U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
OCONOmWOC LAKE
WAUHESHA COUNTY
WISCONSIN
EPA REGION V
WORKING PAPER No, 63
PACIFIC NORTHWEST ENVIRONMENTAL RESEARCH LABORATORY
An Associate Laboratory of the
NATIONAL ENVIRONMENTAL RESEARCH CENTER - CORVALLIS, OREGON
and
NATIONAL ENVIRONMENTAL RESEARCH CENTER - LAS VEGAS, NEVADA
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REPORT
ON
OCONQMOWX LAKE
WAUKESHA COUNTY
WISCONSIN
EPA REGION V
WORKING PAPER No, 63
WITH THE COOPERATION OF THE
WISCONSIN DEPARTMENT OF NATURAL RESOURCES
AND THE
WISCONSIN NATIONAL GUARD
JUNE, 1975
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1
CONTENTS
Page
Foreword
List of Wisconsin Study Lakes iv, v
Lake and Drainage Area Map vi
Sections
I. Introduction 1
II. Conclusions i
III. Lake and Drainage Basin Characteristics 3
IV. Lake Water Quality Summary 4
V. Literature Reviewed 8
VI. Appendices 9
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ii
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 ANALVSIS*
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 [ 5314(a,b)],
and water quality monitoring [ lO6 arid 3O5(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 Wisconsin
Department of Natural Resources. 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, rnultivariate 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.
ACKNOWLE DGMENT
The staff of the National Eutrophication Survey (Office of
Research & Development, U. S. Environmental Protection Agency)
expresses sincere appreciation to the Wisconsin Department of
Natural Resources for professional involvement and to the Wisconsin
National Guard for conducting the tributary sampling phase of the
Survey.
Francis H. Schraufnagel , Acting Assistant Director, and Joseph
R. Ball of the Bureau of Water Quality, and Donald R. Winter, Lake
Rehabilitation Program, provided invaluable lake documentation and
counsel during the Survey. Central Office and District Office per-
sonnel of the Department of Natural Resources reviewed the prelim-
inary reports and provided critiques most useful in the preparation
of this Working Paper series.
Major General James J. Lison, Jr., the Adjutant General of
Wisconsin, and Project Officer CW-4 Donald D. Erickson, who directed
the volunteer efforts of the Wisconsin National Guardsmen, are also
gratefully acknowledged for their assistance to the Survey.
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iv
NATIONAL EUTROPHICATION SURVEY
STUDY LAKES
STATE OF WISCONSIN
LAKE NAME COUNTY
Altoona Eau Claire
Beaver Dam Barron
Beaver Dam Dodge
Big Eau Pleine Marathon
Browns Racine
Butte des Morts Winnebago
Butternut Price, Ashland
Castle Rock Flowage Juneau
Como Walworth
Crystal Vilas
Delavan Walworth
Eau Claire Eau Claire
Geneva Walworth
Grand Green Lake
Green Green Lake
Kegonsa Dane
Koshkonong Jefferson, Rock, Dane
Lac La Belle Waukesha
Middle Walworth
Nag wicka Waukesha
Oconomowoc Waukesha
Okauchee Waukesha
Petenwell Flowage Juneau
Pewaukee Waukesha
Pigeon Waupaca
Pine Waukesha
Poygan Winnebago, Waushara
Rock Jefferson
Rome Pond Jefferson, Waukesha
Round Waupaca
Shawano Shawano
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V
LAKE NAME COUNTY
Swan Columbia
Tainter Dunn
Tichigan Racine
Townline Oneida
Trout Vilas
Wapogassett Polk
Wausau Marathon
Willow Oneida
Winnebago Winnebago, Fond Du Lac,
Cal umet
Wisconsin Columbia
Wissota Chippewa
Yellow Burnett
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o CONOMOWOC
0 Tributary Sampling
)< Lake Sampling Site
LAKE
Site
ct__Direct Drainage Area Boundary
Indirect Drainage Basin
Map LocaUon
4130’
06
-a.
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OCONOMOWOC LAKE
STORET NO. 5532
I. INTRODUCTION
Oconomowoc Lake was included in the National Eutrophication Survey
as a water body of interest to the Wisconsin Department of Natural
Resources. The inlet and outlet of the lake were sampled (Appendix C),
but no wastewater treatment plants impact the lake. Therefore, this
report relates only to the lake sampling data.
