EPA-670/2-74-072
October 1974
Environmental Protection Technology Series
ASSESSING EFFECTS ON
WATER QUALITY BY
BOATING ACTIVITY
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
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EPA-670/2-74-072
October 1974
ASSESSING EFFECTS ON WATER QUALITY
BY BOATING ACTIVITY
By
Yousef A. Yousef
Florida Technological University
College of Engineering
Orlando, Florida 32816
Contract No. 68-03-0290
Program Element No. 1BB038
Project Officer
Thomas H. Roush
Industrial Waste Treatment Research Laboratory
Edison, New Jersey 08817
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
' t>y 'I""' Su|>*-rint t-
Print inn < iff ii
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REVIEW NOTICE
The National Environmental Research Center--
Cincinnati has reviewed this report and approved its
publication. Approval does not signify that the
contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products
constitute endorsement or recommendation for use.
11
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FOREWORD
Man and his environment must be protected from the adverse ef-
fects of pesticides, radiation, noise and other forms of pollution,
and the unwise management of solid waste. Efforts to protect the
environment require a focus that recognizes the interplay between
the components of our physical environment -- air, water, and land.
The National Environmental Research Centers provide this multidis-
ciplinary focus through programs engaged in
• studies on the effects of environmental contaminants
on man and the bioshpere, and
0 a search for ways to prevent contamination and to re-
cycle valuable resources.
Research studies on possible detrimental effects to man's re-
creational sources from usage of engined boats will help interested
regulatory agencies and local groups to implement the required pro-
gram for the preservation of our water resources. Emphasis of prior
investigations has been on exhaust emissions. However, this pre-
liminary study investigates the effects of agitation and mixing by
motor boats and assesses the water quality implications that re-
sult from this activity.
A. W. Breidenbach, Ph.D.
Director
National Environmental Research
Center, Cincinnati
m
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ABSTRACT
This research endeavor was directed towards an assessment of effects on
water quality in shallow water bodies due to mixing by boating activity.
Definition of the problem, isolation of effects and conditions, and de-
termination of areas for further research were stressed.
Eight sampling locations on four selected lakes in Orange County, Florida,
were studied. Heavy boating activity exists on Lake Mizell, Lake Osceola,
and Lake Haiti and in the Winter Park chain of Lakes with an average horse-
power almost twice that of the estimated national average and a total of
814 registered motorboats during 1972 in the City of Winter Park. The
fourth, Lake Claire, is located on the Florida Technological University
campus and boating activity is permitted only for research studies. Boats
equipped with different horsepower motors were run for limited periods
of time in the area of sampling locations which vary in depth between
1.2 and 10.7 meters. Changes in several water quality parameters before
and after boating activity have been documentated. Also water quality para-
meters on weekends and during week days were studied to investigate the
significance of heavy boating activity. Three major parameters namely
dissolved oxygen, resuspension of sediments and nutrients, were emphasized.
The results from these studies suggested that agitation and mixing by
motorboats could increase the turbidity and average particle size of
suspended material through the water column. The increase in turbidity
was generally dependent on water depth, motor power and availability and
nature of sediment deposits. A decrease in turbidity was noticed one
hour after cessation of boating. However, changes in collodial suspensions
within the water columns have not been investigated. Increase in turbidity
was accompanied by an increase in organic carbon and phosphorus concentra-
tions. Dissolved and particulate phosphorus seemed to increase in water
samples collected after boating activity, at least on a temporary basis.
Agitation and mixing by boating activity destratified the lake, and in some
cases, increased oxygen concentration and the rate of oxygen uptake by sus-
pended matter. Results from other parameters such as pH, specific conduc-
tance, temperature, and nitrogen were not conclusive. Long term research
studies are recommended.
This report was submitted in fulfillment of EPA Contract No. 68-03-0290
by the Florida Institute of Technology under the sponsorship of the
Environmental Research Agency. Work was completed as of June 1, 1974.
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CONTENTS
Page
Abstract iv
List of Figures vi
List of Tables vi1
Acknowledgments ix
Sections
I Conclusions 1
II Recommendations 2
III Introduction 3
Objectives and Scope 5
IV Description of Test Lakes 6
V Field Studies 12
Experimental Procedure 12
Exploratory Studies 13
VI Dissolved Oxygen 17
The Winter Park Chain of Lakes 17
Lake Claire 22
VII Resuspension of Sediments 31
Lake Sediments After Boating Activity 32
Turbidity 36
Water Depth 36
Motor Power 36
Time of Operation 42
Particle Size of Resuspended Sediments 44
VIII Nutrients 50
Mixing of Lake Water 50
Experimentation and Results 51
References
58
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FIGURES
No. Page
1 Sampling Locations on the Winter Park Chain of Lakes . . 9
2 Sampling Locations on Lake Claire 10
3 Typical Changes in Dissolved Oxygen Profiles Result-
ing from Boating 16
4 Dissolved Oxygen and Temperature Profiles on Lake
Mizell at S1 18
5 Dissolved Oxygen and Temperature Profiles on Lake
Osceola at S^ 19
6 Dissolved Oxygen and Temperature Profiles on Lake
Maitland at Sg 20
7 Dissolved Oxygen and Temperature Profiles on Lake
Maitland at S, 21
0
8 Dissolved Oxygen and Temperature Profiles on Lake
Claire at Sy 23
9 Photographic Pictures Before and After Operation of
a 50 HP Motorboat on Wekiva Springs 33
10 Photographic Pictures Demonstrating Resuspension of
Bottom Sediments from Operation of a 50 HP Motorboat . . 34
11 Photographic Pictures Showing the Plume Formation and
Mixing Process From Operation of a 50 HP Motorboat ... 35
12 Relationship Between Motor Power of Fjngined Boats
and Mixing Depth in Lakes 43
13 Particle Size of Resuspended Sediments due to Boat-
ing Activities 45
14 Resuspension of Sediments by 28 HP Motorboat at
Lake Claire 46
15 Millipore Filter Residue From 50 ml Lake Mizell
Water Before and After Boating at Shore Area 47
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TABLES
No. Page
1 Summary of Outboard Motor Population .......... 3
2 Motor Boats Registered During 1972, City of Winter
Park .......................... 4
3 Boating Activities on Winter Park Chain of Lakes
During the Summer ................... 7
4 Morphometric Features of the Lakes
5 Description of Test Locations
6 Water Quality Determinations Before Outboard Engined
Boating Activity .................... 14
7 Water Quality Determinations After Outboard Engined
Boating Activity .................... 15
8 Dissolved Oxygen Profiles at Lake Mizell During
August 1973 ...................... 24
9 Dissolved Oxygen Profiles at Lake Osceola During
August 1973 ...................... 25
10 Dissolved Oxygen Profiles at Lake Maitland During
August 1973 ...................... 26
11 Temperature Profiles at Lake Mizell .......... 27
12 Temperature Profiles at Lake Osceola .......... 28
13 Temperature Profiles at Lake Maitland ......... 29
14 Water Quality Determination After Boating Activity
Across Lake Mizell ................... 37
15 Water Quality Determination After Boating Activity
Across Lake Osceola ........ .......... 38
16 Water Quality Determination After Boating Activity
Across Lake Maitland ...... ............ 39
17 Turbidity Measurements Before and After Outboard
Motorboat Activity ................... 40
vii
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TABLES, (cont'd.)
No. Page
18 Turbidity Measurements Before and After Cessation
of Boating Activity 41
19 Changes in Mixing Depth as Related to Changes in
Motor Power 42
20 Effect of Operational Time on Turbidity 44
21 Particle Size of Lake Claire and Lake Mizell Suspended
Solids 49
22 Nutrients in Water Samples from Lake Mizell 52
23 Nutrients in Water Samples from Lake Osceola 53
24 Nutrients in Water Samples from Lake Maitland ..... 54
25 Nutrients in Water Samples from Lake Claire 55
26 Summary of Nutrient Concentrations in Lake Water
Samples 55
27 Dissolved and Particulate Phosphorus 57
Vlll
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ACKNOWLEDGMENTS
The author wishes to acknowledge with graditude the assistance of the
many individuals who helped make this investigation possible.
Special acknowledgments are extended to all students at Florida Techno-
logical University who participated in this project. Special recognition
must go to Mr. Lorran R. Hears, photographer, who freely and willingly
took the underwater pictures.
Appreciation is also extended to Mr. W. L. McClintock, Superintendent,
and his staff in the Environmental Division of The Public Works Depart-
ment, City of Winter Park, Florida. Their valuable contribution and
assistance in collecting the samples and running the experiments made
this study possible.
Funding for this project was provided by the Environmental Protection
Agency, Industrial Waste Treatment Research Laboratory, Edison, New
Jersey. The interest and assistance of Mr. Thomas H. Roush and Mr. Leo
T. McCarthy is most gratefully appreciated.
IX
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SECTION I
CONCLUSIONS
1. Dissolved oxygen profiles and turbidity measurements generally in-
dicate a mixing of the water column following boating activity. This
was also supported by underwater photography.
2. Under test conditions, the mixing depth appears to vary directly with
horsepower of the motor. The effective mixing depth reached up to
15 feet below the water surface for a 50 HP motor.
3. Resuspension of solids from the bottom and aquatic macrophytes was
observed following boating activity. Changes in turbidity was de-
pendent on water depth, motor power, operational time and type and.
nature of sediment deposits. In the shallow shore areas with water
depth less than 5 feet, physical changes in turbidity and floating
matter at the surface were observed within less than five minutes of
boating activity.
4. One hour after cessation of boating activity, a decrease in turbidity
measurements was observed.
5. The increase in turbidity was generally accompanied by an increase in
organic carbon and phosphorus concentration. Most of the organic
carbon was dissolved, and most of the phosphorus was particulate.
The extent and significance of these changes in nutrients and their
possible contribution to the eutrophication problem is not known.
6. Temperature, pH, conductivity and TKN were deemed poor indicators of
mixing in the lakes tested.
7. Under certain conditions, increases in the total dissolved oxygen was
noted following boating activity. The oxygen transfer to the water
body depends primarily on the oxygen deficit in the water column.
Also, there is evidence that resuspended particles throughout the water
column may exert a higher oxygen uptake rate.
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SECTION II
RECOMMENDATIONS
During the course of this study, as much information as possible was
collected within the budget and time limitations. The mixing process
and water quality changes after limited boating activity were documented.
However, the nature and significance of these changes are not known.
Therefore, long term studies within the following areas of research are
recommended.
1. Increase in turbidity was attributed to boating activity. Release
of nutrients from the resuspended solids, their availability to
autotrophic organisms and their impact on the eutrophication problem
is not known. In particular, the significance of increasing the
phosphorus concentration in the water column through mixing the
lower levels of water, which are rich in phosphorus content, through-
out the entire column depth need to be investigated.
2. It is desirable to study the net oxygen balance due to mixing
effects. For example, to determine if the oxygen added to water
from aeration is adequate to replace the oxygen possibly consumed
by increased sediment uptake. Factors and conditions that will
tend to increase the oxygen uptake rate need to be identified.
3. Underwater photography could be helpful in development of a math-
ematical model to predict the size and nature of resuspended
particles under a set of operational conditions. Also the mixing
process itself needs to be defined.
4. The effect of water column mixing and resuspension of solids on re-
distribution and changes in autotrophic organisms and benthos
deserves further investigation.
5. Work is needed to determine if the water column mixing and solid
resuspension is detrimental to the ecology of a lake and if so under
what conditions?
