
at minimum levels. Figures 2, 3, and 4 present hydrographs of three
typical USGS gaging stations in the Upper Basin.
Flow patterns are distinctly different in the Lower Basin below
Hoover Dam. In the area from Hoover Dam to the Arizona-Mexico Border,
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4
streamflows are highly regulated by releases and diversions from large im-
poundments on the mam stem and major tributaries. A typical hydrograph is
given in Figure 5 for the USGS gaging station immediately below Parker Dam
in the Lower Colorado River Basin,
CONDUCT OF SURVEY
Three Basmwide stream sediment surveys have been carried out to
date and are reported on here. The dates of the three field surveys were as
follows:
First survey - August 8-24, 1960
Second survey - March 6-23, 1961
Third survey - August 1-15, 1961
The above sampling periods were selected to coincide with certain
hydrologic conditions in the Upper Basin. By reference to Figures 2, 3,
and 4, it is seen that the first survey was conducted soon after the spring
snow-melts. These snow-melts produced high flows which resulted in scouring
of the river bottom and transport of large quantities of sediment to the
Lower Basin.
This survey period was representative of relatively clean river beds.
The second survey of March 1961 followed an extended period of low flow with
resulting accumulation of bottom sediment material. River conditions during
the third survey of August 1961 approximated those of the August 1960 study.
Several factors were considered in selecting the various stream
sampling stations. The major criteria were the need to obtain data on back-
ground radioactivity levels of sediments upstream from uranium mining and
milling activity and the deposition of radioactive sediments below such
activity. Figures 6, 7, 8, and 9 show locations of all sediment stations
with the exception of the Lake Mead samples. Results of Lake Mead sampling
are given later in this report. The large majority of stations were situated
below uranium milling and mining areas. A complete description of all
stations is provided in Appendix B.
Several methods were employed in collection of stream sediments.
Samples were obtained either by an Ekman dredge, Petersen dredge, or by
hand. The majority of the samples represented a composite of sediment at
quarter-points across the width of the stream, and were collected by hand
when wading was feasible. When this was not possible samples were taken by
means of a dredge lowered from a bridge or boat. When it was not possible
to obtain a composite sample across the stream., sediments were gathered along
the accessible shores. Both riffle and pool samples were collected at some
locations in order to observe any variation in radioactivity content of these
two types of sediment. Approximately one pint of sample was obtained at all
locations.
The conduct of the three Basinwide sediment surveys included collec-
tion of bottom muds from Lake Mead. In addition, a special mud sampling
study was conducted during October 24--28, i960, of Lake Mead in conjunction
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WYOMING
UTAH
COLORADO
PREEN
JENSENJJJ*'
OURAY
SCALE IN MILES
0.5
MAYBE LL,
i.
F'
[7] URANIUM MILL
SEDIMENT SAMPLING STATION
LOCATIONS
AUG. I960 - AUG. 1961
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
DEPARTMENT OFHEALTH^DUCATION,® WELFARE
PUBLIC HEALTH SERVICE
RESION VIII DENVER,COLORADO
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17
GREEN
RIVER /l'<
$
21
22 _
^MOAB
lla\23
20
*24
RIFLE
10
12
IS
GRAND*
O JUNCTIOC
5
13
vV
6 I
60
/
58
64
SLICK
ROCK
JRAVAN 63
^ATURITA
9
/
SILT
GUNNISON
GO URANIUM MILL
SEDIMENT SAMPLING STATION
LOCATIONS
AUG I960- AUG. 1961
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
DEPARTMENT OF HEALTH, EDUCATION.flfWELfifc RE
PUBLIC HEALTH SERVICE
REGION VIII
OENVER.COLO
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MONTICELLO
27
SO
37.
DURAN60 fiT
MEXICAN HAT z
MONUMENT
VALLEY 1(3
_ UTAH
ARIZONA
56
COLORADO
soaNEW MEXICO
.SHlPROCK
... FARMINGTON^
PAGE
LEEfe FERR
55
50»
54
S3
34
Mqewopi«ftSH
TUBA CI JY
0 URANIUM MILL
33
SEDIMENT SAMPLING STATION
LOCATIONS
AUG. I960- AUG. 1961
COLORADO "RIVER BASIN
WATER QUALITY CONTROL PROJECT
v'CAMERON
20
30
40
50
SCALE IN MILES
DEPARTMENTOF HEALTH,EOUCATION.aWELBXRE
PUBLIC HEALTH SERVICE
REGION VIII DENVER.COLORADO
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BOULDER CITY}
FOR LAKE MEAD STATIONS
SEE FIGURE 12
LAKE I ( ME AO
HOOVER r QAM >
LAKE \ MOHAVE
DAVIS
DAM
NEEDLES
HAVASU
LAKE
PARKE
RARKER 45
IMPERIAL lvJ}AM
LACUNAR OAM
0 10 20 30 40 SO
SCALE IN MILES
SEDIMENT SAMPLING STATION
LOCATIONS
AUG. I960 - AUG. 1961
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
DEPARTME N T 0 F HE A I.T H, EDUC ATION.SWE L FA R E
PUBLIC HEALTH SERVICE
REGION VIII
DENVER,COLORADO
FIGURE 9
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5
with the annual Lake survey by the Bureau of Reclamation, For clarity in
report presentation, the data from Lake Mead are considered separately from
the other results.
All samples from the surveys were analyzed for radium-226 concent.
All samples from the first Basinwide sediment survey were also analyzed for
gross alpha and gross beta radioactivity.
PRESENTATION OF DATA
The data obtained from the three Basinwide sediment surveys have been
subdivided into several groups m order to provide clarity and in order to
obtain better interpretation. Median values, as well as range and average,
are shown since it was noted that a small number of very high results in a
data group significantly affected the average-
Gross radioactivity data have been omitted from the detailed tables
because gross radioactivity determinations were performed only on the samples
collected in August 1960. Averages and ranges of gross alpha and gross beta
determinations have, however, been included in summary tables.
The detailed tables include individual results for riffle and pool
samples collected at various sampling locations.
A. Background Sediments
Bottom sediment samples were collected at 20 locations unaffected
by uranium mining and milling activities. The radioactivity levels of
these sediments are indicative of natural background levels. Individual
data for this group of stations are presented in Table II whereas average
and median values are given in Table III.
The data in Table II show that with the exception of five values,
the Ra-226 content of Basin sediments representing natural background
conditions is 1.5 (4ic/g or less. Table III shows that the average Ra-226
level is 1.1 w-ic/g for the 45 samples obtained. The values in Tables II
and III confirm earlier survey results on natural background levels of
radium in river sediments (8,9).
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6
TABLE II
Radioactivity - Natural Background Sediments
August 1960 - August 1961
Radium-226 (uuc/g)
Station Location Aug. 1960 March 1961 Aug. 1961
0.5
Lay Creek
1.6
1.8
3
Yampa River
< 1.0**
—
—
Green River
< 1.0**
1.0
1.0
7P***
Green River
0.8
—
—
9R
Colorado River
1.4
1.4
1.0
9P
Colorado River
2.1
1.8
1.2
17
Green River
0.9
0.6
0.9
33
Moenkopi Wash
1.3
0.9
1.1
52R
San Juan River
0.8
1.2
0.8
52P
San Juan River
< 1.0**
0.7
1.1
57
Animas River
1.3
1.4
1.1
62R
San Miguel River
< 1.0**
1.1
1.0
62P
San Miguel River
1.0
0.9
0.9
71
Gunnison River
1.6
1.1
0.9
72
Tomichi Creek
1.2
1.2
1.1
74*
Eagle River
1.3
75
Colorado River
1.5
76
Roaring Fork River
1.2
78
Gunnison River
0.8
79
Tomichi Creek
0.9
80
Uncompahgre River
1.2
81
San Miguel River
0.8
82
Little Snake River
1.2
83
White River
0.9
*Stations 74-83 collected December 1961
**Not used in average
*** R=Riffle; P=Pool
TABLE III
Summary Table on Radioactivity of Natural Background Sediments
Radioactivity - uuc/g
Gross Alpha* Gross Beta* Radium-226
Average 7.9 44 1.1
Median 8.4 44 1.1
Range 3.1-13 19-84 0.6-2.1
Number of Samples 14 14 45
*Gross activity only determined for August 1960 Survey
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7
TABLE IV
Radioactivity - Main-Stem Colorado River Bottom Sediment
August 1960 - August 1961
Radium-226 (p-iic/g)
Station
Location
Aug. 1960
March 1961
Aug. 1961
75**
Above Glenuood Springs, Colo.
—
1.5
9R
At Silt, Colo.
1.4
1.4
1.4
9P
At Silt, Colo.
2.1
1.8
1.2
10R
Above new UCNC Uranium Mill at
Rifle, Colo.
1.5
1.9
1.1
10P
Above new UCNC Uranium Mill at
Rifle, Colo.
2.4
1.9
--
11R
Below Rifle, Colo.
2.8
1.2
1.0
IIP
Below Rifle, Colo.
2.2
—
25*
12
At Debeque, Colo.
1.9
2.7
1.9
13R
Above Grand Junction, Colo.
2.2
1.9
2.1
13P
Above Grand Junction, Colo.
1.5
--
—
15
At Loma, Colo.
