U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
BEAR LAKE
FREEBORN CQUtfTY
MINNESOTA
EPA REGION V
WORKING PAPER No, 110
PACIFIC NORTHWEST ENVIRONMENTAL RESEARCH LABORATORY
An Associate Laboratory of the
NATIONAL ENVIRONMENTAL RESEARCH CENTER - CORVALLIS, OREGON
NATIONAL ENVIRONMENTAL RESEARCH CENTER - LAS VEGAS, NEVADA
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REPORT
ON
BEAR LAKE
MINNESOTA
EPA REGION V
WORKING PAPER No, 110
WITH THE COOPERATION OF THE
MINNESOTA POLLUTION CONTROL AGENCY
AND THE
MINNESOTA NATIONAL GUARD
JANUARY, 1975
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CONTENTS
Page
Foreword ii
List of Minnesota Study Lakes iv, v
Lake and Drainage Area Map vi
Sections
I. Introduction 1
II. Conclusions 1
III. Lake Morphonietry 2
IV. Precipitation 2
V. Lake Water Quality Summary 3
VI. Appendix 7
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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 fresh water lakes and
reservoi rs.
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 [ 3O3(e)], water
quality criteria/standards review [ 3O3(c)], clean lakes [ 3l4(a,b)],
and water quality monitoring [ lO6 and §305(b)] activities mandated
by the Federal Water Pollution Control Act Amendments of 1972.
* The lake discussed in this report was included in the National
Eutrophication Survey as a water body of interest to the Minnesota
Pollution Control Agency. Tributaries and nutrient sources were
not sampled, and this report relates only to the data obtained
from lake sampling.
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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.
AC KNOWLEDGMENT
The staff of the National Eutrophication Survey (Office of
Research & Development, U. S. Environmental Protection Agency)
expresses sincere appreciation to the Minnesota Pollution Control
Agency for professional Involvement and to the Minnesota National
Guard for conducting the tributary sampling phase of the Survey.
Grant J. Merritt, Director of the Minnesota Pollution Control
Agency, John F. McGuire, Chief, and Joel G. Schilling, Biologist,
of the Section of Surface and Groundwater, Division of Water Quality,
provided invaluable lake documentation and counsel during the course
of the Survey; and the staff of the Section of Municipal Works, Divi-
sion of Water Quality, were most helpful in identifying point sources
and soliciting municipal participation in the Survey.
Major General Chester J. Moeglein, the Adjutant General of
Minnesota, and Project Officer Major Adrian Beltrand, who directed
the volunteer efforts of the Minnesota National Guardsmen, are also
gratefully acknowledged for their assistance to the Survey.
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iv
NATIONAL EUTROPHICATION SURVEY
STUDY LAKES
STATE OF MINNESOTA
LAKE NAME COUNTY
Albert Lea Freeborn
Andrusia Beltrami
Badger Polk
Bartlett Koochiching
Bear Freeborn
Bemidji Beltrami
Big Stearns
Big Stone Big Stone, MN; Roberts,
Grant, SD
Birch Cass
Blackduck Beltrami
Blackhoof Crow Wing
Budd Martin
Buffalo Wright
Calhoun Hennepin
Carlos Douglas
Carrigan Wright
Cass Beltrami, Cass
Clearwater Wright, Stearns
Cokato Wright
Cranberry Crow Wing
Darling Douglas
Elbow St. Louis
Embarass St. Louis
Fall Lake
Forest Washington
Green Kandlyohi
Gull Cass
Heron Jackson
Leech Cass
Le Homme Dieu Douglas
Lily Blue Earth
Little Grant
Lost St. Louis
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V
LAKE NAME COUNTY
Madison Blue Earth
Malmedal Pope
Mashkenode St. Louis
McQuade St. Louis
Mi nnetonka Hennepi n
Minnewaska Pope
Mud Itasca
Nest Kandiyohi
Pelican St. Louis
Pepin Goodhue, Wabasha, MN;
Pierce, Pepin, WI
Rabbit Crow Wing
Sakatah Le Sueur
Shagawa St. Louis
Silver McLeod
Six Mile St. Louis
Spring Washington, Dakota
St. Croix Washington, MN; St. Croix,
Pierce, WI
St. Louis Bay St. Louis, MN; Douglas, WI
Superior Bay St. Louis, MN; Douglas, WI
Swan Itasca
Trace Todd
Trout Itasca
Wagonga Kandiyohi
Wailmark Chisago
White Bear Washington
Winona Douglas
Wolf Beltrami, Hubbard
Woodcock Kandiyohi
Zumbro Olmstead, Wabasha
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V I
BEAR LAkE
I ke sOmpIi
MI & .
zo’uA
FlAP LOCATlO
(
I
—
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BEAR LAKE
STORE! NO. 2706
I. INTRODUCTION
Bear Lake was included in the National Eutrophication Survey as
a water body of interest to the Minnesota Pollution Control Agency.
