<4*
905R82102
CLEAR TECHNICAL REPORT NO. 256
WATER QUALITY TRENDS
AT TWO NEARSHORE STATIONS
WESTERN LAKE ERIE
by
Audrey A. Rush
Partially supported by grants from:
U.S. Environmental Protection Agency
Great Lakes National Program Office
Region V, Chicago, Illinois
» y,-S. Environmental Protection Agency
. GLNPO U.-.-y Collection (PL-12J)
77 West Je-cason Boulevard,
Chicago, IL 60604-3590
THE OHIO STATE UNIVERSITY
CENTER FOR LAKE ERIE AREA RESEARCH
COLUMBUS, OHIO
JUNE 1982
-------
11
ACKNOWLEDGEMENTS
I would like to take this opportunity to thank those
who provided assistance throughout the course of this
project. Sincere thanks go to my advisor, Dr. Charles E.
Herdendorf, who directed and guided me throughout the study.
I would also like to thank the members of my graduate
committee, Dr. N. Wilson Britt and Dr. Robert M. Sykes for
their time and advice. Sincere appreciation is also
extended to Dr. C. Lawrence Cooper, who provided valuable
advice throughout my graduate career.
My gratitude goes to my future husband, Bob Lynch, who
provided much moral support and spent many hours preparing
figures and tables; and to all the persons associated with
the Center for Lake Erie Area Research (CLEAR) who made my
time very rewarding and enjoyable.
-------
Ill
ACKNOWLEDGEMENTS ii
LIST OF TABLES v
LIST OF FIGURES vi
INTRODUCTION 1
Purpose and objectives 1
Previous investigations 3
DESCRIPTION OF STUDY AREAS 6
Lake Erie and the western basin 6
Maumee River and Bay (The C&O Docks). ... 9
Locust Point 13
METHODS AND MATERIALS 14
Site selection 14
Sampling frequencies and techniques .... 16
Locust Point 16
The C&O Docks 20
Selection of prarameters for analysis
(general limnological considerations). . 20
Conductivity 22
Chloride 22
Total dissolved solids 24
Turbidity and suspended solids 25
Alkalinity 26
Dissolved oxygen 27
Nitrates and nitrogen compounds 28
Phosphorus 29
-------
IV
METHODS AND MATERIALS (Cont.)
Statistical procedures 32
RESULTS 39
Locust Point 39
Monthly means 39
Yearly means 43
Seasonal blocking 51
Summary 63
C&O Docks 63
Monthly means 63
Yearly means 75
Seasonal blocking 78
Summary 88
DISCUSSION 94
CONCLUSIONS 108
LITERATURE CITED 110
-------
V
LIST OF TABLES
1. Analytical methods for water quality
determinations at Locust Point (1974-1980). . . 18
2. Power level and percent full power of the
Davis-Besse Nuclear Power Station during
sampling dates 19
3. Analytical methods for water quality deter-
minations at the C&O Docks (1970-1979) 20
4. Statistical values for monthly means at
Locust Point (1974-1980) 40
5. Comparison of trends using monthly and
yearly means at two levels of statistical
significance for selected parameters at
Locust Point 44
6. Statistical values for yearly means at
Locust Point (1974-1980) 45
7. Statistical values for seasonal yearly
means at Locust Point (1974-1980) 52
8. Comparison of trends using seasonally
blocked yearly means at two levels of
statistical significance for selected
parameters at Locust Point 54
9. Statistical values for monthly means at
the C&O Docks (1970-1979) 65
10. Comparison of trends using monthly and
yearly means at two levels of statistical
significance for selected parameters at
the C&O Docks 66
11. Statistical values for yearly means at
the C&O Docks (1970-1979) 77
12. Statistical values for seasonal yearly
means at the C&O Docks (1970-1979) 83
13. Comparison of trends using seasonally
blocked yearly means at two levels of
statistical significance for selected
parameters at the C&O Docks 85
-------
VI
LIST OF FIGURES
1. The western basin of Lake Erie
2. The C and O Docks in relation to
Maumee River and Bay ............... 12
3. Water quality stations near the Davis-Besse
Nuclear Power Station at Locust Point ......
4. Average seasonal water temperature
fluctuation at Locust Point ........... 3-7
5. Trends for nitrate monthly means at
Locust Point ...................
6. Residuals of the linear regression for nitrate
monthly means at Locust Point (1974-1980) .... 42
7. Trends for conductivity yearly means at
Locust Point ...................
8. Trends for suspended solids yearly means
at Locust Point
15. Trends for total alkalinity yearly means
using seasonal blocking at Locust Point
16. Trends for nitrate yearly means using
seasonal blocking at Locust Point
48
9. Trends for turbidity yearly means at
Locust Point ................... 49
10. Trends for total alkalinity yearly means
at Locust Point ................. 50
11. Trends for conductivity yearly means using
seasonal blocking at Locust Point ........ 5g
12. Trends for chloride yearly means using
seasonal blocking at Locust Point ........ 5-7
13. Trends for suspended solids yearly means
using seasonal blocking at Locust Point ..... ^g
14. Trends for turbidity yearly means using
seasonal blocking at Locust Point ........ gg
-------
Vll
FIGURES (Cont.)
17. Summary of long term changes for selected
parameters at Locust Point (1974-1980) ...... 64
18. Trends for chloride monthly means at
the C&O Docks ................... 67
19. Residuals of the linear regression for
chloride monthly means at the C&O Docks ...... 69
20. Trends for total alkalinity monthly
means at the C&O Docks .............. 70
21. Residuals of the linear regression for
alkalinity monthly means at the C&O Docks ..... 71
22. Trends for nitrate monthly means at
the C&O Docks ................... 72
23. Residuals of the linear regression for
nitrate monthly means at the C&O Docks ...... 73
24. Trends in total phosphorus monthly
means at the C&O Docks ..............
25. Residuals of the linear regression for total
phosphorus monthly means at the C&O Docks ..... 75
26. Trends in chloride yearly means at
the C&O Docks ................... 79
27. Trends in total alkalinity yearly means
at the C&O Docks ................. 80
28. Trends in nitrate yearly means at
the C&O Docks ................... 01
29. Trends in total phosphorus yearly means
at the C&O Docks ,
82
30. Trends for chloride yearly means using
seasonal blocking at the C&O Docks 07
31. Trends for total alkalinity yearly means
using seasonal blocking at the C&O Docks on
32. Trends for nitrate yearly means using
seasonal blocking at the C&O Docks
-------
viii
FIGURES (Cont.)
33. Trends for total phosphorus yearly means
using seasonal blocking at the C&O Docks ..... 91
34 . Summary of long term changes for selected
parameters at the C&O Docks (1970-1979) ...... 93
35. Lake Erie water level data, (1960-1980)
36. Comparison of 1979 values for total dissolved
solids at Locust Point with the trend curve
from Beeton(1970) . . ............... 102
37. Comparison of major ionic species
comprising conductivity from 1906-1979 ...... 106
38. Comparison of 1979 values for calcium,
sulfate, and chloride at Locust Point
with trend curves from Beeton (1970) ...... . 107
-------
INTRODUCTION
Purpose and objectives
Since the late 1960's, much concern has developed re-
garding the water quality of Lake Erie. Researchers and the
public became alarmed when the Lake showed signs of eutro-
phication, i.e., increasing phosphorus loads, prolonged
periods of anoxia, and increases in suspended and dissolved
substances. Biological indicators of eutrophication, such
as transitions in phytoplankton abundance and fish species,
became readily apparent (Beeton, 1970; Leach and Nepszy,
1976).
In 1964, the governments of the United States and
Canada informed the International Joint Commission (IJC)
that sewage and industrial wastes were polluting Lake Erie
(IJC, 1969a). The U.S. subsequently began a surveillance
program and submitted a final report in 1969. As a direct
result of this report, the U.S. and Canada signed the Great
Lakes Water Quality Agreement on April 15, 1972. Deteriora-
tion of Great Lakes water was thus recognized, which re-
sulted in a set of common objectives to restore and enhance
Great Lakes water.
-------
2
One purpose of surveillance programs initiated in Lake
Erie is to seek to identify historical trends, especially
among water quality parameters that may be changing due to
human influences. Trend analysis has recently attracted the
attention of many Great Lakes research groups. Two major
problems have arisen in attempting to analyze large data
bases through time: a satisfactory definition of what
exactly constitutes a "trend" and, more importantly, de-
veloping an adequate method of removing large variations in
raw data due to seasonality and general limnological near-
shore conditions. Such variation could tend to mask a trend
that really exists, or, conversely, it could indicate a
trend where none actually exists.
In 1978, the IJC defined trend as a linear regression
equation having a slope significantly different than zero as
determined by a t-test or F-test. Recently, the Data Man-
agement and Interpretation Work Group (1980) recommended the
following definition of trend in Lake Erie water quality:
"To relieve any ambiguity and to pro-
vide a uniform methodology of testing
for trend we propose an operational
definition of trend which narrows it to
a change at a constant rate, that is,
trend will be understood as simple
linear trend. Trend can thus be as-
sessed by regressing the character of
interest upon time:
y = b + b, x + e
where b is the characteristic of in-
terest and x is time; coefficient b,
is tested for statistical signifi-
cance. "
-------
The purpose of this study is to determine the extent,
if any, of water quality changes over the past decade
(1970-1980). Two data bases from Lake Erie western basin
sites are analyzed using the Data Management and Interpreta-
tion Work Group's definition trend (i.e., simple linear
regression). Statistical methods are employed in an attempt
to smooth large variability present in the data. Results
are then compared with those of previous investigators in an
attempt to assess rates of change in water quality.
Previous investigations
One of the earliest and most comprehensive investiga-
tions of Lake Erie water quality changes was undertaken by
Beeton (1961, 1967, 1970). Data for his analyses were col-
lected from various sources throughout Lake Erie and include
those from municipal water intakes, fisheries studies, and
some early pollutional studies. The significance of
Beeton's findings lies in the long time period of reported
changes (1902-1960) and water quality parameters which are
discussed: chlorides, total dissolved solids, calcium, sodi-
um plus potassium and sulfates. Phosphorus and nitrates
were not included in his results probably because of the
scarcity of data for these parameters in early years.
Since Beeton's publications, documentation of Lake
Erie changes has been fairly extensive. Several researchers
(Richards, 1981; Weiler and Heathcote, 1979; Gregor and
-------
4
Ongley, 1978) have identified water quality changes occur-
ring since the late 1960's in specific nearshore zones of
Lake Erie. These authors used differing trend techniques in
order to filter large sources of variability inherent in
nearshore waters. Trends in main lake water quality from
1966 to 1980 have been summarized by Dobson (1981), specifi-
cally in regard to nutrient chemistry in the central and
eastern basins. Weiler, and Chawla (1968) used Beeton's data
to document trends in ionic species composition of specific
conductance from 1906-1967. Fraser and Wilson (1981) docu-
mented trends in loading estimates to Lake Erie from
1967-1976. Sedimentation rates since 1850 have been docu-
mented through pollen analysis by Yahney (1978).
Many researchers have commented on present concentra-
tions of chemical parameters in comparison with individual
data points of the past. The Michigan Department of Natural
Resources (1981) compared present day loadings of the
Detroit River to those of 1968. Rawson (1951) compares
samples taken from the Niagara River with those collected in
the 1930's. Other investigations document changes through
cruise means as yearly means on a lake-wide basis in compar-
ison with earlier reported concentrations (Ownbey and Kee,
1967; Scheffield, et al, 1975; Dobson, et al, 1974).
Two special voumes - specifically a report to the
International Joint Commission (1969a) and a special issue
of the Fisheries Research Board of Canada (1976) contain
-------
much useful information on Lake Erie status with respect to
physical and chemical water quality.
-------
DESCRIPTION OF STUDY AREAS
Lake Erie and the western basin
Although its surface area is slightly larger than Lake
Ontario, Lake Erie is the smallest of the Laurentian Great
Lakes with respect to volume (470 km ). Mean water depth
throughout the Lake is only 18 meters; a maximum depth of 64
meters occurs just off Long Point in the eastern basin
(Schelske & Roth, 1973). The Lake has a maximum width of 90
km between Port Stanley and Painesville and a maximum length
of 390 km between Toledo and Buffalo.
Mean daily water temperature ranges from -2 to -3 C in
winter to 21 to 23°C in midsummer. Winds vary seasonally in
both velocity and direction with southwest flow dominating
and average speeds ranging from 14 to 26 km/hr. Storm
events, often characterized by easterly and northerly winds,
predominate in winter and spring. A stronger southerly com-
ponent as well as periods of calm are present in the summer.
Fall is characterized by predominating southerly winds and
increased wave action (Sly, 1976).
Precipitation within the Lake Erie watershed averages
79 cm annually, while precipitation in the Lake proper aver-
ages 83 cm annually. Mean annual evaporation from the Lake
surface has been calculated to be 90 cm. This implies that
approximately 7 cm of water are evaporated from the surface
over average annual precipitation. This net loss of water
-------
7
is unique to Lake Erie and can be attributed to the extreme
shallowness and large surface area which allows rapid heat-
ing of the Lake waters (Jones & Meredith, 1972).
Approximately 25-30% of the annual precipitation on
the drainage basin is in the form of snowfall. Peak land
drainage normally occurs in late February through March
(Witherspoon, 1971). During this spring thaw, large quan-
tities of silt and sediments are transported along with the
heavy volume of water draining into Lake Erie.