1.0
2.2
1.5
16R
At Westwater, Utah
1.7
1.8
1.0
16P
At Westwater, Utah
1.2
—
--
19
Above Dolores River
2.1
1.5
1.2
21
Belou Dolores River
4.3
3.2
2.0
22
3 miles below Station 21
1.5
2.0
2.2
23
Above Moab, Utah
3.1
3.1
1.9
24
Below Moab, Utah
3.0
2.8
1.9
24.5
At Hite, Utah
--
1.3
1.1
34
At Lee'- Ferry, Ariz.
1.3
1.3
1.7
38
Below Hoover Dam
0.9
0.9
1.1
39
Immediately above Davis Dam
1.5
2.3
2.0
40
3 miles above Davis Dam
0.6
0.9
0.8
41
At Needles, Calif.
1.0
0.4
0.4
42
0.5 mi. above Parker Dam
2.6
2.2
1.6
43
Lake Havasu, 1 mi, above Parker
Dam
3.3
2.3
2.2
44
4 mi. above Parker Dam
2.3
1.8
3.1
45
At Parker, Ariz.
1.3
--
1.1
46
4 mi. above Imperial Dam
0.8
0.4
1.1
47
0.5 mi. above Imperial Dam
1.1
0.8
0.8
48
1 mi. above Imperial Dam
0.9
0.5
0.9
49
At Yuma, Ariz.
< 1.0*
0.8
0.5
*Not used in average
**Sediment sample collected December 1961
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8
B. Main-Stem Colorado River Sediments
Individual data are presented in Table IV on the radioactivity content
of bottom sediments collected from the main-stem Colorado River. Excluding
Lake Mead stations, a total of 27 locations were sampled. These stations
cover the Colorado River from 10 miles above Glenwood Springs, Colorado to
Yuma, Arizona. Four stations are wichin the confines of Lakes Havasu and
Mohave.
Table V presents a summary of radioactivity results for all sediments
collected from the main-stem Colorado River.
TABLE V
Summary Table on Radioactivity of Main-Stem Colorado River Sediments
Radioactivity - uuc/g
Gross Alpha* Gross Beta* Radium-226
Average 10 40 1.7
Median 10 34 1.5
Range 1.2-27 14-84 0.4 - 25
Number of Samples 30 30 84
*Gross activity determined for August 1960 Survey only
The data in Table IV show a sizeable variation in radium content
of main-stem river bottom sediments. The 84 individual sampling results
have an average of 1.7 m-ic/g radium with a range of 0.4 - 25 mj.c/g. The
twelve samples collected from four stations in Lake Havasu and Mohave
(Stas. 39, 42, 43, and 44) belou Lake Mead have an average radium content
of 2.3 (i(ic/g with a range of 1.5-3.3 |iM.c/g. Also the three stations below
Lake Mead and Lake Havasu (Stas. 38, 40, 41) and all river stations down-
stream of Lake Havasu (Stas. 45-49; see Figure 9) show a composite average
Ra-226 content of 0.8 n^c/g with a range of 0.4-1.3 n(ic/g for 22 samples.
All sediments collected from the eight river stations belou Lake
Mead show radioacLivity results in the range of natural background. By
reference to radioactivity values for Lakes Havasu and Mohave given above
and those for Lake Mead to be presented later in this report, these data
demonstrate that these three Lakes are collectively the final resting place
for radioactive sediments discharged above Lake Mead. This observation will
subsequently be discussed in greater detail.
C. Locations Immediately Downstream from Uranium Mills
In order to illustrate the effect of uranium mill wastes upon down-
stream river sediments, it is desirable to group the data from stations
located immediately below uranium milling activities. Table VI presents
these stations arranged in downstream order from the Upper Basin to the Lower
Basin. Table VII offers a summary of the data information in Table VI.
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9
TABLE VI
Radioactivity - River Bottom Sediments Immediately Below
Uranium Mills
Radium-226 (uuc/g)
S tation Location Aug. 1960 March 1961 Aug. 1961
1
Lay Creek
76
34
0.9
1.5
Lay Creek
—
15
2.1
10R
Colorado River
1.5
1.9
1.1
10P
Colorado River
2.4
1.9
11R
Colorado River
2.8
1.2
1.0
IIP
Colorado River
2.2
—
24
73
Tomichi Creek
1.3
--
--
70
Gunnison River
1.4
0.8
0.7
59R
Dolores River
2.9
5.9
1.4
59P
Dolores River
1.9
2.4
2.1
61R
Dolores River
1.6
1.0
61P
Dolores River
5.8
3.4
1.9
63R
San Miguel River
4.7
1.4
1.9
63P
San Miguel River
11
1.5
1.3
65
San Miguel River
7.5
9.9
11
24
Colorado River
3.0
2.8
1.9
18R
Green River
2.3
1.2
1.2
18P
Green River
1.5
1.8
1.7
56R
Animas River
8.6
46
2.6
56P
Animas River
19
38
6.2
50R
San Juan River
1.2
0.8
0.9
50P
San Juan River
1.9
--
27
South Creek
275*
7.6
31R
San Juan River
1.7
1.7
0.4
31P
San Juan River
1.8
2.9
0.8
*Not used in average
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10
TABLE VII
Summary Table of Radioactivity of Sediments Immediately Below Uranium Mills
Radioactivity - (uuc/g)
Gross Alpha* Gross Beta* Radium-226
Average
46
97 6.6
Median
21
55 1.9
Range
1.9 - 12o5
1.5 - 1310 0.4 -
Number of Samples
23
23 65
*Gross activity determined
for August
1960 Survey only
Comparison of the above data with that of Tables III and V is of
interest. It may be seen that the average radium content of sediments
obtained immediately below uranium mill locations is about six times that
of background sediments and four times those collected from the main-stem
Colorado River.
D. Major Sub-basins
In order to observe the radioactive sediment distribution within
major sub-basins of the Colorado River Basin all sampling stations have
been grouped according to the following sub-basins:
(a) Green River; (b) Upper Main-Stem; (c) San Juan, and (d) Lower
Main-Stem, Figure 10 shows all of the major sub-basins of the Colorado
Basin.
No samples were taken from the Little Colorado and Gila Sub-Basins,
because uranium activity is minimal or absent in these areas.
Table VIII presents the radioactivity data for each of the major
sub-basins of the Colorado Basin. The Upper Main-Stem Sub-Basin has been
further broken down into the Gunnison River system and the San Miguel-Dolores
River system in order to better evaluate the contribution of radioactive
sediment from these two systems.
Table IX presents a summary of the data given in Table VIII. Several
interesting observations are apparent from this table. Of the four major
sub-basins it is seen that the average radium-226 is least in the Lower
Main-Stem (1.3 for 39 samples) while the San Juan Sub-Basin has the highest
average radium-226 (4.2 for 60 samples). The breakdown of the Upper Main Stem
shows the average radium-226 in the San Miguel-Dolores system (3.3 for 66
samples) to be twice as high as in the Gunnison system (1.7 for 55 samples).
It is also interesting to note that the average radium-226 concentration
in sediments in the Lower Main Stem is essentially identical to the average
presented in Table III for natural background sediments, and that the
average radium content of all sediments in Colorado River Basin (excluding
those in Lake Mead) is slightly more than twice that found in natural
background sediments.