II. CONCLUSIONS
A. Trophic Condition:
Survey data and a report by others (Lueschow, et al., 1970)
indicate Oconomowoc Lake is meso-eutrophic. Of the 46 Wisconsin
lakes sampled, four had less and one the same mean total phos-
phorus, six had less and one the same mean dissolved phosphorus,
27 had less mean inorganic nitrogen, six had greater Secchi disc
transparency, but only three lakes had less mean chlorophyll a.
In Auqust, dissolved oxygen was depleted at station 1 (at 45 feet)
and was essentially depleted at station 2 (at 55 feet).
Survey limnologists did not observe any aquatic nuisances
during sampling visits; however, the lake has had extensive
aquatic weed and Chara control programs (Lueschow, et al.,
1970; Lueschow, 1972).
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2
B. Rate-Limiting Nutrient:
The algal assay results indicate the lake was phosphorus
limited at the time the sample was taken (11/11/72). The
lake data indicate phosphorus limitation at the other sampling
times as well.
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3
III. LAKE AND DRAINAGE BASIN CHARACTERISTICS
•A. Lake Morphornetryt:
1. Surface area: 785 acres.
2. Mean depth: 31.5 feet.
3. Maximum depth: 60 feet.
4. Volume: 24,723 acre-feet.
5. Mean hydraulic retention time: 209 days.
B. Tributary and Outlet:
(See Appendix A for flow data)
1. Tributaries -
DrainaQe area Mean flow
Name ( mi )* ( cfs)*
Oconomowoc River 83.9 56.4
Minor tributaries &
immediate drainage - 3.7 3.3
Totals 87.6 59.7
2. Outlet -
Oconomowoc River 88.8** 597**
C. Precipitation***:
1. Year of sampling: 38.7 inches.
2. Mean annual: 30.7 inches.
t Ball, 1973.
* Drainage areas are accurate within ±0.5%; mean daily flows are accurate
within ±40%; mean monthly flows are accurate within ±35%; and normalized
monthly flows are accurate within ±35%.
** Includes area of lake; outflow adjusted to equal sum of inflows.
*** See Working Paper No. 1, “Survey Methods, 1972”.
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4
IV. LAKE WATER QUALITY SUMMARY
Oconomowoc 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 two stations on the lake and from a number of depths at each
station (see map, page vi). During each visit, a single depth-
integrated (15 feet to surface) sample was composited from the sta-
tions for phytoplankton identification and enumeration; and during
the last visit, a single five-gallon depth—integrated sample was
composited for algal assays. Also each time, a depth-integrated
sample was collected from each of the stations for chlorophyll a
analysis. The maximum depths sampled were 45 feet at station 1 and
55 feet at station 2.
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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5
A. Physical and chemical characteristics:
FALL VALUES
(11/11/72)
Parameter Minimum Mean Median Maximum
Temperature (Cent.) 7.9 7.9 7.9 8.0
Dissolved oxygen (mg/l) 9.0 9.5 9.4 9.9
Conductivity (jrnihos) 450 459 460 480
pH (units) 7.7 7.8 7.7 7.9
Alkalinity (mg/l) 192 198 194 218
Total P (mg/i) 0.011 0.014 0.014 0.019
Dissolved P (mg/i) 0.007 0.009 0..009 0.014
NO 2 + NO 3 (mg/i) 0.090 0.110 0.090 0.120
Ammonia (mg/i) 0.130 0.233 0.310 0.320
ALL VALUES
Secchi disc (inches)
18 115
116 187
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6
B. Biological characteristics:
1. Phytoplankton* -
Sampling Dominant Number
Date Genera per ml
06/21/72 1. Dinobryon 488
2. Cyclotella 126
3. Microcystis 77
4. Anabaena 68
5. Chroococcus 63
Other genera 371
Total 1,193
08/19/72 1 . Microcystis 380
2. Fragilaria 181
3. Dinobryon 175
4. Chroococcus 127
5. Flagellates 114
Other genera 307
Total 1 ,284
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 ( ig/1 )
06/21/72 01 4.8
02 2.1
08/19/72 01 1.3
02 1.6
11/11/72 01 2.5
02 6.1
* The November sample was lost in shipment.
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7
C. Limiting Nutrient Study:
1.
Autociaved, filtered, and nutrient
spiked —
Ortho P
Spike (mg/i) Conc. (mg/i)
Inorganic N
Conc. (mg/i)
Maximum yield
mg/1-dry wt.)