The Lake Erie basin resulted from glacial scour
carving Upper Devonian shales. Along the southern shore of
the western basin, the Findlay Arch upwarps a rim of lower
dolomite, outcroppings of which are visible in the Bass
Islands. These bedrock features are evident only as island
outcrops and isolated shoreline features. Through the past
10,000 years, fine grained sediments have covered offshore
bedrock areas of the western basin to a near level bottom
surface (Sly, 1976). A thorough geological discussion of
the post-glacial history can be found in Hough (1958).
The western basin of Lake Erie is unique in many re-
spects. It is separated from the central basin of the Lake
by a north-south series of islands extending between Point
Pelee and Catawba Island (Figure 1). The presence of this
cuesta on the eastern margin of the basin, combined with the
dominant flow of the Detroit River, generally produces a
clockwise current within the basin. The bottom of the basin
-------
Figure 1. The western basin of La~ke Erie.
-------
is primarily a flat mud plain with a maximum depth of 20
meters and a mean depth of 8 meters. It is the shallowest
and smallest of the three basins (Upchurch, 1976).
Extensive municipal and industrial influences are ex-
erted on the waters of Western Lake Erie. It has been esti-
mated that as much as 98% of the basin water is used by U.S.
industry alone (IJC, 1969a). Heavily populated centers in
the Detroit and Toledo .areas influence water quality through
municipal waste disposal and storm runoff. The combination
of extensive cultural inputs and extreme shallowness has
resulted in the identification of the western basin of Lake
Erie as the most eutrophic portion of the entire Great Lakes
basin (Vollenweider et al., 1974; Sly, 1976).
The main source of input into the lake is the Detroit
River, which contributes 80% of the total water supply and
93% of the western basin supply (Federal Water Pollution
Control Administration, 1964). The Detroit River dominates
water quality and flow in the western basin. Any signifi-
cant decrease in river flow or its water quality could have
serious adverse effects on a basin-wide and lake-wide scale.
Maumee River and Bay (C&O Docks)
The Maumee River is considered to be the largest major
tributary in the Great Lakes basin, excluding connecting
channels such as the Detroit River. It contributes 2.4% of
the total water input to the western basin. Lesser contri-
-------
10
butions to the water supply arise from the Huron, Raisin,
Portage and Sandusky Rivers (Monke and Beasely, 1975).
The river is formed by the union of the St. Mary's
River and the St. Joseph River at Fort Wayne, Indiana. It
flows northeasterly through Ohio to Toledo where it empties
into Maumee Bay in the western basin. The estuarine portion
of the river extends to Perrysburg, Ohio, approximately 25
km upstream, where the ,first set of riffles are located. It
is a large, warm water river which drains intensively culti-
vated cropland having low relief (total drainage area:
17,058 sq km; Herdendorf and Zapatosky, 1977). The soils in
the drainage basin are formed from lacustrine deposits and
glacial till underlain by mostly Silurian and Devonian
limestones and dolomites. Bedrocks of sandstone and shale
occur, but are less prevalent (Herdendorf and Cooper, 1975).
The average flow into the western basin from the
Maumee River is low, approximately 133 m /s (ranging from
3 3
0.9 m /s to 2,662 m /s). Despite the low average flow, it
has been estimated that 1.8 million tons of fine-grained
sediments (silt and clay) are transported into the western
basin annually (Yahney, 1978). This amounts to 37% of the
total sediment load into Lake Erie (FWPCA, 1964).
The mouth of the Maumee River receives the sum of in-
dustrial and municipal discharges from the city of Toledo as
well as upstream agricultural runoff. The U.S. Corps of
Engineers maintains a navigation channel with a mean depth
-------
11
of 6.8 m from Lake Erie beyond the harbor light upstream to
river mile 7.0 at the Anderson grain elevators. Dredge
spoil disposal sites are situated on both sides of the chan-
nel within Maumee Bay. Toledo's municipal sewage treatment
plant is located on the north shore of the river, approxi-
mately one mile upstream from the river mouth (Figure 2).
Tertiary treatment for phosphorus removal was initiated in
1974 (Reynold Gerson, personal communication).
Maumee Bay is separated from the western basin by two
spits: Woodtick Peninsula, which extends southeasterly from
the Michigan shore, and Little Cedar Point, extending north-
westerly from the Ohio shore (Figure 1). The bottom of the
Bay is a broad shelf which gently slopes toward the north-
east and has a maximum depth of 6 m. Bottom sediments are
primarily composed of lacustrine clay overlain by silt.
Sand deposits which were deposited from littoral currents
from the southwest predominate near Little Cedar Point
(Herdendorf et al., 1977).
The Chesapeake and Ohio (C&O) Docks are located at the
mouth of the Maumee River, just west of the Bayshore Power
Station (Figure 2). This study site was chosen to detect
changes in water quality of Maumee River water entering
Maumee Bay and western Lake Erie. Trends in water quality
at this site are assumed to identify changes in
agricultural, industrial, and municipal usage within the
drainage basin.
-------
12
CO
0)
(U
e
O
-P
O
-H
-P
(1J
C
-H
o
O
Q
O
13
G
O
0)
.c
0)
-H
-------
13
Locust Point
Locust Point is located on the Southern Shore of west-
ern Lake Erie, approximately 21 miles east of Toledo. It is
the site of the Davis-Besse Nuclear Power Station which was
built on a 386 ha site in Carrol township, Ottowa County.
Locust Point is maintained by diverging littoral currents
which carry sand and si-It originating from the north through
Detroit River flow and from the west through Maumee flow
(Reutter and Herdendorf, 1976).
The lake bottom of this area has a gentle slope from
shore to about 4,000 ft lakeward. Two sand bars parallel
the shoreline at approximately 120 ft and 280 ft offshore.
Between the beach and the first sand bar, the lake bottom
contains a thin layer of silt and shells over sand. Lake-
ward from the sand bars a medium to fine-grained sand bottom
extends to 800 ft offshore. Here a 500-700 ft wide strip of
hard clay is found followed by a sand and gravel bottom
until the rocky reefs are reached about three miles offshore
(Reutter and Herdendorf, 1976).
This particular site was chosen due to its nearshore
location. Monitoring programs in the nearshore zone are
likely to identify problem areas indicative of degredational
trends within the lake. On the other hand, nearshore re-
gions are likely to reveal positive changes as a result of
remedial measures before such changes are observed in the
open lake.
-------
14
METHODS AND MATERIALS
Site Selection
The Locust Point and C&O Dock sites were chosen from
eight sampling sites located along the south shore of Lake
Erie. Data were retrieved for all eight stations from the
Environmental Protection Agency's STORET data base storage
system. Simple linear regressions were performed on raw
data at each site; the sum of which might be indicative of
overall lakewide changes (Rush, 1981). Data from the Locust
Point site and the mouth of the Maumee (C&O Docks) were
secured independent of the STORET system. Data for Locust
Point were received from Toledo Edison Company (TECO) and
CLEAR technical reports while data from the C&O Docks were
received from Toledo Pollution Control Agency (TPCA) (E.
Russell, personal communication). The in-depth analyses
presented in this thesis include only those performed on
original data (i.e., non-STORET sources) from the C&O Dock
and Locust Point sites for one or more of the following
reasons:
(1) The data in the STORET system appear, on occasion,
to be of dubious quality. Comparisons of STORET
data and original data from lab bench sheets sup-
plied by TECO and TPCA personnel did not corres-
pond for many parameters. Sources of discrepancy
between the two data bases may be attributed to
-------
15
excessive handling upon entry.
(2) Comparable periods of record did not exist for all
sampling sites in the STORET file. In addition,
periods of record for given parameters were often
inconsistent at any one site.
(3) Data were often collected at irregular intervals,
daily, weekly, or monthly, thus making blocking
techniques us.ed to smooth variation extremely
difficult.
(4) Methodologies used in analyses often were not con-
sistent during periods of record for which data
are stored. Variation in the data due to these
types of changes is often difficult to evaluate on
a long-term scale.
STORET data were not used in this analysis because
they contain multiple sources of entry error not found in
original data. Water quality data from the C&O Docks and
Locust Point were collected at regular intervals and were
consistent in analytic procedure over the period of record.
This consistency in sampling and analytic procedure coupled
with original entry into The Ohio State University computer
system serves to minimize error sources present in other
data bases.
Original data used in this analysis can be found in
the Center for Lake Erie Area Research Library System.
-------
16
Sampling frequencies and techniques
Locust Point.. Studies of the aquatic environment in the
vicinity of Locust Point were initiated in 1974 to evaluate
the impact of unit operation of the Davis-Besse Nuclear
Power Station. Eighteen water quality parameters were sam-
pled at monthly intervals during the ice-free periods by
Toledo Edison Company (TECO). Both surface and bottom sam-
ples were collected at three stations (Figure 3). Station 1
(41°37.3'N, 83°15.7°W) was chosen as a control due to its
eastern location (i.e., down current from outfall or in-
take). Station 8 is located directly above the intake pipe
for the power plant and is located approximately 3,000 ft
from the shore (41°36.0'N, • 83°07.4'W). Station 12 is situ-
ated above the outfall, approximately 1,000 ft from shore
(41° 37.8'N, 83°07.4'W). Techniques and procedures used for
analyses throughout the sampling period are listed in Table
1.
Actual plant operation was limited during the sam-
pling period; only four sampling dates coincided with power
generation (Table 2). Appraisal of the power plant's impact
on the aquatic ecosystem in the vicinity of Davis-Besse
showed no diffference in most parameters due to unit opera-
tion (Herdendorf and Reutter, 1980). Magnesium concentra-
tion was the only parameter which indicated a significant
difference between preoperational (before 1977) and postop-
erational periods. Noted increases of magnesium, however,
-------
17
-------
18
TABLE 1. Analytical methods for water quality
determinations at Locust Point (1974-1980)
Parameter
Units
Source Analytical Method
Dissolved Oxygen mg/1
Conductivity
umhos/cm at
25°C
Calcium
Magnesium
Sodium
Chloride
Nitrate
Sulfate
Phosphorus
mg/1 (Ca)
mg/1 '(Mg)
mg/1 (Na)
mg/1 (Cl)
mg/1 (N03)
mg/1 (S04)
mg/1 (Total
as P)
Alkalinity mg/1 (Total
as
Suspended Solids mg/1
as CaCO-)
Dissolved Solids mg/1
Turbidity
F.T.U.
APHA* Azide Modification
ASTM Field and Routine
Lab measurements
APHA* EDTA Titrimetric
Method
APHA* Magnesium by
calculation
ASTM Flame Photometry
APHA* Mercuric Nitrate
Method
ASTM Colorimetric with
Brucine-Sulfanilic
Acid
ASTM Volumetric method
APHA* Ascorbic Acid
method
APHA* Acid titration
APHA* Non Filterable
Residue Dried at
103-105°C.
USEPA# Filterable Residue
Gravimetric, Dried
at 180 C.
APHA* Nephelometric
method
ASTM= American Society of Testing and Materials
* APHA= American Public Health Association
# USEPA=United States Environmental Protection Agency
-------
19
TABLE 2. Power level and percent full power of
Davis-Besse Nuclear Power Station during sampling dates
Year
1977
1977
1977
1977
1977
1977
1977
1978
1978
1978
1978
1978
1978
1978
1979
1979
1979
1979
1979
1979
1979
1979
Sampling
Date
Month (Gregorian)
May
June
July
August
September
October
November
May
June
July
August
September
October
November
April
May
June
July
August
September
October
November
146
173
194
242
255
298
326
131
180
206
299
256
290
305
120
144
172
212
241
270
303
332
Daily Avg.
Power Level
(MWe-net)*
0
0
0
0
0
0
73
0
0
0
0
799
0
0
0
0
0
870
870
0
0
0
Percent
Full Power
(MWe-NetX.115)
0.0
0.0
0.0
0.0
0.0
0.0
8.4
0.0
0.0
0.0
0.0
91.9
0.0
o.o
o.o
o.o
0.0
100.0
100.0
0.0
0.0
0.0
* net megawatt
net power multiplied by .115
-------
20
may be due to a nearshore trend phenomenon rather than unit
operation.
The C&O Docks. Beginning in 1970, the Toledo Pollution
Control Agency (now called the City of Toledo Division of
Water Reclamation Laboratory) collected and analyzed surface
grab samples from the C&O Docks in the mouth of the Maumee
River for surveillance purposes (41°41'46.0"N, 83°21'29.9"W,
Figure 2). Samples were collected at approximately weekly
intervals from January, 1970 through December, 1979.
Although several winter samples throughout the period of
record were missed due to extensive ice cover, periodicy of
sampling remained fairly regular. Methods of analyses
remained constant throughout the period of record and are
listed in Table 3.
Selection of parameters for analysis (general limnological
considerations)
Of the seventeen physical and chemical water quality
parameters analyzed from the C&O Docks and eighteen at
Locust Point, nine parameters were selected for analysis and
discussion due to several factors. Selection was based pri-
marily on qualities that would characteristically describe
general water chemistry; the basic components of which un-
derlie all subsequent biological processes within an aquatic
system. Specific parameters were chosen that would ade-
-------
21
TABLE 3. Analytical methods for water quality
determinations at the C&O Docks (1970-1979)
Parameter
Units
Source Analytical method
Dissolved Oxygen
Conductivity
Chloride
Nitrate
Phosphorus
Alkalinity
Suspended Solids
mg/1
umhos/cmat 25°C
mg/1 (Cl)
mg/1 (N03)
mg/1 (Total
as P)
mg/1 (Total
as
mg/1
as CaCO.,)
Dissolved Solids mg/1
Turbidity
JTU
APHA Azide Modification
APHA Conductivity Meter
APHA Mercuric Nitrate
Method
APHA Brucine Method
APHA Ascorbic Acid
Method
APHA Acid Titration
APHA Non-Filterable
Residue Dried at
103-105°C
APHA Total Filterable
Residue Dried at
180°C.