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MAJOR SUB-BASINS
OF THE
COLORADO RIVER BASIN
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
U S DEPT OF HEALTH, EDUCATION, a WELFARE
PUBLIC HEALTH SERVICE
REGION VIII DENVER, COLORADO
-------
11
TABLE VIII
Radioactivity - Sediments for Major Sub-Basins of the
Colorado River Basin
Radium-226 (mac/g)
Station Location Aug. 1960 March 1961 Aug. 1961
1. GREEN RIVER SUB-BASIN
82 **
Little Snake River
-
-
1.2
83 **
White
River
-
-
0.9
0.5
Lay Creek
-
1.6
1.8
1.0
Lay Creek
126*
34*
0.9
1.5
Lay Creek
-
15
2.0
2
Lay Creek
4.0
6.9
3.9
3
Yampa
River
< 1.0*
-
1.0
4
Yampa
River
1.2
1.2
0.8
5R
Yampa
River
1.1
-
3.0
5P
Yampa
River
0.8
-
-
6
Green
River
0.8
. 6
0.7
7R
Green
River
< 1.0*
1.0
0.9
7P
Green
River
0.8
-
-
8
Green
River
< 1.0*
-
0.6
17
Green
River
0.99
0.6
0.9
18R
Green
River
2.3
1.2
1.7
18P
Green
River
1.5
1.8
0.9
25
Green
River
1.8
1.2
1.0
2. UPPER MAIN-STEM SUB-BASIN
A. Gunnison River System
74 **
Eagle River
-
-
1.3
75 **
Colorado River
-
-
1.5
76 **
Roaring Fork River
-
-
1.2
9R
Colorado River
1.4
1.4
1.0
9P
Colorado River
2.1
1.8
1.2
10R
Colorado River
1.5
1.9
1.2
10P
Colorado River
2.4
1.9
m
11R
Colorado River
2.8
1.2
1.0
IIP
Colorado River
2.2
-
17
12
Colorado River
1.9
2.7
1.9
13R
Colorado River
2.2
1.9
2.1
13P
Colorado River
1.5
-
.8
78 **
Gunnison River
-
-
.9
79 **
Tomichi Creek
1.2
1.2
1.1
72
Tomichi Creek
1.6
1.1
0.9
71
Gunnison River
1.4
0.8
0.7
-------
12
Radium-226
Station Location Aug. 1960 March 1961 Aug. 1961
70
Gunnison River
1.0
0.7
0.7
69
Gunnison River
-
-
1.2
80
Uncompahgre River
1.0
1.3
1.6
68R
Gunnison River
1.0
1.0
-
68P
Gunnison River
< 1.0*
1.0
0.5
14
Gunnison River
1.0
2.2
1.5
15
Colorado River
1.7
1.8
1.0
16
Colorado River
B. San
Miguel-Dolores River System
19
Colorado River
5.5
1.5
1.4
58R
Dolores River
1.9
1.8
1.6
58P
Dolores River
2.5
1.8
1.9
59R
Dolores River
2.9
2.4
1.4
59P
Dolores River
1.9
5.9
2.2
60
Dolores River
1.0
1.4
0.6
61R
Dolores River
1.6
-
1.0
61P
Dolores River
5.8
3.4
1.9
81 **
San Miguel River
-
-
0.8
62R
San Miguel River
< 1.0*
0.9
0.7
62P
San Miguel River
1.0
1.1
0.9
63R
San Miguel River
4.7
1.4
1.3
63P
San Miguel River
11
1.5
1.9
64
San Miguel River
2.8
8.7
2.0
65
San Miguel River
7.5
9.9
11
66
Dolores River
4.5
8.4
8.0
67R
Dolores River
1.5
4.3
12
67P
Dolores River
2.7
7.8
-
20
Dolores River
7.6
6.3
4.0
21
Colorado River
4.3
3.2
2.0
22
Colorado River
1.5
2.0
2.2
23
Colorado River
3.1
3.1
1.9
24
Colorado River
3.0
2.8
1.9
24.5
Colorado River
-
1.3
1.1
3. SAN JUAN SUB-BASIN
57
Animas
River
1.3
1.4
1.1
56R
Animas
River
8.6
46
2.6
56P
Animas
River
19
38
6.2
55R
Animas
River
6.7
22
2.9
55P
Animas
River
3.3
5.8
-
54R
Animas
River
3.1
3.7
1.8
54P
Animas
River
2.9
4.9
0.9
53R
Animas
River
2.2
3.6
2.0
-------
13
Station Location
53P Animas River
52R San Juan River
52P San Juan River
51R San Juan River
5IP San Juan River
50R San Juan River
50P San Juan River
50.5 San Juan River
26 South Creek
27 South Creek
28 San Juan River
29 Montezuma Creek
30 San Juan River
31R San Juan River
31P San Juan River
34 Colorado River
4. LOWER MAIN-STEM SUB-BASIN
33 Moenkopi Wash
33.5 Moenkopi Wash
38 Colorado River
39 Lake Mohave
40 Lake Mohave
41 Colorado River
42 Lake Havasu
43 Lake Havasu
44 Lake Havasu
45 Colorado River
46 Colorado River
47 Colorado River
48 Colorado River
49 Colorado River
Radium-226
Aug. 1960 March 1961 Aug. 1961
2.5
3.9
1.3
0.8
3.9
0.7
< 1.0*
1.2
1.1
1.4
0.7
0.8
1.0
-
-
1.2
0.8
0.9
1.9
-
-
-
0.8
0.8
2.6
7.5
2.0
253*
-
7.6
< 1.0*
0.9
1.0
< 1.0*
0.6
0.7
< 1.0*
1.3
1.1
1.7
1.7
0.4
1.8
2.9
0.8
1.3
1.3
1.7
1.3
0.9
1.1
-
0.6
1.2
0.9
0.9
1.1
1.5
2.3
2.0
1.0
0.9
0.8
1.0
0.4
0.4
2.6
2.1
1.6
3.3
2.3
2.2
2.3
1.8
3.1
1.3
-
1.1
0.8
0.4
1.1
1.1
0.8
0.8
0.9
0.5
0.9
< 1.0*
-
0.5
*Not used in average
**Sediment sample collected December 1961
-------
14
TABLE IX
Summary of Sediment Radioactivity for Major Sub-Basins of the
Colorado River Basin
Sub-Basin
Radioactivity - (ig^c/gm)
Gross Alpha* Gross Beta* Radium-226
1. GREEN RIVER
Average 11
Median 10
Range 4.0-579
Number of Samples 13
2. UPPER MAIN-STEM
(Total) Average 16
Median 12
Range 2.6-55
Number of Samples 41
42
45
19-831
13
45
42
18-84
41
1.9
1.0
0.6-126
35
2.5
1.8
0.5-17
121
A. Upper Main-Stem
(Gunnison River System)
Average 9.3
Median 7^8
Range 3.1-19
Number of Samples 19
42
35
18-84
19
1.7
1.0
0.5-17
55
B. Upper Main-Stem
(San Miguel-Delores System)
Average 23
Median 20
Range 4.0-55
Number of Samples 22
47
43
25-74
22
3.3
2.6
0.6-12
66
3. SAN JUAN
Average
Median
Range
Number of Samples
4. LOWER MAIN-STEM
(Excluding Lake Mead)
Average
Median
Range
Number of Samples
Average of all Colorado River
Basin Sediments
Average
Median
Range
Number of Samples
16
12
1.4-1255
22
7.5
5.1
1.2-22
13
13
10
1.2-1255
89
59
45
19-1310
21
33
29
14-68
13
44
43
14-1310
88
4.2
1.4
0.7-253
60
1.3
1-1
0.4-3.3
38
2.4
1.4
0.4-253
254
* Gross activity determined for August 1960 Survey only
-------
15
LAKE MEAD SURVEYS
A. INTRODUCTION
The preceding discussion has shown the distribution of radioactivity
in sediments of the Colorado River Basin. Such radioactivity has resulted
in large part from the discharge over a number of years of waste ore solids
from the uranium mills in the Basin.
Lake Mead, impounded by Hoover Dam, has trapped almost all of the
transported sediment load of the Colorado River Basin. Therefore it is ex-
pected that most of the radioactivity carried by sediments in Colorado River
water has been deposited within the confines of Lake Mead and remains there
indefinitely. Initially the majority of this load settled in the Upper Lake
some 70 to 80 miles above Hoover Dam. In subsequent years the sediments
gradually move closer to Hoover Dam.
Lake Mead serves as the domestic water supply for the nearby com-
munities of Las Vegas, Boulder City, and Henderson, Nevada. Downstream from
Hoover Dam are large diversions for irrigation and municipal use in southern
California, southeastern Arizona and Mexico.
B. HYDROLOGY AND LIMNOLOGY OF LAKE MEAD
Hoover Dam began impounding the waters of the Colorado River to form
Lake Mead, on February 1, 1935. The original maximum capacity of Lake Mead was
32,471,000 acre-feet, including dead storage. Accumulation of sediment in
the reservoir had reduced the maximum capacity by 1960 to approximately 30
million acre-feet. Sediment is deposited at an average rate of 175,000,000
tons per year which reduces the Lake capacity by more than 100,000 acre-feet
annually. Lake Mead may store in excess of two years' equivalent of runoff
of the Colorado and Virgin Rivers. The latter have a combined average annual
flow reaching Lake Mead of 12.6 million acre-feet per year over the period of
record (11,12,13).
At the time of the Colorado River Basin Project survey of Lake Mead in
October 1960, the Lake had a water surface elevation of 1,169 feet, a useable
content of nearly 20 million acre-feet, a surface area of 195 square miles,
and a maximum depth of approximately 420 feet. The profile of the Lake is
shown in Figure 11.
Circulation currents found in Lake Mead follow more or less regular
season patterns and are caused by differences in water density in the vertical
plane. These differences are due directly to variations in temperature,
salinity and suspended sediment content of lake water. Turbidity currents,
which are actually density currents containing high concentration of suspended
sediment,are always present near the upper end of the Lake in the vicinity of
Pierce Ferry but these flows rarely are sustained over the entire length of the
lake. When these currents reach the dam, a rapid rise in water-sediment
interface forms immediately upstream of the dam (12).
During winter the inflowing Colorado River water is of greater
density than the water in the reservoir, due to lower temperature and
greater salinity and hence, flows along the bottom. The spring runoff, due
-------
MAXIMUM WATER SURFACE ELEVATION
zoo
WATER SURFACE ELEVATION, OCTOEER, I960
LAKE MEAD BOTTOM PROFILE
ALONG COLORADO RIVER
CHANNEL
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
100
SEDIMEN
APPROXIMATE
OCTOBER,I960
TERFACE
MENT INTER!,
1948
1000
m
ORIGIN/L COLORADO, ItlVER
PROFILE
900.
to
800.
CD <=
> r
m
zi
o a
> o
00
> <
1 f!