6. The effect of boating activity on the stability of a thermocline
and the various conditions under which the two interact needs
definition.
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SECTION III
INTRODUCTION
Outboard engined boats are increasing in number and average horsepower.
Their possible detrimental effects to water bodies has been of growing
concern. Various studies on exhaust emission have been initiated; how-
ever, agitation and mixing due to boating activity have not been eval-
uated.
There, has been a growing concern to those interested in the preserva-
tion of our natural resources over the possibility that outboard en-
gined boats could be detrimental to our lakes and water bodies. The
outboard motor sales are increasing in number and average size as
shown in Table 1. Table 1 shows a summary of the major usable motor
population and sales statistics between year 1950 and 1971 as reported
by the Boating Industry Association (BIA). Over 981 of all outboard
motors in use are of the two-stroke cycle type (7 ). The sales in-
creased from 430,000 in 1970 to 495,000 in 1971 and the average size
motor increased from 31 to 35.6 HP. Information on inboard powered boats
is not included.
Table 1. SUNMARY OF OUTBOARD M3TOR POPULATION
YEAR
1950
1955
1960
1965
1970
1971
SALES,
thousands
367
515
468
393
430
495
AVERAGE
HP SOLD
6.9
12.9
27.4
28.2
31.0
35.6
OUTBOARD
M3TORS IN USE,
thousands
2811
4210
5800
6645
7215
7300
In the area of central Florida, there were 11,010 registered pleasure
boats in Orange County, 7,950 in Seminole County, and 1,233 in Osceola
County during 1971-72 (5). Data of the horsepower in these counties
are difficult to obtain. However, the City of Winter Park, Orange
County registered during 1972 a boat population of 814 with motors
ranging between 1.25 and 260 HP. The distribution and power range of
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these motor boats are shown in Table 2. The average horsepower for
boats used in the City of Winter Park is 67.05 HP (22).
Table 2. MOTOR BOATS REGISTERED DURING 1972
City of Winter Park
POWER RANGE,
HP
1 -
11 -
33 -
51 -
101 -
151 -
201 -
TOTAL
Avg.
10
30
50
100
150
200
260
Power
NUMBER OF BOATS
39
62
238
353
93
13
16
814
67.05 HP
In recent years, several investigations have been carried out to deter-
mine the environmental effects due to emission exhausts (7,12). A re-
cent search of the Smighsonian Science Information Exchange's records,
in December 1973, showed no relevant notices of research projects re-
lated to agitation by outboard engined boats to be registered with them.
Current studies supported by the Environmental Protection Agency are re-
lated to the investigation of the effects of outboard motor emissions.
However, no work has been done to evaluate the effects of agitation by
motor boats on water bodies. The extent of water quality degradation
in shallow lakes due to resuspension of organic matter and nutrients
from bottom sediments is unknown and cannot be ignored or underestimated.
Research is, therefore, required to define the magnitude of the changes
in water quality by mechanical mixing and the rationale for the control
of boating activity if such control is deemed to be necessary.
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OBJECTIVES AND SCOPE
The overall objective of this endeavor is to determine whether mechani-
cal agitation as a result of outboard engined boating activity could
induce possible detrimental effects on the water quality in shallow
lakes (less than 30 feet). The results of such work will supplement
and compliment the other research regarding outboard engines. Also,
it will help interested regulatory agencies and local groups to imple-
ment the required program to provide guidelines on motor boat usage for
state and local authorities.
Specifically, an assessment of the effects on water quality in shallow
water bodies due to mixing by boating activity in order to define the
problem, isolate effects and conditions and determine areas of further
research will be accomplished during this phase of study. Studies
of selected lakes in central Florida, mainly in the Winter Park Chain
of Lakes and on the Florida Technological University campus, have been
initiated. Boating for limited periods of time using boats equipped
with different horsepower motors has been considered to determine changes
in turbidity, suspended solids, total organic and inorganic carbon, bio-
chemical oxygen demand, dissolved oxygen, temperature, pH, phosphorus,
and nitrogen.
Due to geographical and budget limitations, only shallow Florida lakes
were observed. Hence, if any implications concerning the effects of
mechanical mixing found in this investigation are applied to other
geographical areas, it must be considered as the responsibility of the
reader.
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SECTION IV
DESCRIPTION OF TEST LAKES
Lakes classed as oligotrophic, mesotrophic and various stages of eutrophi-
cation exist in the area of central Florida. Orange County along has ap-
proxirately 218 lakes with a total surface area of 44,251 acres (17921.7
hectares) within the St. John's Basin (4). The surface area of the lakes
varies between one (0.405 hectares) and 30,671 acres (12421.8 hectares)
and the maximum water depth varies between less than 5 feet (1.52 meters)
deep and more than 30 feet (9.14 meters) deep. Studies have indicated
that cultural influences, such as population characteristics, fertilized
cropland and urban areas in the lakes watershed, are the most influential
factors in determining the trophic states of Florida lakes (18,19).
Four lakes in Orange County Florida, have been used during the course of
this study. Three of them are in the Winter Park chain of lakes, namely
Lakes Mizell, Osceola, and Maitland. The fourth, Lake Claire, is
located on the Florida Technological University campus. The Winter Park
chain of lakes are used for boating activities but motor boats are
generally not permitted on Lake Claire. A survey made by the lake patrol
in the City of Winter Park Police Department showed the estimated number
of boats operating at any time of a given day during the week as pre-
sented in Table 3 (22). Boating activities during the winter months is
approximately one half that of summer months.
Motor boats were used on Lake Claire for research activities after
obtaining special permission from the FTU administration.
Morphometric characteristics of the lakes are presented in Table 4 (4).
A map showing the Winter Park chain of lakes and the six sampling
locations is presented in Figure 1. A topographic map for Lake Claire
is shown in Figure 2. The water depth in Lake Claire varies between
4 and 12 feet with an average value of 7.5 feet (17).
The Winter Park chain of lakes are eutrophic and excessive growth of
higher aquatic plants such as Hydrilla and Vallisneria extend through
the entire depth in several areas of the lakes^Currently, the City of
Winter Park is heavily involved in weed control programs through the use
of chemicals on the lakes. On the other hand, Lake Claire is an oligo-
trophic lake and is used for experimentation during the course of this
study.
Wekiva Springs in Orange County were used for underwater photography
because of the clarity of its water. Pictures were taken to document
the process of mixing of the entire water column and the subsequent
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Table 3. BOATING ACTIVITIES ON WINTER PARK CHAIN OF LAKES DURING THE SIMMER
LAKE
Mizell
Virginia
Osceola
Maitland
RANGE IN NUMBER OF BOATS OPERATING ON
Mon.
0 - 2
2 - 12
2 - 12
5 - 16
Tues.
1 - 2
2 - 12
2 - 12
5 - 16
Wed.
1 - 2
2 - 12
2 - 12
5 - 16
Thurs.
1 - 2
3 - 14
2 - 12
5 - 16
Fri.
1 - 3
3 - 15
3 - 15
6 - 18
Sat.
2 - 6
5 - 25
5 - 18
10 - 40
Sun.
1 - 4
4 - 20
4 - 16
8 - 32
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Table 4. MORPHOMETRIC FEATURES OF THE LAKES
LAKES
Mizell
Osceola
Maitland
Claire
SURFACE
AREA
Hectares
25.1
63.5
182.7
8.1
DEPTH
(Meters)
Maximum
6.1
7.0
10.7
3.7
Average
4.0
4.3
4.6
2.3
DRAINAGE
AREA
Sq. Km
--
--
50.0
--
ELEVATION
(MSL)
Meters
20.12
20.12
20.12
19.51
COUNTY
Orange
Orange
Orange
and
Seminole
Orange
REMARKS
Streams flowing
out of the lake
Streams flowing
both in and out
of the lake
Streams flowing
both in and out
of the lake
Landlocked lake
oo
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FIGURE I - SAMPLING
LOCATIONS ON THE
WINTER PARK CHAIN
OF LAKES
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FIGURE 2- SAMPLING LOCATIONS ON
LAKE CLAIRE
10
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resuspension of aquatic sediments as a result of running an engined
boat.
Description of the test location is presented in Table 5. The test sites
are 4 to 35 feet deep (1.2 to 10.7 meters) as shown in Table 5.
Table 5. DESCRIPTION OF TEST LOCATIONS
LAKE
Mizell
Osceola
Maitland
Claire
Wekiva
Springs
SAMPLING
LOCATION
Sl
S2
S3
S4
S5
S6
S7
S8
--
DEPTH
Feet
16
5
8
18
8
35
11
4
5-10
Meters
4.9
1.5
2.4
5.5
2.4
10.7
3.4
1.2
1.5-3.0
11
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SECTION V
FIELD STUDIES
The water quality in shallow water bodies are usually affected by diur-
nal and seasonal variations, environmental conditions and turbulence of
water. Probable changes in water quality caused by agitation from motor
boats are complex and difficult to isolate from natural conditions. Agi-
tation could influence the dispersion and floatation of plankton, could
disturb the benthic organisms, resuspend settled solids, increase tur-
bidity and affect the chemical interactions at the sediment-water inter-
face. The long term effects from intermittent boating activities are
not known, however, physicochemical water quality parameters before
and after limited boating in shallow lakes (less than 30 feet deep)
were evaluated.
EXPERIMENTAL AND ANALYTICAL PROCEDURES
Recreation boats equipped with different size motors were run across
the sampling locations from one shore of the test lake to another.
Boats were run for limited periods of time and at an estimated speed of
15 to 30 miles/hour (24.14 to 48.28 km/hour). Physico-chemical parameters
of the water were monitored at sampling locations before and after boating
activity. These parameters included dissolved oxygen (DO), temperature,
pH, specific conductance, turbidity, carbon, nitrogen and phosphorus
analysis.
The temperature and DO profiles were measured in the field using YSI 54
Oxygen Meter. The membrane electrode was usually calibrated in the
laboratory and water samples were collected and fixed in the field to
check the calibration of the DO meter. The azide modification of the
iodometric method as described in the Standard Methods for the Examina-
tion of Water and Wastewater was used to check the calibration (20). A
Corning Model 610 Expand Portable pH Meter was also used in the field
to measure the hydrogen ion concentration. The Lab-Line Lectro Mho-
Meter Model MC-1, Mark IV was used for measuring the specific conduc-
tance.
Water samples were collected from various levels in the water column by
using a Wildco Water Sampler Model 1220. These samples were preserved
and transported to the laboratory according to the EPA Methods for
Chemical Analysis of Water and Wastes (16). The turbidity was measured
by the Hach 2100 turbidimeter. The Beckman Model 915 Total Organic
Carbon Analyzer was used for determination of OC and 1C. Colorimetric
Techniques as recommended by the Environmental Protection Agency (16)
12
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were used for determination of total Kjeldahl nitrogen (TKN), Ortho-
phosphates (OP) and total phosphorus (TP). A Beckman DB-GT Spectro-
photometer was used in the colorimetric analysis.
