5A/TIB-26
RADIOACTIVITY LEVELS
IN THE
ENVIRONS OF THE ROCKY FLATS PLUTONIUM PLANT
COLORADO
1970
PART II
December 15, 1973
TECHNICAL INVESTIGATIONS BRANCH
SURVEILLANCE AND ANALYSIS DIVISION
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
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This report presents the findings of the September 1970 environmental
radiation study conducted in the environs of the Rocky Flats Plutonium Plant
(near Golden, Colorado). The field study and subsequent laboratory analyses
were conducted by the staff of the Radiological Activities Section, Division
of Technical Support, Water Quality Office, Environmental Protection Agency,
Cincinnati, Ohio (an organizational unit of the Federal Water Quality Adminis-
tration at the time of the study; reorganized into EPA in December 1971).
Due to personnel transfers and changes in program responsibilities, a report
on the study was not completed by the Radiological Activities Section prior
to its dissolution from the EPA organizational structure during the first half
of 1973. Since the primary investigators are now members of the Technical
Investigations Branch, Surveillance and Analysis Division, and the environ-
mental impact of the Rocky Flats Plant is a Region VIII concern, publication
is undertaken as a regional responsibility.
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TAgLE OF CONTENTS
Page
FOREWORD i
LIST OF TABLES iii
LIST OF FIGURES iv
INTRODUCTION 1
SAMPLING PROCEDURES 2
RESULTS 8
Water 8
Bottom Sediment and Soil 8
Fish and Benthos 17
SUMMARY ( 21
REFERENCES 22
APPENDICES
Appendix A BIOLOGICAL STUDY OF GREAT WESTERN RESERVOIR. . A-l
Appendix B MEASUREMENTS OF CORE SAMPLES B-l
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LIST OF TABLES
NO. Title Page
I SAMPLING STATIONS 6
II ELECTRO-FISHING - SPECIES OF FISH 7
III RADIOACTIVITY IN WATER SAMPLES 9
IV PLUTONIUM IN BOTTOM SEDIMENT SAMPLES 10
V PLUTONIUM IN BOTTOM SEDIMENT CORE SAMPLES 11
VI PLUTONIUM IN FISH 12
VII PLUTONIUM IN BENTHIC INVERTEBRATES 13
VIII PLUTONIUM CONCENTRATIONS IN VARIOUS FOOD 19
ITEMS AND PLANTS
A-I TOTAL NUMBER AND KINDS OF BOTTOM ORGANISMS A-2
COLLECTED FROM GREAT WESTERN RESERVOIR AND
STANDLEY LAKE
iii
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LIST OF FIGURES
NO. Title Page
I BOTTOM SEDIMENT SAMPLING STATIONS 3
II SAMPLING STATIONS FOR BOTTOM SEDIMENT AND BENTHIC. ... 4
INVERTEBRATES / GREAT WESTERN RESERVOIR AND
STANDLEY LAKE
III SAMPLING STATIONS FOR CORE SAMPLES / GREAT WESTERN ... 5
RESERVOIR AND STANDLEY LAKE
IV PLUTONIUM (pCi/gram) IN BOTTOM SEDIMENT SAMPLES / ... 15
GREAT WESTERN RESERVOIR AND STANDLEY LAKE
V PLUTONIUM (pCi/gram) IN THE TOP ONE INCH SECTION OF. . . 16
CORE SAMPLES / GREAT WESTERN RESERVOIR AND STANDLEY
LAKE
A-I DISTRIBUTION OF BOTTOM ORGANISMS PER SQUARE FOOT IN . . A-3
GREAT WESTERN RESERVOIR AND STANDLEY LAKE
iv
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INTRODUCTION
During the week of February 20, 1970, representatives of the Federal
Water Quality Administration visited the Rocky Flats Plant of the Atomic Energy
Cormiission (located approximately 21 miles northwest of Denver, Colorado,
between Golden and Boulder). The purpose of the visit was to obtain informa-
tion on liquid radioactive waste management practices at the facility and the
environmental surveillance activities in the plant environs. Coincidently
with the site visit, limited water and bottom sediment sampling was conducted
to obtain independent data on plutonium levels in surface waters receiving
drainage (liquid wastes and land runoff) from the site and in other nearby
lakes. The findings of the investigation were reported previously in 1971. U)
As a follow-up to the February 1970 investigation, an intensive field
study was conducted during the period of September 21-25, 1970. The basic
objectives were to determine plutonium levels in the resident biota of Great
Western Reservoir and Standley Lake and the overall distribution of plutonium
in the bottom sediment of Great Western Reservoir. At least to the date of
the study, off-site surveillance by the plant contractor, Dow Chemical Company,
was limited to water and soil sampling; plutonium in aquatic biota was a
monitoring void. Stations on Walnut Creek and Woman Creek, including Mower
Reservoir, were revisited to obtain additional data on plutonium in bottom
sediment and document changes which had occurred in the intervening seven month
period.
