U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
HOLBROOK RESERVOIR
OTERO COUPJTY
COLORADO
EPA REGION VIII
WORKING PAPER No, 772
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY - CORVALLIS, OREGON
and
ENVIRONMENTAL MONITORING & SUPPORT LABORATORY - LAS VEGAS, NEVADA
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REPORT
ON
HOLBROOK RESERWIR
OTERO COIMY
COLORADO
EPA REGION VIII
WORKING PAPER No, 772
WITH THE COOPERATION OF THE
COLORADO DEPARTMENT OF HEALTH
AND THE
COLORADO NATIONAL GUARD
JULY, 1977
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1
CONTENT
Page
Foreward ii
List of Colorado Study Lakes and Reservoirs iv
Lake and Drainage Area Maps v, vi
Sections
I. Introduction 1
II. Conclusions 1
III. Lake and Drainage Basin Characteristics 2
IV. Lake Water Quality Summary 3
V. Mean Nutrient Concentrations in Ungaged Streams 6
VI. Literature Reviewed 7
VII. Appendices 8
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11
FOREWORD
The National Eutrophication Survey was initiated in 1972 in
response to an Administration commitment to investigate the nation-
wide threat of accelerated eutrophication to freshwater lakes and
reservoirs.
OBJECTIVES
The Survey was designed to develop, in conjunction with state
environmental agencies, information on nutrient sources, concentrations,
and impact on selected freshwater lakes as a basis for formulating
comprehensive and coordinated national, regional, and state management
practices relating to point-source discharge reduction and non-point
source pollution abatement in lake watersheds.
ANALYTIC APPROACH
The mathematical and statistical procedures selected for the
Survey's eutrophication analysis are based on related concepts that:
a. A generalized representation or model relating
sources, concentrations, and impacts can be constructed.
b. By applying measurements of relevant parameters
associated with lake degradation, the generalized model
can be transformed into an operational representation of
a lake, its drainage basin, and related nutrients.
c. With such a transformation, an assessment of the
potential for eutrophication control can be made.
LAKE ANALYSIS
In this report, the first stage of evaluation of lake and water-
shed data collected from the study lake and its drainage basin is
documented. The report is formatted to provide state environmental
agencies with specific information for basin planning [§303(e)], water
quality criteria/standards review [§303(c)], clean lakes [§314(a,b)],
and water quality monitoring [§106 and §305(b)] activities mandated
by the Federal Water Pollution Control Act Amendments of 1972.
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111
Beyond the single lake analysis, broader based correlations
between nutrient concentrations (and loading) and trophic condi-
tion are being made to advance the rationale and data base for
refinement of nutrient water quality criteria for the Nation's
fresh water lakes. Likewise, multivariate evaluations for the
relationships between land use, nutrient export, and trophic
condition, by lake class or use, are being developed to assist
in the formulation of planning guidelines and policies by EPA
and to augment plans implementation by the states.
ACKNOWLEDGEMENT
The staff of the National Eutrophication Survey (Office of
Research & Development, U. S. Environmental Protection Agency)
expresses sincere appreciation to the Colorado Department of
Health for professional involvement, to the Colorado National
Guard for conducting the tributary sampling phase of the Survey,
and to those wastewater treatment plant operators who voluntarily
provided effluent samples.
The staff of the Water Quality Control Division provided
invaluable lake documentation and counsel during the Survey,
reviewed the preliminary reports, and provided critiques most
useful in the preparation of this Working Paper series.
Lt. Colonel Paul A. Parsons, the Deputy Adjutant General of
Colorado, and Project Officer Colonel Hershel C. Yeargan, who
directed the volunteer efforts of the Colorado National Guardsmen,
are also gratefully acknowledged for their assistance to the Survey.
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IV
NATIONAL EUTROPHICATION SURVEY
STUDY LAKES AND RESERVOIRS
STATE OF COLORADO
NAME
Barker
Barr
Blue Mesa
Cherry Creek
Cucharas
Dillon
Grand
Green Mountain
Hoi brook
Meredith
Milton
Navajo
Shadow Mountain
COUNTY
Boulder
Adams
Boulder
Arapohoe
Huerfano
Summi t
Grand
Summit
Otero
Crowley
Weld
Archuleta, CO; San
Juan, Rio Arriba, NM
Grand
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HOLBROOK RESERVOIR
Tributary Sampling Site
X Lake Sampling Site
Land Subject to Inundation
Map Location
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ARKANSAS
Colo.