EXPLORATORY STUDIES
In late June and early July 1973, a 100 horsepower outboard engined boat
was run for approximately 20 minutes at Lake Mizell, Osceola, and Mait-
land. The changes in temperature, dissolved oxygen concentrations, pH,
turbidity, and nutrients were measured. The water quality analysis
before and after boating are shown in Table 6 and Table 7. The results
from Lake Mizell showed apparent changes in dissolved oxygen but no
apparent changes in turbidity and nutrient concentrations. The location
tested in this lake is 16 feet deep. The locations tested on Lake
Osceola and Maitland are 6 to 8 feet deep and showed changes in turbidity
and nutrient concentrations. Increases in nutrient concentrations were
associated with increase in suspended solid concentrations. Changes in
dissolved oxygen profiles are shown in Figure 3. It is interesting to
notice that Lake Mizell has a very shallow photic zone, less than two
feet, and a noticeable decline in dissolved oxygen concentration with
depth. However, after agitation, mixing between layers did occur and
the DO concentrations were homogenized.
This initial phase of studies was followed by extensive surveys of
water quality parameters at various boating time intervals during July
and August, 1973, at the Winter Park Chain of Lakes. These lakes are
used for recreational activities as indicated in Table 3, and the
surveys were planned in order to detect differences in water quality
parameters during heavy boating activities. Studies before and after a
national holiday (July 4), during week days and on weekends were per-
formed. On these lakes, it was also possible to study the effects of
limited boating activities using different power engines and locations
on the lakes with different depths.
Boating activities on Lake Claire are not allowed and a special permis-
sion was granted to run boats for research purposes starting in Sept-
ember, 1973. Lake Claire is oligotrphic with low pH (about 5.0) and
limited aquatic plants. Studies on the lake included changes in water
quality parameters at a shore area and mid-width (S_, Sg). Attempts
were also made to evaluate the effect of depth, motor horsepower,
elapsed time of operation, and characteristics of resuspended particles.
The results and discussion are presented in the following sections.
13
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Table 6. WATER QUALITY DETERMINATIONS BEFORE BOATING ACTIVITY
(100 HP Motor)
LAKE
Mizel
Os ceo la
Osceola
Maitland
DATE
July 5
July 5
June 26
June 26
TIME
13:30
14:30
10:30
11:00
LOCA-
TION
Sl
S3
s
S5
DEPTH
FT.
1
2
3
5
10
15
1
5
1
5
6
1
5
6
7
KAKAMbTliR BEFORE BOATING
Temp
°C
30.5
30.0
29.0
31.0
30.0
28.0
28.0
28.0
28.5
28.5
28.5
D.O.
mg/1
8.0
3.0
2.0
2.2
2.0
8.0
9.0
6.5
5.2
4.8
8.0
6.6
6.0
pH
6.8
6.70
7.00
7.00
7.60
7.45
7.65
Turb
JTU
3.0
5.0
1.8
4.0
1.6
1.2
Carbon mg/1
1C
11.0
11.5
15.8
15.8
18.9
17.3
OC
7.2
7.0
3.2
1.8
2.5
2.3
TKN
mg/1
N
0.23
0.25
0.25
0.50
P mg/1
OP
.06
.10
.05
.08
.05
.04
TP
0.2
.16
.14
.21
.07
.08
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Table 7. WATER QUALITY DETERMINATIONS AFTER BOATING ACTIVITY
(100 HP Motor)
LAKE
Mizel
Osceola
Os ceo la
Maitland
DATE
July 5
July 5
June 26
June 26
TIME
13:30
14:30
10:30
11:00
LOCA-
TION
Sl
S3
o
s,
o
Sr
DEPTH
FT.
1
2
3
5
10
15
1
5
1
5
6
1
5
6
7
PARAMETER AFTER BOATING
Temp
30.5
30.0
29.0
31.0
30.0
28.5
28
28
29
28.5
28.5
D.O.
mg/1
5.5
4.5
4.5
4.0
3.5
2.0
8.1
9.0
7.2
6.9
6.9
7.8
7.8
8.0
pH
6.7
6.95
6.95
7.45
7.7
Turb
JTU
2.8
•
7.0
8.0
2.1
4.9
Carbon mg/1
1C
11.0
15.0
18.0
18.9
17.0
6.5
5.5
32
2.9
5.9
TKN
mg/1
N
0.3
0.30
1.0
3.0
P mg/1
OP
.06
0.2
0.42
.08
.06
TP
0.2
0.32
0.61
.10
.08
-------
DISSOLVED OXYGEN , MG/L
2468
246 8 10
10
15
JULY 5
LAKE MIZELL,S
H
UL
X
1-
OL
••• ^
2468
rl
L LJ
JUNE 26
LAKE MAITLAND , S,
JULY 5
2 4 6 8 10
LAKE OSCEOLA , S.
D.O. BEFORE BOATING
D.O. AFTER BOATING
FIGURE 3- TYPICAL CHANGES IN DISSOLVED
OXYGEN PROFILES RESULTING FROM 20
MIN. BOATING ON THE WINTER PARK CHAIN
OF LAKES
16
-------
SECTION VI
DISSOLVED OXYGEN
Oxygen transfer in lakes from the atmosphere attributed to motor boats is
influenced by turbulence, oxygen saturation deficit, and eutrophic stage of
the lake. The turbulence created is a function of motor power, speed, and
boat characteristics such as weight and position, depth, and dimensions of
the propeller. In shallow, eutrophic lakes where stratification and hypo-
limnion dissolved oxygen depletion exist, mixing between layers occur and
may result in considerable reduction of dissolved oxygen in the upper layers.
The dissolved oxygen level changes will depend on the operation time of the
boat and lake conditions. Also, in a non-stratified lake with oxygen
levels close to saturation, relatively small amounts of oxygen would be
transfered to the water. Changes in oxygen balance due to agitation in
lakes are not defined.
THE WINTER PARK CHAIN OF LAKES
In the Winter Park Chain of Lakes, there was an increase in dissolved oxy-
gen as noted in the profiles on days of heavy boat traffic as compared to
days with less boating activity. This tendency was supported by oxygen
profiles taken before and after July 4, on weekends, and during week days.
However, natural variation could not be determined within the scope of this
study.
Figures 4 to 7 indicate dissolved oxygen and temperature profiles on Lakes
Mizell, Osceola, and Maitland in the period from June 26 to July 31, 1973.
All the profiles were measured in the afternoon hours between 13:00 and
16:00 pm. The shallowness of these lakes suggests that thermal stratifi-
cation should be unimportant and indeed most of them do not exhibit the
classical thermoclines with stagnant hypolimnia. Only the deep holes in
the bay area of Lake Maitland are sufficiently deep to develop stable stra-
tification and oxygen deficient bottom waters as observed in sampling loca-
tion S6, Figure 7.
Figure 4 shows that the dissolved oxygen profiles for Lake Mizell measured
on July 5, 1973, exhibit lower dissolved oxygen concentrations as compared
to profiles measured on June 26 or July 17. This phenomenon is specific
for Lake Mizell and in contrast to profiles measured on Lake Osceola and
Lake Maitland where the profiles were higher during the same period of time
as indicated in Figures 5 and 6. Lake Mizell differs morphometrically from
other lakes in the Winter Park Chain of Lakes. It is the smallest and is
located upstream of the other lakes as indicated by the map in Figure 1.
Also Lake Mizell has a very shallow photic zone and the dissolved oxygen
concentration decline rapidly with depth as shown in Figure 3.
It must be realized that the dissolved oxygen profiles taken on July 5 across
the water column of Lakes Mizell, Osceola and Maitland were measured after
17
-------
DISSOLVED OXYGEN , MG/L TEMPERATURE , °C
n 2 4 6 8 10 20 25 30
10
15
0
5
10
15
0
5
10
15
0
5
10
15
JUNE 26
0
5
10
15
JULY 5
5
10
15
JULY 17
FIGURE 4, -DISSOLVED OXYGEN AND
TEMPERATURE PROFILES ON LAKE
MIZELL AT S,
18
-------
DISSOLVED OXYGEN, MG/L TEMPERATURE t °C
2 4 6 8 10 20 25 30
JUNE 26
O.
UJ
O
T I
5
JULY 5
JULY 17
JULY 24
FIGURE 5. -DISSOLVED OXYGEN AND
TEMPERATURE PROFILES ON LAKE
OSCEOLA AT S3
19
-------
DISSOLVED OXYGEN.MG/L TEMPERATURE.°C
246 8 10 ^20 25
30
JUNE 26
5 --•
JULY 5
Q.
UJ
O
i i ill i
5
7
JULY 12
5--
0
JULY 17
5
5
0
JULY 24 5
—r 0
JULY 31 5
FIGURE 6. — DISSOLVED OXYGEN AND
TEMPERATURE PROFILES ON LAKE
MAITLAND AT S5
20
-------
02468
DISSOLVED OXYGEN. MG/L
024680246 8024680246 8
Q.
UJ
20
30
40
JULY 5 JULY 12
JULY 17 JULY 24 JULY 31
0
HI 'o
20
TEMPERATURE. °C
20 25 30 20 25 30 20 25 30 20 25 30 20 25 30
Q.
UJ
30
FIGURE 7.-DISSOLVED OXYGEN AND TEMPERATURE
PROFILES ON LAKE MAITLAND AT
-------
heavy boating activities on July 4 which is a national holiday. It is
also believed that the boating activity was responsible for the increase
in dissolved oxygen concentrations on Lakes Osceola and Maitland. Boat-
ing activities can increase the dissolved oxygen concentration and tend
to homogenize the dissolved oxygen between layers as indicated from
Figures 3, 4, 5, 6. It is interesting to notice that changes in dis-
solved oxygen concentrations following motorboat activity can be noticed
through an estimated depth of 15 feet (4.6 meters).
Dissolved oxygen and temperature profiles for Lakes Mizell, Osceola,
and Maitland during the month of August are presented in Tables 8 to 13.
It is noteworthy that although the dissolved oxygen concentration at Lake
Mizell on Sunday, August 5, at 15:00 had increased in the upper three
feet, the lower layers had decreased as compared to readings taken at
11:30 am on the same day. This evidence indicates that mixing between
the lower layers is responsible for the reduction in DO concentrations.
The same phenomenon was repeated on Saturday, August 11, in the after-
noon. On Sunday, August 19, the lake was stirred up for 90 minutes
using a 260 inboard motor boat and the DO level showed an increase
through the entire profile of the lake. The same general trend was
observed at Lake Osceola, where dissolved oxygen concentrations in the
lower layers were lower in the afternoon hours, unless heavy boating
traffic would offset the difference.
The data presented in Tables 11, 12, and 13 suggest that boating activities
in shallow lakes may have no noticeable effects on temperature profiles.
LAKE CLAIRE
Typical dissolved oxygen profiles at Lake Claire following limited boat-
ing activity is shown in Figure 8. The solid lines represent the DO
profiles before boating while the dotted lines represent the DO profiles
after boating. In general there was an increase in DO concentration
across the entire section of the lake. It is also important to note
that temperature changes due to boating were undetectable.
On September 18, 19, and 20 the temperature varied between 28 and 30°C
across the entire section of the lake. On November 24, the temperature
varied between 22.5 and 20.ST while it was 13 to 13.5°C on December 21.
On November 24, it can be roughly estimated that 1.21 mg/1 0, was added
to the deeper section of the lake, while 4.45 mg/1 was added to the shore
area. In other words, an average of 2.83 mg/1 0- was added due to boating
for 90 minutes using a 28 HP engined boat. Basea on these calculations,
an average increase in dissolved oxygen concentration of 1.9 mg/1/hour of
operation was added to the lake. It is obvious that the oxygen deficit
and depth are important parameters in the oxygen transfer.