By virtue of the fact that this report presents the findings of the
September 1970 study, it constitutes a supplement to the previous April 1971
report.
- 1 -
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SAMPLING PROCEDURES
Sampling stations for water, benthic organisms (benthos), and bottom
sediment are listed in TABLE I and shown in FIGURES I-III. With the exception
of sediment and benthos collection stations on Great Western Reservoir and
Standley Lake, the sampling locations were identical to those established during
the February 1970 study. As noted in the preceding section, all samples were
collected during the period of September 21-25.
Water sampling was limited to three stations (TABLE I) with a daily grab
sample (approx. 4 liters) collected at each station throughout the study period.
It was assumed that samples collected from the shallow water at the dam faces
were representative of the raw water pumped to the treatment plants serving the
cities of Broomfield (Great Western Reservoir) and Westminster (Standley Lake).
Uranium and plutonium analyses were conducted on composite (3 or 5 days) or the
separate grab samples.
Bottom sediment samples were collected from Great Western Reservoir and
Standley Lake (FIGURES II and III) with dredges, Petersen or Eckman, and a core
sampler. At all other stations (creeks or impoundments), sediment samples were
collected by scraping the bottom area below the water line with a hand trowel.
The use of the hand trowel probably produced samples more representative of a
thinner surface layer than those obtained with a dredge, particularly the
Petersen dredge. Similar to the collection of sediment samples, benthos samples
were collected with dredges. These samples were sieved in the field using a
U.S. Standard No. 30 sieve. All material retained on the sieve was preserved
in a 5% formalin solution for subsequent sorting and identification of the in-
vertebrates and plutonium analysis.
Fish samples were collected with electro-fishing equipment from the
shallow water areas near the dam and inlet of both Great Western Reservoir and
Standley Lake. The fish were placed on ice immediately after collection and
maintained in a frozen state until processed for plutonium analysis. A list
of the species collected from each area is presented in TABLE II.
Soil samples were collected at two of the three stations previously
sampled in February.
(1) Grazed area just to the southeast of the road culvert conveying
Woman Creek under Indiana Street.
(2) Ungrazed area near the southeast corner of Great Western Reservoir.
These samples were collected with a hand trowel to a depth of 1/8-1/4 inches.
- 2 -
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&
A-1
AUTREY RESERVOIR
I
GO
I
U.S. ATOMIC
ENERGY COMMISSION
ROCKY FLATS PLANT
GREAT WESTERN RESERVOIR
MOWER RESERVOIR
„M-2
STANDLEY LAKE
o
FIGURE I
BOTTOM SEDIMENT SAMPLING STATIONS
x
KILOMETERS
CALKINS
LAKE
CA-I
POMONA LAKE
-------
STANDLEY LAKE
(NOT TO SCALE)
0 0.5
« ¦
KILOMETERS
FIGURE IT
SAMPLING STATIONS FOR BOTTOM SEDIMENT S BENTHIC INVERTEBRATES
GREAT WESTERN RESERVOIR 8 STANDLEY LAKE
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•4C GREAT WESTERN RESERVOIR
•7C
•\
1
1 ®I3C
I4C\
cn
i
STANDLEY LAKE
(NOT TO SCALE)
KILOMETERS
FIGURE TSL
.SPILLWAY
SAMPLING STATIONS FOR CORE SAMPLES
GREAT WESTERN RESERVOIR a STANDLEY LAKE
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TABLE I
SAMPLING STATIONS
Sample Type Station Number
Water WC-1
Bottom Sediment A-l
CA-1
W-l
M-l
M-2
WC
WC-1
WC-2
WC-3
WC-4
1-20 & 1C-12C
21, 22, 13C, & 14C
Benthos 1, 3-12, & 14-17
21 & 22
Fish
Description
Walnut Creek at Indiana Street
Great Western Reservoir at dam face
Standiey Lake at dam face
Autrey Reservoir; approximately 4 miles
northeast of plant; Boulder County
Calkins Lake; north shore
Woman Creek at Indiana Street
Mower Reservoir at mouth of diversion
ditch; west end
Mower Reservoir; east end at dam face
Walnut Creek at mouth; inlet of Great
Western Reservoir
Walnut Creek at Indiana Street
Main stem of Walnut Creek; 50 feet down-
stream of confluence of south fork
with middle and north forks
Middle fork of Walnut Creek; 50 feet
upstream of confluence with north fork
South fork of Walnut Creek at site bound-
ary
Great Western Reservoir
Standley Lake
Great Western Reservoir
Stand ley Lake
Great Western Reservoir; inlet and near
dam face
Standiey Lake; inlet and near dam face
- 6 -
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TABLE II
ELECTRO-FISHING - SPECIES OF FISH
Location
Great Western Reservoir
(A) Near inlet
(B) Near dam
Standley Lake
(A) Near inlet
(B) Near dam
Species
Carp
Northern Common Shiner
Western White Sucker
Carp
Green Sunfish
Johnny Darter
Northern Common Shiner
Western White Sucker
Carp
Green Sunfish
Large mouth Bass
Northern Common Shiner
Western White Sucker
Yellow Perch
Black Bullhead
Carp
Green Sunfish
Large mouth Bass
Yellow Perch
- 7 -
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RESULTS
Analytical results for water, bottom sediment, benthos, and fish samples
are presented in TABLES 111-V11. With the exception of water samples which
were analyzed for both dissolved plutonium and uranium, radiological analysis
was limited to the measurement of plutonium. Analytical procedures were the
same as those described in the April 1971 report.U)
Water
Plutonium and uranium in the water samples from Walnut Creek, Great Western
Reservoir, and Standley Lake were essentially at baseline levels (TABLE III)
and relatively unchanged from February 1970 levels. Dissolved uranium concen-
trations were less than 2.5 ug/1; typical of natural background in surface
waters. Dissolved plutonium concentrations were less than 0.03 pCi/1 which
was considered in 1970 to be a baseline condition attributable to atmospheric
fallout. In comparison with the February 1970 results, the only difference
was the absence of an elevated uranium concentration in Walnut Creek (at Indiana
Street) originating from plant waste discharges. However, this finding is not
of great consequence since the elevated concentration observed in February was
not large and could be questioned as a normal variation in background.