APHA Visual Methods
APHA = American Public Health Association
-------
22
quately describe changes due to sediment loading, nutrient
loading, changes in dissolved substances and buffering capa-
cities. Selection was also based on those parameters which
were common in analyses to both study locations. A brief
summary of general limnological significance of each water
quality parameter is described below.
Conductivity. Conductance is defined as a measure of
the ability of a solution to conduct a current (Sawyer and
McCarty, 1978). It is influenced by ion activity which is
directly proportional to ionic concentrations. Cations in
cultural effluents require an anion in order to maintain
electrical neutrality (Upchurch, 1976). Niney-eight percent
of conductance in Lake Erie has been estimated to consist of
six principal anions and cations: chloride, bicarbonate,
and sulfate; and calcium, magnesium, and sodium (Don, 1981).
Concentrations of these species in solution are influenced
primarily by wind disturbances, runoff, discharge, and bio-
logical activity (Poulton and Palmer, 1973).
Conductivity values vary with water temperature. All
values reported are thus corrected to 25°C. It has been
estimated that the error involved in the actual calculation
of specific conductance at 25 C from a sample which was
measured at some other temperature is slightly greater than
2% (Don, 1981).
Chloride. Chloride in lake water is conservative, not
being subject to decay or biological degredation. In addi-
-------
23
tion, chloride ions do not combine with other aqueous or
solid phases and are not removed from the system by precipi-
tation, adsorption, metabolic processes, or chelating
(Upchurch, 1976). This implies that the mass balance of
chloride in Lake Erie is relatively straight forward; the
sum of inputs minus outputs must equal the amount of change
of material within the lake, either by changes in loading
rates and/or lake leveLs.
Chlorides in Lake Erie originate from a variety of
sources. Salt deposits under the Detroit-Windsor area were
discovered and tapped around the turn of the century (Pound,
1940; Eskew, 1948). Salt brine provides the basic raw ma-
terials for the production of soda ash and other alkali pro-
ducts. Industry alone is responsible for 60.2% of the
chloride input into the western basin. Other contributions
arise from the upstream watershed (i.e., the Detroit River,
23.4%), salt for deicing purposes, 8.4%, and non-point
sources, 7.8%. Human waste contributes only 0.9% of the
total input (Ownby and Kee, 1967).
Although adverse biological effects of high chloride
levels have not been fully established, it is estimated that
the following critical levels could be deleterious to spe-
cified beneficial water uses (McKee and Wolf, 1963):
domestic water supply 250 mg/1
irrigation 100 mg/1
industrial uses 50 mg/1
-------
24
Thus it is essential to monitor chloride concentrations
to evaluate rates of increase in Lake Erie. Contamination
through a severe rate increase could ultimately cause
serious impairment to the uses of lake water.
Total dissolved solids. Total dissolved solids is the
amount of dissolved material in natural waters. It is com-
prised mostly of carbonate, sulfate, calcium, magnesium and
chloride compounds with, smaller contributions from nitrogen
and phosphorus (Larkin & Northcote, 1958; Welch, 1980). It
is related to conductivity by a factor of 0.5 to 0.9 depend-
ing on ionic strength of the solution but are commonly esti-
mated by multiplying specific conductance by 0.65 in Great
Lakes waters (Great Lakes Basin Commission, 1976).
A significant portion of the present total dis-
solved solids levels of the Great Lakes is the result of
natural chemical equilibria between the water and sediments
(Kramer, 1964). Total load of dissolved solids is derived
from dissolution of minerals in the drainage basins and
cultural inputs from municipal, industrial, and rural waste
discharge (Hasler, 1947).
Increases of total dissolved solids have been re-
ported for Lake Erie from 1915 to 1965 (UC, 1969a) but the
build-up to 1965 values was not in itself a serious problem.
It did, however, indicate large accumulations of materials.
The International Joint Commission objective of 200 mg/1 for
Lake Erie is based on a philosophy of maintaining non-degra-
-------
25
dation but does not comply with the definition of a specific
water quality objective as the level of a substance which
will provide for and protect a designated water use (IJC,
1975a).
The toxicity of dissolved solids to freshwater
aquatic life is that level which has an osmoconcentration
equal to the body fluids of the organism. The range of en-
vironmental osmotic conditions tolerated by animals is
great, whereas the tolerated range of internal osmotic
conditions is much less. Niney-six hour mean toxicity
threshholds range from 3,710 mg/1 TDS in Dapnia to 23,000
mg/1 TDS for cyprinids. Lower levels of dissolved solids
may interfere with reproductive capabilities. Fathead min-
nows (Pimephales promelas promelas) did not exhibit spawning
behavior at levels of 2,000 mg/1 (Prosser and Brown, 1966).
Turbidity and suspended solids. The major limnological
significance of turbidity and suspended solids lies in their
limiting effect upon water transparency or light penetra-
tion. The amount of light entering an aquatic system is a
fundamental factor governing production and distribution of
phytoplankton, which in turn is responsible for zooplankton
and ultimately fish populations (Pinsak, 1967).
It has been estimated that suspended solids and
turbidity are directly related by a factor of 0.92 (Kemp, et
al, 1976). In addition, turbidity correlates positively
with total solids but varies somewhat inversely with phyto-
-------
26
plankton (Weiler and Heathcote, 1979). It has been demon-
strated that turbidity in Lake Erie above three Jackson
Turbidity Units (JTU's) are not caused by high phytoplankton
densities (Burns, 1976a). Turbidity, then, is chiefly due
to resuspension of inorganics during storm events, shore
erosion, or loading from rivers.
Turbidity varies somewhat seasonally, but variation
in values are more often attributed to changes in climatic
conditions (e.g., storm events). The seasonal variation
exhibited in western Lake Erie is most likely due to weather
associated with seasonal changes (Chandler, 1940).
Alkalinity. Alkalinity is defined as the capacity of a
solution to neutralize acids; thus it serves as an indirect
measure of a water's buffering capacity (Snoeyink and
Jenkins, 1980). Major chemical species contributions to
— — 2
alkalinity are bicarbonates (HCO_ ), carbonates (CO_ ) and
hydroxide (OH ). These species result from dissolution of
basin materials, such as calcite and dolomite, which
predominate throughout Lake Erie.
Since most aquatic organisms are acclimated to a
specific pH range, the buffering ability of natural waters
is important in preventing large or rapid changes in pH.
Alkalinity itself has no harmful or toxic effects on aquatic
organisms. Instead, it protects aquatic organisms from
deleterious pH changes and reduces the toxicity of some
poisons (Reid, 1961).
-------
27
Hydrogen ion concentration is largely responsible
for chemical species composition of alkalinity. Below pH
8.3, total alkalinity is due almost entirely to bicarbonate
ions. Since the mean pH of Lake Erie ranges from 7.5-8.4
(Robertson et al., 1974), bicarbonate concentration is pre-
sumed to be solely responsible for alkalinity values (Sawyer
and McCarty, 1978). Due to the basin substrate, Lake Erie
has a typically high alkalinity content and thus is able to
buffer small pH decreases which may be occurring from in-
creased acid precipitation.
Dissolved oxygen. A major water quality indicator, dis-
solved oxygen is probably one of the most important chemical
substances in natural waters (Reid, 1961). It is essential
to most forms of aquatic life and its concentration often
determines species composition in a system. It is also di-
rectly responsible for many chemical processes in an aquatic
environment. Dissolved oxygen enters water by diffusion
from the atmosphere or photosynthetic activity and is re-
moved by respiration of aquatic organisms and by oxidation
of inorganic matter. It is of primary concern in the
central and eastern basins, where summer hypolimnetic de-
pletion has resulted in anoxia (Charlton, 1980). Since
stratification is uncommon in the western basin, (especially
in the nearshore zone and at the Maumee River mouth), oxygen
depletion is expected near the sediment-water interface only
during prolonged calm periods.
-------
28
Nitrates and nitrogen compounds. Nitrogen is a nutrient
that, in excess quantities and providing no other nutrient
is limiting, stimulates aquatic growth and accelerates
eutrophication. The atmosphere, 80% of which is nitrogen,
supplies a ready source to aquatic systems. This source is
not usually assimilated directly by aquatic organisms but
can be converted to nitrogen compounds by certain bacteria
and algae, if aquatic concentrations are depleted. Since it
is readily available, nitrogen is not considered to be a
limiting factor for organic growth in an unpolluted system
(Dobson, et al., 1974).
Nitrogen usually enters a lake in the form of ni-
trates, nitrites, ammonia, and organic compounds. These
compounds originate from a variety of natural sources in-
cluding drainage and precipitation. Contributions from farm
fertilizers, manure, industry, and organic wastes from muni-
cipalities add to the total nitrogen load (Brezonik, 1972).
The nitrogen cycle is largely biological. In-
organic nitrogen is present as highly oxidized nitrate (NO3)
and nitrite (NO2) or reduced molecular nitrogen (N_) and
ammonia (Allen and Kramer, 1972). Nitrate tends to be the
predominant form in surface waters and is the preferred form
for uptake by vascular plants. There is considerable evi-
dence that ammonia is the preferred form for assimilation by
plankton, since it is already at the reduction level of
organic nitrogen (Feth, 1966).
-------
Considerable seasonal variability exists for nitro-
gen compounds. In spring months, high concentrations of
nitrites and nitrates are carried into the western basin of
Lake Erie via spring runoff (Burns, 1976a). During the
summer months, nitrates and nitrites found in the water
column are low due to assimilation by organisms. In fall,
nitrogen levels rise as dead and decaying organic matter
release nitrogen compounds back into solution. On the other
hand, relatively small seasonal variations exist for ammo-
nia. This can be attributed to rapid oxidizability of this
compound and preferred uptake of ammonia by plankton
(Snoeyink and Jenkins, 1980).
Critical levels of inorganic nitrogen have been
calculated to be about 0.3 mg/1 by several researchers
(Sawyer, 1967; Upchurch, 1976). Above this value, large
algal blooms can be expected, provided phosphorus is not
limiting. Thus in a system such as Lake Erie where phos-
phorus is not limiting, increasing nitrate levels may
produce algal blooms.
Phosphorus. Phosphorus compounds are perhaps the most
important parameter when discussing lake eutrophication.
The only natural source of phosphorus into an aquatic system
is weathering of phosphatic rock. Approximately 95% of this
rock is in the apatite form, which is highly insoluble and
settles quickly (Burns, 1976b). Thus in undisturbed
systems, phosphorus is limiting and is assimilated as soon
-------
30
as it becomes available. Phosphorus is then conserved in
the food chain as it cycles from producer to consumer to
decomposer and eventually back to producer (Welch, 1980).
In a system highly influenced by cultural inputs,
such as Lake Erie, phosphorus enters the system through in-
dustry, agriculture, and most importantly, municipal waste.
Sewage and detergent uses may contribute up to 60% of the
total phosphorus inputs- into Lake Erie (Bouldin, et al,
1976). Lesser contributions arise from agricultural and
land runoff (30%). The remaining inputs are derived from
erosion (Baker and Kramer, 1973).
Total phosphorus is the sum of all forms of sus-
pended, dissolved, and adsorbed phosphorus. The signifi-
cance of total phosphorus lies in its ability to convert to
soluble forms which are most readily incorporated into plant
biomass (Reid, 1961). Several factors affect which forms of
phosphorus are predominant. It has been estimated that as
much as 80% of the phosphorus entering Lake Erie is sedi-
mented within the basin (Burns and Nriagu, 1976). This
sedimented phosphorus supplies a ready source of soluble
forms for utilization through resuspension. High pH and low
oxygen concentrations near the sediment-water interface also
aid in the release of these compounds into solution (Berg,
1958). Rising lake levels increase insoluble forms by in-
creasing the surface area of water-exposed rock (Dobson,
1981).
-------
31
The western basin has an extremely high elimination
coefficient for phosphorus and large continuous inputs of
this element are required to maintain phosphorus at observed
levels (Burns and Ross, 1972). If phosphorus inputs into
the Lake are reduced from present amounts of 41,000 metric
tons per year (Burns, 1976b) to 14,600 metric tons per year
as planned (U.S. Department of State, 1972), the western
basin would respond rapidly with concentrations of phos-
phorus decreasing with time. A decrease of this magnitude
may result in non-apatite phosphorus loadings near the
pre-1850 values (Burns, et al, 1976). Control of inputs is
economically feasible through sewage treatment and phosphate
bans on detergents. Secondary sewage treatment removes only
20% of phosphorus present in municipal waste, while tertiary
treatment is capable of 75-90% removal (Charlton, 1980). A
detergent ban imposed on New York inland waters resulted in
a reduction of 50-60% in effluent phosphorus (Bouldin, et
al., 1976).
Phosphorus control has sparked a great deal of de-
bate in the last decade. The charge has been made that
phosphorus has been simplistically isolated as a single
causal factor to eutrophication in a highly complicated
system (Weaver, 1969). However, whole-lake experiments of
oligotrophic lakes by Schindler and Fee (1974) showed that
control of phosphorus alone appears to be the sole realistic
strategy in controlling lake eutrophication. In a series of
-------
32
fertilization experiments, increases in nitrogen or organic
carbon showed no significant increases in algal abundance or
composition, while phosphorus levels and algal abundance
showed a significant positive correlation.