Using the same approach, it is possible to calculate the DO increase at
Lake Mizell following 20 minutes of boating by a 100 HP engined boat,
22
-------
10
DISSOLVED OXYGEN, MG/L
0
2468^ 2468- 2468
101- <
10
S7 ,SEP. 18
S?,SER 19
S ,SEP. 20
2 4 6 8 10
UJ
o
10
2 4 6 8 10
1
S? ,NOV. 24
2 4 6 8 10
S8 ,NOV. 24
•DO BEFORE BOATING
DO AFTER BOATING
10
246 8 10
DEC. 21
S8tDEC.2l
FIGURE 8-CHANGES IN DISSOLVED OXYGEN
PROFILES ATTRIBUTED TO LIMITED BOAT-
ING ON LAKE CLAIRE
23
-------
Table 8. DISSOLVED OXYGEN PROFILES AT LAKE MIZELL DURING AUGUST 1973
LOCATION
Sl
DEPTH
ft
1
2
3
5
7
8
9
10
11
12
13
14
15
20
DISSOLVED OXYGEN (rag/1)
8/05
11:30
hrs
8.4
8.3
8.1
7.5
5.4
3.2
2.4
2.1
0.2
15:00
hrs
8.7
8.0
3.8
3.8
3.3
3.1
2.8
1.8
0.9
0.6
8/06
17:00
hrs
9.6
9.8
9.8
6.4
3.6
0.6
0.2
8/07
13:30
hrs
8.6
7.2
6.1
4.6
3.7
2.3
0.6
0.3
8/11
9:00
hrs
8.2
8.0
7.8
6.8
6.0
4.3
1.4
0.3
0.2
16:00
hrs
6.7
4.5
3.5
2.7
2.3
1.6
0.3
8/14
13:30
hrs
8.8
8.2
8.2
7.7
6.3
3.8
1.5
0.5
0.2
8/16
14:00
hrs
8.1
7.9
8.1
8.0
7.7
6.9
4.3
2.7
0.5
0.2
8/19
9:00
hrs
8.0
7.9
7.4
6.9
5.1
3.9
0.7
0.5
0.2
14:30*
hrs
8.6
8.6
8.6
8.6
6.7
3.7
3.1
0.5
8/20
11:00
hrs
8.0
8.1
8.0
6.9
5.7
4.7
3.7
2.1
0.4
0.3
8/21
13:30
hrs
8.7
8.7
8.7
8.3
6.6
5.4
5.4
1.9
1.1
0.2
Is)
•pfc
* The lake was stirred up by a 260 H.P. motor engined boat for 1.5 hours.
-------
Table 9. DISSOLVED OXYGEN PROFILES AT LAKE OSCEOLA DURING AUGUST 1973
LOCATION
S3
~
s.
A
*T
DEPTH
•UJ-UT J.I1
ft
1
2
3
4
5
6
7
8
9
10
1
3
5
7
8
10
12
13
14
15
16
17
18
20
D I S
8/05
10:30
hrs
8.4
8.4
8.1
8.0
3.9
7.7
7.6
7.6
7.1
6.4
3.6
2.9
2.3
16:30
hrs
8.6
8.5
6.0
5.3
4.9
8.5
8.5
8.5
8.1
7.6
6.8
6.2
3.6
2.6
8/06
15:00
hrs
8.5
8.4
8.2
6.0
8.5
8.4
9.1
8.5
6.0
4.4
3.0
1.7
8/07
15:00
hrs
7.8
7.4
6.7
5.7
5.0
4.4
1.8
1.2
0.2
SOLVED OXYGEN (mg/1)
8/09
15:00
hrs
9.0
8.6
8.7
8.1
8.5
8.2
8.0
7.1
6.7
5.8
0.2
0.2
8/11
10:00
hrs
8.1
8.0
7.5
6.8
6.6
8.4
8.2
7.8
7.2
6.4
4.6
3.0
0.8
0.2
0.2
16:30
hrs
8.6
7.3
6.4
6.0
5.6
4.7
8.9
8.4
7.3
6.3
5.5
4.6
2.9
0.8
0.2
0.2
8/14
14:00
hrs
8.6
8.4
8.2
7.1
8.3
8.4
8.0
7.1
6.5
5.0
0.3
0.2
8/19
10:00
hrs
7.8
7.2
7.6
7.8
7.8
7.1
6.5
8.3
8.3
8.2
7.7
7.1
5.7
4.1
0.3
0.3
15:00
hrs
9.0
9.2
9.3
8.3
8.3
9.2
9.2
9.2
9.2
8.2
8.1
7.1
6.6
0.8
0.3
0.3
8/20
11:00
hrs
8.7
8.5
8.7
8.4
8.3
9.8
9.6
9.0
8.7
7.5
4.9
3.1
1.0
0.3
0.3
14:00*
hrs
9.6
9.3
9.7
8.6
8.2
9.7
9.7
9.7
8.4
8.3
7.8
6.8
5.5
4.1
0.3
K)
tn
* Lake is stirred up for 45 minutes by a 260 H.P. motor engined boat.
-------
Table 10. DISSOLVED OXYGEN PROFILES AT LAKE MAITLAND DURING AUGUST 1973
LOCATION
s
"
or
5
DEPTH
ft
1
3
5
7
10
12
15
18
20
22
25
28
30
1
3
5
6
7
DISSOLVED OXYGEN (mg/1)
8/05
9:30
hrs
6.8
6.6
6.6
6.8
5.9
5.0
3.8
2.8
0.3
0.1
0.1
0.1
7.2
7.2
6.6
7.0
17:00
hrs
7.1
6.9
6.7
6.4
5.4
5.0
2.7
0.2
0.2
8.2
8.2
8.1
7.7
8/06
16:00
hrs
8.2
6.9
6.0
5.0
3.7
2.2
1.5
1.2
0.7
0.5
8.5
8.4
8.2
6.0
8/07
14:30
hrs
6.0
5.8
5.7
5.3
4.5
4.0
2.8
1.4
0.3
0.2
7.6
8.0
8.5
8.4
8/09
14:30
hrs
6.2
5.7
5.7
5.6
5.3
4.5
3.5
2.2
1.3
0.2
0.3
8.2
7.5
7.5
7.7
8/11
10:00
hrs
6.2
6.0
5.6
5.0
4.6
4.0
2.7
1.4
0.8
0.3
0.2
0.2
7.2
6.9
6.4
5.9
17:00
hrs
6.9
6.3
5.3
4.5
4.1
3.3
3.3
2.7
1.7
0.8
0.6
0.3
8.4
7.6
7.1
6.9
8/14
15:00
hrs
6.5
6.2
6.3
6.1
6.1
5.3
3.9
1.2
0.3
0.2
0.1
8.0
8.0
8.1
7.6
8/19
10:00
hrs
6.3
6.3
6.4
6.4
6.8
5.4
1.9
0.7
0.2
0.2
0.2
7.4
7.4
7.3
7.2
16:00
hrs
6.8
6.7
6.6
6.1
6.2
5.4
2.9
0.7
0.2
0.2
0.2
8.8
8.5
8.5
10.0
9.5
8/20
11:30
hrs
7.1
7.0
7.0
6.7
6.6
6.0
3.1
0.3
0.2
0.2
8.8
8.3
8.2
9.0
9.0
15:00*
hrs
7.7
7.6
7.6
7.7
7.1
6.5
4.1
0.6
0.3
0.2
9.5
9.3
9.3
9.0
7.9
to
ON
* Lake is stirred up for 45 minutes by a 260 H.P. motor engined boat.
-------
Table 11. TEMPERATURE PROFILES AT LAKE MIZELL DURING AUGUST 1973
LOCATION
Sl
DEPTH
ft
1
2
3
5
7
8
9
10
11
12
13
14
15
20
TEMPERATURE °C
8/05
11:30
hrs
29.0
29.0
29.0
28.5
28.5
28.5
28.0
28.0
15:00
hrs
31.0
30.5
29.5
28.5
28.5
28.5
28.0
28.0
28.0
8/06
13:30
hrs
30.0
30.0
28.5
28.0
28.0
27.5
8/07
17:00
hrs
30.5
30.0
29.0
29.0
28.5
28.0
27.5
8/11
9:00
hrs
29.2
29.2
29.2
29.0
29.0
29.0
28.5
28.0
16:00
hrs
30.5
30.5
30.5
30.0
29.5
29.0
28.5
8/14
13:30
hrs
31.0
30.5
30.0
29.5
29.5
29.0
29.0
29.0
28.5
28.0
8/16
14:00
hrs
31.0
31.0
30.2
30.0
30.0
29.7
29.3
29.0
29.0
29.0
28.5
8/19
9:00
hrs
29.5
29.5
29.5
29.0
28.5
14:30*
hrs
30.5
30.5
30.0
30.0
30.0
29.5
29.0
28.5
8/20
11:00
hrs
30.0
30.0
30.0
29.5
29.0
29.0
28.5
28.0
8/21
13:30
hrs
30.4
30.2
29.8
29.7
tvj
--J
* The lake was stirred up by a 260 H.P. motor engined boat for 1.5 hours.
-------
Table 12. TEMPERATURE PROFILES AT LAKE OSCEOLA DURING AUGUST 1973
LOCATION
S3
S4
*T
DFPTO
J^/UJT XI 1
ft
1
2
3
4
5
6
7
8
9
10
1
3
5
7
8
10
12
13
14
15
16
17
18
20
TEMPERATURE °C
8/05
10:30
hrs
29.0
28.5
28.5
28.0
29.0
29.0
28.5
28.5
28.5
28.0
28.0
28.0
16:30
hrs
29.5
29.5
29.5
29.0
30.5
30.0
29.5
29.0
29.0
29.0
29.0
28.5
28.5
8/06
15:00
hrs
30.0
30.0
28.5
28.5
30.0
30.0
29.5
29.0
28.5
28.0
28.0
28.0
28.0
8/07
15:00
hrs
30.5
30.0
29.5
29.0
29.0
29.0
28.5
28.5
28.0
8/09
35:00
hrs
31.0
30.5
30.0
29.5
31.0
30.0
29.5
29.2
29.0
28.5
28.3
28.0
8/11
10:00
hrs
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
28.5
28.5
16:30
hrs
30.5
30.0
30.0
30.0
29.5
29.0
30.5
30.5
30.0
30.0
29.5
29.0
28.5
28.0
8/14
14:00
hrs
31.0
30.5
30.5
29.5
29.5
20.5
30.0
29.5
29.0
29.0
29.0
29.0
27.5
8/19
10:00
hrs
29.5
29.5
29.5
29.5
29.5
29.5
29.5
29.5
29.0
29.0
29.0
15:00
hrs
31.0
31.0
30.5
29.5
31.0
30.5
30.5
30.0
29.5
29.0
29.0
8/20
11:00
hrs
30.0
30.0
29.5
29.5
30.0
30.0
30.0
29.7
29.2
29.0
29.0
14:00*
hrs
31.0
31.0
30.0
29.5
30.0
30.0
30.0
30.0
29.5
29.0
29.0
00
* Lake is stirred up for 45 minutes by 260 H.P. motor engined boat.