Map Location
HOLBROOK RESERVOIR
® Tributary Sampling Site
X Lake Sampling Site
o 5
10 Km.
Scale
Mi.
38°15 —
38°10 —
Dye
Reservoir
38°05'—
HOLBROOK
RESERVOIR
103 50'
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HOLBROOK RESERVOIR
STORE! NO. 0809
I. INTRODUCTION
Accurate flow data could not be provided for Hoi brook Reservoir
by the U.S. Geological Survey because water enters and leaves through
ungaged inlet and outlet canals. Therefore, this report primarily per-
tains to the lake sampling data. However, results of analyses of tribu-
tary samples are presented in Appendix D.
II. CONCLUSIONS
A. Trophic Condition:
Survey data indicate that Hoi brook Reservoir is eutrophic.
It ranked ninth in overall trophic quality when the 13 Colorado
lakes and reservoirs sampled in 1975 were compared using a combina-
tion of six parameters*. Nine of the water bodies has less median
total phosphorus, nine had less median dissolved orthophosphorus,
eight had less median inorganic nitrogen, 11 had less mean chloro-
phyll a_, and all of the others had greater mean Secchi disc trans-
parency.
Survey limnologists reported algal blooms in August and
October and estimated that macrophytes occupied 30% of the shore-
line shallows at those times.
B. Limiting Nutrient Study:
The results of the algal assay indicate that nitrogen was
limiting at the time the sample was taken (05/06/75).
The reservoir data indicate nitrogen limitation in May and
October and phosphorus limitation in August.
* See Appendix A.
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III. RESERVOIR AND DRAINAGE BASIN CHARACTERISTICS1"
*f"f*
A. Morphemetry :
1. Surface area: 2.72 kilometers2.
2. Mean depth: 2.5 meters.
3. Maximum depth: 6.4 meters.
4. Volume: 6.908 x 10s m3.
B. Precipitation*:
1. Year of sampling: 25.3 centimeters.
2. Mean annual: 31.8 centimeters.
t Table of metric conversions—Appendix B.
tt Anderson, 1974.
* See Working Paper No. 175, "...Survey Methods, 1973-1976",
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3
IV. WATER QUALITY SUMMARY
Hoi brook Reservoir was sampled three times during the open-water
season of 1975 by means of a pontoon-equipped Huey helicopter. Each
time, a near-surface sample for physical and chemical parameters was
collected from one station on the reservoir (see map, page v). During
each visit, a depth-integrated (near bottom to surface) sample was
collected for phytoplankton identification and enumeration, and a
similar sample was taken for chlorophyll a_ analysis. During the first
visit, a single 18.9-liter depth-integrated sample was collected for
algal assays.
The sampling results are presented in full in Appendix C and are
summarized in the following table.
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PARAMETER
TEMP (C)
DISS OXY (MG/D
CNDCTW (MCROMO)
PH (STAND UNITS)
TOT ALK (MG/L)
TOT P (MG/L)
ORTHO P (MG/L)
N02»N03 (MG/L)
AMMONIA (MG/L)
KJEL N (MG/L)
INORG N (MG/L)
TOTAL N (MG/L)
CHLP.PYL A (UG/L)
SECCHI (METERS)
A. SUMMARY OF PHYSICAL AND
1ST SAMPLING ( 5/ 6/75)
1 SITES
KANGE MEAN MEDIAN
13.6 - 13.6 13.6 13.6
1650.
e.i
147.
0.127
o.oaa
0.020
0.050
1.700
0.070
1.720
28.7
0.3
- 1650.
8.1
- 147.
- 0.127
- 0.028
- 0.020
- 0.050
- 1.700
- 0.070
- 1.720
- 28.7
0.3
1650.
8.1
147.
0.127
0.028
0.020
0.050
1.700
0.070
1.720
28.7
0.3
1650.
8.1
147.
