U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
CLEAR LAKE
CERRO GORDO COUNTY
IOW
EPA REGION VII
WORKING PAPER No, 497
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY - CORVALL1S, OREGON
and
ENVIRONMENTAL MONITORING & SUPPORT LABORATORY - LAS VEGAS, NEVADA
•&G.P.O. 699-440
-------
REPORT
ON
CLEAR LAKE
CERRO QORDO COUNTY
IOWA
EPAEGIGNVII
WORKING PAPER No, 497
WITH THE COOPERATION OF THE
IOWA DEPARTMENT OF ENVIRONMENTAL QUALITY
AND THE
IOWA NATIONAL GUARD
AUGUST, 1976
-------
CONTENTS
Page
Foreword ii
List of Iowa Study Lakes iv
Lake and Drainage Area Map v
Sections
I. Introduction 1
II. Conclusions 1
III. Lake and Drainage Basin Characteristics 3
IV. Lake Water Quality Summary 4
V. Literature Reviewed 8
VI. Appendices 9
-------
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.
-------
m
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
freshwater 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 Iowa Department of Environ-
mental Quality for professional involvement, to the Iowa National
Guard for conducting the tributary sampling phase of the Survey,
and to those wastewater treatment plant operators who voluntarily
provided effluent samples and flow data.
The staff of the Water Quality Division of the Department of
Environmental Quality 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.
Major General Joseph G. May, the Adjutant General of Iowa,
and Project Officer Colonel Cleadeth P. Woods, who directed the
volunteer efforts of the Iowa National Guardsmen, are also grate-
fully acknowledged for their assistance to the Survey.
-------
IV
LAKE NAME
Ahquabi
Big Creek Reservoir
Black Hawk
Clear
Darling
Lost Island
MacBride
Prairie Rose
Rathbun Reservoir
Red Rock Reservoir
Rock Creek
Silver
Spirit
Viking
West Okoboji
NATIONAL EUTROPHICATION SURVEY
STUDY LAKES
STATE OF IOWA
COUNTY
Warren
Polk
Sac
Cerro Gordo
Washington
Clay, Palo Alto
Johnson
Shelby
Appanoose, Wayne
Marion
Jasper
Worth
Dickinson
Montgomery
Dickinson
-------
CLEAR LAKE
x Lake Sampling Site
— 43'08'
\— 43'06
-------
CLEAR LAKE
STORE! NO. 1904
I. INTRODUCTION
Clear Lake was included in the National Eutrophication Survey
as a water body of interest to the Iowa Department of Environmental
Quality. Tributaries and nutrient sources were not sampled, and
this report relates only to the lake sampling data.
Clear Lake is a natural, eutrophic lake located in Cerro Gordo
County in north central Iowa. The watershed consists mainly of woods
and agricultural lands. There are no surface streams supplying water
to the lake (Percy, 1953).
The lake is heavily used for recreation. The Iowa Conservation
Commission estimates that 500,000 persons visit the parks and beaches
around the lake each year. Over 70% of the shoreline of the lake is
occuppied by private homes, cabins, and commercial establishments.
Walleyes, crappies, and white bass are the major game fish species
found in Clear Lake, but perch, northern pike, and muskellunge can also
be caught (Mayhew, 1975).
II. CONCLUSIONS
A. Trophic Condition:
Survey data indicate that Clear Lake is eutrophic. Of
the 15 Iowa lakes and reservoirs sampled in 1974, Clear Lake
ranked fourth in overall trophic quality when compared using
-------
2 ...
a combination of six water quality parameters*. Four of the
water bodies had less median total phosphorus, four had less
and two had the same median orthophosphorus, two had less
median inorganic nitrogen, nine had less mean chlorophyll a_,
and six had greater mean Secchi disc transparency.
Survey limnologists did not observe any concentrations
of algae but did note the occurrence of emergent weeds along
the north and east shorelines.
B. Rate-Limiting Nutrient:
The algal assay results indicate that Clear Lake was
phosphorus limited at the time the assay sample was collected
(04/18/74). The lake data indicate phosphorus limitation in
April but nitrogen limitation in September.
* See Appendix A.