-------
Table 13. TEMPERATURE PROFILES AT LAKE MAITLAND DURING AUGUST 1973
LOCATION
S6
\J
s
5
DFPTH
UL-tF 11 1
£t
1
3
5
7
10
12
15
18
20
22
25
28
30
1
3
5
6
7
TEMPERATURE °C
8/05
9:30
hrs
28.5
28.5
28.0
28.0
26.5
25.0
22.0
21.5
29.0
29.0
29.0
29.0
17:00
hrs
29.5
29.0
29.0
28.5
28.5
28.0
28.0
24.0
21.5
29.5
29.5
29.5
29.0
8/06
16:00
hrs
29.5
29.0
29.0
29.0
28.5
28.5
28.0
26.5
24.0
23.0
29.5
29.5
29.0
29.0
8/07
14:30
hrs
30.5
29.5
29.0
29.0
29.0
29.0
28.5
28.0
24.0
21.0
30.0
30.0
29.5
29.5
8/09
14:30
hrs
30.5
30.0
29.5
29.2
29.0
29.0
29.0
28.0
27.5
24.0
20.5
30.5
30.0
30.0
29.5
8/11
10:00
hrs
29.0
29.0
29.0
29.0
29.0
29.0
29.0
28.0
27.8
26.0
24.5
22.0
29.0
29.0
17:00
hrs
30.0
30.0
29.8
29.5
29.2
29.0
29.0
29.0
28.2
26.5
24.5
22.5
30.0
30.0
8/14
15:00
hrs
30.5
30.0
29.8
29.5
29.2
29.0
29.0
28.5
28.0
24.5
21.5
31.0
30.0
30.0
8/19
10:00
hrs
29.5
29.5
29.5
29.5
29.5
29.0
29.0
28.0
24.5
23.0
29.5
29.5
29.5
29.5
16:00
hrs
30.5
30.5
30.0
29.5
29.0
29.0
29.0
27.5
24.5
23.0
31.0
31.0
31.0
30.5
30.0
8/20
11:30
hrs
30.0
30.0
30.0
29.5
29.5
29.0
29.0
28.0
25.8
25.1
30.0
30.0
30.0
30.0
15:00*
hrs
30.5
30.5
30.5
30.5
30.0
29.2
29.0
28.0
24.7
24.5
31.0
31.0
30.2
tSJ
* Lake is stirred up for 45 minutes by a 260 H.P. motor engined boat.
-------
Figure 3. The average increase in DO through the entire depth is 1.07
mg/1 which is equivalent to 3.21 nig/I/hour of boating activity.
The dissolved oxygen emissions in the exhaust gas constituents and mass
emissions retained in water phase for four outboard motors were measured
in recent studies (7). These emissions are dependent on the mode of
operation and the maximum values varied between 1560 grams of CL per
hour of operation for a 4.0 HP motor and 17700 grains per hour for a 65
HP motor. Using the same approach, it is possible to predict the
transfer efficiency of CL to the water phase. However, it is beyond
the scope of this report.
In brief, dissolved oxygen is transferred to the water body from the
atmosphere and the exhaust gas during the operation of engined boats on
lakes. The rate of transfer is dependent on turbulence created by boat,
motor power, water depth and oxygen deficit. It is also believed that
boating activity tends to increase the rate of oxygen uptake by
resuspended organic particles. This increase was responsible for the
decrease in DO concentrations in the lower levels at Lake Mizell on
weekends and following heavy boating activities as shown from Table 8.
30
-------
SECTION VII
RESUSPENSION OF SEDIMENTS
Aquatic sediments are accumulated deposits of settleable and colloidal
organic solids which are permanently water logged and continuously
regenerated by deposition. In shallow, small lakes, the sediments
are formed largely from material brought in from the shoreline,
surrounding swamps, and drainage basins. However, in deeper and large
lakes, the deposits are produced from dead planktonic organisms and
organic material (9).
Sediments as a pollutant and as a transporting agent are found to play
a predominant role in determining the quality of surface waters (15,21).
Settled or suspended sediments may serve as a sink or source for
nutrients and other contaminants. The exchange of elements and compounds
at the water-sediment interface is affected by various physical,
chemical, and biological factors. Investigators found that the influence
of bottom sediments on overlying water quality becomes significant only
when the dissolved oxygen concentration at the water sediment interface
falls below 1 or 2 mg/1 causing a corresponding decrease in electrode
potential in the upper few millimeters of sediment (14). Substantial
quantities of phosphate, silicate, and ammonia along with other elements
such as manganese and iron are . liberated at lower electrode potentials.
Nutrient flux from the sediments of two lakes was investigated^and ++
concluded that 15 to 30 percent of the four major cations (Ca , Mg ,
Na , K ) in lake water resulted from the sediments (14). Also, the
release of organic compounds and nutrients such as phosphates and
ammonia could be retarded by maintaining a minimum dissolved oxygen
concentration of 2 mg/1 in the overlying water (2).
Aquatic sediments and detritus consume oxygen when stirred in aerated
water. Oxygen uptake by thin layers of subsurface sediment show vary-
ing proportions of chemical and biological oxygen consumption. The
oxygen consumption per unit weight is affected by particle size, nature
and amount of organic material, size and metabolism of microorganisms
associated with the sediments, and detritus particles (8). Studies
in Denmark concluded that detritus consumed up to three orders of
magnitude more oxygen per dry weight than sand, and uptake rates were
inversely related to particle diameter and directly related to the
particle organic content. The particulate oxygen uptake rate fell
between 0.1 and 10 mg O^/gm organic matter/hour (8 ). These effects
of agitation from mixing by boating have not been investigated.
31
-------
LAKE SEDIMENTS AFTER BOATING ACTIVITY
In shallow eutrophic lakes, outboard motor boats seem to resuspend
those sediments previously deposited on aquatic plant leaves, stems,
and on the lake bottom. Resuspension of these sediments is affected
by water depth, particle size and composition, motor power, boat charac-
teristics, and condition of the lake.
Areas close to shoreline, particularly those areas with less than 5 feet
of water depth and loose detritus and sludge deposits, show rapid changes
in turbidity due to boating activities.
Limited boating activities on Winter Park Chain of Lakes, Lake Claire,
and Wekiva Springs were conducted. Changes in turbidity measurements,
size of particles in suspension, and resuspension of bottom sediments
have been investigated. However, the effect of agitation attributable
to boating activity on relocation or changes in benthic organisms
have not been studied. It is also interesting to note that motor boats
will chop up aquatic plants which may result in their dispersion over
the entire area of the lake and facilitate their transport from one lake
to another if vegetative reproduction is a part of the species life
history.
A series of underwater photographs were taken to demonstrate
the process of resuspension of sediments by a 50 HP motor boat at
Wekiva Springs, Figures 9, 10 and 11. Wekiva Springs was selected
because the high clarity of its water made photography feasible. The
pictures show a series of exposures before and during motor activity.
It was visibly noticeable that sediments were resuspended from plant
leaves, stems and bottom deposits. The water depth varied between 4
and 8 feet and aquatic plants extend from bottom to top in many areas
of the springs. Preliminary studies showing changes in turbidity and
particle size of suspended solids were performed. The turbidity
increased from 2.3 to 4.5 and 6.5 JTU after operating a 50 HP motor
boat in the springs for 15 minutes. Figure 9 presents various pictures
showing the clarity of water at Wekiva Springs, the size of motor used
and shape of the plumes produced by running the boat. The plume is
shown by a conical shape with a narrow angle. The magnitude and extent
of its influence on the water body is not known. Figure 10 shows a
series of pictures demonstrating the resuspension of bottom sediments
attributed to boating activity at Wekiva Springs. A cloud of bottom
sediments tend to resuspend and then moves away or partially resettle
as the boat leaves the area. Figure 11 shows a closer exposure to the
propeller, plume and bubbles formed. It would have been inter-
esting if these pictures were extended for a number of engine,
propeller, hull and speed combinations to better understand the tur-
bulence induced by motor boat activity. Figure 11 presents a series of
photographs showing the shape of the plume produced from
operation of the propeller attached of a 50 HP motor boat and the
subsequent mixing process at the Wekiva Springs.
32
-------
Figure 9. PHOTOGRAPHS BEFORE AND AFTER OPERATION OF
A 50 H.P. MOTORBOAT ON WEKIVA SPRINGS.
33
-------
Figure 10. PHOTOGRAPHY DEMONSTRATING RESUSPENSION
OF BOTTOM SEDIMENTS FROM OPERATION OF
A 50 H.P. MOTORBOAT.
34
-------
6
Figure II. PHOTOGRAPHS SHOWING THE PLUME FORMATION
AND MIXING PROCESS FROM OPERATION OF A
50 H.P. MOTORBOAT.
35
-------
TURBIDITY
Variations in turbidity caused by resuspension of settled sediments
were determined under various operational conditions of engined boats.
Measurements were taken by Hach 2100 Turbidimeter. Attempts were made
to determine the effects of: A) water depth, B) motor power, C) time of
operation and D) particle size of the resuspended sediments.
A) Water Depth: To study the effect of water depth on turbidity
measurements, a 10 HP engined boat was run across Lake Mizell, Osceola,
and Maitland for a short period of time (less than 1 hour) and samples
were collected from the shallow shore areas and deeper areas at mid-
width. The data collected are presented in Table 14 to Table 16. It
is noteworthy that visible increase in turbidity was observed in shore
areas of less than 5 feet deep after a short period of time (less than
5 minutes). However, longer operation time and more powerful engines
may be required to stir up deeper areas in the lakes.
Data from Table 15 on Lake Osceola showed an increase in turbidity from
2.5 to 22.0 JTU in shore areas while slight increase at mid-width
from 1.7 to 2.0 JTU was noticed. The same basic trend was observed at
Lake Mizell and Lake Maitland.
B) Motor Power: Turbidity measurements associated with running boats
engined with various power motor are presented in Tables 17 and 18.
It appears from the data that the turbidity increases by increasing the
motor power. For example, Lake Claire (S^) showed little or no changes
in turbidity when the boat was equipped with a 28 HP motor. However,
changes in turbidity throughout the entire depth of the lake was noticed
when the boat was equipped with 50 or 115 HP motors. Also, Lake Osceola,
at depths of 6 to 7 feet, a 10 HP motor did not seem to change the
turbidity as indicated in Tables 14 and 16.
From the data presented in Tables 14 to 18, an estimate for the
effective mixing depth from different motor power could be predicted.
The effective mixing depth (FM)) could be defined as the water depth
where the turbidity measurements show a definite increase through out
the entire depth of the lake as noted by surface changes. This would
eliminate sampling errors which may reflect increases in turbidity
of water samples taken close to the bottom. It is also assumed that the
operation time is nearly constant.
The data in Table 19 suggests a direct relationship between the motor
power and effective mixing depth as shown in Figure 12. Of course,
this would depend on other factors such as bottom sediments and speed
of the boat. Figure 12 suggests a strong correlation between EMD and
motor powers provided all other variables are constant.