Control 0.005
0.006 P 0.011
0.012 P 0.017
0.024 P 0.029
0.060 P 0.064
0.060 P + 10.0 N 0.064
10.0 N 0.005
0.268
0.268
0.368
0.268
0.268
10.268
10.268
0.2
0.6
2.3
4.9
5.9
24.0
0.2
2. Discussion -
The control yield of the assay alga, Selenastrum capri-
cornutum , indicates the potential primary productivity of
Oconomowoc Lake was relatively low at the time the sample
was taken (11/11/72). Also, the increased yields with
increased levels of orthophosphorus indicate the lake was
phosphorus limited at that time (note the lack of yield
response when only nitrogen was added).
The lake data indicate phosphorus limitation at the
other sampling times as well; i.e., mean N/P ratios were
29/1 in June and 20/1 in August, and phosphorus limitation
would be expected.
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8
V. LITERATURE REVIEWED
Ball, Joseph R., 1973. Personal communication (lake morphometry).
WI Dept. Nat. Resources, Madison.
Lueschow, Lloyd A., 1972. Biology and control of aquatic nuisances
in recreational waters. Tech. Bull. No. 57, WI Dept. Nat.
Resources, Madison.
__________ James N. Helm, Donald R. Winter, and Gary W. Karl; 1970.
Trophic nature of selected Wisconsin lakes. Trans. Wisc. Acad.
Sci., Arts & Ltrs., vol. 58, pp. 237-264.
McKersie, Jerome, George Hansel, Floyd Stautz, and Dick Narf; 1969.
Report on an investigation of the pollution in the upper Rock
River drainage basin made during 1967-1968. WI Dept. Nat.
Resources, Madison.
Poff, Ronald J., and C. W. Threinen, 1963. Surface water resources
of Waukesha County. WI Cons. Dept., Madison.
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9
VI. APPENDICES
APPENDIX A
TRIBUTARY FLOW DATA
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TRIBuTARY FLOW INFORMATION FOP WISCONSIN
9/30/74
LA’(E CODE 5532
OCONOMO OC 1A E
TOTAL r’RAINAGE AREA OF LAKE
88. PR
SUB —024 1 i A CE
TRIBUTARY A 2 F.A
NORMALIZED FLOWS
JAN FEB MAR APR MAY JUN JUL AUG
SEP OCT NOV DEC HEAN
MEAN MONTHLY FLOWS AND DAILY FLOWS
TRIBUTARY MONTH YEAR MEAN FLOW DAY
9 72 140.00
10 72 160.00
ii 72 I?0.00
12 72 45.00
1 73 96.00
2 73 73.00
3 73 170.00
4 73 390.00
5 73 270.00
6 73 100.00
7 73 ?9.00
B 73 19.00
9 72 130.00
10 72 150.00
ii 7 110.00
I’ 72 43.00
I 73 90.00
73 68.00
3 73 160.00
4 73
5 73 250.00
6 73 98.00
7 73 27.00
B 73 IR.00
9 72 10.00
10 7’ 11.00
II 72 8.00
I? 72 1.10
I 73 2.70
7 73 1.30
3 73 4.10
4 73 4P . OQ
73 20.00
6 73 4.70
7 73 2.50
B 73 1.70
79.00 94.00 42.00 30.00 38.00 39.00 54.00 33.00 60.03
74.00 88.00 40.00 28.00 36.00 37.00 51.00 31.00 56.37
4.40 5.20 2.30 1.60 2.10 2.10 3.00 1.80 3.2R
FLOW DAY FLOW DAY
23 220.00
9 37.00
II 73.00
IA 230.00
14 260.00
12 270.00
16 94.00
1 43.00
26 20.00
23 200.00
9 35.00
11 68.00
18 210.00
14 250.00
I? 260.00
IN 90.00
I 40.00
26 19.00
23 15.00
9 2.60
II 1.10
18 6.60
14 31.00
12 21.00
lb 44.00
1 3.60
26 1.70
FLOW
553241
553242
5537 17
BR. 80
83.90
4.90
34.00 38.00 100.00 140.00
32.00 36.00 94.00 130.00
1.90 2.10 5.50 7.60
TOTAL OBATUAGF AREA OF LAfuE =
SUM OF SUB—DRAINAGE AREAS =
SUMMARY
88.80
TOTAL FLOW IN =
TOTAL FLOW OUT =
716.40
721 .00
553?A I
553?A?
