U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
RABBIT LAKE
CROW WING COUN1Y
MINNESOTA
EPA REGION V
WORKING PAPER No, 99
PACIFIC NORTHWEST ENVIRONMENTAL RESEARCH LABORATORY
An Associate Laboratory of the
NATIONAL ENVIRONMENTAL RESEARCH CENTER - CORVALLIS, OREGON
and
NATIONAL ENVIRONMENTAL RESEARCH CENTER - LAS VEGAS, NEVADA
697.032
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REPORT
ON
RABBIT LAKE
CROW WING COUNTY
MINNESOTA
EPA REGION V
WORKING PAPER No, 99
WITH THE COOPERATION OF THE
MINNESOTA POLLUTION CONTROL AGENCY
AND THE
MINNESOTA NATIONAL GUARD
JANUARY, 1975
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1
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 and Drainage Basin Characteristics 2
IV. Lake Water Quality Summary 3
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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 fresh water 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 [ 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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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.
ACKNOWLEDGMENT
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 Beltrani
Big Stearns
Big Stone Big Stone, MN; Roberts,
Grant, SD
Birch Cass
Bi ackduck Bel trami
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 Kandiyohi
Gull Cass
Heron Jackson
Leech Cass
Le Home 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
Minnetonka Hennepin
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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vi
Ciirilcer Lake
RI%8 J
X I .. I ke sernpIrn site
MAP LOC.ATION
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RABBIT LAKE
STORET NO. 2771
I. INTRODUCTION
Rablit 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 indicate Rabbit Lake is eutrophic. Of the
60 Minnesota lakes sampled in the fall when essentially all
were well—mixed, 16 had less mean total phosphorus, ten had
less mean dissolved phosphorus, but only one had less mean
inorganic nitrogen. Of all 80 Minnesota lakes sampled, 12
had less mean chlorophyll a, and eight had greater mean Secchi
disc transparency.
Dissolved oxygen was depleted in the deepest samples in
July and September. Blue-green algae were prominent in all
phytoplankton samples.
B. Rate—Limiting Nutrient:
The lake data indicate nitrogen limitation in July and
October but phosphorus limitation in September.
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2
III. LAKE AND DRAINAGE BASIN CHARACTERISTICS
A. Lake Morphometry±:
1. Surface area:
2. Mean depth: 23
3. Maximum depth:
4. Volume: 12,585
B. Precipitation*:
1. Year of sampling: 28.8 inches.
2. Mean annual: 24.8 inches.
fDNR lake survey map (1967); mean depth by random-dot method.
* See Working Paper No. 1, “Survey Methods”.
531 acres.
.7 feet.
50 feet.
acre-feet.
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IV. LAKE WATER QUALITY SUMMARY
Rabbit Lake was sampled three times during the open-water season
of 1972 by means of a pontoon-equipped Huey helicopter. Each time,
samples for physical and chemical parameters were collected from a
number of depths at a single station on the lake (see map, page vi).
During each visit, a single depth-integrated (15 feet to surface)
sample was taken for phytoplankton identification and enumeration;
and a similar sample was collected for chlorophyll a_ analysis. Dur-
ing the last visit, a single five-gallon depth-integrated sample was
composited for algal assays. The maximum depth sampled was 38 feet.
The results obtained are presented in full in Appendix B, and the
data for the fall sampling period, when the lake essentially was well-
mixed, are summarized 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 Appendix B.
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4
A. Physical and chemical characteristics:
FALL VALUES
(10/24/72)
Parameter Minimum Mean Median Maximum
Temperature (Cent.) 6.5 6.5 6.5 6.6
Dissolved oxygen (mg/i) 9.5 10.0 10.0 10.6
Conductivity (iimhos) 275 278 280 280
pH (units) 7.9 7.9 7.9 7.9
Alkalinity (mg/i) 105 105 105 106
Total P (mg/i) 0.028 0.033 0.036 0.036
Dissolved P (mg/i) 0.009 0.015 0.015 0.020
NO + NO (mg/i) 0.020 0.020 0.020 0.020
Ani onia mg/l) 0.010 0.033 0.010 0.080
ALL VALUES
Secchi disc (inches) 58 107 118 144
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5
B. Biological characteristics:
1. Phytoplankton —
Sampling Dominant Number
Date Genera per ml
07/02/72 1. Dinobryon 416
2. Flagellates 386
3. Anabaena 145
4. Microcystis 139
5. Elakotothrix 60
Other genera 246
Total 1 ,392
09/04/72 1. Microcystis 1,248
2. Flagellates 190
3. Fragilaria 108
4. Aphanocapsa 108
5. Anabaena 99
Other genera 290
Total 2,043
10/24/72 1. Anabaena 1,962
2. Melosira 1,623
3. Fragilaria 1,509
4. Chroococcus 792
5. Flagellates 283
Other genera 3,039
Total 9,208
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 )
07/02/72 01 6.1
09/04/72 01 2.6
10/24/72 01 11.4
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C. Limiting Nutrient Study:
There was a significant loss of nutrients in the assay
sample between the time of collection and the beginning of
the assay, and the results are not indicative of conditions
in the lake at the time the sample was collected.
The lake data indicate nitrogen limitation in July (N/P
ratio = 10/1) and October (N/P = 4/1) but phosphorus limitation
in September (N/P = 24/1).
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7
APPE 1DIX A
PHYSICAL and CHEMICAL DATA
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