Tributaries and nutrient sources were not sampled, and this report
relates only to the data obtained from lake sampling.
II. CONCLUSIONS
A. Trophic Condition:
Survey data show that Bear Lake is eutrophic. Of the 60
Minnesota lakes sampled in the fall when essentially all were
well-mixed, 36 had less mean total phosphorus, 32 had less
mean dissolved phosphorus, and 56 had less mean inorganic ni-
trogen. Of the 80 Minnesota lakes sampled, 61 had less mean
chlorophyll a_, and 73 had greater Secchi disc transparency.
Survey limnologists observed heavy blue-green algal blooms
in July and late August and noted the presence of abundant
rooted aquatic vegetation.
B. Rate-Limiting Nutrient:
A significant loss of nutrients occurred in the assay sam-
ple from the time of collection to the beginning of the assay,
and the results are not indicative of conditions in the lake at
the time of sampling.
The lake data indicate nitrogen limitation in early July and
late August (N/P ratios were 9/1) but phosphorus limitation in
late October (N/P = 55/1).
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III. LAKE MORPHOMETRY*
A. Surface Area: 1,374 acres.
B. Mean Depth: 2.3 feet.
C. Maximum Depth: 4.0 feet.
D. Volume: 3,160 acre feet.
IV. PRECIPITATION
A. Year of Sampling: 42.4 inches.
B. 1ean Annual: 28.7 inches.
* DNR lake survey map (1958); mean depth by random-dot method.
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V. LAKE WATER QUALITY SUMMARY
Bear Lake was sampled three times during the open-water season
of 1972 by means of a pontoon-equipped Huey helicopter. Each time,
a surface sample for physical and chemical parameters was collected
from one station on the lake (see map, page vi). 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 last visit, a
five-gallon depth-integrated sample-was collected for algal assays.
The.results obtained are presented in full in the Appendix, and
the data for the-fall sampling period, when the lake was well-mixed,
are sumarized below. Note-, however; the Secchi disc summary is
based on all values.
For differences in the various parameters at the other sampling
times, refer to the Appendix.
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A. Physical and chemical characteristics:
FALL VALUES
(10/29/72)
Parameter Surface Sample 0ni y
Temperature (Cent.) 7.5
Dissolved oxygen (mg/i) 12.1
Conductivity (iimhos) 500
pH (units) 8.2
Alkalinity (mg/i) 186
Total P (mg/i) 0.066
Dissolved P (mg/i) 0.030
NO + NO (mg/i) 1.480
Am onia mg/1) 0.170
ALL VALUES
Minimum Mean Median Maximum
Secchi disc (inches) 23 28 30 30
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B. Biological characteristics:
1. Phytoplankton -
Sampling
Date
07/01/72
Dominant
Genera
1. Merismopedia
2. Microcystis
3. Synedra
4. Anabaena
5. Flagellates
Other genera
Number
per ml
52,963
32,963
6,667
4,074
2,563
11,511
1. Microcystis
2. Lyngbya
3. Merismopedia
4. Fragilaria
5. Aphanocapsa
Other genera
1. Microcystis
2. Dinobryon
3. Flagellates
4. Fragilaria
5. Lyngbya
Other genera
110,741
97,614
31 ,815
25,307
17,354
11,569
34,707
218,366
12,932
3,233
2,782
2,707
2,105
10,376
Total
08/ 30/7 2
10/29/72
Total
Total 34,135
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2. Chlorophyll a -
(Because of instrumentation problems during the 1972 sampling,
the following values may be in error by plus or minus 20 percent.)
Sampling Station Chlorophyll a
Date Number ( pg/i )
07/01/72 01 62.5
08/30/72 01 92.6
10/29/72 01 28.6
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VI. Appendix
7
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STOPET QETPIEVAI DATE 7’i/V’/iO
?7060 1
43 33 06.0 093 30 06.0
bEA LA$
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