0.127
0.026
0.020
0.050
1.700
0.070
1.720
28.7
0.3
CHEMICAL CHARACTERISTICS FOR nOLB-iOOK LAKE
STORET CODE 0309
2ND SAMPLING ( 8/22/75)
1 SITES
RAMiE.
21.6 - 21.6
6.0 - 6.0
2368. - 2368.
8.6 - 8.6
10. - 10.
0.367 - 0.367
0.002 - 0.002
0.020 - 0.020
0.140 - 0.140
3.100 - 3.100
0.160 - 0.160
3.120 - 3.120
146.9 - 146.9
0.2 - 0.2
3RD SAMPLING (10/ 7/75)
1 SITES
MEAN
21.6
6.0
2368.
8.6
10.
0.367
0.002
0.020
0.140
3.100
0.160
3.120
146.9
0.2
MEDIAN
21.6
6.0
2368.
8.6
10.
0.367
0.002
0.020
0.140
3.100
0.160
3.120
146.9
0.2
RANGE
18.3
1812.
8.9
85.
0.329
0.037
0.020
0.030
3.000
0.050
3.020
160.2
0.3
- 18.3
- 1812.
8.9
85.
- 0.329
- 0.037
- 0.020
- 0.030
- 3.000
- U.050
- 3.020
- 160.2
0.3
MEAN
18.3
1812.
8.9
85.
0.329
0.037
0.020
0.030
3.000
0.050
3.020
160.2
0.3
ME 01 A.-
18.3
1812.
8.9
85.
0.32v
0.037
0.020
0.030
3.000
0.050
3.020
160.2
0.3
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B. Biological Characteristics:
1. Phytoplankton -
Sampli ng
Date
05/06/75
OB/22/75
10/07/75
2. Chlorophyll a_ -
Sampling
Date
05/06/75
08/22/75
10/07/75
Dominant
Genera
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
Oscinatoria sp.
Synedra sp.
Flagellates
Stephanodiscus sp.
Cryptomonas sp.
Other genera
Total
Anabaenopsis sp.
Oscillatoria sp.
Anabaena sp.
Cryptomonas sp.
Scenedesmus sp.
Other genera
Total
Anabaenopsis sp.
Oscillatoria SJD .
Nitzschia s_p_.
Cryptomonas sp.
Stephanodiscus sp.
Other genera
Total
Station
Number
1
1
1
Algal Units
per ml
36,005
16,440
6,083
2,137
1,973
4,185
66,823
34,071
11,005
,111
,111
,508
2,
2,
1,
1.808
52,614
31,245
13,077
7,487
2,595
799
1,099
56,302
Chlorophyll a
(yg/1)
28.7
146.9
160.2
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6
C. Limiting Nutrient Study:
1. Autoclaved, filtered, and nutrient spiked -
Ortho P Inorganic N Maximum yield
Spike (mg/1) Cone, (mg/1) Cone, (mg/1) (mg/1-dry wt.)
Control 0.042 0.192 63.3
0.050 P 0.092 0.192 69.4
0.050 P + 1.0 N 0.092 1.192 96.0
1.0 N 0.042 1.192 93.1
2. Discussion -
The control yield of the assay alga, Selenastrum capri-
cornutum, indicates that the potential primary productivity
of Hoi brook Lake was extremely high at the time the algal
assay sample was collected (05/06/76).
There was a significant increase in yield when only nitro-
gen was added, but no such response occurred when only phos-
phorus was added. Therefore, nitrogen limitation is indi-
cated at that time.
The reservoir data indicate nitrogen limitation in May and
October (the mean inorganic nitrogen to orthophosphorus ratios
were 3 to 1 and 1 to 1, respectively). However, phosphorus
limitation is indicated in August (the mean N/P ratio was
80/1).
V. MEAN NUTRIENT CONCENTRATIONS IN UNGAGED STREAMS
Mean Total P Mean Total N
Tributary Cone, (mg/1) Cone, (mg/1)
Outlet Ditch A-l 0.210 1.955
Ditch A-2 0.440 3.630
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VI. LITERATURE REVIEWED
Anderson, R. Dennis, 1974. Personal communication (waterbody infor-
mation and morphometry). CO Dept. of Health, Denver.