553727
29 ‘50.00
28 340.00
29 230.00
28 320.00
29 19.00
25.00
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APPENDIX B
PHYSICAL and CHEMICAL DATA
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STORET RETRIEVAL DATE 74/09/30
553201
43 06 00.0 088 26 30.0
OCONOMOWOC LAKE
55 WISCONSIN
11EPALES 2111202
5 0048 FEET DEPTH
00010 00300 00077 00094 00400 00410 00630 00610 00665 00666
DATE TIME DEPTH WATER DO TRANSP CNDUCTVY PH T ALK NO?&NO3 NH3—N PHOS—TOT PHOS—DIS
FROM OF TEMP SECCHI FIELD CACO3 N—TOTAL TOTAL
TO DAY FEET CENT HG/L INCHES UICROMI4O SU HG/I MG/I MG/L MG/L P MG/L P
72/06/2) 08 20 0000 14.6 9.3 108 400 8.20 192 0.090 0.070 0.012 0.011
08 20 0015 18.9 10.8 380 8.40
08 20 0023 10.1 15.4 400 8.40 198 0.090 0.040 0.014 0.006
08 20 0045 5.9 420 7.40 212 0.070 0.920 0.076 0.028
72/08/19 08 iS 0000 125 410 8.40 180 0.070 0.070 0.008 0.005
08 15 0004 25.4 8.8 400 8.40 183 0.070 0.070 0.008 0.006
08 15 00)5 21.2 12.8 435 8.10 192 0.150 0.140 0.009 0.007
08 15 0025 13.8 14.1 440 7.95 204 0.120 0.100 0.008 0.005
08 15 0035 7.5 6.1 450 7.60 224 0.160 0.280 0.009 0.006
08 15 0045 6.6 0.0 500 7.30 244 0.120 2.380 0.020 0.011
72/11/11 11 25 0000 187 480 7.70 2)8 0.090 0.310 0.012 0.007
11 25 0004 7.9 9.4 460 7.70 192 0.090 0.320 0.013 0.008
11 2S 0015 7.9 9.3 460 7.70 200 0.090 0.320 0.015 0.010
IL 25 0022 7.9 9.0 465 7.70 192 0.090 0.320 0.014 0.009
11 25 0030 7.9 9.3 465 7.70 208 0.090 0.310 0.012 0.007
11 25 0043 7.9 9.2 470 7.70 200 0.090 0.310 0.011 0.008
32217
DATE TIME DEPTH CHLPPHYL
FROM OF A
TO DAY FEET UG/L
72/06/21 08 20 0000 4.8J
72/08/19 08 15 0000 1.3J
72/11/11 11 25 0000 2.5J
J VALt)’- I\N()/’ J I 0 ‘- I
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STORET RETRIEVAL DATE 74/09/30
553202
43 06 00.0 088 27 30.0
OCONOMOWOC LAKE
55 WISCONSIN
1 1EPALES 2111202
S 0050 FEET DEPTH
00010 00300 00077 00094 00400 00410 00630 00610 00665 00666
DATE TIME DEPTH WATER DO TRANSP CNDUCTVY PH T ALK NO2 NO3 NH3—N PHOS—TOT PHOS—DIS
FROM OF TEMP SECCHI FIELD CACO3 N-TOTAL TOTAL
TO DAY FEET CENT MG/I INCHES HICROHHO SU MG/L HG/I HG/L MG/L P MG/L P
72/06/21 14 30 0000 16.8 9.0 18R 0.060 0.060 0.011 0.010
14 30 0030 8.5 10.2 385 R.00 182 0.160 0.040 0.010 0.006
- 14 30 0045 6.3 6.8 400 7.60 186 0.270 0.060 0.012 0.010
72/08/19 07 40 0000 151 410 8.40 174 0.050 0.060 0.009 0.006
07 40 0004 25.5 8.7 405 8.43 175 0.050 0.050 0.008 0.005
07 40 0015 21.9 8.9 425 8.10 176 0.050 0.050 0.008 0.007
07 40 0025 18.5 430 7.90 184 0.090 0.080 0.009 0.006
07 40 0035 9.4 5.6 450 7.60 195 0.310 0.060 0.011 0.007
07 40 0045 7.3 4.3 455 7.55 194 0.380 0.050 0.011 0.007
07 40 0055 6.5 0.02 460 7.40 210 0.050 0.410 0.042 0.028