Phosphorus levels may also determine species compo-
sition. It has been demonstrated that increased phosphorus
loading in the Great Lakes not only result in increased
phytoplankton growth, but also depleted silica, which, in
turn became limiting. Continued silica depletion may cause
a change from diatom predominance to blue-green algal pre-
dominance (Lin and Schelske, 1981).
Statistical procedures
Several problems arise when dealing with long-term
nearshore data sets. The most difficult problem arises due
to the extreme degree of temporal variability. Seasonal
fluctuations tend to mask long-term trends because they in-
crease overall variance. This effectively decreases the
achieved statistical significance when testing for trend
(Weiler and Heathcote, 1979). Furthermore, a normal distri-
bution has been shown to be atypical of the behavior of
diverse water quality parameters. Non-normal distributions
result from the effect of physical factors such as wind,
lake currents and variable loadings (Palmer and Sato, 1968).
In addition, non-normal distributions may result when two or
more factors are primarily responsible for observed
-------
33
variation, such as temperature affecting dissolved oxygen
and biological effects on nutrients.
The central limit theorem of parametric statistics
states that almost regardless of the shape of the original
population, certain statistics, most importantly, the
arithmetic mean, tend to be normally distributed as sample
size (N) becomes large (Richmond, 1957; Wallis and Roberts,
1956). Thus, a distribution of means approaches that of a
normal distribution as N approaches infinity.
Overall sampling and analytical errors add to the
total variance. These sources of variation are often diffi-
cult, if not impossible to identify, especially within the
context of extreme variability due to limnological nearshore
conditions. Richards (1980) found that the overall sampling
and analytical errors are not large enough to mask small
scale limnological differences in the water masses of Lake
Erie. This was evidenced by the fact that replicate sample
differences analyzed by the same laboratory were generally
greater than split differences of one sample analyzed by
separate labs. Consequently, these relatively small varia-
tions are not considered to have a significant effect on
reported findings.
Data from the Locust Point site and the Maumee Bay
site were entered on disk using the Center for Lake Erie
Area Research Computer Data Center (CDC). The tapes of
these data were then transferred to the Amdahl (470/V6) com-
-------
34
puter at The Ohio State Instructional and Research Computer
Center where most of the analysis was conducted through
standard programs produced by the Statistical Analysis
System (SAS, version 79.5; Barr, et al, 1976).
Differences between surface and bottom samples col-
lected at Locust Point as well as station differences were
tested for significance through analysis of variance. No
significant difference -(P<.05) was found for any parameter
between depths or stations. Consequently, all data were
pooled to enhance statistical significance.
Monthly means from both study locations were generated
and linearly regressed through time. The slope of the line
was tested for two levels of significance (P<.05 and P<.10)
using an F-Test. The F-statistic is derived by dividing the
model mean square by the error mean square. Student's
t-tests (testing of means) were not used due to the large
number of tests that would be required. A greater number of
statistical tests performed to achieve a single result
increases the likelihood of producing Type-I errors, i.e.,
rejecting the null hypothesis (the slope is not statis-
tically different from zero), when it should not be rejected
(Steel and Torrie, 1980).
In order to test for linearity of the data, the resid-
uals of the regression line were calculated and plotted
through time for parameters exhibiting a significant change.
A relatively wide band of residuals indicate that the varia-
-------
35
bility in the data is constant with respect to time. Al-
though this is not a definitive test against a quadratic or
cubic factor, it does provide some evidence for linearity
(Draper and Smith, 1966).
Smoothed trend curves were constructed and superim-
posed on the linear model. These curves were constructed
through a method of averaging yearly means (Dobson, 1981).
Means were plotted at yearly intervals beginning at the six
month point (i.e., six months, 18 months, 30 months, etc.).
The averages of adjacent pairs of means were calculated and
plotted. Adjacent pairs of smoothed values were then aver-
aged again. This process provides points at three month
intervals creating a somewhat detailed curve.
Aggregation of the data into relatively large time
periods tends to homogenize the effects of process variables
at work in the nearshore zone. Yearly means were calculated
in order to achieve maximum coefficients of determination.
The coefficient of determination is defined as the square of
the correlation coefficient - the amount of variability in
selected parameters explained by the independent variable
(in this case, time). Yearly means and their standard devi-
ations were then plotted and tested for trend. In addition,
smoothed trend curves were constructed using a similar tech-
nique as that for monthly means.
Due to the fact that samples were not collected at the
Locust Point site during winter months, sampling was initi-
-------
36
ated on different dates in the spring in successive years.
Earlier spring samples are normally higher in value due to
runoff than samples collected at later dates. This provides
an additional source of variation not found in the continu-
ous sampling program at the Maumee River mouth site. In
order to qualify this source of variability, as well as
homogenize seasonal components, the annual cycle was sepa-
rated into seasons, selected on a basis of average annual
water temperature fluctuation (Figure 4). The winter season
is omitted from the Locust Point analysis because data was
not collected during that time. Yearly means were plotted
for each season and regressed through time. Trends are then
assessed by season.
Percent contribution of major ions comprising conduc-
tivity for 1979 values was plotted against the previous
findings of Weiler and Chawla (1968). Percentages were cal-
culated by dividing each contributing concentration by the
sum of the three major cations and anions (magnesium, calci-
um, sodium, bicarbonate, chloride, and sulfate). Excluding
bicarbonates, ionic species were sampled at the Locust Point
site only. Consequently, the Maumee Bay site was not
included in the anlaysis. Bicarbonates were assumed to be
the sole contributor to alkalinity, since the mean pH was
below 8.3. Any alkalinity due to carbonates or hydroxide
ions that may have been present were assumed to be
negligible. Thus, the contribution to total conductivity
-------
37
d
o
-rH
-U
-P
O
0)
-P
2 o
M OO
as
-P r-
CTl
QJ
-P
-H
.S
-------
38
from bicarbonates were calculated directly from alkalinity
values.
Trends in water quality parameters were summarized for
both locations by reporting trends of yearly means as a per-
cent change per year. In this way, all parameters can be
visually inspected on one figure. Confidence intervals of
95% and 90% were constructed around this percentage value.
If the confidence interval crosses the zero change line, it
can be assumed that neither increase nor decrease of the
parameter trend is significant at the given significance
level (Polak, 1978).
Weather activity influences certain parameters, such
as turbidity, suspended solids and phosphorus through re-
suspension. In order to quantify this influence, concen-
trations of these parameters were regressed against mean
monthly wind velocity (mph) at Toledo airport (National
Oceanic and Atmospheric Administration, 1974-1980). A
positive correlation suggests that weather activity is
responsible for observed changes in the parameters which may
be occurring in the nearshore zone of western Lake Erie.
-------
39
RESULTS
Locust Point
Monthly means. Regression analysis performed on
monthly means at the Locust Point site indicated that a
significant change occurred from 1974 to 1980 for nitrate
at P<.05 (Table 4). Figure 5 graphically depicts an in-
crease from 2.4 mg/1 in 1974 to 7.5 mg/1 in 1980. Al-
though the linear regression line is significant at the
2
.05 level, the coefficient of determination (R ) is rather
low (Table 4), indicating a large source of variability
is not explained by time in months. Visual inspection of
Figure 5 reveals large seasonal variation in the data.
High values occur early in the sampling period for each
year, are generally depleted in the summer months and in-
crease again in the fall.
A residual plot of the linear regression for nitrate
(Figure 6) indicates that a rather wide band exists for
these values. Extreme values of residuals are evident in
1977,1978, and 1980, due to the high spring values occur-
ing in those years.
The smoothed trend curve superimposed on the regres-
sion line somewhat follows the residual values (Figure 5).
A notable increase in nitrate values occurred from 1974 to
1977. From 1977 to 1979, a decrease is observed, followed
by an increase from 1979 to 1980 of the same magnitude as
-------
40
TABLE 4. Statistical values for monthly
means at Locust Point (1974-1980)
Degrees
Parameter of Freedom
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
55
55
55
55
55
55
55
55
55
Slope
+0.4021
0.000*
+0.222*
+0.063*
+0.181**
+0.069*
-0.001*
+0.059*
0.000*
PR>F
(Significance of
R2 Slope)
.073
.000
.035
.001
.029
.051
.000
.090
.000
.0543
.9921
.1647
.7798
.2095
.0952
.9331
.0249
.8792
* mg/I/month
** FTU/month
umhos/cm/month
-------
41
-P
c
-H
O
-P
(fi
3
O
O
tn
c
fd
a)
g
-P
G
O
g
0)
-P
-P
-H
C
O
4-1
10
T3
C
0)
in
Cr>
-H
(N
-------
42
0 •
•
•
•
*
•
* *
•
* m
•
*
•
•
m *
s
*
•
J
•
*
£
. •
•
•
•
.
•
a*
•
•
• *
• * ' ' '
ininmoinoin ommm
CN o r-- in CN o CN inr^ocN
rH rH I 1 r rH rH
. ^T
CO
.
CN
'r-
.
rr
•vo
. vo
m
. CO
^r
• o
^
CN
m
CO
CN
o
CN
CN
-P
C
O
e
-P
ca
M
-P
-H
O
O
-H
03
W
0)
rri
tn 0
.£ M
-P
^ i_i
O (0
g 0)
G
ti -t
•rH rH.
^— ^
0
Q) ^1
S -P
-H
EH MH
O
ID
rH
rO
rrj
•H
UI
(U
PJ
0
Cn
-H
EM
, .
o
CO
en
rH
1
r^
en
rH
—
4J
£
-H
0
PH
-P
W
3
O
O
-P
rO
cn
G
(fl
0
g
aq.paq.TN
-------
43
the 1974-1977 increase.
Although not significant at P<.05, the linear regres-
sion slopes for conductivity and alkalinity are signifi-
cantly increasing at P<.10 (Table 5). These increases
amount to approximately 14% from 1974 to 1980 for conduc-
tivity and 8.5% from 1974 to 1980 for alkalinity. Again,
2
R values are quite low, indicating a large source of
variability is not explained through time.
Yearly means. Calculation of regression equations
for yearly means resulted in increases in conductivity,
suspended solids, turbidity and alkalinity at the .05
significance level. Figures 7-10 depict yearly means,
ranges and standard deviations of these parameters. A
significant decrease of P<.10 was found for chloride only
(Table 5). In addition, significance in the trend for
nitrate values at the .05 significance level was lost
during yearly averaging, while significance at the .10
level was retained. Inspection of Table 6 in comparison
2
with Table 4 indicates large increases in R values. This
is due to homogenizing the large variability through the
averaging process.
Figure 7 shows increases in conductivity values from
265 ymohs/cm in 1974 to 304 umohs/cm in 1980, an increase
of approximately 15% over the period of record. The
smoothed trend curve follows the regression line fairly
well, with the exception of a slight depression occurring
-------
44
TABLE 5 . Comparison of trends using monthly and
yearly means at two levels of statistical
significance for selected parameters at
Locust Point
Parameter
Monthly Means
a=.05 a = .10
Yearly Means
a=.05 a = .l(
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
0
0
0 -
0
0
0
0
+
0
+
0
0
0
0
+
0
+
0
+
0
+
0 0
+
+ +
0 0
0 +
0 0
+ = positive trend
- = negative trend
0 = trend is not statistically significant
-------
45
TABLE 6. Statistical values for yearly
means at Locust Point (1974-1980)
Degrees
Parameter of Freedom
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Alkalinity
Dissolved Oxygen
Nitrate
Phosphorus
* mg/l/yr
** FTU/yr
6
6
6
6
6
6
6
6
6
Slope
+6.3251
-1.818*
+3.53*
+1.638*
+2.984**
+0.905*
-0.069*
+0.787*
+0.001*
PR>F
_ (Significance of
R^ Slope)
.764
.324
.645
.191
.671
.640
.098
.524
.004
.0100
.0985
.0296
.3264
.0242
.0307
.4948
.0660
.8955
umhos/cm/yr
-------
46
en
td
0)
6
1
I
1
1
1
1
1
r
t
i
^
i
\
\
i
i
\
»
i
\
\
i
1
i
i
t
i
\,
* N
j ]
\\
\ i
\ j
/(
\
(0
0 0)
• °^ -H
-H
-P
O
.OO 3 •
r**« Tl 1 1
G C
O -H
0 O
r*^* frt Lj
(U O -P
>H M-l W
r^. *& O
C [ 1
0)
J_J -p
EH rtJ
IT) n iu
^ ni
r- £
dn
-H
Cu
OOOO OOC3 OO OO OO
CNO CO
-------
47
o
in 1975 and 1976. In addition, the R value for this
parameter (.764) was the highest among those exhibiting
a significant trend.
Figures 8 and 9 depict linear and smoothed trend
curves for total suspended solids and turbidity, respec-
tively. These two parameters exhibit similar significance
2
levels, R values, and smoothed and linear curves, suggest-
ing that a rather close relationship exists between them.
Total suspended solids increased from 25 mg/1 in 1974 to
46 mg/1 in 1980, while turbidity increased from 20 to 38
FTU's for the same period of record. Smoothed curves show
slight depressions for both parameters in 1975 and slight
increased in 1979. However, the curve for turbidity appears
to follow the regression line more closely than that for
suspended solids, the latter of which exhibits slight in-
creases in 1977 and 1978.
Although a significant increase is not visually evi-
dent for alkalinity values (Figure 10), the regression line
2
is significant at the .05 level. In addition, R values
are rather high, indicating the observed variability is
adequately explained by time. The smoothed trend curve
follows the regression line fairly closely, excepting in-
creases in 1976 and 1979 and a slight decrease from 1977
to 1979.