-------
VII. APPENDICES
APPENDIX A
LAKE RANKINGS
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TO BF. US?:
LAKE
CODE LAKE NAME
0601 BARKER RESERVOIR
0603 BARK LAKE
Ort03 BLUE MESA RESERVOIR
0804 CHEHRY CREEK LAKE
0805 CUCHARAS RESERVOIR
0806 DILLON RESERVOIR
0807 GRAND LAKE
0808 GREEN MOUNTAIN RESERVOIR
0809 HOLBROOK LAKE
0610 LAKE MEREDITH
0811 MILTON RESERVOIR
0813 NAVAJO RESERVOIK
0813 SHADOrt MOUNTAIN LAKE
MEDIAN
TOTAL P
0.023
0.930
0.019
0.054
0.263
0.009
0.013
0.010
0.339
0.397
0.846
0.036
0.030
MEDIAN
INO»& N
0.045
1.090
0.040
0.04Q
0.040
0.040
0.040
0.040
0.070
0.110
3.280
0.050
0.040
500-
MEAN SEC
419.000
451.333
395.750
469.333
490.000
181.750
366.500
391.167
490.333
489.667
429.333
479.400
427.000
MEAN
CrtLORA
5.333
28.767
6.817
23.322
27.400
3.150
4.900
5.833
111.933
164.678
5.900
2.180
5.700
15-
MIN 00
9.400
10.200
13.800
10.000
14.800
9.200
10.300
9.100
9.000
10.400
9.300
10.000
9.300
MEDIAN
OISS ORTHO
0.006
0.730
0.005
0.007
0.015
0.002
0.003
0.002
0.026
0.098
0.808
0.013
0.003
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PCR~E:NT or LAKES KJ.TM HIGHC.P VALUES »NUM«FR OF LAKES W'T*. HIC-ME* VALUES,)
LAKE
CODE LAKE NAME
OPOi BASHER WESER'.'OIH
0802 8ASS LAKE
0803 BLUE MESA RESERVOIR
0804 CHERRY CREEK LAKE
0805 CUCHARAS RESERVOI*
OB06 OILLON RESERVOIR
0807 GRAND LAKE
0808 GREEN MOUNTAIN RESERVOIR
0809 HOLdROOK LAKE
0810 LAKE MEREDITH
0811 MILTON RESERVOIR
0812 NAVAJO RESERVOIR
0813 SHADOW MOUNTAIN LAKE
MEDIAN
TOTAL P
eg (
0 (
75 (
42 (
33 (
100 (
83 (
92 <
25 (
17 <
8 (
50 <
67 (
7)
0)
9)
5)
4)
12)
10)
11)
3)
2)
1)
6)
8)
MEDIAN
INORG N
4? <
8 (
87 <
87 (
58 (
58 (
87 <
58 (
25 (
17 (
0 (
33 (
87 (
5)
1)
9)
9)
6)
6)
9)
6)
3)
2)
0)
4)
9)
500-
MEAN SEC
67 (
^2 (
75 (
33 <
8 (
100 (
92 <
83 (
0 (
17 <
50 (
25 (
58 (
81
5)
9)
4)
1)
12)
11)
10)
0)
2)
6)
3)
7)
MEAN
CHLORA
75 C
17 (
42 (
33 (
25 <
92 (
83 <
58 (
8 (
0 (
50 <
100 (
67 (
9)
2)
5)
4)
3)
11)
10)
7)
1)
0)
6)
12)
8)
15-
MIN DO
58 (
29 (
8 (
46 (
0 (
75 (
29 (
92 (
100 (
17 (
75 (
46 (
75 (
7)
3)
1)
5)
0)
8)
3)
11)
12)
2)
8)
5)
8)
MEDIAN
DISS OHTHO P
58 (
6 <
67 (
50 (
33 (
96 (
79 (
96 (
25 <
17 (
0 (
42 (
79 (
7)
1)
8)
6)
4)
11)
9)
11)
3)
2)
0)
5) .
9)
INOtX
NO
358
104
354
291
157
521
453
479
183
85
113
296
433
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LAKES RANKED BY INDEX NOS.