36
-------
Table 14. WATER QUALITY DETERMINATION AFTER BOATING
ACTIVITY ACROSS LAKE MIZEL
OCTOBER 26, 1974
(10 HP Motor)
LOCATION
West
Shore
s2
Mid-
Width
S1
i
East
Shore
DEPTH
BELOW
SURFACE
Ft
1
2
3
1
2
3
5
7
9
10
12
14
16
1
2
3
PARAMETER
BEFORE BOATING
Temp
6C
25.0
25.0
24.0
24.0
24.0
23.5
23.5
23.2
23.0
23.0
23.0
23.0
24.5
24.0
24.0
D.O.
rag/1
8.8
8.5
7.6
7.5
7.5
7.5
7.2
6.7
6.4
5.2
4.3
3.6
8.0
7.2
6.1
PH
8.1
7.5
7.4
8.25
8.25
Turb
JTU
3.9
2.7
4.5
2.3
Cond.
limbos
on
308
292
287
298
OP
mg/1
P
.03
.025
.025
.035
AbThK BUATINU
Temp
°C
24.5
24.5
24.5
24.0
24.0
24.0
23.8
23.5
23.0
23.0
23.0
23.0
23.8
23.8
23.8
D.O.
mg/1
7.2
6.7
6.0
7.4
6.8
6.6
6.3
5.7
4.7
4.5
4.2
3.8
7.0
6.6
6.3
PH
7.6
7.2
7.2
7.1
Turb
JTU
28.0
1.5
22
5.5
(Jond.
y mhos
cm
290
290
287
290
OF
mg/1
P
0.11
.05
.075
.055
-------
Table 15. WATER QUALITY DETERMINATION AFTER BOATING
ACTIVITY ACROSS LAKE OSCEOLA
OCTOBER 11, 1974
(10 HP Motor)
LOCATION
South
Shore
Mid-
Width
S3
North
Side
DEPTH
BELOW
SURFACE
Ft
1
2
3
4
1
2
3
4
5
6
7
1
2
3
4
PARAMETER
BEFORE BOATING
T*r
27.0
27.0
27.0
27.0
27.5
27.3
27.3
27.2
27.0
27.0
27.0
27.0
27.0
27.0
27.0
D.O.
mg/1
4.7
3.9
3.2
3.0
6.9
6.5
6.5
3.3
2.1
2.1
2.1
6.9
6.5
—
6.5
pH
6.1
7.3
7.6
Turb
JTU
2.5
1.7
2.3
Phos]
mi
Ortho
.03
.025
.03
ahorus
I/I
Total
.04
.03
.04
AfrTfcK BOATING
T^
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
27.0
D.O.
mg/1
8.0
7.6
6.0
5.7
8.0
8.0
8.0
7.3
6.5
6.0
5.5
7.7
6.5
—
6.1
pH
7.6
7.6
7.6
Turb
JTU
22.0
2.0
23.0
Phosphorus
•K/l
Ortho
.05
.03
.12
Total
.05
.05
.37
oo
-------
Table 16. WATER QUALITY DETERMINATION AFTER BOATING
ACTIVITY- ACROSS LAKE MAITLAND
OCTOBER 26, 1974
(10 HP Motor)
LOCATION
Bush
Mid-
Width
S5
Isle
of
Sicily
DEPTH
BELOW
SURFACE
Ft
1
3
5
7
1
2
3
5
7
1
2
3
5
PARAMETER
BHt'Okt BOATING
Temp
°C
24.5
24.5
23.5
23.0
24.0
24.0
24.0
23.5
23.0
24.0
23.5
23.5
23.5
D.O.
mg/1
7.8
7.8
6.8
7.2
7.6
7.2
7.0
6.7
7.1
7.3
6.7
6.7
6.5
PH
7.6
8.2
7.95
Turb
JTU
0.7
1.5
8.0
0.5
Cond.
ymhos
cm
216
215
210
OP
mg/1
P
.015
.02
.05
.015
AhThK BOATING
Temp
c
24.0
24.0
24.0
24.0
24.5
24.5
24.5
24.0
23.5
24.0
24.0
24.0
D.O.
mg/1
8.4
7.9
7.5
7.2
7.8
7.5
7.1
6.8
7.7
7.2
7.0
6.6
PH
8.2
8.2
8.0
Turb
JTU
1.2
0.7
30
2.7
.
Cond.
Vimhos
cm
217
210
225
225
OP
mg/1
P
.01
.01
.055
.02
to
-------
Table 17. TURBIDITY MEASUREMENTS BEFORE AND AFTER
BOATING ACTIVITY
LAKE §
SAMPLING
LOCATION
Osceola1
S3
Maitland1
S5
Mizell1
Sl
Osceola1
s.
o
Claire2
s7
/
Osceola3
Shore
f£
Shore
Mizell
S2
Shore
Maitland
Shore
Shore
Claire1*
S7
/
So
8
DATE
June 26
June 26
July 5
July 5
Sept 18
Sept 20
Oct 11
Oct 26
Nov 4
TIME
1030
1100
1400
1430
1630
1630
1100
1400
1500
930
DEPTH
ft
1
r
1
1
5
1
10
1
10
1
1
1
1
1
15
1
1
6
1
1
10
1
4
MOTOR
POWER
HP
100
100
100
100
100
28
10
10
10
115
TURBIDITY, JTU
Before
Boating
1.6
1.2
3.0
1.8
4.0
1.7
1.7
2.3
2.8
2.5
1.7
2.3
3.0
2.7
4.5
2.3
1.5
8.0
0.5
5.3
6.6
5.5
6.5
After
Boating
2.1
3.2
2.8
7.0
8.0
1.8
1.9
2.3
2.7
*
22.0
2.0
23.0
28.0
1.5
22.0
5.5
0.7
30.0
2.7
5.5
8.0
14.0
12.0
1 20-minute boating
2 Boating for 20 hours at intervals
3 Boating for 30 minutes across the lake
4 One hour boating
40
-------
Table 18. TURBIDITY MEASUREMENTS BEFORE AND AFTER
CESSATION OF BOATING ACTIVITY
LAKE $
SAMPLING
LOCATION
Claire1
s7
/
s
°
c 2
7
1
c 3
7
/
'
S8
O
Mizell1*
Sl
J.
S2
fa
DATE
Nov 24
Dec 12
Dec 21
Dec 26
TIME
1400
WATER
SAMPLE
DEPTH
ft
1
3
6
9
10
1
3
1
3
6
9
10
1
3
6
9
11
1
3
1
3
6
9
12
15
1
3
MOTOR
POWER
HP
28
50
50
TURBIDITY, JTU
Before
Boating
6.5
5.0
4.7
6.7
13.0
4.5
4.5
5.8
6.0
6.8
6.8
6.1
6.4
6.5
6.3
6.0
1.4
1.6
1.3
1.6
1.9
—
2.3
2.0
After
Boating
6.5
6.0
6.5
11.5
15.0
8.0
10.0
6.5
6.5
6.5
7.0
6.5-
7.5
7.8
8.0
8.0
9.5
9.5
22.0
2.4
2.4
2.4
2.0
2.0
2.4
3.4
13.0
One Hour
After
Cessation
of Boating
5.8
6.2
6.0
2.0
1.7
1.9
2.5
1 Four hour boating
2 Five hour boating
3 Four hour boating
11 Three hour boating
41
-------
Table 19. CHANGES IN MIXING DEPTH AS RELATED
TO CHANGES IN MOTOR POWER
LAKE
Claire
Osceola
Claire
Mizell
SAMPLING
LOCATION
S7
S3
S7
Sl
DATE
Sept. 18
Oct. 26
Nov. 4
Dec. 26
EMD
" Ft.
10
6
10
15
M.
3.0
1.8
3.0
4.6
MOTOR
POWER
HP
28
10
28
50
It is also important to notice that the turbidity showed a noticeable
decrease one hour after cessation of boating activities as shown in
Table 18. It must be understood that colloidal particles and their
relocation have not been studied.
C) Operational Time: The extent of the effects of motor boat activity
on water quality parameters would be influenced by the time of running
the boat. Naturally, the resuspended solids are limited by their
availability at the bottom or on plant leaves and stems.
An interesting experiment was run at Lake Claire while the boat was
stationary. A 50 HP motor equipped boat was tied to a tree and was
held stationary in the lake at distances 10 to 100 feet from the shore.
The motor was allowed to run and water samples were collected from
boat side at different time intervals. The data collected are presented
in Table 20.
The data shown in Table 20 shows that turbidity at Sg increases in the
vicinity of the boat area within the first five minutes of operation.
However, by operating the motor boat for 30 minutes, the resuspended
solids evidently were transported away from the area by prop wash
currents. The same phenomenon was observed on February 28 and March
5th. The turbidity seems to increase in the vacinity of the boat to
reach a maximum value which is followed by a decline as the operational
time increases.
42
-------
15
20 30 40
MOTOR POWER, H.P.
50
FIGURE 12-RELATIONSHIP BETWEEN MOTOR
POWER OF ENGINED BOATS AND MIXING
DEPTH IN LAKES
43
-------
Table 20. EFFECT OF OPERATIONAL TIME ON TURBIDITY
MOTOR
POWER
"HP"
50
50
LAKE
Claire
Claire
DATE
Mar. 5, 1974
Feb. 28, 1974
LOCATION
S8
S8
S7
DEPTH
Ft.
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
5.0
5.0
OPERA-
TIONAL
TIME
Min.
0
5
30
60
0
30
0
30
0
30
TURBID-
ITY
JTU
6.5
8.3
5.6
5.5
8.4
6.5
7.0
5.5
7.5
8.0
D) Particle Size: Water samples collected before and after boating in
Lake Claire, Mizell, and Wekiva Springs were microscopically examined
using the Bausch and Lomb Dunazoom Research Laboratory Microscope and
Integrated Camera Series. The microscope was calibrated using a stage
micrometer with two millimeter range and each millimeter is divided
into 100 deviations as shown in the picture on Figure 13. The mean
and range of particle size diameter of sediments in five portions of
each water sample were determined.
Figures 13 to 15 show the change in concentration and particle size
of suspended particles on Lake Claire and Lake Mizell. Also, a picture
of nonfilterable residue on a millipore filter paper from 50 ml water
sample before and after boating activity at Lake Mizell is shown in
Figure 15. This figure reflects the change in suspended solids at the
shore area of Lake Mizell after running a 50 HP motor boat. The
pictures show a definite increase in suspended solids concentration and
particle size. It seems reasonable to assume that resuspended solids
are generally larger in size or coagulation of particles may take place
after mixing. Relocation of colloidal particles and mixing of plankton
44
-------
—
-.
00 Qi 02 03 a4 OS 06 Q7 OJ 09 LO
FIGURE 13. PARTICLE SIZE OF RESUSPENDED SEDIMENTS DUE TO BOATING ACTIVITIES,
-------
(a) One Foot Below Surface Shore Area, So
(b) Five Feet Below Surface, S6
FIGURE]/!. RESUSPENSION OF SEDIMENTS BY 28 HP MOTORBOAT
AT LAKE CLAIRE, ON JAN. 31, 1974.
-------
FIGURE 15. MILLIPORE FILTER RESIDUE FROM 50 ml LAKE MIZELL WATER
BEFORE AND AFltR BOATING AT SHORE AREA.
-------
within the water column and their impact on the ecological system in
the lake have not been investigated. Assumably, distribution
characteristics of biota within the entire depth of the lake will be
influenced by agitation from mixing by motor boats.
Particle sizes of resuspended sediments from Lake Mizell and Lake Claire
are presented in Table 21. The resuspended particles are generally less
than 0.1 millimeter diameter except in shallow areas close to the
shore where the resuspended particle size may reach a maximum of 0.3
mm. There appears to be a direct relationship between resuspended par-
ticle size and turbidity values.
48
-------
Table 21. PARTICLE SIZE OF LAKE CIAIR AND LAKE MIZELL SUSPENDED SOLIDS
DATE
Jan 31, 1974
Feb 28, 1974
Mar 5, 1974
Dec 26, 1974
LOCATION
CLAIR
S7
S8
S7
S8
S8
MIZELL
Sl
S2
DEPTH
Ft
1
5
1
1
5
1
1
1
3
6
9
12
15
1
3
4
MOTOR
POWER
HP
28
28
50
50
50
50
OPERATION
TIME
Min.