-------
48
t!
•H
rH
o
w
0)
t3
C
------- An error occurred while trying to OCR this image.
-------
50
o
GO
03
r^
to
0)
-in
o o
in -^<
o o o o
m CM r-i o
o o o o
cri oo r- vo
>i
,-H
tO
-P
•H
rH
fO
4J
O
-P
O
<4-l
CO
T3
G
0)
O
rH
CD
Cn
•H
4->
c
•H
-P
CO
O
O
4->
10
CO
fi
tO
CD
g
r—i i—I •—i i—I r~»
(eOD^o SB I/6m)
-------
51
Seasonal blocking. In an attempt to homogenize sea-
sonal variability, yearly means were blocked by season and
regressed through time. Significant statistics for all
nine parameters are found in Table 7. Table 8 summarizes
these statistics as trends at the two tested levels of
significance. Figures 11-16 graphically depict trends for
conductivity, chloride, suspended solids, turbidity,
total alkalinity and intrate.
It should be noted that the trend plots were con-
structed on different scales for successive seasons.
Since spring values were generally higher for most para-
meters (with the exception of alkalinity), the y-coordi-
nate was expanded to accommodate differences in ranges.
Significant increases at P<.05 and P<.10 in conduc-
tivity values occurred only during spring and early summer
seasons. Visually evident but statistically insignificant
increases are noted for late summer and fall (Figure 11).
Figure 12 shows trends by seasons for chloride concen-
trations. Significant increases at both levels occur for
spring and fall values while significant decreases occur
during early and late summer. This discrepancy is due
to the extremely small values reported in 1979. When
these values are removed from the regression analysis, the
trends reverse and significanntly increase through time.
In addition, the slope attained for the fall season is
significantly increasing at P<.10 (Table 8).
-------
52
TABLE 7. Statistical values for seasonal
yearly means at Locust Point (1974-1980)
Parameter
Season
Slope
R
* mg/l/yr
** FTU/yr
1 umhos/cm/yr
PR>F
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Spring
Early Summer
Late Summer
Fall
Spring
Early- Summer
Late Summer
Fall
Spring
Early Summer
Late Summer
Fall
Spring
Early Summer
Late Summer
Fall
Spring
Early Summer
Late Summer
Fall
+8.5301
+7.160
+2.702
+3.028
*
+1.031
-0.176
-0.527
+0.283
*
+5.455
+5.899
+1.395
+5.745
*
+0.635
+7.324
+2.565
+3.084
**
+3.255
+7.537
+5.588
+1.619
.172
.221
.058
.007
.340
.020
.165
.098
.132
.547
.150
.414
.065
.228
.162
.094
.099
.734
.669
.065
.0106
.0039
.1564
.1284
.0002
.4059
.0139
.0626
.0270
.0001
.0196
.0001
.4285
.0643
.0916
.1348
.0569
.0001
.0001
.1316
-------
53
TABLE 7. (Cont.)
Parameter
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
Season
Spring
Early Summer
Late Summer
Fall
Spring
Early Summer
Late Summer
Fall '
Spring
Early Summer
Late Summer
Fall
Spring
Early Summer
Late Summer
Fall
Slope
-1.876*
+0.944
+0.0661
+0.669
-0.199*
+0.016
-0.068
-0.120
+1.426*
+1.555
+0.860
+0.125
+0.001*
+0.002
+0.003
+0.003
R2
.010
.392
.064
.120
.230
.051
.033
.187
.162
.397
.606
.020
.000
.001
.045
.070
PR > F
.5514
.0001
.1364
.0384
.0826
.4360
.5367
.1128
.0149
.0001
.0001
.4097
.9551
.9344
.4690
.3618
*mg/l/yr
-------
54
TABLE 8 . Comparison of trends using seasonally
blocked yearly means at two levels of
statistical significance for selected
parameters at Locust Point
Parameter Season a = .05 a= .10
Conductivity Spring + +
Early Summer + +
Late Summer 0 0
Fall 0 0
Chloride Spring + +
Early Summer 0 0
Late Summer - -
Fall 0 +
Suspended Solids Spring + +
Early Summer + •+•
Late Summer + +
Fall + +
Dissolved Solids Spring 0 0
Early Summer 0 +
Late Summer 0 +
Fall 0 0
Turbidity Spring 0 +
Early Summer + +
Late Summer + +
Fall 0 0
Alkalinity Spring 0 0
Early Summer + +
Late Summer 0 0
Fall + +
+ = positive trend
- = negative trend
0 = trend is not statistically significant
-------
55
TABLE 8. (Cont.)
Parameter Season a=.05
Dissloved Oxygen Spring 0
Early Summer 0 0
Late Summer 0 0
Fall 0 0
Nitrate Spring + +
Early Summer + +
Late Summer + +
Fall 0 0
Total Phosphorus
Spring
Early Summer
Late Summer
Fall
0
0
0
0
0
0
0
0
+ = positive trend
- = negative trend
0 = trend is not statistically singificant
------- An error occurred while trying to OCR this image.
-------
57
30-
28-
26-
o*
3 24-
a>
•o
^H
o 22-
r-l
£.
u
20-
18-
J
J
5- ,--1
;,-- J
SPRING
-f-
*
.,••"{
r
1
.
.
}
30 -
28 -
26 •
24 •
•
J 22
20 '
18 '
EARLY SUMMER
f
1
-r-
jn.
UJ
iL J
" • *
TTT
L J
1 *
74 75 76 77 78 79
74 75 76 7*7 78 79
22-
3 181
v
•a
•H
p 161
LATE SUMMER
22
20 -|
18 A
16
14 ^
12
—I 1 1 1 1 1
74 75 76 77 78 79
FALL -r-
74 75 76 77 78 79
Year
Figure 12. Trends for chloride yearly means using
seasonal blocking at Locust Point.
-------
58
Suspended solids (Figure 13) is the only parameter
which exhibits significant increases throughout all four
seasons. The largest slope (5,899 mg/l/yr) is found for
the early summer months. This season also possesses the
highest R values.
While no trends were found for dissolved solids at
P<.05, significant increases at P<.10 occur for the early
summer and late summer - seasons (Table 8).
Turbidity trends were significant only during early
and late summer seasons for P<.05, while the spring values
are significant at the .10 level (Figure 14).
Seasonal blocking for alkalinity values produced some
rather strange results (Figure 15). Although the steep-
est slope occurs in the spring, the early summer trend is
the only significant one found (Table 6). The lack of
significance of the large decrease occurring for spring
values may be attributed to an extremely large error mean
square, which effectively lowers the F-statistic.
The data in Figure 16 and Tables 7 and 8 indicate
that nitrate values are significantly increasing for all
seasons except fall, where increased values are not sta-
tistically significant. Visual inspection of Figure 16
reveals large variation of yearly means except for those
reported in late summer.
------- An error occurred while trying to OCR this image.
-------
60
40 i
20 -.
=' 100 -
t,
>, 80
•o
•H
XI
t*
60 -
40 •
20 -
•u
SPRING
40 -
20 -
100 •
80 -
t
40
20 -
Ef-RLY SU.'-WER
•
"ift-
f'lL
70 -
60
i s°
fc!
>, 40 ^
^
-H
•a
~H
^ 30 -
20 -
10 -
74 75 76 77 78 79 80 74 75 76 77 78 79 80
Year
70
LATE SUMMER
-fc
-EJ-
60
50
40 -
30 •
20 -
10 -
J- -'- ~- -L 79 8b
FALL
1 111
-74 75 76 77 78
74 75 76 77 78 79 8t)
Year
Figure 14. Trends for turbidity yearly means using
seasonal blocking at Locust Point.
------- An error occurred while trying to OCR this image.
------- An error occurred while trying to OCR this image.
-------
63
Summary. Trends for all parameters included in the
analysis are summarazed in Figure 17. Inspection of the
figure indicates significant increases have occurred from
1974 to 1980 for conductivity, suspended solids, turbid-
ity, and alkalinity at the .05 level. At P<.10, chloride
is significantly decreasing and nitrate is significantly
increasing. No significant trends were found for dissolved
solids, dissolved oxygen, or total phosphorus.
The C&O Docks
Monthly means. Linear regression analysis performed
on monthly means at the Maumee Bay site revealed a signifi-
cant trend at P<.05 and P<.10 from 1970 to 1979 for
chloride, alkalinity, nitrate and total phosphorus. Dis-
solved oxygen exhibited no change at the .05 level, while
a significant increase is observed at the .10 level
(Tables 9 and 10). No significant differences through
time were found for conductivity, suspended solids, dis-
solved solids, or turbidity.
Figure 18 shows both linear and smoothed curves for
chloride ion concentrations for the period of record. An
increase of about 1.5 mg/l/yr has been calculated from
the linear monthly slope. This amounts to a total increase
from 1970 to 1979 of 15 mg/l/yr or 47%. The smoothed
curve depicted in the figure indicates a general decrease
from 1972 to 1974. Increases in chloride concentration
------- An error occurred while trying to OCR this image.
-------
65
TABLE 9• Statistical values for monthly means
at the C & O Dock (1970-1979)
Degrees
Parameter of Freedom
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
85
114
114
112
114
114
114
107
110
Slope
-0.4061
+0.125*
+0.126*
+0.235*
+0.128**
-0.222*
+0.013*
-0.023*
-0.004*
PR>F
_ (Significance of
R Slope)
.022
.161
.007
.013
.013
.125
.027
.188
.239
.1708
.0001
.3698
.2185
.2190
.0001
.0810
.0001
.0001
* mg/I/month
** JTU/yr
umhos/cm/yr
-------
66
TABLE 10. Comparison of trends using monthly and
yearly means at two levels of statistical
significance for selected parameters at
the C & 0 Docks
Monthly means
Parameter a =.05 a =.10
Conductivity 0 0
Chloride + +
Suspended Solids 0 • 0
Dissolved Solids 0 0
Turbidity 0 0
Alkalinity
Dissolved Oxygen 0 +
Nitrate
Total Phosphorus
Yearly means
a =. 05 ot =. 10
0 0
+ +
0 0
0 0
0 0
-
0 +
-
-
+ = positive trend
- = negative trend
0 = trend is not statistically significant
------- An error occurred while trying to OCR this image.
-------
68
occurred from 1974 to 1978 followed by a slight decline
in 1979.
Residuals analysis of the linear regression for
chloride (Figure 19) reveals a band relatively constant
with respect to time, indicating the trend is adequately
described as a linear function. Peak values occurring
at month 54 and month 103 correspond to extreme values
found in the fall of 1974 and the spring of 1979, respec-
tively.
Decreases in alkalinity values are evident from Figure
20. The regression line indicates that alkalinity at this
site is decreasing at a rate of 2.66 mg/l/yr as CaCO_. The
smoothed trend curve produces a rather consistent oscilla-
tion occurring with a period of about three years. Re-
siduals analysis (Figure 21) of the regression equation
reveals a somewhat wide band with peaks and depressions
corresponding to those found in Figure 20.
Nitrate values have declined from 4.4 mg/1 in 1970
to 1.65 mg/1 in 1979, which amounts to a 62% reduction
during the decade (Figure 22). The smoothed trend curve
reveals a somewhat similar oscillation to that of alka-
linity values, but is not as visually evident. Figure 23
illustrates a somewhat narrowing band of residuals through
time. This may be indicative that a non-linear relation-
ship is occurring for nitrates through time.
Figure 24 depicts phosphorus monthly means regressed
-------
69
CO
o
0)
T3
•H
M
O
rH
.C
O
o
•H
in
en
in
O
m
CM
"I
CN
vo
• m
en
.£
-P
fi
i
c
•H
-H
B
Cn
0)
0)
C
0)
>M
O
cn
ui
^
O
o
Q
O
T3
C
-------
70
0)
x:
-P
in
G
(C
Q)
6
•P
G
o
-H
c
-H
(t3
(0
-P
O
-P
O
14-1
en
•n
G
0)
O
CN
0)
-H
Cn
O
o
Q
O
T3
G
fl
O
-------
71
•
•
•
.•
•
• •
• •
*
•
•
•
• .
*
t
• •
•
• • •
. •
•
• •
' •
•
•
0
• •
•
• .
•
•
•
•
0
•
•
• • .
•
•
*.
*
• *
• •
0
•
«
• .
• *
•
«
•
*
*
•
*
* •
» •
*
•
» •
•
. •
• .
•
•
•
• •
• •
• • •
• •
• .
•
•
•
•
rH
' rH
rH
r~f
• o
i — i
rH
cn
^
03
. rH
r^.
_ rH
kO
. rH
in
rH
• -«r
rH
" m
rH
CN
-
. rH
rH
' rH
1 1 1 1 1 1 1 • ' ' ' ' °"
ooooooo
vrj -* CN CN ^T V£>
III
>1
rH
XI
1 t
-M
c
0
£
•s^.
;>1
-p
-H
fi
-H
rH
(0
^
rH
HJ
M
o
4-1
C
O
-r-t
"l~1
tn
tn
0)
• .
H
^. tn
cn CD
x; n
-P
C M
O
^
r-f
^>
CP
•H
rv.
KM
.
cn
>i
o
O
Q
O
T3
C
cO
O
0)
A
-P
-P
rO
cn
C
nj
0)
g
-------
72
tn
r^
>
o
• oj
o
-o
-O
-------
73
. •
•
•
•* •
• *
•
.