-------
III. LAKE AND DRAINAGE BASIN CHARACTERISTICS1"
A. Lake Morphometry :
1. Surface area: 14.74 kilometers2.
2. Mean depth: 3.0 meters.
3. Maximum depth: 5.7 meters.
4. Volume: 44.220 x 106 m3.
5. Mean hydraulic retention time: unknown.
C. Precipitation*:
1. Year of sampling: 75.2 centimeters.
2. Mean annual: 74.7 centimeters.
t Table of metric conversions--Appendix B.
tt Harrison, 1975.
* See Working Paper No. 175, "...Survey Methods, 1973-1976",
-------
4
IV. LAKE WATER QUALITY SUMMARY
Clear Lake was sampled three times during the open-water season
of 1974 by means of a pontoon-equipped Huey helicopter. Each time,
samples for physical and chemical parameters were collected from one
or more depths at three stations on the lake (see map, page v). During
each visit, a single depth-integrated (near bottom to surface) sample
was composited from the stations for phytoplankton identification
and enumeration; and during the first visit, a single 18.9-liter depth-
integrated sample was composited for algal assays. Also each time,
a depth-integrated sample was composited from each of the stations
for chlorophyll ^analysis. The maximum depths sampled were 3.0 meters
at stations 1 and 2 and near-surface at station 3.
The sampling results are presented in full in Appendix C and are
summarized in the following table (the July nutrient samples were not
preserved properly and were not analyzed).
-------
A. SUMMARY OF PHYSICAL AND CHEMICAL CHARACTERISTICS FOR CLEAR LAKE
STORET CODE 1904
PARAMETER
TE*IP (C)
OISS OXY (MG/L)
CNDCTVY (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)
CHLRPYL A (UG/L)
SECCHI (METERS)
1ST SAMPLING ( 4/18/74) 2ND SAMPLING ( 7/ 3/74)
3 SITES 3 SITES
RANGE MEAN MEDIAN RANGE MEAN MEDIAN
8.8 - 11.4 9.4 9.0 23.5 - 24.2 23.7 23.6
10.4 - 11.8 11.2 11.4 6.4 - 8.2 7.1 7.1
24. - 184. 87. 81. 394. - 400. 397. 397.
8.3 - 8.7 8.4 8.3 8.6 - 8.7 8.6 8.6
0.006
0.240
0.080
12.4
1.4
~ 0.057
• 0.031
~ 1.000
- 0.200
- 1.300
~ 1.080
- 2.200
- 29.4
1.4
1HO.
0.036
0.014
0.390
0.173
1.217
0*563
1.607
18.1
1.4
0.190 »«»•«» _««*»»««*««****•«•»»•»*
12.6 6.1 - 31.1 15.8 10.3
1.4 0.5 - 0.9 0.7 0.8
3RD SAMPLING ( 9/
3 SITES
RANGE MEAN
13.5 - 14.9 14.6
9.0 - 9.8 9.3
251. - 286. 271.
8.3 - 8.5 8.4
155.
0.059
0.007
0.020
0.040
1.000
0.060
1 .020
15.1
0.4
- 100.
- 0.097
~ 0.011
• 0.030
. 0.050
- 1.500
- 0.070
- 1.520
- 22.1
0.9
0.078
0.010
0.023
0.041
1. 186
0.064
1.209
18.2
0.7
'23/74)
MEDIAN
14.6
9.2
272.
8.4
164.
0.078
0.010
0.020
0.040
1.100
0.060
1.130
17.5
0.9
-------
B. Biological Characteristics:
1. Phytoplankton -
Sampling
Date
04/18/74
07/03/74
09/23/74
2. Chlorophyll a_ -
Sampli ng
Date
04/18/74
07/03/74
09/23/74
Dominant
Genera
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
Dinobryon sp.
Melosira sp.
Frag il aria sp.
Asterionella sp.
Flagellates
Other genera
Total
Melosira sp.
Microcystts sjj.
Coelosphaerium sj>.
Oocystis sp.
Fragilaria sp.
Other genera
Total
Microcystis sj>.
Aphanocapsa SJD.
Flagellaria sp.
Blue-green filaments
Cryptomonas SJD.