As a matter of general interest, surface runoff from rainfall was the
reason for the high suspended solids concentration in Walnut Creek on the last
day of sampling, September 25.
Bottom Sediment and Soil
In terms of a general comparison among stations sampled during both the
February and September studies, plutonium levels in sediment collected in
September (TABLE IV) were equal to or less than the corresponding February
results. Considering the two impoundments assumed to be free of any impact
from emissions from the Rocky Flats Plant - Calkins Lake and Autrey Reservoir,
plutonium concentrations in sediment were 0.04 and 0.07 pCi/gram, respectively.
These data were identical with the February results; reaffirming the conclusion
that the baseline concentration in the bottom deposits of area surface waters
was <,0.10 pCi/gram. From the standpoint of absolute values, sediment from
Mower Reservoir exhibited an apparent two-fold increase in plutonium between
February and September. However, it seems likely that this was a pseudo-increase
attributable to normal concentration variations and the relative imprecision of
the soil sampling procedure, particularly in an area of low contamination.
Sharp reductions in the plutonium content of Walnut Creek sediment were
observed in September. This is illustrated by the following comparative tabu-
lation of data from the two studies conducted during 1970.
- 8 -
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TABLE III
RADIOACTIVITY IN WATER SAMPLES
Plutonium Content
Station
Date
Suspended
Sol ids
(mg/1)
of
Suspended Solids
(pCi/gram)(a)
Dissolved
Plutonium
(pCi/1)
Di ssolved
Uranium
(uq/1)
Walnut Creek at Indiana Street
(WC-1)
9/21-23
(Composite)
9/24
9/25
89
53
390
10
15
3
0.02
<0.03
<0.03
1.6
1.3
0.3
Great Western Reservoir at dam
face
9/23-25
(Composi te)I")
13
<10
<0.02
2.1
Standley Lake at dam face
9/21-25
(Composi te)
5
-
<0.01
2.4
(a) Dry weight basis
(b) No analysis for samples collected on 9/21 and 22.
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TABLE IV
PLUTONIUM IN BOTTOM SEDIMENT SAMPLES
Station Water Depth Plutonium Content
Station Number (meters) (pCi/gram)la'
Autrey Reservoir A-l - 0.07
Calkins Lake CA-1 - 0.04
Walnut Creek
South fork at site boundary WC-4 - 0.14
Middle fork WC-3 - 0.16
Main stem, below confluence WC-2 - 0.29
with middle fork
Indiana Street WC-1 - 0.60
At mouth WC - 0.26
Great Western Reservoir 1 0.61 0.34
2 0.92 0.86
3 - 0.49
4 0.92 0.57
5 - 0.58
6 - 0.34
7 - 0.61
8 3.05 0.52
9 1.52 0.30
10 1.98 0.25
11 6.71 0.57
12 4.88 0.08
13 1.83 0.16
14 - 0.15
15 1.83 0.14
16 4.57 0.10
17 15.0 0.08
18 16.5 0.31
19 7.32 0.18
20 1.68 0.12
Woman Creek at Indiana Street W-l - 0.20
Mower Reservoir
West end M-l - 0.18
East end M-2 - 0.18
Standley Lake 21 3.05 0.05
22 19.2 0.21
(a) Dry weight basis
- 10 -
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TABLE V
PLUTONIUM IN BOTTOM SEDIMENT CORE SAMPLES
Plutonium
Station Water Depth Section Analyzed Content .