•
. •
•
u •
*
• '
• •
.*
•
•
.' •
• •
•
*
•
• •
f •
«
•
•
•
•
, *
• •
v
9
•
•
* •
* • •
•
•B
*
• •
. •
•
a *
•
. •
v •
. •
•
rH
rH
rH
rH
O
rH
rH
cr>
rH
'co
.rH
r~
.rH
VD
rH
'\n
•
f—j
'*
•
rH
"m
"
rH
'(N
.rH
tH
' rH
j g ! j . | j . j , , j j __ _
VD LO -^J4 <~O fN i — 1 O iH (N CO ^T1 LD VO
1 1 1 1 II
tn
c
m
a)
g
rH
-P
c
o
g
0)
-p
fC
S-l
-H
d
o
c
o
— . -ri
m en
x; en
-P QJ
r* Lj
O tr>
e QJ
r-l
c
•H 5H
— rt5
-------
74
o
OJ
o
o
CO
us in
tn
o
en oo
VD
O
00
o
O
IT)
o
ro
o
CN
x;
4-1
c
o
•c
•H
0)
e
•H
CO
G
03
(U
S
4-1
C
O
Cb
c/j
O
O
4J
C
•H
to
T3
C
0)
(N
CO
^:
o
o
a
C
(0
0)
.c
4J
(d SB I/Bui) snaoqdsoLid
-------
75
through time. Of all parameters found to be changing
significantly for the period of record at the Maumee Bay
site, the phosphorus decrease is the most visually evident;
2
R and significance values (Table 9) provide strong support
of a decrease for this improtant nutrient parameter. The
linear regression line suggests phosphorus values have de-
creased 78% from 1970 to 1979. The smoothed trend curve
superimposed on the linear model indicates relatively
stable concentrations existed from 1970 to 1973. In 1974,
large variation in monthly means produced an upswing in the
curve. A visual decline in phosphorus levels is evident
from 1975 to 1977, followed by a relatively steady state
from 1977 to 1979.
Residuals analysis of the regression line (Figure 25)
indicate that most of the residuals fell below the regres-
sion line before about 1975, after which residuals are
fairly well scattered around the zero line.
Yearly means. Regression analysis using yearly means
produced similar results to analysis using monthly means.
The same parameters exhibited similar trends (Tables 10 and
11). Although the significance levels have decreased in
value due to lower degrees of freedom, R values signifi-
cantly increased over those for monthly means, indicating
large sources of variation were smoothed through averaging
by year. Figures 26 through 29 graphically depict linear
-------
76
CTl
CO
-P
C
o
£
C
•H
0)
-H
EH
a,
CO
O
x:
a
-P
o
-P
o
m
o
-H
CO
Q)
S-4
Cn
Q)
M
(0
0)
C
-H
Q)
M-i
O
CO
in
o
o
Q
C
r3
U
-P
(X3
01
C
03
0)
rs
m o m m
o • o T-I
o
I I
sn^oqdsoqd
m
CN
3 rH
'a x;
•M -P
w c
0) O
r^. £
tn
CN
0)
-------
77
TABLE 11. Statistical values of yearly means
at the C & O Dock (1970-1979)
Degrees
Parameter of Freedom Slope
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
7
9
9
9
9
9
9
9
9
-2.
+1.
+1.
+3.
+1.
-2.
+0.
-0.
-0.
5081
350*
522*
214*
337**
909*
152*
252*
041*
PR>F
(Significance of
R Slope)
.069
.539
.061
.127
.055
.630
.320
.562
.806
.5306
.0156
.4927
.3118
.5136
.0061
.0885
.0126
.0004
* mg/l/yr
** JTU/yr
-------
78
and smoothed curves of yearly means. Slopes for all four
parameters exhibiting significant change (chloride, alka-
linity, dissolved oxygen, nitrate and phosphorus) are
similar to those calculated for monthly means.
Seasonal blocking. Since samples were collected
during winter months at the C&O Docks, five seasons were
created to homogenize seasonal variability. Significant
statistics for all nine parameters are found in Table 12.
Table 13 summarizes these statistics for the two tested
levels of significance.
While conductivity values were not changing signifi-
cantly using regression analysis on monthly and yearly
means (Table 10), seasonal blocking produced a significant
decrease at both a=.05 and a=.10 for the winter season
only. All other seasons exhibit no trend.
Chloride is singificantly increasing at P<.10 and
P<.05 for spring and early summer seasons (Figure 30).
A significant increase is noted for late summer only at the
.10 level (Tables 12 and 13).
Suspended solids is increasing during one season only;
late summer, and is not significant at the .05 level.
Seasonal blocking produced no other trend in this para-
meter.
Turbidity is the only parameter which exhibited no
trend at either significance level for any season (Table 13).
-------
79
o
c
CO
r-
' r-
LD
M
(0
OJ
n
f-
CN
O
OJ
x;
(0
0)
c
(0
.
rH
S-l
0)
0)
x:
u
c
-H
01
TD
C
(1)
vo
(N
0)
H
3
cn
-H
03
^
O
O
Q
O
CO
o
in
o
CN
(I/But)
-------
80
o o
r1* ro
CN rsj
i •
o
01
l-l
1
c
L
r
r~
r
(
\
1
yf
1
l\
I
1 1
1 I
(/
[y
1
D
n
-1
/
j
\\
H
tf\
'1
) I
/
K
\
/
c
r-
T-
1
D
^
H
1
1
1
1
C
r
> > ' i
5 0
cn
C/5
>i
O
0
Q
O
C
(0
cn C)
£^_
QJ
-P
-P
'"*" rrt
in
~r^- (1)
•H
^-^ 0)
in >i
^in c -P
r~ O -H
e c
-H
•H fO
.-^< ^ X
[~^ rH
0) (0
e
-H rH
EH rd
-JP 4J
^ O
-M
C
-H
1^
C
Q)
t— i _
r^
r-
0)
3
cr>
-H
I/BUI)
-------
81
- CPi
oo
vo
in
03
CU
n
CM
o
r-
u
o
Q
o
'O
c
U
(0
Cfl
c
cu
>i
rH
OJ
Q)
-U
-P
-H
C
c
•H
C
(1)
oo
CN
-------
82
a)
-p
its
w
c
o
x:
tn
O
CU
m
-P
o
-P
c
-H
w
0)
5-1
EH
CTl
OJ
-------
83
TABLE 12. Statistical values for seasonal
yearly means at the C&O Docks (1970-1979)
Parameter
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Season
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Slope
+10.8121
+ 3.890
+ 2.349
-11.290
-23.715
+ 1.756*
+ 2.077
+ 0.832
+ 0.839
+ 2.142
- 1.315*
- 0.831
+ 3.361
+ 0.403
+ 7,049
+ 2.270*
+ 6.417
+ 7.787
- 6.259
+ 1.142
**
+ 0.457
- 0.100
+ 3.010
+ 0.423
+ 4.355
R2
.223
.040
.020
.296
.552
.662
.467
.397
.108
.270
.023
.006
.348
.004
.098
.079
.310
.424
.172
.003
.006
.000
.296
.004
.102
PR>F
.2850
.6333
.7617
.1635
.0347
.0042
.0292
.0510
.3524
.1235
.6757
.8293
.0725
.8544
.3788
.4294
.0946
.0413
.2329
.8905
.8287
.9787
.1038
.8682
.3676
* mg/l/yr
** JTU/yr
1 umhos/cm/yr
-------
84
TABLE 12. (Cont.)
Parameter
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
Season
Spring
Early Summer
Late Summer
Fall
Winter
Spring,
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Slope
*
- 2.254
- 0.650
- 2.423
- 4.235
- 3.580
*
+ 0.075
+ 0.186
+ 0.307
+ 0.258
+ 0.122
*
- 0.388
- 0.264
- 0.047
- 0.216
- 0.397
*
- 0.022
- 0.034
- 0.038
- 0.047
- 0.078
R2
.231
.017
.336
.417
.256
.264
.066
.447
.320
.296
.580
.188
.115
.273
.454
.420
.478
.325
.674
,547
PR>F
.1594
.7172
.0792
.0436
.1351
.1527
.3612
.0344
.0882
.1043
.0105
.2111
.3364
.1492
.0327
.0427
.0268
.0851
.0036
.0145
* mg/l/yr
-------
85
TABLE 13. Comparison of trends using seasonally
blocked yearly means at two levels of statistical
significance for selected parameters at the C&O Docks
Parameter
Conductivity
Chloride
Suspended Solids
Dissolved Solids
Turbidity
Season
Spring
Early Summer
Late Summer
'Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
Spring
Early Summer
Late Summer
Fall
Winter
a = .05
0
0
0
0
-
+
+
0
0
0
0
0
0
0
0
0
0
+
0
0
0
0
0
0
0
a=.10
0
0
0
0
—
+
+
+
0
0
0
0
+
0
0
0
+
+
0
0
0
0
0
0
0
+ = positive trend
- = negative trend
0 = trend is not statistically significant
-------
86
TABLE 13. (Cont.)
Parameter
Season
a=.05
a=.10
Alkalinity
Dissolved Oxygen
Nitrate
Total Phosphorus
Spring 0
Early Summer 0
Late Summer 0
Fall
Winter 0
Spring 0
Early Summer 0
Late Summer +
Fall 0
Winter 0
Spring
Early Summer 0
Late Summer 0
Fall 0
Winter
Spring
Early Summer
Late Summer 0
Fall
Winter
0
0
0
0
0
0
0
+
0
positive trend
negative trend
trend is not statistically significant
-------
87
-C
U
T
1
JC
u j«
Year
Year
Figure 30. Trends for chloride yearly means using
seasonal blocking at the C&O Docks.
-------
88
Seasonally blocked trends for total alkalinity are
depicted in Figure 31. Decreases at both significance
levels were found during the fall season, while the late
summer season exhibited a trend for P<.10. The spring,
early summer, and winter seasons produced no significant
trends.
Table 13 reveals increases for dissolved oxygen in
the late summer season,at both levels of tested signifi-
cance. An increase in the fall is significant at P<.10
but not at P<.05.
Nitrate values are decreasing significantly at both
P<.05 and P<.10 for the spring and winter seasons (Table 13).
Visually evident but insignificant decreases are occurring
for spring, early summer and late summer as well (Figure 32).
Total phosphorus is the only parameter which is
decreasing during all five seasonally blocked time periods.
Although the trend is not significant at P<.05 for
late summer, it is significant at P<.10 (Table 13). The
2
R values for this parameter are among the highest for
all seasons when compared to those of the other parameters
(Table 12). Inspection of Figure 33 indicates that lower-
ed yearly means after 1974 may be responsible for the
decreasing trend. This phenomenon is especially evident
for early summer, late summer and fall.
Summary. Figure 34 illustrates a summary of trends
for all parameters included in the analysis. Conductivity,
-------
89
T
ID
i"! Hill
JL
i
o
u
Year
Figure 31. Trends for total alkalinity yearly means
using seasonal blocking at the C&O Docks.
-------
90
Year
O>
E
Year
Year
Figure 32. Trends for nitrate yearly means using
seasonal blocking at the C&O Docks.
-------
91
Sv.
o
-El
,
™...
4L
1-
Figure 33. Trends for total phosphorus yearly means
using seasonal blocking at the C&O Docks,
-------
92
suspended solids, dissolved solids, and turbidity are not
significantly changing at the Maumee Bay site as evidenc-
ed by the confidence intervals intersecting the zero
percent change line. Significant decreases have occurred
for the period of record for alkalinity, nitrate and phos-
phorus; the last of wich exhibits the greatest decrease
and the narrowest confidence intervals. Chloride and
dissolved oxygen were the only parameters at this site
which exhibited a significant increase from 1970 to 1979.
The latter parameter is significant at P<.10 but not at
P<.05.
------- An error occurred while trying to OCR this image.
-------
94
DISCUSSION
Trend analysis performed on the two western basin
locations indicate that with the exception of a decrease
for yearly means in chlorides and a decrease for one season-
al statistic for dissolved oxygen, all parameters at the
Locust Point site which exhibit significant trends are
significantly increasing through the period of record.
Trend analysis of yearly and monthly means for parameters
at the C&O Dock indicate significant decreases for alka-
linity, nitrate, and total phosphorus, while chloride and
dissolved oxygen are increasing. Seasonal blocking of the
data reveals additional increases for suspended and
dissolved solids, while conductivity is found to decrease
during the winter season.
The only parameters which showed significant change
at both levels of significance at the Locust Point study
site are increases for monthly means in nitrate values,
while increases in monthly means for conductivity and
alkalinity values at a=.10 are observed. Increases in
yearly means of conductivity, suspended solids, turbidity,
and alkalinity are observed for both significance levels.
In addition, regressing yearly means revealed an increase
in nitrate values and a decrease in chlorides.
-------
95
Significance of the trend for nitrate found in monthly
means was lost at the .05 significance level during yearly
averaging, but was regained for three of the four seasonal
periods after seasonal blocking. Thus, while statistical
analyses conflict for this nutrient, a general increase
in nitrate concentrations may be occurring at this site.
Nitrate increases since the late 1960's have been
substantially documented. Gregor and Ongley (1978) found
that a highly significant increase in nitrates occurred for
the northern nearshore zone of Lake Erie from 1967 to 1973.
Increases have also been reported near Long Point in the
eastern basin from 1967 to 1978 (Weiler and Heathcote,
1979). Dobson (1981) reported a 1.5-fold increase in ni-
trate levels from 1970 to 1980 for eastern basin main lake
waters.