410
U.S— MEXICO BORDER
420
390
FROM SOUTHERLY
400
380
370
COLORADO RIVER MILEAGE
360
350
-------
16
to its low salinity, flows out over the lake water. In summer, with in-
creasing salinity of inflow, the downlake spread of river water occurs as
an interflow about 80 feet below the surface. In the fall during which
season the second sediment survey of Lake Mead was conducted, the decreasing
temperature of the inflowing ri\;er water causes it to sink to greater depths
as the season progresses. At this time, there is downlake flow along the
bottom to the vicinity of Iceberg Canyon and Sandy Point. However, as denser
lake water is encountered at the greater depths, there is likely a flow
spreading horizontally downlake to Virgin Canyon which further slopes gradu-
ally toward the surface. Concurrently, two large cellular circulations, one
producing uplake movement of surface water and the other producing uplake
movement of bottom water, exist in the autumn above the Virgin Basin. (12,13).
Thus, during the second Lake survey, bottom sediment down to about Iceberg
Canyon was likely in contact with recent inflow, while the interface below
this point to near Virgin Basin was in contact with an uplake flow of water,
which had been impounded from a previous time.
C|. CONDUCT OF LAKE MEAD SJRVEYS
Four sepaiate radioactivity surveys have been conducted in Lake Mead.
The first, third and fourth surveys on Lake Mead correspond in time to the
three Basin-v7ide studies of August 1960, March 1961, and August 1961, and
may be considered as part of these studies. Because of time and equipment
limitations, adequate areal coverage of the lake was not obtained by this
sampling program.
The second Lake Meac survey was undertaken during the U. S. Bureau
of Reclamation's annual survey of the Lake on October 24-28, 1960, and
provided more comprehensive data on radioactivity of both sediments and
waters. The U. S. Bureau of Reclamation provided Colorado River Project
personnel with boat transportation and operator facilities on the October
24-28, 1960 survey when il was necessary to sample in the main part of the lake.
A 1200 to 2000 cc Kemmerei-type sampler was used to obtain all deep-
water sediment samples„ A skiff, normally towed by the main boat, provided
access for sampling in shallow watei at: the head ends of the reservoir on the
Colorado River and also on the Virgin River. At these locations, sediment
and, in addition, water samples were collected by hand. All sediments from
both deep and shallow waters were obtained from the top layers of water -
sediment interface. Sediments were collected in one pint glass jars.
During the October I960 lake survey, water samples were also collected.
These were taken by a Kemmerer-type sampler from the lake surface and the
liquid-solid interface to investigate possible leaching of Ra-226 and uranium
elements from the bottom sediments to overlying waters. Water samples were
collected in one-quart, polyethylene bottles.
Table X piesent^ a brief description of all Lake Mead sampling
stations and Figure 12 gives a map u£ the location of each sampling station.
In most cases, samples were obtained over the original channel of the river.
Additional comment:; concerning a few of the stations are included as follows:
-------
17
TABLE X
Lake Mead Sediment Sampling Locations
October 1960
Station
No. Description
1. October, 1960 Survey
LM-1 Emery Falls
LM-2 Iceberg Canyon
LM-3 Sandy Point
LM-4 Virgin Canyon
LM-5 East Point
LM-6 Boulder Canyon
LM-7 Hoover Dam
LM-8 The Narrows
LM-9 Overton
LM-10 Virgin Narrows
LM-11 Henderson Intake
2. August 1960, March & August 1961 Surveys
36a
Colorado River at head of Lake Mead
36b
Just above Pierce Ferry
36c
Midlake opposite Pierce Ferry
36d
Midway between Pierce Ferry & Grand Wash
36e
Main Channel opposite Grand Wash
37a
Midway between Sandy Point & Iceburg Reef
37b
Midway between Sandy Point & Virgin Canyon
35a
Near mouth of Las Vegas Wash
35b
Upper end of Las Vegas Boat Harbor
35c
Las Vegas Bay opposite Gypsum Wash
35d
Las Vegas Bay opposite Government Wash
-------
35 A
80ULOER
iCANY
o
c
JO
m
ro
LAS VEOAS
BAY
35CI
350)
35 B
HENDERSON^
INTAKE
LM -6
BOULOER
BASIN
_M - 7
HOOVER DAM
»¦
m *
5 ©
>' z
' >
37/
LM-2
. 36 E
36C"
360
36 A
.LM - I
SANDY
POI NT
LM - 3
PIERCE
FERRY
36 B
VIRGIN
CANYON
LM- 4
LAKE MEAD SAMPLING
LOCATIONS
AUG I960— AUG. 1961
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
DEPARTMENT OF HEALTH,EDUCATION,aWELFARE
PUBLIC HEALTH SERVICE
REGION VIII
DENVER.COLORADO
-------
18
LM-1, Emory Falls; This location was approximately 0.5 miles above
the head of the reservoir at the time of the survey. Water was sampled
near the center of the stream and sediment was collected near the left bank.
LM-5, East Point: The measured depth at this point was somewhat
less than the depth at the next upstream location. Therefore, the sediment
sample uas apparently not taken over the original channel of the river.
LM-8, the Narrows: Samples were collected near the west shore of
the wide, shallow basin at the present mouth of the Virgin River. ''The
Narrows" is a constriction in the river channel immediately below this basin.
LM-10, Virgin Narrows: This location was downstream of the lower
limit of heavy sediment deposits in the Overton Arm. The sampling device
intercepted a hard surface or rock deposit at a depth of 275 feet and sub-
sequently a sediment sample was not collected.
LM-7, Hoover Dam and LM-11, Henderson Intake: Mechanical failure
of the uinch used for lowering and raising the sampling device necessi-
tated postponement of the sample collection at these two locations. Depths
to the interface at both locations were not reported. The Henderson Water
Intake is located on the east side of Saddle Island in Boulder Basin.
All uranium and a portion of the Ra-226 analyses were performed by
the Project Laboratory. Gross radioactivity of the sediment samples was
determined at the R. A. Taft Sanitary Engineering Center at Cincinnati, Ohio.
The remainder of the radium-226 analyses were performed by a private labora-
tory.
D. PRESENTATION OF RESULTS
Water-Radium concentrations in the water samples collected during
the October 1960 Lake Mead Survey are presented in Appendix C.
Sediment-Table XI presents the data obtained on all sediments
collected in Lake Mead. Table XII presents a summary of these data.
It is seen from Table XII that the average radium content of all
sediments collected in Lake Mead is slightly more than two and one-half
times the natural radium content of unpolluted sediments. The sediments
collected during the comprehensive October 1960 survey have an average
radium content almost four times natural background concentrations.
From Table XI it is interesting to note that there appears to be
a progressive decrease in radium content of sediment from the headwaters
of Lake Mead to Hoover Dam (LM-1 through LM-7). Also, Station LM-8
sediment radium is very low indicating natural sediment entering Lake Mead
from the Virgin River.
-------
19
Station
MAIN LAKE
LM-1
36a
b
c
d
e
LM-2
37a
LM-3
37b
LM-4
5
6
7
TABLE XI
Radioactivity of Lake Mead Sediments
Radium-226 -(ug/gm)
Aug. 1960 Oct. 1960 Mar. 1961 Aug. 1961
1.0
2.6
4.6
2.2
5.5
4.7
1.8
4.1
4.5
3.8
5.0
4.0
4.2
3.9
2.9
1.8
3.0
2.3
4.1
4.6
0.6
3.0
3.1
4.9
4.9
OVERTON ARM
LM-8
9
LAS VEGAS BAY
<
1.0*
3.6
35a
-
1.6
1.2
b
2.2
2.3
1.8
c
2.1
1.8
1.9
d
1.9
2.2
0.5
LM-11
2.9
* Not used in average
-------
20
TABLE XII
Summary of Lake Mead Sediment Radioactivity
Radioactivity - (uuc/gm)
Gross Alpha Gross Beta Radium -226
Average 16 55 2.9
Range 7.0 - 32 21 - 70 0.5 - 5.5
Number of Samples 21 10 38
RADIUM-226 TO GROSS ALPHA RATIOS
The determination of radium-226 involves quite lengthy radio-
chemical and counting procedures in order to obtain the desired result. In
contrast, gross radioactivity determinations can be accomplished in a
fraction of the time required for a radium analysis. Oftentimes, a gross
radioactivity analysis has been regarded as a crude device without any real
meaning. Gross alpha determinations however have been found to be sensitive
indicators of pollution from uranium mills. In all types of samples a very
consistent relationship between radium-226 and gross alpha has been found.
Table XIII presents the radium-to-gross alpha ratios for the sedi-
ment samples collected in the Colorado River Basin.
From this table it is seen that there is a relatively narrow range
m the average radium-226 to gross alpha ratio for the various types of
sediments encountered in the Colorado River Basin. This range is 0.16
to 0.26. The average of all samples for which both gross alpha and radium-
226 analyses were performed (176 samples) indicates a radium content of
21% of the gross alpha activity.
Statistical analysis of these data show that the standard deviation
is 0.035. In other words, 95% of all sediment samples in the Colorado
River Basin would be expected to have a radium to gross alpha ratio be-
tween 0.14 and 0.28.
SUMMARY AND DISCUSSION OF DATA
The preceding portion of this report has presented detailed tables
of results of radium-226, gross alpha, and gross beta determinations on
sediments collected throughout the Colorado River Basin during August and
October 1960, and during March and August of 1961. A final summary of
these data is pertinent at this point.
Specifically, 49 samples representing 20 different sampling
stations were collected in locations where the sediment was not influenced
by uranium mining and milling activity. These locations have been referred
to as background locations. All of the samples were analyzed for radium-
226, while 14 of them were analyzed for gross alpha and gross beta activity.