30
5
30
30
5
30
60
180
FAKIJLLLE bl£t mm
BEFORE BOATING
Mean
.02
.03
.038
.02
.038
.023
.085
UD**
UD**
0.1
.01
.01
Range
.01-. 04
.01-. 05
.01-. 07
.01-. 05
.01-0.1
.01-. 05
.05-0.2
UD**
UD**
.03-0.3
Very Few
Very Few
AFTER BOATING
Mean
.037
.045
0.12
.048
.062
.062
0.19
.03
.028
.018
.016
.014
.016
.026
.028
.028
.095
Range
.02-. 08
.02-0.1
.05-. 30
.02-0.15
.03-0.2
.03-0.2
.05-0.5
.01-0.08
.01-0.1
.01-. 05
.01-. 05
.01-. 05
.01-. 05
.01-. 05
.01-0.10
.01-. 05
.05-. 15
** UD is undetectable.
-------
SECTION VIII
NUTRIENTS
Lake sediments concentrate nutrients from cyclical decay of planktonic
material that sinks to the bottom and from runoff and wastewater efflu-
ents discharged into the water body. Nutrients may be released back to
water and lake sediments may act as a reservoir supplying the overlying
water with sufficient nutrients for autotrophic activity (3). Nutrients
of particular concern are nitrogen and phosphorus. However, carbon, iron
and other elements could be growth limiting in some cases. It is also
realized that the substance in least abundance in the environment rela-
tive to the need of any organism will limit the total crop of the organism
(10). Consequently, algal blooms, could occur in limited areas of the
lake where nutrients, light, and temperature are adequate.
MIXING OF LAKE WATER
The epilimnion and the underlying hypolimnion may exist as two separate
zones with little or no mixing. This is largely due to the density
gradient separating the two zones which imposes limitations on exchanges
of heat and dissolved material (1). Agitation and mixing of these zones,
especially in shallow lakes, will evenly distribute the nutrients through
the water column and may sustain a more productive ecosystem. Numerous
investigators have noted general increases in phytoplankton abundance dur-
ing destratification. On the other hand, intermittent water colum mixing
and continuous destratification have been successful, in some cases, in
decreasing phytoplankton abundance, at least on a temporary basis (13).
Most fresh-water phytoplankton have 1.01 to 1.03 specific gravity, thus
are heavier than the medium in which they float (11). As a result, they
will sink slowly when placed in undisturbed water and their growth is
limited by the available nutrients in the immediate surroundings. However,
turbulent water permits more rapid nutrient uptake and so faster division
than would be possible for a stationary cell(ll). The nature and signifi-
cance of nutrient interchange between sediments and overlying water is not
clearly defined. The rate of nutrient interchange is affected by the water
movement and sediment transport which also affects benthos. Changes in
abundance of several dominant species of benthos were observed in shallow
waters during destratification (13).
50
-------
EXPERIMENTATION AND RESULTS
During the course of this study, organic and inorganic carbon concentra-
tions, Ortho and total phosphorus measurements and total Khjeldahl
nitrogen were analyzed for samples of lake water at various levels before
and after limited boating activity. Also, the fraction of nutrients
associated with suspended solids and fractions in solution were deter-
mined.
Changes in nutrient concentrations on Lakes Mizell, Osceola, Maitland,
and Claire are presented in Tables 22 to 25. The average nutrient con-
centrations are summarized in Table 26. The average values include
samples taken before and after boating activity and also include samples
taken one foot below the water surface and one foot above the bottom
sediments. The high concentration of phosphorus presented in Table 26
is mainly attributed to the higher concentration in the water samples
above the bottom sediments. The data indicates that the increase in
trubidity after limited boating activity is generally associated with
a similar increase in organic carbon and phosphorus concentrations.
The data presented in Tables 22 and 23 shows that the phosphorus content
in most of the water samples taken one foot above the bottom of the lake
is several times higher than the phosphorus content in samples taken one
foot below water surface. This is particularly true in deep sampling
locations on the lakes, S, and S., where the DO content is minimal. It
is known that the distribution of phosphorus in a water column of a lake
is generally not homogeneous (6). The dissolved phosphates tend to
reach uniform concentration throughout the column; however, particulate
phosphate compounds counteract this tendency. This seems to agree with
the data presented in Table 27. Filtered water samples taken from Lake
Mizell and Lake Claire throughout the water column exhibited fairly uni-
form concentration of phosphorus after filtration through 0.45 urn milli-
pore filter. It is also obvious that most of the phosphorus concentration
is associated with the suspended solids in the water samples. Before
boating an average orthophosphate in the filtrate was 0.006 mg/1 "P" as
compared to 0.029 mg/1 in the non-filtered samples. After boating acti-
vity the average has increased to .01 mg/1 in the filtrate and 0.034
mg/1 in the non-filtered samples as shown in Table 27. It is believed
that boating activity tends to increase the dissolved and particulate
phosphates in the water column in shallow lakes at least on a temporary
basis. The dissolved orthophosphate averaged 21 to 291 of that present
in water samples.
Twenty-four samples were taken from Lake Claire on December 11 to Dec-
ember 14 showed that the dissolved organic carbon averaged 5.2 mg/1 as
compared to 0.6 mg/1 associated with suspended solids. Most of the or-
ganic carbon is found in solution and amounts to 90% of the total
organic carbon.
51
-------
Table 22. NUTRIENTS IN WATER SAMPLES FROM LAKE MIZELL
DATE
6/26
7/5
7/17
8/5
8/11
8/14
8/16
8/19
8/22
12/26
1/3
1/4
TIME
9:30
14:00
14:00
11:30
15:30
9:15
16:00
13:30
13:45
14:45
9:15
14:35
13:00
12:15
LOCA-
TION
Sl
si
1
Sl
Sl
i
S1
1
Sl
ST
1
S1
1
Si
1
S1
i
S-
2
Sl
_L
s->
2
S1
1
S,
2
DEPTH
Ft
1
1
10
1
1
1
1
1
1
1
1
1
1
15
1
15
}
15
1
3
6
9
12
15
1
3
1
3
6
9
12
15
1
3
1
15
1
3
CARBON
,«tj/l "C"
1C
13.2
11.0
11.5
11.0
10.8
10.7
10.1
10.8
11.8
10.4
11.0
11.2
10.4
12.8
10.4
10.0
11.1
13.8
OC
7.5
7.2
7.0
6.5
8.4
6.7
6.7
7.4
6.2
7.4
7.8
7.2
8.6
25.2
7.1
22.5
8.9
10.9
TKN
mg/1
"N"
--
0.3
--
0.2
0.4
0.56
0.5
1.5
.45
.30
.30
.44
.56
.42
.44
1.2
1.3
.86
,78
.76
.86
.82
2.62
0.75
0.82
0.86
0.73
0.8
1.16
0.82
0.82
1.16
1.76
0.82
0.73
0.92
0.75
PHOSPHORUS
mg/1 "P"
OP
0.12
0.06
0.10
0.06
.04
.025
.03
.03
0.8
.025
.031
.01
0.02
0.03
0.02
0.53
0.03
0.06
.015
.02
.01
.005
.005
0.15
.01
.01
.01
.01
.01
.01
.015
.015
.01
.02
.005
.007
.005
.007
TP
--
0.2
0.16
0.2
.05
--
--
--
--
--
--
--
0.1
.32*
.06
.75*
.12
.12
.025
.028
.025
.022
0.03
0.35
.015
.03
.02
.01
.02
.03
.02
.03
.02
.02
.015
.02
REMARKS
After 20 min boat-
ing- 100 HP motor
After 1 hour boat-
ing -35 HP motor
After 45 min boat-
ing- 260 HP motor
k
After boating-
50 HP motor
* High phosphorus content in samples taken one foot above the bottom.
52
-------
Table 23. NUTRIENTS IN WATER SAMPLES FRCM LAKE OSCEOLA
DATE
7/26
7/5
7/17
7/24
7/31
8/5
8/7
8/9
8/11
8/14
8/19
8/20
8/22
10/11
TIME
10:30
14:30
13:30
15:00
14:30
11:00
16:00
14:30
15:00
10:00
16:30
14:00
9:45
13:45
15:00
11:00
LOCA-
TION
S3
J
S3
J
S3
«j
S4
*T
S4
S3
S4
S4
•*
S4
S4
S4
S4
*T
S4
S4
*T
S4
^
S3
*J
Shof'e
Area
S3
Shore
Area
DEPTH
Ft
1
1
1
5
1
5
1
8
1
10
1
16
1
1
1
1
1
1
1
1
1
1
16
1
16
1
8
1
16
1
1
1
CARBON
mg/1 "C"
1C
18.8
18.9
15.8
15.8
15.0
18.0
15.0
15.7
14.6
14.5
14.1
14.1
15.1
14.4
14
13.9
13.4
12.6
14.3
13.0
14.5
18.2
13.6
16.0
17.1
14.0
15.4
14.2
14.0
[_ OC
2.7
2.6
1.8
3.2
5.5
TKN
mg/1
"N"
i n
.1. . \t
Ojc
. £3
_
, 9 U.JU
S.t
7.6
7.3
6.2
5.5
3.9
4.7
3.8
4.2
5.0
4.3
3.5
3.6
5.3
8.3
6.5
5.6
7.0
2.0
4.9
6.0
5.0
6.5
6.0
n n^
u • uj
n n^
\J . U O
0.18
0.3
0.42
0.5
0.4
--
0.18
0.4
0.5
0.5
0.32
0.4
0.42
0.4
1.50
1.60
1.6
1.6
PHOSPHORUS
mg/1 "P"
OP
.05
0.08
.08
0.14*
0.25
0.56*
0.05
0.03
0.02
0.02
0.02
3.3*
0.02
.025
.02
0.02
.015
.015
.015
0.01
0.03
0.03
1.0*
0.03
.38*
.02
.03
.02
.02
.025
.03
.03
0.12
TP
.07
0.10
0.14
0.21
0.34
0.61
0.11
.05
0.05
0.06
0.04
3.5
--
--
--
--
--
--
--
--
--
0.06
1.13
0.06
0.75
0.12
0.12
0.13
0.13
.03
.05
.05
0.37
REMARKS
After 20 min boat-
ing- 120 HP motor
After 20 min boat-
ing- 100 HP motor
Exceptionally high
"P" in filtered
samples
After 45 min boat-
ing -260 HP motor
After 30 min boat-
ing- 10 HP motor
* High phosphorus content in samples taken one foot above the bottom.