Other genera
Total
Algal Units
per ml
5,340
3,432
2,091
884
793
2.649
Station
Number
1
2
3
1
2
3
1
2
3
15,189
5,919
3,277
1,609
536
536
2.242
14,119
8,662
3,948
471
236
236
2.416
15,969
Chlorophyll a
(ug/D
12.6
12.4
29.4
6.1
10.3
31.1
15.1
17.5
22.1
-------
7
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 0.010 0.485 2.8
0.050 P 0.060 0.485 18.4
0.050 P + 1.0 N 0.060 1.485 31.9
1.0 N 0.010 1.485 3.9
2. Discussion -
The control yield of the assay alga, Selenastrum capri-
cornutum, indicates that the potential primary productivity
of Clear Lake was moderately high at the time the sample was
taken (04/18/74). Also, a six-fold increase in yield with
the addition of only orthophosphorus indicates that the lake
was limited by phosphorus at that time. Note that the
addition of only nitrogen produced a yield not significantly
greater than the control yield.
The lake data also indicate phosphorus limitation in
April; i.e., the mean inorganic nitrogen to orthophosphorus
ratios were 24 to 1 or greater at all stations. However, the
September lake data indicate that the lake was nitrogen limited;
i.e., the mean N/P ratios were 8 to 1 or less at all stations,
and nitrogen limitation would be expected.
-------
8
V. LITERATURE REVIEWED
Harrison, Harry M., 1975. Personal communication (lake morphemetry).
IA Cons. Comm., Des Moines.
Mayhew, James, 1975. Personal communication (lake uses and develop-
ment). IA Cons. Comm., Des Moines.
Percy, William 6., 1953. "Some limnological features of Clear Lake,
Iowa". IA St. Coll. Jour. Sci. 28(2):189-207.
-------
VI. APPENDICES
APPENDIX A
LAKE RANKINGS
-------
LAKE DATA TO BE USEO IN RANKlNGb
LAKE
CODE LAKE NAME
1901 LAKE ACOUAdI
1902 BIG CREEK RESERVOIR
1903 BLACK HAWK LAKE
1904 CLEAR LAKE
1905 LAKE DARLING
1906 LOST ISLAND LAKE
1907 LAKE MACBPIDE
1908 PRAIRIE ROSE LAKE
1909 RATHBUN RESERVOIR
1910 RED ROCK LAKE
1911 ROCK CREEK LAKE
1912 SILVER LAKE
1913 SPIRIT LAKE
1914 VIKING LAKE
1915 WEST LAKE OKOBOJI
MEDIAN
TOTAL H
0.06?
0.046
0.185
0.059
0.077
0.146
0.061
0.056
0.071
0.180
0.065
0.193
0.041
0.075
0.046
.MEDIAN
1NO«G N
0.3J5
6.465
0.130
0.070
1.475
0.065
2.035
0.210
1.170
1.880
1.400
0.565
0.090
0.130
0.060
500-
MEflN SEC
469.333
436.500
488.167
465.125
482.500
421.167
456.444
463.667
475.889
473.400
480.500
482.667
422.667
459.000
380.444
MEAN
CNLOHA
8.600
16.867
49.740
17.400
13.817
36.100
17.067
17.350
12.039
14.730
18.367
95.300
12.622
26.033
7.722
15-
HIN DO
8.200
14.800
15.000
8.600
9.200
8.400
15.000
8.600
14.000
14.000
8.400
10.000
9.000
14.200
15.000
MEDIAN
OISS OKTuO V
0.009
0.011
0.020
0.010
0.012
0.021
0.010
0.010
0.008
0.104
0.007
0.034
0.007