Station Number (meters) (Inches)la' (pCi/qratnrb'
Great Western Reservoir 1C 0.76 0-1 0.36
1-2 0.58
2-3 1.0
3-5.25 0.43
2C 0.76 0-1 0.44
1-2 0.71
2-3 0.26
3C 2i14 0-1 0.38
1-2 0.29
2-3 0.19
4C 1.37 0-1 0.10
1-2 0.09
5C 2.14 0-1 0.09
1-2 0.04
2-3 0.07
6C 3.05 0-1 0.06
1-2 0.06
7C 7.77 0-1 0.27
1-2 0.34
2-3 0.06
3-4 0.09
8C 6.40 0-1 0.41
1-2 0.29
2-3 0.05
9C 11.9 0-1 0.42
1-2 0.26
2-3 0.07
3-4.25 0.07
IOC 11.0 0-1 0.09
1-2 0.03
11C 15.2 0-1 0.33
1-2 0.27
2-4 0.11
6-7 0.41
7-8 0.40
13-14.5 0.06
12C 5.49 0-1 0.08
1-2 0.03
Standley Lake 13C 3.05 0-1 0.09
1-2 0.11
14C 19.2 0-1.25 0.28
1.25-2.25 0.22
2.25-3.25 0.13
3.25-4.25 0.32
7.25-8.25 0.12
11.25-12.25 0.37
12.25-14.75 0.18
14.75-15.75 0.11
(a) The limits of the range are measurements in inches from the top surface of
the core sample. No correction for compaction during sample collection (refer
to Appendix B).
(b) Dry weight basis - 11 -
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TABLE VI
PLUTONIUM IN FISH
Station
Great Western Reservoir
(A) Near Inlet
(B) Near dam
Standiey Lake
(B) Near Inlet
(B) Near dam
Species
Number
of F1sh
Total
Length
(cm)
Orqan
Sample
Weight, .
(qramsr8'
Plutonlui
Concentrat'
(pCi/k1loqr<
Carp
15
45-85
Whole
52.0
<2.0
3
283-364
Flesh
420
<0.3
H
Liver
10.0
<20
n
Bone
35.0
<4.2
tt
Roe
240
0.9
Northern Conmon
153
30-81
Whole
171
9.6
Shiner
Western White
15
70-132
Whole
99
3.0
Sucker
8
140-272
Flesh
259
<0.6
It
Bone
19.0
9.4
Carp
2
71
Whole
12.6
<7.0
2
2951378
Flesh
318
<0.4
n
Liver
5.0
<32
M
Bone
27.5
• <5.6
Green Sunflsh
32
31-48
Whole
27.0
<3.0
56
49-76
Whole
196
1.0
20
90-125
Flesh
146
<1.0
0
Liver
6.0
30
n
Bone
12.0
<14
10
129-151
Flesh
163
<0.9
m
Liver
8.0
<20
n
Bone
19.0
<8.2
Northern Conmon
50
30-75
Whole
79.6
3.7
Shiner
Western White
8
130-180
Flesh
lib
<1.3
Sucker
H
Bone
10.0
<16
Carp
2
3294390
Flesh
249
<0.7
It
Liver
4.5
<37
n
Bone
29.0
<5.8
Green Sunflsh
7
40-48
Whole
13.0
<13
Largemouth Bass
7
61-90
Whole
45.0
<1.1
Northern Conmon
9
55-74
Whole
27.0
<6.2
Shiner
Western White
1
83
Whole
158
<1.1
Sucker
Yellow Perch
25
46-70
Whole
50.0
<1.4
4
106-130
Whole
72.0
<1.7
6
171-231
Flesh
335
<1.1
II
Liver
2.5
<73
It
Bone
20.0
<8.4
Black Bullhead
1
165
Whole
125
<1.2
Carp
4
335-368
Flesh
589
<0.3
II
Liver
17.0
<9.9
II
Bone
56.0
1.9
a
Roe
32.0
14
Green Sunfish
4
69-106
Whole
45.0
<3.4
7
125-147
Flesh
95.0
1.8
II
Liver
4.0
<18
II
Bone
9 0
<19
3
155-177
Flesh
89.0
<0.8
II
Liver
4.0
<36
II
Bone
13.0
32
Largemouth Bass
3
43-59
Whole
«- Sample Lost ¦*
Yellow Perch
1
106
Whole
15.0
<10
5
160-192
Flesh
100
<1.5
It
Liver
1.0
<160
Bone
10.0
<17
(a) Live weight basis
- 12
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TABLE VII
PLUTONIUM IN BENTHIC INVERTEBRATES
Station
Walnut Creek at Indiana
Street
Great Western Reservoir
Sta. 1
Sta. 4
Sta. 7
Sta. 8
Sta. 9
Sta. 10
Sta. 11
Sta. 12
Sta. 13
Sta. IS
Sta. 16
Sta. 17
Sta. 18
Sta. 19
Sta. 20
Invertebrate
Standley Lake
Sta. 21
Sta. 22
Blackflles
Caddlsflies
Mayflies
Nidges
Other
Crayfish
Predominately Midges
Midges and Sludgeworms
Midges and SIudgeworins
Midges and Sludgeworms
Midges and Sludgeworms
Midges and Sludgeworms
Midges and Sludgeworms
Predominately Sludgeworms
Predominately Midges
Damselflies, Scuds, Midges,
and Sludgeworms
Predominately Sludgeworms
Midges and Sludgeworms
Midges and Sludgeworms
Predominately Sludgeworms
Midges
Mayflies, Caddlsflies, Scuds,
Midges, and Sludgeworms
Midges and Sludgeworms
Predominately Sludgeworms
Sample
Dry Weiqht
M
2247
3511
225.4
92.6
83.3
12.4
6.4
20.8
39.5
2.9
11.1
4.7
19.7
4.7
2.9
3.4
0.9
1.8
5.9
9.0
10.3
12.1
3.0
8.6
6.1
11.3
10.3
12.9
3.5
2.0
3.6
19.8
21.5
3.4
18.3
2.6
22.8
9.5
18.7
Plutonium
Concentration
(pCI/qramlU)
0.07
o.og
<0.4
<0.9
<1.0
None Detected
55
<5.0
<2.0
<28
<7.0
<17
<5.0
<17
<27
<23
<85
<43