Nitrate trends at the Maumee Bay site substanitally
conflict with those found at Locust Point. Significant
decreases found at the C&O Docks during analysis of both
monthly and yearly means most probably reflect improve-
ments in Toledo's sewage treatment operations. Inspec-
tion of Tables 12 and 13 reveal that decreases during the
winter and spring seasons are resposible for observed
decreases in yearly and monthly means. Figure 32 provides
evidence of improved sewage treatment practices being
resposible for observed trends. The most substantial re-
duction occurs after 1974 and is especially evident in the
-------
96
early summer, fall, and winter seasons when storm by-pass
is less likely to occur.
Conflicting trends at the two locations suggest
sources of nitrate input other than the Maumee River are
influencing lake-wide trends. The International Joint
Commission in 1977 identified large loading increases
for nitrates in the Detroit River. Thus, increases at
the Locust Point site reflect inputs from the Upper Great
Lakes, while substantial decreases from the Maumee River
do not appear to have a significant impact.
Phosphorus concentrations exhibit a significant de-
crease in Maumee Bay, while no change is observed at Locust
Point for any of the three analyses performed. Inspection
of Figure 24 reveals that a relatively stable concentra-
tion of total phosphorus was present from 1970 to 1974,
after which a substantial decline is visually evident.
In addition, seasonal blocking produced significant de-
creases during all five seasonal periods. Figure 33 re-
veals a substantial decrease after 1974 for all five
seasons. Thus, tertiary sewage treatment initiated in
1974 is most likely responsible for the observed decrease.
Several researchers have documented substantial de-
creases in phosphorus concentrations through the past 10
to 15 years. A decrease of 88% in phosphorus loading in
the Detroit River has been calculated by the Michigan
-------
97
Department of Natural Resources (1981). This decrease
has been attributed to improvements in the five waste
water treatment plants for the Detroit metropolis.
Negative trends have also been documented for the Cleveland
area (Richards, 1981), the entire Ontario nearshore zone
(Gregor and Ongley, 1978) , and the eastern basin (Weiler
and Heathcote, 1979).
The seemingly steady-state condition for phosphorus
occurring at the Locust Point site may be reflective of
release of deposited phosphatic materials from the sedi-
ments balancing decreased inputs from major tributaries.
Increases in turbidity, dissolved solids, and suspended
solids occurring at the Locust Point site indicate that
storm activity is responsible for observed trends. In
order to test the possibility of weather influences on
these parameters, mean monthly wind velocity (mph) data
from the Toledo Airport were correlated against the month-
ly means for turbidity, suspended solids and total phospho-
rus. Correlation coefficients of .58 for turbidity, .44
for suspended solids, and .56 for total phosphorus are all
significant at P<.01 (Steel and Torrie,1980). In addition,
monthly average wind velocity and the maximum wind velocity
observed for each month were regressed against time in
months. The F-statistic for both of these regressions
(F=5.89 and F=16.08, respectively) are highly significant
-------
98
(P<.005), indicating that increased storm activity are
responsible for observed trends. Thus, it is very likely
that increases in these parameters are responsible for the
observed steady condition occurring in phosphorus concentra-
tions at Locust Point.
Trends in alkalinity are conflicting for the two
study sites. While alkalinity values show a substantial
decrease from 1970 to 1979 at the Maumee Bay site, a
significant increase is found at Locust Point, especially
during the early summer and fall seasons. Decreases in
monthly and yearly means observed at the Maumee Bay site
are due to decreases occurring for the late summer and
fall seasons (Table 13). Figure 31 reveals that visually
evident but insignificant decreases are occurring for the
other seasons as well. Decreases at the C&O Dock are likely
reflecting increased acid precipitation (Dillon, 1978).
Alkalinity increases observed at Locust Point can be ex-
plained by the immense buffering capacity that persists
in the Great Lakes basin coupled with influences from in-
creased storm activity dissolving limestone and dolomitic
rock in the western basin. This is especially evident
through increases observed during the early summer and fall
seasons when wind and wave action are enhanced.
Chloride concentrations have not significantly changed
at Locust Point through trend analysis of yearly or monthly
-------
99
means. When the data is blocked by season, however,
chloride is significantly increasing during the spring and
fall seasons (Table 8). The decrease observed for the
late summer season is attributed to extremely low values
occurring in 1979 (Figure 12). When these values are
removed, substantial increases can be observed for all
seasons with the exception of early summer.
A substantial increase is found at the C&O Dock when
yearly means and monthly means are regressed through time.
Inspection of Table 13 and Figure 30 reveals that increas-
es occurring in the spring, early summer, and late summer
seasons are resposnible for observed trends. Since the
winters of 1977, 1978, and 1979 were particularly severe
in terms of snowfall, increases in this parameter are most
likely reflective of salt usage for deicing purposes.
Previous investigations throughout Lake Erie from
1964 to 1973 indicate significant decreases occurred.
These decreases have been explained by an increase in the
flushing fate from the Detroit River. Flow increased
from 4437 m3/s in 1964 to 6734 m3/s in 1973 (IJC,1974;
Gregor and Ongley, 1978). Water level data from 1960 to
1980 is shown in Figure 35. Inspection of the figure
indicates that a rise in lake levels did occur from 1964
to 1973, but since then have leveled off. Dilutional
effects are thus not considered as a causal factor for
-------
100
o
CO
en
-------
101
observed trends.
Although no trends were reported at either location
for dissolved oxygen when analyzed via monthly or yearly
means, seasonal blocking produced decreases for all
seasons except early summer at Locust Point. Only the
spring value was significant at P<.10 but not at P<.05.
Seasonal blocking at the C&O Docks, however, produced
increases in all seasons with late summer and fall pro-
ducing significance of the trend. Again, improved sewage
treatment may be responsible by decreasing biochemical
oxygen demand.
While no significant trend in dissolved solids was
found at either location through analysis of monthly or
yearly means, seasonal blocking produced increases at both
locations for the early summer and late summer periods.
Dissolved solids have been substantially increasing in
Lake Erie since around 1910 (Beeton, 1961;IJC,1969a). Al-
though slight increases are reported for these seasons,
yearly means from the Locust Point site (1974-1980)
plotted against whole lake observations of Beeton (1970)
indicate that the increase which typified the first half
of the century is no longer evident and indicates a stabil-
ization of the trend to diminishing levels (Figure 36).
Statistical techniques performed on data from Locust
Point produced varying results. Regression analysis for
-------
102
o
CO
C/3
T3
-H
,—I
O
W
T3
,H
O
M
CO
-rH
-P
O
o
4-t
CO
0)
o °>
01 r—
'2 m
CJ
LO
• o\
o
. CM
C
O
cn
-H
S-l
o
o
O
r-
en
c
O
-P
0)
S-l
d
o
13
C
OJ
S-l
-P
OJ
x:
-p
-ri
-P
C
•H
O
-P
cn
3
o
o
tJ
o
. o
o
. 0\
CD
m
0)
^1
d
O O
in *r
CM CM
O
CM
CM
O
O
CM
O
en
O
CO
o
vo
O
CO
(I/6ui) spx^os paAiossTQ
-------
103
monthly means produced a significant trend in conductivity,
alkalinity, and nitrates. The extreme variability inherent
in the nearshore zone serves to limit achieved statistical
significance. In addition, monthly sampling techniques
serve to increase variability which is somewhat smoothed
in a continuous sampling cycle similar to that at the C&O
Docks.
Regressions performed on yearly means resulted in
2
higher R values and a greater number of parameters ex-
hibiting significance in trend. Thus, most of the varia-
bility is removed simply by yearly averaging. The nitrate
trend, however, fell below the P<.05 significance level
during regression on yearly means. This is due to a large
decrease in the degrees of freedom used for calcualation
of the F-statistic.
Seasonal blocking serves to identify periods during
the year which are most reflective of actual trend phenome-
non. Inspection of Table 7 reveals that the highest R
values and significance levels can be found for certain
parameters such as turbidity, phosphorus, and suspended
solids during the summer seasonal periods when weather
influences are minimal. Other parameters such as chloride
and conductivity reveal significance in the spring and
early summer when inputs of these constituents is large
due to runoff.
-------
104
Regression of yearly means in comparison with monthly
means at the Maumee Bay site produced similar trends. As
expected, R values increased due to decreased variability
through the averaging process. Significance levels dropped
somewhat during yearly averaging resulting from a decrease
in degrees of freedom. Residual analysis of the linear re-
gression indicates that all parameters exhibiting a signifi-
cant trend, with the exception of nitrate, are adequately
explained by the linear model. The nitrate regression is
influenced by a severe decrease in values beginning in 1976.
Prior to that year, nitrate appears to have remained
relatively stable.
Seasonal blocking for parameters at the C&O Docks
produced significant trends in the spring and early summer
seasonal periods for chlorides and nitrates only. Lack of
significance in the other parameters for these two seasons
(with the exception of total phosphorus) may be attribut-
ed to extreme variable loading conditions that persist
early in the year. Significance of suspended solids,
dissolved solids, dissolved oxygen, and alkalinity all
appear during the late summer and fall seasons when
variability due to Maumee River flow is diminished.
Weiler and Chawla (1968) documented changes in Lake
Erie water quality through triangular percentage plots of
major ionic species comprising conductivity. Their results
-------
105
indicated that major shifts occurred from 1906 to 1948
with respect to chloride and sodium concentrations. An
even greater increase in these ions took place between 1948
and 1967. When concentrations from the Locust Point loca-
tion are plotted against Weiler and Chawla's data, a re-
version back to 1948 values is evident (Figure 37). This
reversal may be due to increases in alkalinity (or bicarbon-
ates) and magnesium ion occurring at this site.
Chemical species sampled at Locust Point which were
common to reported trends of Beeton (1970) were plotted
against his findings (Figure 38). Although this technique
is not definitive due to Beeton's variety of source loca-
tions, it does provide evidence of decreases in trends,
with the exception of sulfates, which took place during the
past 70 years.
Figures 36,37 and 38 provide evidence that Lake Erie
is not deteriorating at the rate which typified the first
part of the century, and may be reverting to pre-1959
values.
-------
106
A/VWASSA
\/\'7\
HCO
-^- Data from Weiler and Chawla (1968)
• Data from Locust Point (1979)
Figure 3-7 . Comparison of major ionic species comprising
conductivity from 1906-1979.
-------
107
(0
(3)
X
0)
'CJ
-H
!-l
O
rH
-C
O
C
03
(0
m
-------
108
CONCLUSIONS
1. Linear regression analysis performed on monthly means
for nine selected parameters at Locust Point indicated
a significant increase occurred from 1974 to 1980 for
nitrates, conductivity and alkalinity. No decreases
were found for any parameter using this method.
2. Analysis of yearly means at Locust Point indicated
significant increases in conductivity, suspended
solids, turbidity, alkalinity and nitrates. These in-
creases are attributed to increased precipitation and
wind acitvity in recent years.
3. Linear trend analysis performed on monthly and yearly
means produced similar results for parameters sampled
in Maumee Bay. Increases were found from 1970 to 1979
for chloride and dissolved oxygen, while decreases were
found for alkalinity, nitrate and total phosphorus.
4. Conflicting trends occurring for both locations are
attributed to limnological processes affecting the
nearshore zone coupled with Detroit River influences
that dominate the Locust Point site but do not influ-
ence Maumee Bay. Localized remedial activities in
-------
109
the Toledo area are also responsible for observed
conflicts.
5. Seasonal blocking at both locations served to identify
periods during the year which are most reflective of
actual trend phenomenon by homogenizing the variability
due to seasonality. This technique aids in the iden-
tification of periods during the year which are in-
fluencing observed trends in yearly or monthly data.
6. Comparison of relatively recent data with those of
past investigations imply that deterioration of Lake
Erie which typified the first half of the century is
no longer evident. Stabilization of trends vay be
occurring even to the point of diminishing levels.
-------
110
LITERATURE CITED
Allen, H.E. and J.R. Kramer. 1972. Nutrients in Natural
Waters. John Wiley and Sons. New York: 475 pp.
Baker, D.B. and J.W. Kramer. 1973. Phosphorus Sources and
Transport in an Agricultural River Basin of Lake Erie.
Proc. Conf. Great Lakes Res. 16:858-871.
Barr, A.J., J.H. Goodnight, J.P. Sail, and J.T. Helwing.
1976. A User's Guide to SAS. SAS Institute, Raleigh,
N.C. 494 pp.
Beeton, A.M. 1961. Environmental Changes in Lake Erie.
Trans. Am. Fish. Soc. 90:153-159.
. 1969. "Changes in Environment and Biota of
the Great Lakes," pp. 150-187 In Eutrophication:
Causes, Consequences, Corrections. National Academy
of Sciences, Washington, D.C.
. 1970. Statement on Pollution and
Eutrophication of the Great Lakes. University of
Wisconsin. Center for Great Lakes Studies, Special
Report, No. 11. Milwaukee, Wisconsin.
Berg, K. 1958. "Investigations on Pure Lake." Folia
Limnologica Scandinavia. No. 10. 188 pp.
Bouldin, D.R., H.R. Caperer, G.L. Casles, A.E. Durfee, R.C.
Loehr, R.T. Oglesby, and R. J. Young. 1976. "Lakes
and Phosphorus Inputs - A Focus on Management." Plant
Sciences Information Bulletin No. 127. Cornell
University, Ithaca, NY. 13 pp.
Brezonik, D.O. 1972. "Nitrogen; Sources and
Transportation in Natural Water." pp 1-50. In H.E.
Allen and J.R. Kramer (ed.) Nutrients in Natural
Waters. John Wiley and Sons. New York.