7 7/Il/Il II 50 0000 99 450 7.90 192 0.110 0.140 0.014 0.009
11 50 0004 8.0 9.8 450 7.90 194 0.110 0.130 0.015 0.010
11 50 0015 7.9 9.8 450 7.90 192 0.120 0.130 0.019 0.012
11 50 0022 7.9 9.9 450 7.90 194 0.110 0.140 0.017 0.014
11 50 0035 7.9 9.8 455 7.90 195 0.110 0.130 0.015 0.010
32217
DATE TIME DEPTH CHLRPHYL
FROM OF A
TO DAY FEET UG/L
12/06/21 14 30 0000 2.1J
72/08/19 07 40 0000 1.6J
72/11/11 11 50 0000 6.1J
J VALUF r
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APPENDIX C
TRIBUTARY DATA
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STJPFT °ETPJEVAL flAT 74/IC/02
S3?A1 LS553241
43 0’:, 30.0 0 ? 30.0
OC(ThJOMOWOC
1 - TLANO
U/3CONOM’J 3’ LAP €
US 1 P3 L)( OF OCONOMOWOC
11 ALES 2111204
4 0000 FEET DEPT -I
0O 30 ()O’E ,?S 00 10 O0 71 006 ’55
1) TF T1’IF flEPTI- •‘ O7 NO3 TOT KJFL r -I3—N P flS— )1S PHOS—TOT
OF ; J—T1)T ‘ L N TOT t L O T 4O
TO 1)AY FF T M(3/L ‘-11 /L P -IC ’/L M1’/L P MG/L P
72/09/21 15 10 0.379 e.c. 50 o.i 0.021 0.105
72/11/OS 1130 0.1 0.7R0 0.033 0.005 0.017
7?/ 1 ?/Q 14 10 0.1 0.’- P0 0.0 I 0 0.009 0.01 ’
71/01/0 - 15 0 3.1 C.S 0 0.0 3 0.00 ’ 0.0?0
71/02/11 14 IE 0.273 (. ‘00 0.024 0.009 0.020
71/fl3/1 10 0 0.17 2.700 0.105 0.011
73/’)6/IL. ii 10 0.3 O 1.7 (’ 0.052 0.O0 0.030
71/04/29 14 00 3.250 1.000 0.0? 0.005K 0.015
73/0 /12 1’ I 0.?70 1.100 ).0f 7 0.010 0.015
71/05/2 14 44 0.?40 1.300 0.071 0.014 0.025
73/0’/1 131S 0.1 1.050 0.074 0.007 0.0?O
73/07/Ot 11 00 0.130 0.5 ’ 0 0.04? 0.011
7 /Ø /7’ 1310 0.O’6 0.510 0.fl S O 0.011
K V,’LUr Nt i” TO L
T— i 1’ flJt’ T [ )
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STO ET RETPTEVAL DATE 74/10/02
K V LU ‘cNfl dN TO - L ’
r—l N 1\D1C TF)
LS553?A2
43 05 30.0 088 27 30.0
UCONO 1OWOC Rt E’
55 15 HARTLANU
J/0CONOMO OC LAKE
US 16 BRD& W OF OKAUCHEE
1 IFPALES 2111204
4 0000 FEET DEPTH
00630
00625
00610
00671
00665
DATF
T [ ’.IF
r)FPTH
NO2 NO3
TOT KJEL
NH3-N
Pr4OS—DIS
PHOSTOT
FROM
OF
N—TOTAL
N
TOTAL
OPT’-40
TO
DAY
FEFT
MG/L
MG/L
MG/L
M(/L P
MG/L P
7?/09/?3
iS
00
0.297
1.100
0.340
0.004
0.024
72 ,11/05
13
40
0.099
0.580
0.050
0.005K
0.015
72/ 12/00
14
00
0.?S0
C.610
0.022
0.00 5K
0.019
71/01/06
15
45
0.290
0.730
0.02 ’
0.005K
0.020
71/02/11
14
1?
0.340
0.720
0.007
0.005K
0.025
73/01/18
10
45
0.430
1.000
O.O?6
0.007
0.155
73/04/14
13
45
0.350
0.940
0.014
0.004
0.035
73/04/?4
14
15
0.176
1.100
0.016
0.006
0.0?5
73/OS/i?
14
30
0.220
0.970
0.O f’
0.010
0.030
71/05/2
14
50
0.160
1.2 0
0.052
0.008
0.035
73/06/16
13
25
0.0’7
1.20’)
fl.04
n.nOcK
0.030
71/07/01
13
10
0.010K
1.000
0.06C
0.005K
0.O 0
7l/Q /?6
0.013
C. 7 O
0.046
0.O0
0.020
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