24
<9.0
<8.0
<7.0
<26
<9.0
<13
<7.0
<7.0
<6.0
<20
<35
<20
<4.0
4.0
<20
<5.0
<33
6
<9.0
<5.0
(a) Dry weight basis
- 13 -
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Walnut Creek Station
Plutonium Concentration
(pCi/qram)
February September
South fork at site boundary
Middle fork
Main stem, below confluence with
middle fork
Indiana Street
At mouth; inlet to Great Western
Reservoir
3.51
0.50
3.41
0.92
1.75
0.14
0.16
0.29
0.60
0.26
These data indicated scouring of contaminated sediment from the creek bed
and/or coverage of contaminated zones by less contaminated soil washed into
the creek without reaccumulation to previously observed maximal levels by mass
transport from the aqueous phase. Assuming that the routine discharge of
plutonium-bearing liquid wastes is the major source of sediment contamination,
the reduced September'concentrations were apparently the result of high flow
shortly before the collection of samples. Unfortunately, flow data required
for a truly meaningful interpretation of the limited sediment data are not
existent. In the case of Woman Creek, no significant difference was observed
between the February and September results - 0.23 and 0.20 pCi/gram, respec-
tively.
The results for "dredge" samples and the top one-inch sections of core
samples showed that nearly the entire bed of Great Western Reservoir contained
plutonium at concentrations in excess of the baseline value, 4 0.10 pCi/gram.
Plotted in FIGURES IV and V, only the extrapolated shaded areas represent
bottom deposits containing 0.10 pCi/gram or less of plutonium. The area or
sector of greatest contamination appeared to be the central section of the
reservoir (inlet to dam) with maximum concentrations near the inlet. In the
inlet area, the maximum concentration in the top one-inch section was 0.86
pCi/gram (Station 2) with an average concentration of 0.50 pCi/gram for
Stations 1-8 and 1C-3C. Sediment samples from the northern arm (Stations 13,
14, and 15) showed plutonium concentrations only about 50% higher than the
baseline value - average concentration of 0.15 pCi/gram for the three stations.
Bank sloughing was observed in this arm.
Core samples from Great Western Reservoir showed that the thickness of
deposited plutonium-contaminated sediment was 2 inches or more at all loca-
tions (TABLE V). Near the face of the dam in the deep-water area, plutonium
contamination on the order of four times the baseline level was found at a
sediment thickness of 7 to 8 inches (Station 11C). At Station 10C, adjacent
to Station 11C in the deep-water area, baseline concentrations were obtained
from the core sample. However, these findings are consistent when the dif-
ferences in bottom conditions are taken into account. Unlike Station 11C
where the layer of "black" sediment was 8" thick (compacted in the core tube),
14 -
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U1
I
w^nut
• 06I
•030 jm GREAT WESTERN RESERVOIR
•057
0.2I#\
) mo.05
STANDLEY LAKE
(NOT TO SCALE)
m SPILLWAY
KILOMETERS
§£ 0.10 pCi/gram
FIGURE Ur
PLUTONIUM (pCI/gram) IN BOTTOM SAMPLES
GREAT WESTERN RESERVOIR ft STANDLEY LAKE
-------
I
»"»
CT>
I
GREAT WESTERN RESERVOIR
STANDLEY LAKE
(NOT TO SCALE)
KILOMETERS
*0.10 pCi/gram
FIGURE JL
PLUTONIUM (pCI/gram) IN THE TOP ONE-INCH SECTION OF CORE SAMPLES
GREAT WESTERN RESERVOIR a STANDLEY LAKE
SPILLWAY
-------
only the top one inch section of the core collected at Station IOC was of
similar composition. Below one inch, clay was found at Station IOC. The
finding that plutonium contamination is not restricted to the surface layer
of bottom sediment suggests a contamination source of some duration; pre-
sumably, the continuously occurring discharge of liquid wastes from the Rocky
Flats Plant.'