These data showed an average radium content of 1.1 mac/gm with a range of
0.6 - 2.1 |i|jc/gm.
-------
21
TABLE XIII
Radium-226 - Gross Alpha Ratios
Colorado River Basin Sediments
Table No. Sediment Type Ra-226/Gross Alpha
II Background Locations Average 0.17
Range 0.06-0.45
Number of Samples 17
IV Main-Stem Colorado River Average 0.22
Range 0.05-0.48
Number 30
VI Immediately Downstream Average 0.20
From Uranium Mills Range 0.07-0.63
Number of Samples 23
VIII Major Sub-Basins
1. Green River Sub-Basin Average 0.16
Range 0.06-0.31
Number of Samples 13
2. Upper Main-Stem
Sub-Basin
a. Gunnison River System
Average 0.19
Range 0.07-0.45
Number of Samples 18
b. San Miguel-Dolores
River System Average 0.19
Range 0.07=0.45
Number of Samples 21
3. San Juan Sub-Basin Average 0.23
Range 0.05-0.63
Number of Samples 22
4. Lower Main Stem Average 0.26
Sub-Basin Range 0.11-0.48
Number of Samples 12
XII Lake Mead Sediments Average 0.22
Range 0.10-0.41
Number of Samples 20
ALL COLORADO RIVER BASIN Average 0.21
SEDIMENTS Range 0.05-0.63
Number of Samples 176
-------
22
For the sediment surveys reported here, 254 samples representing
121 different sampling stations were collected in all parts of the Colorado
River Basin. In order to obtain an over-all view of the data, Tabic _-.IV
presents a general summary table.
TABLE XIV
Radium-226 in Colorado River Basin Sediments
Concentration
uuc/gm
Multiples of
Background
Number of
Samples
Percent of
Totals
< 1.1
> 1.1-5
5-10
10
< 1
1 to 4.5
4.5 to 9
> 9
95
132
15
12
254
38
52
6
4
100
Average of All Sediments: 2.4 (i|ic/gm
' 1 Background
Sediments:
1.1 (i|ic/gm
From Table XIV it is seen that about 40 percent of all sediments
collected in the basin were equal to natural background concentrations of
radium, while half of the samples were between 1 and 4.5 times background
levels. Ten percent of the samples were greater than 4.5 times background.
The data have shoim,among other things, that Lake Mead has been
essentially the final resting place for the radium contaminated sediments
of the Basin. Uith the closure of Glen Canyon Dam upstream, Lake Powell
will then become the final resting place for future radium contaminated
sediments. The data also show that a small fraction of the contaminated
sediment has at t-uc? passed through Lake Mead to be trapped by Lakes
Mohave and Havasu. The sediments in these two lakes are 1.5 to 2 times
natural background radium concentrations. The sediments in the stream stretches
between Lake Mead and Lake Mohave and between Lake Mohave and Lake Havasu
are all less than the 1.1 |i|ac/gm of radium found as an average for back-
ground stations in the Basin. From Lake Havasu to the Arizona-Mexico border
the sediment radium content is essentially no different from natural back-
ground concentrations.
With regard to the effects of hydrology on the deposition and
accumulation of radium-bearing sediment the data yield some other
interesting observations. Daily hydrographs have been presented earlier
for three typical locations in the Upper Colorado River Basin. As
pointed out, two of the surveys were conducted soon after subsidence of
flood flows and one just before the spring snow-melts. Earlier studies
on the Animas(8) showed that the radium content of sediments increased
considerably duiing extended periods of low flow, due to accumulation of
mill solids, vliich wei e picked up anc transported furthei' dowistrrccntiT
during high flow periods. In order tc provide additional ir.fcreation
-------
23
on the accumulation of radium in sediments the data from the March 1961
Basin-wide survey were averaged and compared to averages of the data from
the two August surveys. These are discussed below.
Sediments collected in locations unaffected by uranium mining and
milling activity showed an average radj.um-226 content of 1.21 (i(ic/gm for
the March 1961 survey compared to 1.25 n^c/gm for the two August surveys.
This is an interesting comparison and is what would be generally expected;
namely, that in natural background locations the radium content of the
sediment should remain constant and unaffected by any changes in flow
patterns of the river.
Sediments collected immediately downstream from uranium mills showed
an average radium-226 content of 8.73 (anc/gm for the March 1961 survey and
an average of 3.24 for the two August surveys. These data clearly show the
accumulation of radium in sediments during extended low flow periods.
Another interesting comparison is obtained when the data from samples
collected only on the main-stem Colorado River are treated in the above man-
ner. These data show an average radium content of 1.71 |i(ic/gm for the
March 1961 survey and an average of 1.66 wic/gm for the two August surveys.
These data tend to indicate that in a very large river such as the Colorado
the amount of scour and transport of bottom sediment even during low flow
periods in most cases is significant enough to prohibit much accumulation.
Also the accumulation of radium-bearing ore solids is probably masked by the
tremendous volumes of other sediment material. In a smaller river the ac-
cumulation might be more readily apparent.
When all sediments other than natural background sediments are
considered, as a whole, the data show an average radium-226 content of
4.19 |i(ig/gm for the March 1961 survey and an average of 2.22 |i|ic/gm for
the two August surveys.
The values of 8.73 |ip.c/g and 4.19 ^|ic/gm are largely influenced
by a very few samples taken from dry washes immediately below several
uranium mills.
Excluding these, the data show a great reduction of sediment
radium content since 1956^). This is a result of improved waste disposal
practices at the uranium mills in the Basin.
The data also show that the river sediments can be useful indicators
of radiological contamination. Such samples accumulate radioactivity
and yield information on conditions for an extended period of time sub-
sequent to collection. Water samples on the other hand yield information
on instantaneous values at time of collection.
It was mentioned earlier that both riffle and pool samples were
collected from various locations to observe if there was significant
variation in radium content of these two types of samples. The data
have been sho^m in the various tables which have been presented.
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24
Observation of the riffle and pool data shows that while some of
the pool sediment contained more radium than did riffle sediment, the
data are generally not significantly different at a given location. In
some cases the riffle sediment contained more radium than pool sediment.
At two locations the pool sediment contained quite a bit more radium than
did riffle sediment (Stations 56, and 63, Table VIII).
RADIUM LEACHABILITY
The quantity of radium-226 which can be leached from uranium mill
waste solids and river sediment material by overlying waters is governed
by a complex combination of chemical and physical factors. A brief dis-
cussion of results of recent laboratory studies on this subject is presented
below.
The results showed that -
1. Significant quantities of radium in terms of current
maximum permissible concentrations can be leached from
uranium mill waste solids and from river sediments.
2. The amount of radium which is leached from uranium
waste solids and river sediments is primarily governed
by the liquid to solid ratio (ral/gm) as shown by
distilled water-leaching tests. The effect is greater
for uranium waste solids than for river sediments. In
the case of uranium waste solids the amount of radium
leached from a given quantity of solids versus the volume
of leaching liquid is seen to follow an "S" shaped curve.
Such a curve is shown in Appendix A. At low liquid
volumes (10 ml - 30 ml) the amount of radium leached
is practically independent of the quantity of solids,
the amount leached being governed by the amount of
barium sulfate precipitation taking place.
3. There appears to be essentially no time dependence
after 15 minutes on the amount of radium leached from
uranium mill waste solids and river sediments, so far
as laboratory experiments are concerned. These
effects most probably have a different time relation
in a river.
4. The diffusion of radium from the interior to the
surface of particles was found to be insignificant
and unimportant. This was true whether the solids
were stored in a dry condition or in a wet environ-
ment. This indicated the radium is only leached from
the surface of such particles and is an important
finding in terms of 'storage" of samples in a
reservoir or in a river during low flows.
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25
5. For a given liquid-solid ratio, repetitive leachings
of solids with distilled water showed essentially
no additional radium being leached after two con-
secutive leachings.
6. The amount of radium which is leached with distilled
water is small compared to that which can be leached
with vigorous leaching agents such as 0.01 M barium
chloride solutions.
7. Of the cations, H+, Na+, K+, Kg"^, Ca"1-1", Sr"1-'", and
at 10~^M, only barium exerts a significant effect
on the amount of radium leached from river sediments,
with considerable amounts being leached by barium.
Barium concentrations in the range which would be
expected to be encountered in natural river waters of
the West leach no more radium than distilled water.
8. The chemical characteristics of natural river waters
from representative locations in the Colorado Plateau
have no different effect on the leachability of radium
than distilled water. In fact, because of high sul-
fate concentrations and precipitation of barium sulfate,
the amount of radium leached from uranium waste solids
by natural waters is significantly less than that
leached by distilled water.
9. The effect of temperature in the range 3° to 25° C
and degree of agitation, as long as the solids are
intimately mixed with the leaching liquid, are not
important parameters in the amount of radium leached.
A more detailed discussion of the results of the laboratory re-
search is given in Appendix A.
A brief discussion is given below of the effect of the discharge
into the water environment of radium-bearing waste solids and the behavior of
radium in this water environment.