53
-------
Table 24. NUTRIENTS IN WATER SAMPLES FROM LAKE MAITLAND
DATE
6/26
7/05
7/12
7/17
7/31
8/05
8/07
8/09
8/11
8/14
8/19
8/20
8/22
TIME
1100
1500
1400
1600
1330
1000
1630
930
1700
1415
1415
1015
1645
1430
1015
1630
1600
LOCATION
S5
S5
S5
S5
S5
S6
S5
S6
sfi
S6
bs
S6
S6
S6
S6
S6
S5
S6
DEPTH
ft
1
1
1
5
1
6
1
7
1
7
1
10
1
1
1
10
1
1
1
1
1
1
1
1
1
1
CARBON,
mc/1
1C
17.3
17.0
15.0
15.0
15.8
15.4
15.1
15.0
14.0
13.6
12.0
12.2
14.3
13.3
13.6
12.7
13.1
13.0
12.4
15.6
11.3
13.6
12.6
12.0
14.5
14.7
OC
2.3
3.9
5.0
20
6.6
7.0
6.5
9.8
5.0
4.6
4.5
5.1
4.4
4.4
5.2
4.7
2.9
1.8
3.7
5.8
7.9
7.0
6.6
5.5
4.8
4.3
TKN,
mg/1
"N"
0.45
0.25
0.25
0.20
0.30
0.40
0.42
0.42
1.60
0.25
0.30
0.15
0.20
0.20
0.08
0.40
0.22
1.80
0.20
PHOSPHORUS ,
mg/1 "P"
SP
0.04
0.06
0.04
0.26
0.02
0.05
0.03
0.06
0.01
0.01
.005
0.01
.015
0.02
.015
.025
0.01
.015
.015
.015
0.03
0.01
0.01
0.01
0.03
0.01
TP
0.08
0.08
0.13
0.57
0.05
0.06
0.10
0.11
0.09
0.06
0.14
0.14
REMARKS
After 20 min.
boating - 100
HP motor
After boating
45 min. - 260
HP motor
High phosphorus content in samples taken at one foot above the bottom.
54
-------
Table 25. NUTRIENTS IN WATER SAMPLES FROM LAKE CLAIRE
DATE
AND
LOCATION
9/18,8-
/
9/20 ,8-
/
11/04 ,8-
/
So
o
12/11,8-
/
So
8
12/11,8-
/
SQ
8
12/12,8-
/
SR
o
DEPTH
ft
1
10
1
10
1
10
1
4
1
3
6
9
10
1
3
6
9
1
3
1
6
9
1
3
BEFORE BOATING
CARBON,
mg/1 C
1C
0.8
0.9
0.9
0.7
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.6
0.6
0.5
0.5
0.5
0.5
OC
3.3
5.2
3.7
3.1
4.5
5.1
4.6
4.4
5.4
5.1
6.5
7.1
4.9
4.8
5.3
5.2
4.5
TKN,
rag/1
N
0.24
0.22
0.24
0.22
0.07
0.31
1.24
0.31
0.22
0.24
0.54
PHOSPHORUS,
mg/1 P
OP
.005
.02
.005
.012
.03
.035
.03
.035
.01
.015
.015
.01
.05
.04
.045
.04
.035
.025
.035
.04
.03
TP
.03
.06
.03
.03
.035
.04
.035
.06
.16
.075
.075
.045
.065
.037
.065
.05
.04
AFTER BOATING
CARBON
mg/1 C
1C
0.8
0.8
0.7
0.8
0.6
0.6
0.6
0.6
0.6
0.6
0.6
OC
2.8
3.6
3.0
4.3
6.9
5.7
5.9
7.4
5.7
7.7
6.0
TKN,
mg/1
N
0.22
0.28
0.32
0.32
0.33
0.35
0.12
0.22
PHOSPHORUS
mg/1 P
OP
.008
.03
.012
.018
.065
.01
.065
.10
.02
.023
.04
.02
.02
.06
TP
.015
.07
.07
.04
.085
.01
.075
.13
.05
.055
.08
.04
.06
.12
REMARKS
Boating - 25 HP motor
Boating - 50 HP motor
One hour after cessation
of boating
19 hours after cessation^
of boating
en
-------
Generally, organic carbon and phosphorus seemed to increase in water
samples taken after boating activity. However, total Khjeldahl nitrogen
data did not reflect any specific pattern. It must also be realized
that this study is limited in scope and budget and more research is needed
to investigate the significance and nature of the changes in nutrient con-
centrations due to agitation from motor boats.
Table 26. SUMMARY OF NUTRIENT CONCENTRATIONS IN LAKE WATER SAMPLES
LAKE
Mizell
Osceola
Mai t land
Claire
CARBON,
mg/1 C
1C
11.2
15.9
14.0
0.6
OC
9.4
4.9
5.7
4.9
TKN
mg/1 N
0.8
0.6
0.4
0.35
PHOSPHORUS
mg/1 P
OP
0.07
0.20
0.03
0.03
TP
0.10
0.35
0.13
0.05
56
-------
Table 27. DISSOLVED AND PAKTICULATE PHOSPHORUS
LAKE
AND
LOCATION
Mizell^
S2
Sl
S2
Claire, S7
S8
DATE
12/26
1/04
11/24
DEPTH
ft
1
3
6
9
12
15
1
3
1
15
1
3
1
3
6
9
11
1
3
Average Concentration,
mg/1 "P"
PHOSPHORUS CONCENTRATION, mg/1 P
Before Boating
Filtered
OP
.003
.005
.005
.005
.003
.003
.008
.003
.02
.005
.01
.005
.005
.005
.006
TP
Non- Filtered
OP
.008
.01
.01
.008
.015
.01
.008
.04
.04
.04
.045
.085
.03
.05
.029
TP
.01
.02
.02
.01
.02
.01
.015
.014
After Boating
Filtered
OP
.005
.01
.005
.005
.003
.005
.005
.005
.005
.003
.005
.007
.015
.02
.065
.005
.01
.005
.02
.01
TP
.015
.025
.015
.01
.02
.025
.02
.01
.02
.015
.015
.018
Non- Filtered
OP
.015
.01
.01
.01
.015
.013
.01
.02
.018
.015
.01
.01
.055
.05
.095
.08
.1
.06
.055
.034
TP
.02
.03
57
-------
REFERENCES
1. Blanton, Jackson 0., "Vertical Entrainment into the Epilimnia of
Stratified Lakes," Limnology and Oceanography, Vol. 18, No. 5
(September 1973).
2. Fillos, J. and A. H. Molog, "Effect of Benthel Deposits on Oxygen
and Nutrient Economy of Flowing Waters," Journal, Water Pollution
Coutrol Federation, Vol. 44, page 644 (1972).
3. Fitzgerald, G. P., "Aerobic Lake Muds for the Removal of Phos-
phorus from Lake Waters," Limnology and Oceanography, Vol. 15, No.
4, pp 550-555 (July 1970).
4. Florida Board of Conservation, Division of Water Resources, "Florida
Lakes: Part III, Gazetteer," Tallahassee, Florida (1969).
5. Florida Department of Natural Resources, "Boats Registered in 1971-
1972," Private Communication (July 2, 1973).
6. Golterman, H. L., "Vertical Movement of Phosphate," Environmental
Phosphorus Handbook, John Wiley § Sons, pp 509-534 (1973).
7. Hare, Charles T. and Karl J. Springer, "Exhaust Emissions from Un-
controlled Vehicles and Related Equipment - Usage Internal Combus-
tion Engines, Part 2 - Outboard Motors," EPA Contract No. EHS-70-
108, APTD-1491, Southwest Research Institute, San Antonio, Texas
(January 1973).
8. Hargrave, Barry T., "Aerobic Decomposition of Sediment and Detritus
as a Function of Particle Surface Area and Organic Content," Lim-
nology and Oceanography, Vol. 17, p 583 (1972).
9. Hesse, P. R., "Phosphorus in Lake Sediments," Environmental Phos-
phorus Handbook, John Wiley $ Sons, p 573 (1973).
10. Hutchinson, G. E., "Eutrophication - The Scientific Background of
a Contemporary Practical Problem," American Scientist, Vol. 61,
pp 269-279 (May-June 1973).
11. Hutchinson, G. E., "A Treatise on Limnology - Volume II, Introduction
to Lake Biology and the LimnoplanktonV J°hn Wiley § Sons, p 302
(May 1967).
12. Jackivicz, Thomas P. and Lawrence N. Kuzminski, "A Review of Out-
board Motor Effects on the Aquatic Environment," JWPCF, Vol. 45,
No. 8, p 1759 (August 1973).
58
-------
13. Lackey, Robert T., "Bottom Funa Changes During Artificial Reservoir
Destratification," Water Research, Pergamon Press, Vol. 7, pp 1349-
1356, printed in Great Britain (1973).
14. Lerman, A. and G. J. Brunskill, "Migration of Major Constituents
from Lake Sediments into Lake Water and Its Bearing on Lake Water
Composition," Limnology and Oceanography, Vol. 16, p 880 (1971).
15. Mortimer, C. H., "Chemical Exchanges Between Sediments and Water
in the Great Lakes - Speculations on Probable Regulatory Mechanisms,"
Limnology and Oceanography, Vol. 16, p 387 (1971).
16. "Methods for Chemical Analysis of Water and Wastes," Environmental
Protection Agency, National Environmental Research Center, Analytical
Quality Control Laboratory, Cincinnati, Ohio (1971).
17. Osborne, John A., "Limnological Studies on Lake Claire," Florida
Technological University, unpublished report (1973).
18. Shanon, Earl E. and Patrick L. Brezonik, "Eutrophication Analysis:
A Multi-variate Approach," Journal of Sanitary Engineering Division,
Proceedings of the American Society of Civil Engineers, Vol. 98,
No. SA1, pp 37-57 (February 1972).
19. Shannon, Earl E. and Patrick L. Brezonik, "Limnological Character-
istics of North and Central Florida Lakes," Limnology and Oceano-
graphy, Vol. 17, pp 97-109 (January 1972).
20. "Standard Methods for the Examination of Water and Wastewater,"
Thirteenth Edition, APHA, AWWA and APCF, New York (1971).
21. Task Committee, "Influences of Sedimentation on Water Quality: An
Inventory of Research Needs," Journal Hydraulic Division, Proceed-
ings American Society of Civil Engineers, Vol. 97, p 1203 (1971).
22. Wells, H. H., "Power Boats Operated in the Winter Park Chain of
Lakes," Winter Park Police Department, Private Communication (July
20, 1973).
59
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-670/2-74-Q72
3. RECIPIENT'S >CCESSION-NO.
4. TITLE AND SUBTITLE
ASSESSING EFFECTS
BOATING ACTIVITY
ON WATER QUALITY BY
5. REPORT DATE
October 1974;Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Yousef A. Yousef
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Florida Technological University
College of Engineering
P. 0. Box 25000
Orlando, Florida 32816
10. PROGRAM ELEMENT NO.
1BB038
11. CONTRACT/GRANT NO.
68-03-0290
12. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final. June 1973 - June 1974
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This research study was directed towards an assessment of effects on water quality in
shallow water bodies (less than 30 feet deep) due to mixing by boating activity. De-
finition of the problem, isolation of effects and conditions and determination of
areas for further research were stressed.
Four shallow lakes in Orange County, Florida, namely Lake Mizell-, Lake Osceola, Lake
Maitland, and Lake Claire were studied. Changes in several water quality parameters
before and after limited boating activity were monitored.
Agitation and mixing by boating activity destratified the lake and in some cases, in-
creased oxygen concentration and the rate of oxygen uptake by suspended matter. An
increase in turbidity was observed and was generally dependent on water depth, motor
power, and nature of bottom deposits. Increase in turbidity was accompanied by an
increase in organic carbon and phosphorus concentration. A decrease in turbidity
was also noticed after cessation of boating activity. Results from other parameters
such as pH, specific conductance, temperature, and nitrogen were not conclusive.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
*Lakes, *Motor Boats, Mixing,*Turbulence,
Limnology, *Water Analysis
Florida Winter Park
Chain of Lakes, Boating,
Shallow Lakes, Destrati-
fication, Nutrients
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
70
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
60
U. S. 60WINMEHT MIMTIMG OFFICE: )97'i-657-585/5308 Region No. 5-11
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