Dredge and core samples from the west end of Standley Lake near the
mouth of Woman Creek (Stations 13C and 21) showed baseline concentrations of
plutonium (TABLES IV and V; FIGURES IV and V). In contrast, samples collected
at Stations 14C and 22 - east end of the lake just offshore of the dam in the
deep-water area, contained plutonium in concentrations on the order of two to
three times baseline. Furthermore, the results for the several sections of
the core sample showed that plutonium contamination was not limited to the
surface, but extended to a thickness of approximately 12 inches (compacted
in the core tube). Since plutonium-bearing liquid wastes are not and have
not been discharged to Woman Creek, the origin of plutonium-contaminated
sediment in Standley Lake would have to be contaminated soil transported and
deposited in the lake by runoff. Although this is a plausible source for the
contamination of the surface layer of sediment, it is not a good explanation
for the finding of plutonium contamination to a thickness of several inches.
To verify the existence of significant zones of plutonium-contaminated sedi-
ment in the lake, or disprove as the case might be, additional monitoring of
a scope similar to that used for Great Western Reservoir will be required.
Until this effort is undertaken, the results for Stations 14C and 22 will be
subject to question on the basis of possible sample contamination.
Similar to the findings for bottom sediment samples from area surface
waters, the two soil samples showed substantially lower plutonium concentra-
tions in comparison to those collected from the same general locations in
February.
Location
Plutonium Concentration
(pCi/gram)
February September.
Grazed area to the south- 2.42
east of the road culvert
conveying Woman Creek under
Indiana Street
0.64
Ungrazed area near the south- 0.42
east corner of Great Western
Reservoir
0.14
Fish and Benthos
Information presented in the literature review of Olafson and Larson^2)
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on the biology and environmental persistance of plutonium leads one to the
conclusion that plutonium entering the Walnut Creek - Great Western Reservoir
system as the result of liquid waste releases ultimately accumulates in the
reservoir sediment with very little transfer to and cycling in aquatic biota.
Among the conclusions reached by Olafson and Larson, the following are perti-
nent to the Rocky Flats "situation."
(1) Plutonium is absorbed by plants growing on contaminated soil to an
infinitesimal degree, although it may be found as an external con-
taminant on vegetation.
(2) Ingested plutonium is absorbed and retained in animal tissues to
only a very small degree.
(3) Based on animal tissue assays, very little plutonium gains entry
into mammalian systems.
In animals, ingested plutonium concentrates in bone and liver tissue. There
is also concentration in reproductive tissue.
The results for benthos and fish (TABLES VI and VII) generally showed
that there was no significant accumulation of plutonium in the biota of
Great Western Reservoir and Standiey Lake. As evidenced by the preponderance
of "less than" results, small sample size, particularly in the case of benthos
samples, prevented the conduct of analyses with the high degree of analytical
sensitivity required for definitively determining absolute concentrations.
Excluding the five positive results, the "best" detection limit for benthos
samples was about 40 pCi per kilogram (live weight)(a) whereas the desired
sensitivity was within the range of 0.1 to 1.0 pCi/kg. Furthermore, con-
sidering sample size, only the positive results for blackflies and caddis-
flies from Walnut Creek at Indiana Street should be given credence as valid,
absolute concentrations.
Although the analysis of fish samples also produced few absolute concen-
trations, larger sample sizes - gram amounts instead of milligrams - enabled
the conduct of analyses with precision consistent with the range of expected
low concentrations (refer to TABLE VIII - plutonium in foodstuffs reported
in 1959 by the U.S. Atomic Energy Commission). Considering edible tissue
(flesh), the plutonium concentrations in all species from both impoundments
were less than 2 pCi per kilogram (live weight). Hence, human consumption of
these fish would be insignificant from the standpoint of resultant radiation
dose because the daily intake limit for the general.public, as recommended
by the National Committee on Radiation Protection^, is approximately 3700
pCi of plutonium. One finding of interest was the apparent accumulation of
plutonium in carp roe. Although beyond the scope of this report, this finding
raises the question of a possible genetic effect on fish.
(a) Calculated on the basis of an assumed moisture content of 90%.
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TABLE VIIl(a)
PLUTONIUM CONCENTRATIONS IN VARIOUS FOOD ITEMS AND PLANTS
Item
Plutonium-239 Concentration
(pCi/kilogram)
Rain
0.18
Alfalfa ash
430 to 800
Milk
0.16
Wheat ash
130 to 670
Swordfi sh
0.34 to 1.0
Pork liver
0.56 to 2.7
Beef meat
0.19 (meat of chuck steak)
180 (fluid)
(a) TABLE 4 in Reference 2 (data from U.S. Atomic Energy Commission,
Quarterly Statement on Fallout in "Fallout from Nuclear Weapons
Tests. Hearings before the Special Subcommittee on Radiation,
Joint Committee on Atomic Energy, Congress of the U.S., May 5-8,
1959," pp. 2188-2198, U.S. Government Printing Office, Washington,
D.C., {1959}).