Upon discharge into a river of uranium mill waste solids which
contain appreciable quantities of radium, there will be an immediate
leaching of some radium with an almost immediate co-precipitation of
this radium as barium-radium sulfate. This comes about because of the
relatively high sulfate content of the river water, the sulfates re-
leased from the solids, and the insolubility of barium sulfate
(KSp=l x 10 ~^®). Of the radium left in solution, a large part will be
adsorbed onto the river sediment and a portion will also probably be
readsorbed back onto the mill solids. The result of these reactions
is that only a small amount of the radium originally dissolved remains
in solution.
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26
A short distance below the mill discharge the bottom sediment material
in the river will consist of a mixture of natural river sediment which contain
radium, and waste ore solids also containing radium. Assuming a period of low
flow, the bulk of the stream sediment \,ill remain undisturbed on the bottom
with only the very fine material being transported in solution. For a low
flow associated with nonturbulent velocities, it is reasonable to expect the
suspended solids concentration to be very low at the surface and increasing
to a maximum at the liquid-solid interface.
The amount of leaching taking place irom the bottom sediment during
these periods oj. low flow will vary depending on particular circumstances. It
is low relative to other conditions of turbulent flow and scour described
below. Because of the small amount oC suspended solids transported during low
flows, it is likely that an equilibrium will exist between the radium in
solution and the radium content of the suspended sediment. A short distance
below a mill, however, the relative proportions of fine ore solids versus the
true river sediment transported \ill in large measure determine the amount of
radium leached from the mixture of solids.
With the advent of spring snow melts and resulting high river flows,
the bottom sediment is thoroughly mixed, picked up and transported furthei
downstream. At this time appreciable amounts of radium are leached from the
transported solids. This has been found to be true from the Animas River and
other studies. There is also at this time another re-distribution of the
radium between mill solids and liver sediments. As the high flows subside and
low flows again set in, a repeat process on a lesser scale, of the previous
low flow conditions occurs.
With each subsequent high flow condition, mixing and transportation
of sediments downstream, the amount of radium which is leached becomes
progressively less. Eventually a situation is reached in which the maximum
amount of radium has been leached, with little further leaching from the
transported solids. With discharge of the river into a large reservoir, the
amount of leaching which takes place in the reservoir sediments is probably
negligible, provided the incoming solids have been transported far enough to
have had the maximum amount of radium leached from them.
The above discussion has neglected several factors which may be of
significance in the behavior of radium in a river. These factors are
(1) the uptake of radium by the aquatic life in the river, algae, insects,
fish, water weeds, etc., (2) use of the river for irrigation, (3) number of
uranium mills discharging effluents into the river, and (4) other factors
depending on local conditions and circumstances.
SUMMARY
The data presented in this report have provided information concerning
the radium content of bottom sediment material throughout the Colorado River
Basin. The data on sediments from locations unaffected by any uranium mining and
milling activity present useful information regarding natural background con-
centrations of radium in such sediment.
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27
On the basis of these natural background radium-226 determinations any
sediments in the Basin xjhich show an average radium content significantly
greater than 1.5 |i|ig/gm can be considered to be contaminated either as a re-
sult of waste discharges from uranium mills or from mining operations.
Assuming that significant discharges of waste ore tailings into the
waters of the Basin have ceased and that waste ore from existing and abandoned
tailings piles is prevented from reaching these waters, it is reasonable to
expect that the sediments of the Basin will become stabilized in their radium
content at the usual natural level. Once such stabilization is reached
sediments showing higher radium content can only result from pollution
activities. By routine monitoring in selected locations sudden increases in
sediment radium can be noted and the source readily determined.
FUTURE IJORK DESIRED
In conjunction with material presented in this report there are
several areas in which further information would be desirable. These areas
are discussed below.
With regard to the Lake Mead sediments it \ ould be desirable to obtain
information regarding the radium content of lake sediments prior to uranium
milling activity in the Basin. During the period December 1947 to April 1949
the U. S. Geological Survey collected core samples of Lake Mead sediment
deposited between 1935 and 1949. Initial contact has been made with the
U.S.G.S. on the possibility of obtaining portions of these early sediments
for radium analyses.
As a follow-up it would also seem desirable to obtain core samples
of sediment deposited since 1949 in order to determine radium content of these
sediments since the advent of intensive uranium mining and milling in the
Basin.
Another aspect which deserves special consideration is a study of the
distribution of dissolved radium in river water, radium in transported
(or suspended) sediment, bottom sediment material and aquatic biota. This
could be done at a particular location by observing the radium distribution
among these phases over a period of time. Such a study would yield additional
information on the fate of radium in the water environment.
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28
REFERENCES
1. Uaste Guide for the Uranium Milling Industry, E. C. Tsivoglou,
and R. L. O'Connell, U. S. Public Health Service, Robert A. Taft
Sanitary Engineering Center, Cincinnati, Ohio (1962).
2. Introductory Nuclear Physics, D. Holiday, John Wiley & Sons,
Inc., Neu York, N. Y. (1950).
3. Process and Waste Characteristics at Selected Uranium Mills,
Field Operations Section, U. S. Public Health Service, Robert A.
Taft Sanitary Engineering Center, Cincinnati, Ohio (1S62).
4. Maximum Permissible Body Burdens and Maximum Permissible Con-
centiations of Radionuclides in Air and Water tor Occupational
Exposure, NCRP, National Bureau of Standards, Handbook 69,
Washington, D. C. (June 1959).
5. International Commission on Radiological Protection, ICRP Part 2.
Report of Committee II on Permissible Dose for Internal Raoiation,
Pergomon Press, Loncon (1959).
6. Report of Survey of Contamination of Surface Waters by Uranium
Recovery Plants, E. C. Tsivoglou, A. F. Bartsch, D. A. Holaday,
D. E. Rushing, U. S. Public Health Service, Robert A. Taft
Sanitary Engineering Center, Cincinnati, Ohio (September 1955).
7. Effects of Uranium Ore Refinery Wastes on Receiving Waters,
Sewage and Industrial Wastes, 30, No. 8, 1012-1027, (August 1958),
8. Survey of Interstate Pollution of the Animas River, Colorado-
New Mexico, E. C. Tsivoglou, et al, U. S. Public Health Service,
Robert A. Taft Engineering Center, Cincinnati, Ohio (May 1959).
9. Survey of Interstate Pollution of the Animas River, Colorado-
Ne\v Mexico, Part II 1959 Surveys, E. C. Tsivoglou, et al, U. S.
Public Health Service, Robert A. Taft Sanitary Engineering Center,
Cincinnati, Ohio (January 1960).
10. The Leachability of Radium-226 from Uranium Mill Wastes
Solids and River Sediments, S. D. Shearer, Ph. D., Disser-
tation, University of Wisconsin, (1962).
11. Surface Water Supply of the United States, 1959, Part 9,
Colorado River Basin, U. S. Geological Survey, Water Supply
Paper 1633.
12. First Fourteen Years of Lake Mead, Harold E. Thomas, U. S.
Geological Survey, Circular 346, Washington, D. C. (1954).
13. Comprehensive Survey of Sedimentation in Lake Mead, 1948-49,
W. 0. Smith, C. P. Vetter, G. B. Cummings, et al, U. S. Geo-
logical Survey, Professional Paper 295, Washington, D. C. (1954).
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29
APPENDIX A
LABORATORY STUDIES ON RADIUM LEACHABILITY
The following discussion presents a summary of the salient findings
of the leachability studies.
It was shown lor uranium waste solids and for river sediments that
an equilibrium was reached lapidly with regard to the amount of radium
leached from the solids as a function of time. After about fifteen minutes
no aoditional radium was leached up to a period of six days. Figure A-l
shows a typical curve.
It was also shown through several tests that radium is more likely
to be leached from uranium waste solids than from natural uranium ore.
This is brought about by the processes which take place during extraction
of uranium from the ore. In this extraction it is reasonable to expect
that, as a result of the sulfuric acid leaching steps, some radium is also
solubilized from the ore. Later in the mill process this radium is re-
precipitated and ends up in the waste solids and is subject to leaching.
One of the most significant finoings of this research was the effect
of liquid-to-solid ratio on the leachability Ot radium. It was found that
for a given quantity of solids a plot of the amount of radium leached
versus volume of leaching liquid described an "S" shaped curve with three
distinct regions. Such a curve is shown in Figure A-2. At low liquid
volumes the amount of radium leached remained constant with increase of
leaching volume. Beyond a certain volume, small increases in volume re-
sulted in large amounts of radium being leached. A third region existed
where large increases in volume lesulted in very little additional radium
being leached. In this third region, the amount of radium which can be
leached is apparently a maximum and is primarily governed by the quantity
of solids available or the total radium reservoir. In the lowest liquid
volume range, the amount of radium leached was independent of the quantity of
solids present.
In fact, it was shown by special tests that, for the particular solids
studied, the amount of radium which could exist in solution at low leaching
volumes was severely limiting and governed almost entirely by the sulfate
present in solution. This is brought about by the fact that the waste solids
had associated with them, as a result of the mill process, large quantities
of sulfate. This sulfate could be easily solubilized by small quantities
of liquid and because of the trace amounts of barium present, precipitation
of barium sulfate resulted. Along with this radium was co-precipitated with
the barium sulfate. This was demonstrated by adding a known amount of standard
radium spike to a sample containing waste solids and distilled water and leach-
ing for a period of time. These tests showed that when radium was added prior
to leaching and filtration, all of it was lost as a result of co-precipitation
with barium sulfate. When the radium was added to a leachate after filtration,
all of it was recovered.