0.017
0.017
-------
PERCENT OF LAKES WITH HIGHER VALUES (NUMBER OF LAKES WITH HIGHER VALUES)
LAKE
CODE LAKE NAME
1901 LAKE ACOUABI
1903 BIG CREEK RESERVOIR
1903 BLACK HAWK LAKE
190* CLEAR LAKE
1905 LAKE DARLING
1906 LOST ISLAND LAKE
1907 LAKE M4CBWIDE
1908 PHAIRIE ROSE LAKE
1909 RATHBUN RESERVOIR
1910 RED ROCK LAKE
1911 ROCK CREEK LAKE
1912 SILVER LAKE
1913 SPIRIT LAKE
191<« VIKING LAKE
1915 WEST LAKE OKOBOJI
MEDIAN
TOTAL P
57 (
89 (
7 (
71 (
29 (
31 (
64 (
79 (
43 (
1* <
50 (
0 (
100 (
36 <
89 (
8)
12)
1)
10)
4)
3)
9)
11)
6)
2>
7)
0)
14)
5)
12)
MEDIAN
INOwG N
50 <
0 (
t>8 <
86 (
21 (
93 (
7 (
57 (
36 (
14 (
29 (
43 <
79 (
68 <
100 (
7)
0)
9)
12)
3)
13)
D
8)
5)
2)
4)
6)
11)
9)
14)
500-
MEAN SEC
43 (
79 (
0 (
50 (
14 (
93 (
71 (
57 (
29 (
36 t
21 (
7 (
86 (
64 (
100 (
6)
11)
0)
7)
2)
13)
10)
8)
4)
5)
3)
1)
12)
9)
14)
MEAN
CHLORA
93 (
57 <
7 (
36 (
71 (
U <
50 (
43 (
86 (
64 (
29 (
0 (
79 (
21 (
100 (
13)
8)
1)
5)
10)
2)
7)
6)
12)
9)
4)
0)
11)
3)
14)
15-
MlN DO
100 (
21 (
7 (
75 (
57 (
89 (
7 (
75 (
39 (
39 (
89 (
50 (
64 (
29 (
7 (
14)
3)
0)
10)
8)
12)
0)
10)
5)
5)
12)
7)
9)
4)
0)
MEDIAN
DISS ORTHO P
79 (
50 (
21 (
64 (
43 (
14 (
64 (
64 (
86 (
0 (
96 (
7 (
96 (
32 (
32 (
11)
7)
3)
8)
6)
2)
8)
8)
12)
0)
13)
1)
13)
4)
4)
INDEX
NO
422
296
110
382
235
324
263
375
319
167
314
107
504
250
428
-------
LAKES RANKED BY INDEX NOS.
RANK LAKE CODE LAKE NAME INDEX NO
1 1913 SPIRIT LAKE 504
2 1915 WEST LAKE OK080JI 428
3 1901 LAKE ACOUA81 422
4 1904 CLEAR LAKE 382
5 1908 PRAIRIE ROSE LAKE 375
6 1906 LOST ISLAND LAKE 324
7 1909 RATHBUN RESERVOIR 319
8 1911 ROCK CREEK LAKE 314
9 1902 BIG CREEK RESERVOIR 296
10 1907 LAKE HACBRIDE 263
11 1914 VIKING LAKE 250
12 1905 LAKE DARLING 235
13 1910 RED ROCK LAKE 167
14 1903 BLACK HAWK LAKE 110
15 1912 SILVER LAKE 107
-------
APPENDIX B
CONVERSION FACTORS
-------
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
Kilograms x 2.205 = pounds
Kilograms/square kilometer x 5.711 = Ibs/square mile
-------
APPENDIX C
PHYSICAL and CHEMICAL DATA
-------
STORE! RETRIEVAL DATE 75/12/23
190401
43 07 30.0 093 24 00.0
CLEAR LAKE
19033 IOWA
DATE
FROM
TO
74/04/18
74/07/03
74/09/23
DATE
FROM
TO
74/04/18
74/07/03
74/09/23
TIME
OF
DAY
12
12
13
13
13
14
14
14
30
30
05
05
DEPTH
FEET
0000
0005
0000
0005
05 0010
55
55
55
TIME
OF
DAY
12
12
13
14
14
14
14
14
30
30
05
55
55
55
55
55
0000
0005
0008
DEPTH
FEET
0000
0005
0000
0000
0001
0005
0007
oooa
00010
WATER
TEMP
CENT
8.9
8.8
23.6
23.6
23.6
14.9
14.9
14.9
00665
PHOS-TOT
MG/L P
0.034
0.048
0.064
0.097
0.078
00300
DO
MG/L
11.
8.
7.
6.
9.
9.
9.
32217
00077 00094
TRANSP CNDUCTVY
SECCHI FIELD
INCHES MICROMHO
4
2
0
4
4
2
5
CHLRPHYL
A
UG/L
12.
6.
15.