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Aside from radiological considerations, benthos and plankton sampling
showed the presence of pollution tolerant organisms in both Great Western
Reservoir and Standley Lake; indicative of enriched or eutrophic conditions.
In the case of Great Western Reservoir, the contributing polluton sources
are domestic-type wastes from the Rocky Flats Plant and agricultural runoff
whereas only the latter is the source to Standley Lake. The pollution biology
aspects of the field study are presented in detail in Appendix A.
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SUMMARY
The September 1970 field study produced the following significant
findings.
(1) Almost the entire bed of Great Western Reservoir was covered
with sediment containing plutonium in excess of the estimated
baseline concentration, 4 0.10 pCi/gram. The thickness of the
layer of plutonium-contaminated sediment was 2 inches or more
at all such sampling stations. The maximum concentration of
approximately 1.0 pCi/gram was obtained at the inlet area of
the impoundment.
(2) Limited sediment sampling in the deep-water area of Standiey
Lake indicated possible sectors of plutonium contamination
attributable to past emissions from the Rocky Flats Plant.
(3) Fish and benthos from Great Western Reservoir and Standiey Lake
did not show significant accumulation of plutonium. In all
species of fish, the concentration in flesh was <2 pCi/kilogram-
live weight. At this low concentration, human consumption at an
abnormally high intake rate of one kilogram per day would be
inconsequential in terms of radiation dose.
In that this study was the initial comprehensive effort at determining
plutonium concentrations in the biota and sediment of Great Western Reservoir
and Standiey Lake, additional monitoring will be necessary to determine the
representativeness of the specific results as maximum, steady-state values
or "points" on curves showing increasing or decreasing trends.
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REFERENCES
Environmental Protection Agency, "Radioactivity levels in the
Environs of the Rocky Flats Plutonium Plant, Golden, Colorado,
1970," Radiological Activities Section, Division of Technical
Support, Water Quality Office (April, 1971).
Olafson, J. H., and Larson, K. H., "Plutonium, Its Biology and
Environmental Persistence," in "Radioecology," edited by V. Schultz
and A. W. Klement, Jr., pp 633-639, Reinhold Publishing Corporation,
New York, New York, and The American Institute of Biological
Sciences, Washington, D. C., (1963).
National Committee on Radiation Protection, "Maximum Permissible
Body Burdens and Maximum Permissible Concentrations of Radio-
nuclides in Air and in Water for Occupational Exposure," U.S.
Department of Commerce, National Bureau of Standards Handbook
69, U.S. Government Printing Office, Washington, D. C. (1959).
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APPENDIX A
BIOLOGICAL STUDY OF GREAT WESTERN RESERVOIR
A biological study was conducted on Great Western Reservoir during the
week of September 21 to 24, 1970. Objectives of the study were to determine:
a) effects on the reservoir of domestic sewage discharged to Walnut Creek, a
tributary to the reservoir, from the Rocky Flats Plutonium Plant, and b) the
existing levels of plutonium in the sediments, benthic invertebrates, and fish
in the reservoir.
In a lake the clean water benthic community is usually composed of many
kinds of organisms, each kind being few in number. When domestic sewage is
discharged to a lake, the number of kinds of benthic organisms are reduced and
the remaining organisms are able to increase in number. A lake receiving
domestic sewage or runoff from surrounding agricultural areas may have an oxygen
consuming layer of decomposing organic material. Such a layer is caused by
either an inflow of suspended organic matter which settles to the bottom or by
the contribution of large amounts of nutrients which cause an increase in the
plankton population during the spring and a resultant die-off and settling of
the plankton each fall.
The water layer above a bottom of decomposing organic material is usually
low in dissolved oxygen and the bottom material supports only small numbers of
pollution tolerant organisms.
Methods
Samples of the benthic invertebrate populations were obtained from Walnut
Creek and the reservoir with either a Petersen dredge or Eckman dredge. Sampling
stations are depicted in FIGURE II. Benthic invertebrates were collected from
all stations except Stations 2, 3, 5, 6, and 14. Dredge samples were sieved
through a U.S. Standard No. 30 sieve and material retained on the sieve was
preserved in five per cent formalin. All samples were picked and invertebrates
identified in Cincinnati, Ohio.
Short five-minute tows were made with a plankton net near the inlet and
middle of Great Western Reservoir and near the middle of Standley Lake. The
concentrated plankton samples were examined to determine the qualitative com-
position of the algal populations in each water body.
Results
The bottom sediments in Great Western Reservoir did not support large
numbers of organisms (TABLE A-I and FIGURE A-I). Only in an area extending
from the inlet of Walnut Creek and the offshore areas near the dam were the
numbers of organisms large enough to merit mention (FIGURE A-I).