Repetitive leaching tests showed a rapid decrease in the amount of
radium leached in consecutive leachings following an initial leaching. The
decrease was greater in the case of sands-slime waste solids than for river
sediments.
-------
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URANIUM
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WATER Q
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CALCULATED LINE BASED ON DILUTION
LEACING AFTER ONE HOUR.
• EXPERIMENTAL POINTS OBTAINED
I 0047 GRAMS 976 RADIUM
TIME IN DAYS
AND ASSUMING NO FURTHER
1000ml DISTILLED WATER
T = 25 - 27 C
-------
VOLUME OF LEACHING LIQUID
COLORADO RIVER BASIN
WATER QUALITY CONTROL PROJECT
RADIUM LEACHED
™ 100
URANIUM MILL WASTE SOLIDS
1.0 GRAM T =25 C
DISTILLED WATER
SEE ENLARGEMENT
1000
2000
LEACHING VOLUME -ml.
5000
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30
Another important finding of the research was that the role of
diffusion is insignificant in the leachability of radium from uranium waste
solids and from river sediments. Prior work reported in the literature
has shown that diffusion of radium from the interior of particles to the
surface was the major factor in the amount of radium leached from natural
ores and from specially prepared salts which contained radium. It was shown
in this work that storage of samples, after repetitive teachings, either in
a dry or wet environment for a long period of time resulted in no appreciable
increase in the amount of radium leached. This was true for uranium waste
solids as well as tor river sediments. Figure A-3 shows a typical curve of
repetitive leaching plus diffusion.
In conjunction with the diffusion studies it was found that if
uranium mill waste solids, which had been leached a number of times with
distilled water, were subsequently leached with 0.01 M barium chloride,
between 30 and 40 per cent of the radium was leached in a one hour leaching.
Tests on river sediments indicated that one hour leachings with 0.01 M barium
chloride solutions removed about 20 pexcent of the radium.
Leaching tests conducted on river sediments using 0.01 M solutions
of the common inorganic cations found in western river waters showed that
barium was the only ion which had any appreciable effect of the amount of
radium leached. This effect on the amount of radium leached increased
in the order Na' k' for elements ,_^n column IA of the Periodic Table and
in the order Mg , Ca~n , Sr~'~*\ Ba^ , for elements in column IIA of the
Periodic Table. This is the effect which would be expected based on the
exchange properties of these cations with respect to a cation like Ra"1"^,
The effect of various concentrations of barium chloride on the
leachability of radium was studied using river sediments as a test material.
The results showed a linear relationship m the range 1.5 x 10"^ M to
M. Below 10 the amount of radium leached was drastically reduced.
At a concentration of 10 m the amount of radium leached was not sig-
nificantly greater than that leached with distilled water. A concentration
of 10"4 M barium chloride would be equivalent to 14 mg/1 of Ba*"1", a con-
centration not very likely to exist in western river waters because of high
sulfates.
Repetitive leaching of a contaminated river sediment with 0.01 M
barium chloride solutions showed a rapid decrease in the amount of radium
leached \ ith a total of 21 percent being leached in four successive hours.
Another significant finding of the research showed that natural
river waters had essentially no different effect on the leaching of radium
than would be observed with distilled water. This is especially true for
river sediments. For uranium mill waste solids, however, the amount of
radium leached with the river waters was considerably less than was found
with distilled water leaching. This was due to the high sulfate present in
the river waters which caused additional precipitation of barium-radium
sulfate.
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15
10
SAMPLE NO.
AFTER II DAYS
DRY STORAGE
AFTER 21 DAYS
WET STORAGE
* 1
SAMPLE NO. 2
AFTER 14 DAYS
DRY STORAGE
AFTER 18 DAYS
WET STORAGE
"51
T
MPLE NO. 3
I QM
I 00 ML 01STI L LED WATER
ONE HOUR LEACH1NQ TIME
T=25* C
AFTER 21 DAYS
DRY STORAGE
SAI
V1PLE
NO. 4
REPETITIVE LEACHING
Uranium Mill Waste Solids
COLORADO RIVER BASIN
WATER QUALITY CONTROL
PROJECT
NO. OF LEACHIN6S
FIGURE A- 3
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31
It was shcn:n that grinding of solids to a particle size of minus
140 mesh resulted in a slight but detectable increase in the amount of
radium leached in the case of uranium waste solids but essentially no
increase in the case of river sediments.
Finally it was shown that by reducing the temperature of leaching
from 25° to 3° C, and by reducing the shaking rate to half, no appreciable
difference in the quantity of radium leached was observed for the uranium
waste solids.
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32
APPENDIX B
The location and description of the various sampling stations
established for the sediment sampling surveys were as follows:
Station
Number
0.5 Lay Creek 50 yards above Maybell, Colo., uranium mill effluent
wash.
1 Mill effluent rash below Maybell, Colo., uranium mill. Sample
taken above Lay Creek, 200' below Highway U. S. 40 culvert
6.4 miles east of Maybell, about 4 miles below the mill.
1.5 Lay Creek 500' below Maybell, Colo., uranium mill effluent wash.
2. Lay Creek above confluence with Yampa River. Sample taken at
bridge on county road about 1/4 mile above confluence with
Yampa River.
3. Yampa River above Lay Creek. Sample taken near Juniper Springs,
Colorado. 4.0 miles from county roac junction with U. S. 40,
4.0 miles east of Maybell.
4. Yampa River below Maybell, Colorado. Sample taken at bridge on
Colorado Route 313 (at Sunbeam) 6.2 miles northeast of junction
with U. S. 40 at Maybell, Colorado.
5. Yampa River near mouth. Sample taken at Mantle Ranch at Castle
Park in Dinosaur National Monument; about 43 miles from junction
of U. S. 40 and Colorado 45.
6. Green River at Jensen, Utah. Sample taken from U. S. 40 highway
bridge with a Petersen dredge from mid-river.
7. Green River near Dutch John, Utah. Sample taken just above the
wooden suspension bridge on temporary Utah 44, about 1 mile above
Flaming Gorge damsite along the north bank of the river.
3. Green River at Ouray, Utah. Sample taken at quarter points from
Utah 33 highway bridge.
9. Colorado River at Silt, Colo. Sample taken approximately 7 miles
upstream of the old Union Carbide Nuclear uranium mill; taken
from two bridges which span two separate channels of the river.
A pool sample was collected from the south channel bridge; a
riffle sample was taken from the north channel bridge.
10. Colorado River at Rifle, Colorado. Sample taken between the old
and the new Union Carbide Nuclear mills from the bridge on Colorado
13.
-------
Colorado River below Rifle, Colorado. Sample taken 3.3 miles
downstream from the new Union Carbide Nuclear mill and 10 miles
west of Rifle at Rulison, Colorado; collected from the bridge
on a side road 1/4 mile from Highway 6.
Colorado River at DeBeque, Colorado. Sample taken at the DeBeque
raw water intake at the bridge on the old highway through DeBeque.
Colorado River above Grand Junction, Colorado. Sample taken at the
bridge on the county road near Clifton, Colorado; 6 river miles
above the U. S. 50 bridge.
Gunnison River near mouth at Grand Junction, Colorado. Sample
taken 0.5 miles above the mouth from the bridge near the AEC
Operations Office.
Colorado River below Grand Junction. Sample taken at the PHS
Basic Data Station at Loma, Colorado; 2.3 miles south from the
crossroads at Loma,
Colorado River at Westwater, Utah. Sample taken at the end of
the road which parallels the D&RGIJ RR.
Green River near Green River, Utah. Sample taken from the U. S.
6-50 bridge just east of Green River, Utah.
Green River below Green River, Utah. Sample taken just upstream
of Crystal Geyser; 4 miles east of Green River, Utah on U. S.
6-50, turn right on dirt road, proceed b miles to river. The pool
sample was collected just upstream of Crystal Geyser; the riffle
was taken about 1/2 mile below the geyser.
Colorado River above Dolores River. Sample taken 3.1 miles up-
stream from Dewey bridge on Utah 128.
Dolores River near mouth. Sample taken at the termination of the
road from Dewey bridge to the river, approximately 0.3 miles
from the bridge.
Colorado River below Dolores River. Sample taken from Dewey
bridge on Utah 128 by dredge.
Colorado River below Dolores River. Sample taken 2-1/2 miles
downstream from Dewey bridge from the east bank.
Colorado River at Moab, Utah. Sample taken from U. S. 160
highway bridge 2 miles west of Moab.
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34
Station
Number
24 Colorado River below Moab, Utah. Sample taken along the east
bank at the entrance to the canyon (The Portal), about 2 miles
below the URECO uranium mill.
24.5 Colorado River at Hite, Utah.
25 Green River at Mineral Canyon. Sample taken about 30 miles
below Green River, Utah. Proceed Dead Horse Point turnoff
9 miles north of Moab on US 160, go 14 miles and turn right
to Mineral Canyon; go 15 miles and take right fork 0.6 miles
to the river bank. Sample collected along the east bank.
26 South Creek above Monticello, Utah, AEC uranium mill. Sample
taken just above municipal sewage treatment plant oischarge.