6
1
1
55
30
37
00031
INCDT LT
REMNING
PERCENT
50.0
1.0
33
117
396
398
398
272
277
272
11EPALES 2111202
4 0012 FEET DEPTH
00400 00410 00610 00625 00630 00671
PH T ALK NH3-N TOT KJEL N02&N03 PHOS-DIS
CAC03 TOTAL N N-TOTAL ORTHO
SU
8.
8.
8.
8.
8.
8.
8.
8.
30
30
60
60
70
43
43
44
MG/L MG/L MG/L MG/L MG/L P
147 0.200 1.300 0.260 0.031
148 0.190 1.200 0.240 0.006
164 0.040 1.100 0.030 0.010
164 0.040 1.100 0.020 0.008
168 0.040 1.000 0.030 0.011
-------
STORET RETRIEVAL DATE 75/13/23
190402
43 07 30.0 093 25 50.0
CLEAR LAKE
19033 IOWA
11EPALES
DATE
FROM
TO
74/04/18
74/07/03
74/09/23
DATE
FROM
TO
74/04/18
74/07/03
74/09/23
TIME DEPTH
OF
DAr FEET
12 50 0000
12 50 0005
12 50 0010
13 30 0000
13 30 0006
14 30 0000
14 30 0005
14 30 0009
TIME DEPTH
OF
DAY FEET
12 50 0000
12 50 0005
12 50 0010
13 30 0000
14 30 0000
14 30 0001
14 30 0005
14 30 0006
14 30 0009
00010
WATER
TEMP
CENT
9.0
9.0
9.0
23.5
23.5
14.6
14.6
14.6
00665
PHOS-TOT
MG/L P
0.026
0.025
0.024
0.059
0.081
0.072
00300
DO
MG/L
11.8
10.4
7.2
7.4
9.0
9.2
9.0
32217
CHLRPHYL
A
UG/L
12.4
10.3
17.5
00077
TRANSP
SECCHI
INCHES
55
34
36
00031
INCDT LT
REMNING
PERCENT
50.0
1.0
00094
CNDUCTVY
FIELD
MICROMHO
24
114
184
396
400
270
270
286
4
00400
PH
SU
8.30
8.30
8.35
8.70
8.60
8.34
8.41
8.41
00410
T ALK
CAC03
MG/L
147
147
148
164
165
163
2111202
0014
00610
NH3-N
TOTAL
MG/L
0.200
0.190
0.180
0.040
0.040
0.040
FEET DEPTH
00625
TOT KJEL
N
MG/L
1.300
1.100
1.200
1.300
1.000
1.300
00630
N02&N03
N-TOTAL
MG/L
0.260
0.290
0.290
0.020
0.020
0.020
00671
PHOS-OIS
ORTHO
MG/L P
0.011
0.009
0.009
0.007
0.011
0.011
-------
STORET RETRIEVAL DATE 75/12/23
190403
43 07 20.0 093 28 00.
CLEAR LAKE
19033 IOWA
00010
DATE TIME DEPTH WATER
FROM OF TEMP
TO DAY FEET CENT
00300 00077 00094
DO TRANSP CNDUCTVY
SECCHI FIELD
MG/L INCHES MICROMHO
47
394
251
74/04/18
74/07/03
74/09/23
DATE
FROM
TO
74/04/18
74/07/03
74/09/23
13 10 0000
11 15 0000
14 05 0000
TIME DEPTH
OF
DAY FEET
13 10 0000
11 15 0000
14 05 0000
14 05 0001
14 05 0004
11.4
24. 2J
13.5
00665
PHOS-TOT
MG/L P
0.057
0.095
6.4
9.8
32217
CHLRPHYL
A
UG/L
29.4
31.1
22.1
18
14
00031
INCDT LT
REMNING
PERCENT
50.0
1.0
11EPALES
4
00400
PH
SU
8.70
8.60
8.53
00410
T ALK
CAC03
MG/L
140
155
2111202
0005 FEET DEPTH
00610
NH3-N
TOTAL
MG/L
0.080
0.050
00625
TOT KJEL
N
MG/L
1.200
1.500
00630
N02&N03
N-TOTAL
MG/L
1.000
0.020
00671
PHOS-DIS
ORTHO
MG/L P
0.017
0.009
J VALUE KNOWN TO BE IN ERROR
------- |