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TABLE A-I
TOTAL NUMBER AND KINDS OF BOTTOM ORGANISMS COLLECTED FROM GREAT WESTERN RESERVOIR AND STANDLEY LAKE
Walnut Creek Great Western Reservoir Standiey Lake
1 3 4 5 6 7 8 9 10 11 12 14 IS 16 17 33 34
Q Q Q 7
411 q Q
Mayflies
Baetls sp 272
Caenis sp 5
Caddlsflies
Cheumatopsyche sp 1924
Neotrichia sp 12
Damselflles
Odonata
Scuds
Hyalella sp 22
Midges
Glyptotendipes sp
Cricotopus sp
Spaniotoma sp 10
Chironomus sp 2 65 7 10 7 21 3 q 4 Q 34 3 24 26 31
ProcladiuT sp 1
Cryptochfronomus sp XI 2 5 Q
Tanytarsus sp 8 2 3
Biting Midges
Stllobezzla sp 10 q
Phantom Midge
Chaoborus sp 13 4 Q
Mosquito
Culicinae Q
Blackflies
SlrauHidae 1671
Snails
Physa sp 3
Sludgeworms IS 24 3 14 24 74 5 2 Q 72 46 19 2 10 S 19 16 10
Crayf1sh 2
TOTAL NUMBER 4359 89 10 24 31 96 28 5 4 76 50 27 36 13 29 52 16 41
TOTAL KINDS 13 62233 10 224283323 2 2
q = Organisms not collected quantitatively, arbitrarily given value of 1 for computing number of kinds
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STANDLEY LAKE
(NOT TO SCALE)
>50 ORGANISMS PER FT2
929 GREAT WESTERN RESERVOIR
CaJ
•\
I
) #41
16 \
SPILLWAY
KILOMETERS
FIGURE A-I
DISTRIBUTION OF BOTTOM ORGANISMS PER SQUARE FOOT
GREAT WESTERN RESERVOIR a STANDLEY LAKE
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The inlet (Station 1) supported a diverse population of organisms that
received nutrients from Walnut Creek. The creek supported an enriched com-
munity of 13 kinds of organisms numbering 4359 per square foot; an indication
that nutrients discharged from the Rocky Flats Plutonium Plant affect the
benthic community immediately upstream from the reservoir. At the inlet or
upper end of the reservoir (Station 1) the population of benthic organisms
was composed of six kinds with a total number of 89 organisms per square foot;
twice as many organisms per square foot as collected in the upper end of
Standley Lake (Station 21) which is not reported to receive domestic sewage.
Great Western Reservoir had low numbers of benthic organisms at all
stations except Stations 12, 16, and 19, where the benthic community was pre-
dominately sludgeworms numbering 74, 72, and 46 square foot, respectively.
The larger numbers of sludgeworms at these stations as opposed to the other
areas of the lake (TABLE A-I) were probably due to nutrients received from
Walnut Creek. Other areas of the reservoir that would have been affected by
nutrients in runoff water, and not domestic waste, such as Stations 10, 13,
and 15, did not support large numbers of sludgeworms. The deep water area
of the Great Western Reservoir represented by Stations 17 and 18 supported
only small numbers of pollution tolerant midges and sludgeworms (TABLE A-I,
FIGURE A-I). The reduced number of organisms in this area of the reservoir
was caused by the presence of a layer of black decomposing organis material
on the bottom. Cores of the bottom material revealed 9 to 21 inches of
black sediment covering the bottom. Bottom samples had a slight hydrogen
sulphide odor. Since a similar black organic material was collected at
Station 22 in Standley Lake, the assumption must be made that both lakes
receive nutrients and organic material from land runoff and such material
settles in the deeper areas where it decomposes. In the case of Great Western
Reservoir, the nutrients received from Walnut Creek add to the effects of
nutrients from agricultural drainage, thus affecting a larger area of the
reservoir.
In the plankton samples from Great Western Reservoir, filter-clogging
organisms such as Melosira sp. abundant, and taste and odor organisms such
as Staurastrum sp. and Ceratium sp. were present, indicating possible water
treatment problems. Pollution tolerant Microcystis sp. was also present,
and indication that the reservoir water contained excessive amounts of nutri-
ents. Standley Lake phytoplankton were predominantly composed of the pol-
lution tolerant algae Microcystis sp. and Anabaena sp., indicating the lake
has received enough nutrient from agricultural runoff to become highly en-
riched or eutrophic.
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APPENDIX B
MEASUREMENTS OF CORE SAMPLES
Penetration Total Length
of of
Station Core Sampler Core Sample
Station Number (inches) (inches)
Great Western Reservoir 1C 5.3 5.3
2C 6 5.5
3C 7 5
4C 5 4.5
5C 6 5
6C 7.5 6.5
7C 24 8.5
8C 10.5 7.3
9C 19 5.3
10C 7.5 4.8
11C 47 15
12C 5 4
Standley Lake 13C 7.5 4.5
14C 43 16.8
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