27 South Creek below Monticello, Utah AEC uranium mill. Sample
taken about 1.0 mile below the discharge from the mill on
T. M. Sorenson property.
23 San Juan River above Montezuma Creek near Aneth, Utah. Proceed
Utah 262, 21 miles to end of pavement. Continue 4.0 miles
through oil fields to the bridge over the San Juan River. Sample
taken by dredge from the bridge.
29 Montezuma Creek near confluence with San Juan River; Utah 262
crosses Montezuma Creek 0.3 miles before the end of the pavement,
20.0 miles from junction with Utah 47. Sample collected about
1000' upstream from the brioge. The stream was dry at the time
of the August 1960 survey.
30 San Juan River above Mexican Hat, Utah. Sample taken near the
USGS weather station.
31 San Juan River below Mexican Hat, Utah. Sample taken about 1/2
mile downstream from the uranium mill effluent discharge to the
river.
32 Uranium mill effluent wash at Mexican Hat, Utah. Sample taken from
the effluent wash which enters the San Juan River below the mill.
33 Moenkopi Wash ac Moenkopi, Arizona. Sample taken at the bridge
on Indian Route 3 just below the Tuba City uranium mill. The
vash was dry at the time of the August 1960 survey.
33.5 Moenkopi Wash below Tuba City, Arizona at U. S. 39 Highway bridge.
-------
Colorado River at Lee's Ferry, Arizona. Sample taken 5 miles
north of U. S. 39 at the end of Lee's Ferry roaa along the
west bank of the river.
Las Vegas Bay area of Lake Mead. Sample collected near the
mouth of Las Vegas Wash.
Temple Bar-Pierce Ferry area of Lake Mead. Sample taken at
the western entrance to Grand Canyon.
Sample taken in Las Vegas Bay opposite Gypsum Wash.
Sample taken in Las Vegas Bay opposite Government Wash.
Colorado River at head of Lake Mead. Sample taken at the
western entrance to Grand Canyon.
Temple Bar-Pierce Ferry area of Lake Mead. Sample taken at the
narrowing of the channel above Pierce Ferry.
Lake Mead. Sample taken at mid-lake opposite Pierce Ferry.
Lake Mead. Sample taken midway between Pierce Ferry and
Grand Wash. Depth at this point was about 25'.
Lake Mead. Sample taken in the Lake Mead main channel opposite
Grand Wash. Depth was about 40'.
Lake Mead. Sample taken midway between Sandy Point and Iceberg
Reef. Depth about 200'.
Lake Mead. Sample taken midway between Sandy Point and Virgin
Canyon toward the south shore of the lake. Depth about 200'.
Colorado River below Hoover Dam. Sample taken at Willow Beach
along the east bank between the concession and the fish hatchery.
Lake Mohave. Sample taken at mid-lake above Davis Dam just above
Bullshead Rock.
Lake Mohave. Sample taken about 3 miles above Davis Dam opposite
the cabins on the east shore.
Colorado River at Needles, California. Sample taken from the
Government bridge by dredge.
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36
Station
Number
40 Lake Havasu. Sample taken about 4 miles above Parker Dam opposite
Bluegill Island.
43 Lake Havasu. Sample taken opposite the Metropolitan Water District
of Southern California intake, about 600' from the west shore.
44 Lake Havasu. Sample taken about 1/2 mile above Parker Dam under
the power lines.
45 Colorado River at Parker, Arizona. Sample taken along the west
bank under the Arizona 72 Highway bridge.
46 Colorado River above Imperial Dam. Sample taken in the reservoir
main channel about 4 miles above Imperial Dam.
47 Colorado River above Imperial Dam. Sample taken in the center of
Squaw Lake off the reservoir main channel.
4o Colorado River above Imperial Dam. Sample taken in the main channel
about 1 mile above the dam.
49 Colorado River at Yuma, Arizona. Sample taken from the U. S. 95
Highway bridge.
50a San Juan River at Shiprock, New Mexico. Sample taken from the
U. S. 660 Highway bridge.
b San Juan River at Shiprock, New Mexico, uranium mill effluent
seepage channel.
50.5 San Juar. River 6 miles below Shiprock, New Mexico.
51 San Juan River belov Farmington,New Mexico. Sample taken near Kirt-
land, New Mexico, below confluence of the Animas River, approximately
1 mile east of Kirtiand.
52 San Juan River above Farmingtcn.New Mexico. Sample taken above the
Animas River confluence, approximately 4 miles east of Farmington
just off New Mexico 17.
53 Animas River at Farmington, New Mexico. Sample taken at the bridge
on New Mexico 17.
54 Animas River at Aztec, New Mexico. Sample taken 1/4 mile upstream
from highway bridge on U. S. 550.
55 Animas River at Colorado-New Mexico state line. Sample taken at the
Riverside PHS Basic Data Station just off U. S. 550.
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37
Station
Number
56 Animas River below Durango, Colorado. Sample taken 2 miles below
the Vanadium Corporation of America uranium mill.
57 Animas River above the Durango uranium mill. Sample taken at the
Fish Hatchery oa U. S. 550.
53 Dolores River above Slick Rock, Colorado. Sample taken from
highway bridge on Colorado 30, about 2.5 miles above the Slick
Rock mill.
59 Dolores River below Slick Rock, Colorado. Sample taken about i/2
mile below tne Slick Rock uranium mill. There was no stream flow
at the time of the August 1960 survey.
60 Dolores River at Bedrock, Colorado. Sample taken from the highway
bridge on the main road through Bedrock.
61 Dolores River above confluence of San Miguel River. Sample taken
0.7 miles above the mouth of the San Miguel River.
62 San Miguel River above Naturita, Colorado. Sample taken from the
farm property adjacent to the river, approximately 1 1/2 miles
above Naturita.
63 San Miguel River below Vancorum, Colorado. Sample taken at the
bridge on a side road 1.2 miles below the mill.
64 San Miguel River above IJravan, Colorado. Sample taken at highway
bridge on Colorado 141, 1.3 miles above the main intersection at
Uravan.
65 San Miguel River below Uravan, Colorado. Sample taken about 1/2
mile above the mouth of the San Miguel River.
66 Dolores River below San Miguel River. Sample taken from the bridge
approximately 3 miles below the mouth of the San Miguel River.
67 Dolores River at Gateway, Colorado. Sample taken immediately below
the Colorado 141 highway bridge.
68 Gunnison River at Delta, Colorado. Sample taken from Colorado 65
highway bridge 6 miles east of Delta.
69 Gunnison River below Gunnison, Colorado. Sample taken along U. S.
50 about u miles west of Gunnison.
70 Gunnison River below the Gunnison uranium mill. Sample taken belox>j
the U. S. 50 highway bridge 1 mile southwest of Gunnison.
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Station
Number
71 Gunnison River above Gunnison, Colorado. Sample taken at the
Colorado 135 highway bridge about 3 miles north of Gunnison.
72 Tomichi Creek above the Gunnison Mining Co. uranium mill. Sample
taken 100' above the bridge on the mill road.
73 Tomichi Creek belov the Gunnison mill. Sample taken about 1 1/2
miles belov/ the bridge on the mill road.
74 Eagle River above Colorado River confluence.
lb Colorado River 10 miles cast of Glenwoocl Springs, Colorado.
76 Roaring Fork River at Glen\;ood Springs, Colorado.
73 Gunnison River 2 miles north of Gunnison, Colorado.
79 Tomichi Creek above Gunnison, Colorado.
JO Uncompahgre River, 5 miles south of Montrose, Colorado.
31 San Miguel River above Naturita, Colorado.
32 Little Snake River 17 miles northwest of Maybell, Colorado.
33 Uhite River at Meeker, Colorado.
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39
APPENDIX C
RADIOACTIVITY OF LAKE MEAD WATERS
In conjunction with the comprehensive October 1960 sediment
survey in Lake Meac, water samples were taken for analysis of radium and
uranium. Samples of surface water, as tell as waier at the liquid-
sediment interface were collected in order to observe if leaching of radium
anc uranium vas taking place fiom the bottom seciment. Table C-l presents
the data obtained.
From this table ic is seen that with the exception of one anomalous
result, all radium concentrations are well below the current MPC of
3.0 iipic/1. Also no significant difference was observed between surface
and bottom water.
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40
TABLE C-l
Radioactivity of Lake Mead Waters
October 1960
Depth of
Station Description Water, Ft.
LM-1 Emery Falls 5
LM-2 Iceterg Canyon 120
LM-3 Sandy Point 208
LM-4 Virgin Canyon 307
LM-5 East Point 275
LM-6 Boulder Canyon 404
LM-7 Hoover Dam 420
LM-8 The Narrows 3
LM-9 Overton 170
LM-10 Virgin Narrows 275
LM-11 Henderson Intake
Depth of
Sample. Ft.
0-1
5
120
5
207
5
307
0-1
275
5
403
5'
420
0-1
0-1
170
5
275
5'
Bottom
Radioactivity
Radium-226 Uranium
tiuc/l. liC/1 .
< 1.0
1.1
< 1.0
3.4
< 1.0
1.3
< 1.0
< 1.0
< 1.0
< 1.0
1.2
< 1.0
< 1.0
< 1.0
0.4
0.5
0.4
0.4
< 1.0
0.9
16
7.3
8.0
10
6.3
6.6
5.5
8.1
8.0
5.8
7.9
8.1
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