RANK LAKE CODE LAKE NAME INDEX NO
1 0806 DILLON RESERVOIR 521
2 0808 GREEN MOUNTAIN RESERVOIR 479
3 0807 GRAND LAKE 453
4 0813 SHADOW MOUNTAIN LAKE 433
5 0801 BARKER RESERVOIR 358
6 0603 SLUE MESA RESERVOIR 354
7 0812 NAVAJO RESERVOIR 296
8 0804 CHERRY CREEK LAKE 291
9 0811 MILTON RESERVOIR 183
10 0809 HOL3ROOK LAKE 183
11 0805 CUCHARAS RESERVOIR 157
12 0802 BARR LAKE 104
13 0810 LAKE MEREDITH 85
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APPENDIX B
CONVERSION FACTORS
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CONVERSION FACTORS
Hectares x 2.471 = acres
Kilometers x 0.6214 = miles
Meters x 3.281 = feet •
Cubic meters x 8.107 x 10 = acre/feet
Square kilometers x 0.3861 = square miles
Cubic meters/sec x 35.315 = cubic feet/sec
Centimeters x 0.3937 = inches
4
Kilograms x 2.205 = pounds
Kilograms/square kilometer x 5.711 = Ibs/square mile
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APPENDIX C
PHYSICAL and CHEMICAL DATA
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STORE! RETRIEVAL DATE 76/09/3*.
DATE TIME DEPTH
FROM OF
TO DAY FEET
75/05/06 1? 30 0000
75/08/22 10 35 0000
75/10/07 14 30 0000
00010
WATER
TEMP
CENT
13.6
21.6
18.3
00300 00077 00094
DO TRANSP CNDUCTVY
SECCHI FIELD
MG/L INCHES MICROMHO
6.0
11
7
11
1650
2368
1812
080901
38 03 45.0 103 36 38.0 3
HOLdKOOK LAKE
08089 COLORADO
100191
11EPALES 2111202
0005 FEET DtPTh CLASS 00
00400
PH
su
8.10
8.60
8.90
00410
T ALK
CAC03
MG/L
147
10
85
00610
NH3-N
TOTAL
MG/L
0.050
0.140
0.030
00625
TOT KJEL
N
MG/L
1.700
3.100
3.000
00630
N02&.N03
N-TOTAL
MG/L
0.020K
0.020K
0.020K
00671
PHOS-DIS
OtfTHO
MG/L P
0.028
0.002K
0.037
00665
DATE TIME DEPTH PHOS-TOT
FROM OF
TO DAY FEET MG/L P
75/05/06 12 30 0000 C.127
75/08/22 10 35 0000 0.367
75/10/07 14 30 0000 0.329
32217 00031
CHLRPHYL INCOT LT
A REMNING
UG/L PERCENT
28.7
146.9
160.2
K VALUE KNOWN TO 8E
LESS THAN INDICATED
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APPENDIX D
TRIBUTARY DATA
-------
STORET RETRIEVAL DATE 76/09/2<»
00630
DATE TIME DEPTH N02kN03
F*OM OF N-TOTAL
TO DAY FEET MG/L
75/06/30 13 15
0.005
0809A1
38 03 37.0 103 36 06.0
HOLnrtOOK OUTLET DITCH
08 7.5 CHERA*
0/HOL8^00K RESERVOIR
100191
00625
TOT KJEL
M
*G/L
1.950
00610
NH3-N
TOTAL
MG/L
0.030
00671
PHOS-OIS
ORTriO
MG/L P
0.020
SEC M BROG
HEHALES
0000 FEET
00665
PHOS-TOT
MG/L P
0.210
1.7 MI S OF ST RT 266
DEPTH CLASS 00
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STORET RETrtIEVi'_ DATE 76/09/P4
DATE
FROM
TO
00630 00625 00610
TIME DEPTH N02&N03 TOT KJEL NH3-N
OF N- TOTAL N TOTAL
DAY FEET MG/L HQ/L MG/L
0809A?
38 04 42.0 103 36 39.0 4
UNNAMtO DITCH
08 7.3 CHE^Aw
T/HOLBROO* RESERVOIR 100191
ST RT 266 dHDG 6 MI wStf OF CHERArt
11EPALES 211130^*
0000 FEET DEPTH CLASS 00
00671 00665
PHOS-OIS PHOS-TOT
ORTHO
MG/L P MG/L r>
75/01/18 14 30
a.oao
1.550
0.600
0.190
0.44U
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