Burns, N.M. and C. Ross. 1972. "Oxygen-nutrient
Relationships within the Central Basin of Lake Erie.
pp. 85-119." In W.M. Burns and C. Ross (ed.) Project
Hypo. Can. Cent. Inland Waters. Burlington, Ont.
Paper 6.
-------
ill
Burns, N.M. 1976a. "Temperature, Oxygen and Nutrient
Distribution Patterns in Lake Erie." J. Fish. Res.
Board. Can. 33:485-511.
Burns, N.M. 1976b. "Nutrient Budgets for Lake Erie." 1970;
J. Fish. Res. Board Can: 33:520-536.
Burns, N.M. and J.O. Nriagu, 1976. "Forms of Iron and
Manganese in Lake Erie Waters." J. Fish. Res. Board
Can. 33:463-470.
Chandler, P.C. 1940. "Limnological Studies of Western Lake
Erie." Ohio Journal of Science. 40:291-336.
Charlton, M.N. 1980. -"Oxygen Depletion in Lake Erie: Has
There Been Any Change?" Canadian J. Fish. Aquat.
Sciences. 37:72-81.
Dillon, P.J. 1978. "Acid Precipitation in South-Central
Ontario: Recent Observations." J. Fish. Res. Bd.
Canada. 35(6):809-815.
Dobson, H.F., H.M. Gilbertson and P.G. Sly. 1974. "A
Summary and Comparison of Nutrients and Related Water
Quality in Lakes Erie, Ontario, Huron and Superior."
J. Fish Res. Board Canada. 31(s):731-738.
Dobson, F.H. 1981. "Tropic Conditions and Trends in the
Laurentian Great Lakes." World Health Organization
Water Quality Bulletin. 6(4):146-160.
Don, F.H. 1981. "Specific Conductance As a Function of
Ionic Concentrations in Lake Erie, 1970 and 1971."
Canadian Cent. Inland Waters. 19 pp.
Draper, N.R. and H.S. Smith. 1966. Applied Regression
Analysis. 1st ed. Wiley and Sons. New York.
Eskew, G.L. 1948. Salt - The Fifth Element. J.G. Ferguson
and Assoc. Chicago, Illinois.
Federal Water Pollution Control Administration, Great Lakes
Region. 1964. Lake Erie Environmental Summary. U.S.
Dept. of Interior. 170 pp.
Feth, J.H. 1966. "Nitrogen Compounds in Natural Water - a
Review." Water Resources Res. 2:41-58.
Fraser, A.S. and K.E. Wilson. 1981. "Loading Estimates to
Lake Erie, 1967-19776." Canadian Cent. Inland Waters
Directorate, Scientific Series No. 120.
-------
112
Great Lakes Basin Commission, 1976. "Great Lakes Basin
Framework Study. Appendix 4, Limnology of Lakes and
Embayments." Public Information Office, Great Lakes
Basin Commission. Ann Arbor, Michigan. 441 pp.
Gregor, D.J. and E.D. Ongley. 1978. "Analysis of Nearshore
Water Quality in the Canadian Great Lakes, 1967-1973."
International Joint Commission, Windsor, Ont. 270 pp.
Hasler, A.D. 1947. "Eutrophication of Lakes by Domestic
Drainage." Ecology. 28:383-395.
Herdendorf, C.E. and C.L. Cooper. 1975. "Environmental
Impact Assessment, of Commercial Sand and Gravel
Dredging in Maumee River and Maumee Bay of Lake Erie."
Center for Lake Erie Area Research Technical Report
No. 41. The Ohio State University, Columbus, Ohio, 75
pp.
Herdendorf, C.E. and J.E. Zapatosky, 1977. "Effects of
Tributary Loading to Western Lake Erie during Spring
Runoff Events." Center for Lake Erie Area Research
Technical Report No. 65. The Ohio State University,
Columbus, Ohio. 140 pp.
Herdendorf, C.E. and J.M. Reutter. 1980. "Environmental
Impact Appraisal of the Davis-Besse Nuclear Power
Station, Unit 1, on the Aquatic Ecology of Lake Erie."
Center for Lake Erie Area Research Technical Report,
No. 125. The Ohio State University, Columbus, Ohio.
173 pp.
Hough, J.L. 1958. Geology of the Great Lakes. University
of Illinois Press, Urbana, Illinois. 313 pp.
International Joint Commission, 1969a. "Pollution of Lake
Erie, Lake Ontario, and the International Section of
the St. Lawrence River." Vol. 2: Lake Erie. By the
International Lake Erie Water Pollution Board and the
International Lake Ontario-St. Lawrence River
Pollution Board.
1974. "Great Lakes Water
Quality." Appendix B; A Report by the Great Lakes
Water Quality Board to the IJC. pp. 68-73.
. 1975a. "Great Lakes Water
Quality, 1974 Annual Report." A report by the Great
Lakes Water Quality Board to the IJC. pp. 52-64.
-------
113
Jones, D.M. and D.D. Meredith, 1972. "Great Lakes Hydrology
by Months, 1946-1968." Proc. 15th Conference Great
Lakes Res. pp. 477-506.
Kemp, A.L., R.L. Thomas, C.I. Dell and J.M. Jaquet. 1976.
"Cultural Impact on the Geochemistry of Sediments in
Lake Erie." J. Fish. Res. Board, Can. 33:440-462.
Kramer, J.R. 1964. Theoretical Model for the Chemical
Composition of Freshwater with Applications to the
Great Lakes. Pub. No. 11, Great Lakes Research
Division. The University of Michigan Press. Ann
Arbor, Michigan.
Larkin, P.A. and T.G. Northcote, 1958. "Factors in Lake
Typology in British Columbia, Canada." Verh.
Interrat. ver Limn. 13:252-263.
Leach, J.H. and S.T. Nepszy. 1976. "The Fish Community in
Lake Erie." J. Fish. Res. Board Can. 33:627-638.
Lin, C.K. and C.L. Shelske. 1981. "Seasonal Variation of a
Potential Nutrient Limitation to Chlorophyll Produc-
tion in Southern Lake Huron." Canadian Journal Fish.
and Aquatic Sciences. 38(l):l-9.
McKee, T.E. and H.W. Wolf. 1963. Water Quality Criteria,
2nd ed. State Water Quality Control Board,
Sacramento, California. 547 pp.
Michigan Department of Natural Resources. 1981. "Detroit
River Water Quality During Water Year 1980."
Comprehensive Studies Section. Unpublished. 7 pp.
Monke, E.J. and D.B. Beasley. 1975. "Sediment Yield and
Discharge from the Maumee River Basin into Lake Erie."
Dep. Agricultural Engineering. Purdue University,
Lafayette, Indiana. Unpublished manuscript. 30 pp.
National Oceanic and Atmospheric Administration. 1974.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
National Oceanic and Atmospheric Administration. 1975.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
National Oceanic and Atmospheric Administration. 1976.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
-------
114
National Oceanic and Atmospheric Administration. 1977.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
National Oceanic and Atmospheric Administration. 1978.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
National Oceanic and Atmospheric Administration. 1979.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
National Oceanic and Atmospheric Administration. 1980.
Climatological Supplemental Data: Ohio. Environ-
mental Data Center. Asheville, N.C.
Ownbey, C.R. and D.A. Kee. 1967. "Chlorides in Lake Erie."
Proc. 10th Conference Great Lakes Res. pp. 382-389.
Palmer, M.D. and O.K. Sato. 1968. "Review of Water Quality
Station Density Statistical Procedures." Ontario
Water Resources Comm., Toronto.
Pinsak, A.P. 1967. "Water Transparency in Lake Erie."
Proc. 10th Conf. Great Lakes Res. pp. 309-321.
Polak, J. 1978. "Nanticoke Water Chemistry." 1976. Ohio
Ministry of Environment. Toronto. 58 pp.
Poulton, D.J. and M.D. Palmer. 1973. "Water Chemistry Data
for the St. Clair River at Corunna, Ontario, as
Determined by Continuous Water Quality Monitor."
Proc. 16th Conference Great Lakes Res. Internat.
Assoc. Great Lakes Res. pp 309-320.
Pound, A. 1940. Salt of the Earth. Atlantic Monthly
Company. Boston, Massachusetts. 265 pp.
Prosser, C.L. and F.A. Brown. 1966. Comparative Animal
Physiology. Chapter II, Water Balance. Saunders
Inc., Philadelphia, Pennsylvania.
Rawson, D.S. 1951. "The Total Mineral Content of Lake
Waters." Ecology. 32:669-672.
Reid, G.V. 1961. Ecology of Inland Waters and Estuaries.
Reinhold Publishing Corp., New York. 375 pp.
-------
115
Reutter, J.M. and C.E. Herdendorf. 1976. "Environmental
Evaluation of a Nuclear Power Plant on Lake Erie:
Predicted Aquatic Impacts." Center for Lake Erie Area
Research Technical Report No. 56. The Ohio State
University, Columbus, Ohio. 242 pp.
Richards, R.P. 1980. "Limnological Surveillance of the
Nearshore Zone of Lake Erie in Central and Eastern
Ohio. Part I: Chemical Limnology." Water Quality
Laboratory. Heidelberg College, Tiffin, Ohio. 216
pp.
Richards, R.P. 1981. "Historical Trends in Water Chemistry
in the U.S. Nearshore Zone, Central Basin, Lake Erie."
Center for Lake Erie Area Research Technical Report
No. 247. The Ohio State University, Columbus, Ohio.
43 pp.
Richmond, S.B. 1957. Statistical Analysis, 2nd edition.
The Ronald Press Co., New York.
Robertson, A., F.C. Eddy, and J.J. Davis. 1974. "Chemical
Intercomparisons." Proc. 17th Conference Great Lakes
Res. pp 682-696.
Rush, A.A. and C. L. Cooper. 1981. "Lake Erie Intensive
Study: Nearshore Water Quality Trends." Center for
Lake Erie Area Research Technical Report No. 248. The
Ohio State University, Columbus, Ohio. 56 pp.
Sawyer, C.N. 1967. "Fertilization of Lakes by Agricultural
and Urban Drainage." Journal of New England Water
Works Association. 61:109-127.
Sawyer, C.N. and P.L. McCarty. 1978. Chemistry for
Environmental Engineering. 3rd ed. McGraw-Hill,
Inc., New York. 520 pp.
Scheffield, C.T., W.E. Carey and B.L. Griswald. 1975.
"Primary Productivity Survey of Central and Western
Lake Erie." Center for Lake Erie Area Research
Technical Report No. 42. The Ohio State University,
Columbus, Ohio. 102 pp.
Scheleske, C.L. and J.C. Roth. 1973. "Limnological Survey
of Lakes Michigan, Superior, Huron and Erie."
University of Michigan, Great Lakes Res. Div.
Publication No. 17. Ann Arbor, Michigan.
-------
116
Schindler, D.W. and E.J. Fee. 1974. "Experimental Lakes
Area: Whole-Lake Experiments in Lake Eutrophication."
J. Fish. Res. Board Can. 31(5):937-953.
Sly, P.G. 1976. "Lake Erie and Its Basin." Journal of
Fisheries Res. Board Can. 33:355-370.
Snoeyink, V.L. and D. Jenkins. 1980. Water Chemistry.
John Wiley and Sons, New York. 463 pp.
Steel, R.G. and J.H. Torrie. 1980. Principles and
Procedures of Statistics, a Biometrical Approach. 2nd
edition. McGraw-Hill Inc. New York. 733 pp.
United States Department of State. 1972. "Great Lakes
Water Quality Agreement with Annexes and Texts and
Terms of Reference between the U.S. and Canada." U.S.
Govt. Printing Office, Washington, D.C.
Upchurch, S.B. 1976. "Chemical Characteristics of the
Great Lakes." In. Great Lakes Basin Framework Study,
Appendix 4; Limnology of Lakes and Embayments. Great
Lakes Basin Commission. Ann Arbor, Michigan. pp.
151-238.
Vollenweider, R.A. and P.J. Dillon. 1974. "The Application
of the Phosphorus Loading Concept to Eutrophication
Research." Pub. No. 13690. Nat. Research Council,
Canada.
Wallis, W.A. and H.V. Roberts. 1956. Statistics, a New
Approach. The Free Press, Glencoe, Illinois.
Weaver, P.J. 1969. "Phosphates in Surface Waters and
Detergents." Journal Water Pollution Cont. Fed.
41:1647-1653.
Weiler, R.R. and V.K. Chawla. 1968. "The Chemical
Composition of Lake Erie." Proc. llth Conference
Great Lakes Res. pp. 593-608.
Weiler, R.R. and I.W. Heathcote. 1979. "Nanticoke Water
Chemistry 1969-1978." Ohio Ministry of Environment,
Toronto. 25 pp.
Welch, E.B. 1980. Ecological Effects of Wastewater.
Cambridge University, 337 pp.
-------
117
Witherspoon, D.F. 1971. "General Hydrology of the Great
Lakes and Reliability of Component Phases." Dept. of
Env. Inland Waters Branch. Technical Bulletin no. 50,
Ottawa.
Yahney, G.K. 1978. "The Determination of Sediment
Dispersal Patterns in^the Western Basin of Lake Erie
by Ca , Mg , and Sr Chemical Analysis of Sediment
Samples." Center for Lake Erie Area Research.
Technical Report No. 93. The Ohio State University,
Columbus, Ohio. 124 pp.
-------
U.S. Environmental Protection Agency
GLNPO Library Collection (PL-12J) ,
77 West Jackson Boulevard,
Chicago, IL 60604-3590
------- |