EPA-600/3-77-125
October 1977
Ecological Research Series
SURVEY OF CHEMICAL FACTORS
IN SAGINAW BAY (LAKE HURON)
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161,
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EPA-600/3-77-125
October 1977
SURVEY OF CHEMICAL FACTORS
IN SAGINAW BAY (LAKE HURON)
by
V. E. Smith, K. W. Lee, J. C. Filkins,
K. W. Hartwell, K. R. Rygwelski and
J. M. Townsend
Cranbrook Institute of Science
Bloomfield Hills, Michigan 48013
Grant No. R802685
Project Officer
Victor J. Bierman, Jr.
Environmental Research Laboratory—Duluth
Large Lakes Research Station
Grosse lie, Michigan 48138
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
DULUTH, MINNESOTA 55804
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DISCLAIMER
This report has been reviewed by the Environmental Research Laboratory,
Large Lakes Research Station, Grosse lie, Michigan, U.S. Environmental Pro-
tection Agency, and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of the U.S. Environ-
mental Protection Agency, nor does mention of trade names or commercial pro-
ducts constitute endorsement or recommendation for use.
ii
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FOREWORD
Our nation's freshwaters are vital for all animals and plants, yet our
diverse uses of water for recreation, food, energy, transportation, and
industry physically and chemically alter lakes, rivers, and streams.
Such alterations threaten terrestrial organisms, as well as those living
in water. The Environmental Research Laboratory in Duluth, Minnesota
develops methods, conducts laboratory and field studies, and extrapolates
research findings
—to determine how physical and chemical pollution affects
aquatic life
—to assess the effects of ecosystems on pollutants
—to predict effects of pollutants on large lakes through use
of models
—to measure bioaccumulation of pollutants in aquatic organisms
that are consumed by other animals, including man
This report contains the results of an intensive sampling and analysis
program on Saginaw Bay, Lake Huron. These results were used to establish
baseline water quality in the bay and to develop mathematical simulation
models which describe the effects of pollutant inputs. Of particular
concern in the present study are the excessive inputs of phosphorus and
nitrogen to Saginaw Bay and the resulting overproduction of algal biomass.
Donald I. Mount, Ph.D.
Director
Environmental Research Laboratory
Duluth, Minnesota
ill
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PREFACE
Water quality factors in Saginaw Bay have been surveyed several times
during the past 40 years. While the present study is by no means definitive,
it represents a much more comprehensive effort - in time, space and variety of
parameters - than any previous survey. This was necessary for two reasons:
to establish a current information base by which the effect of future reduced
loadings to the bay can be judged; and to support on-going EPA modeling pro-
grams that deal with the relationships between nutrient levels and plankton
populations. This survey is continuing at a somewhat reduced level in further
support of the modeling effort. The results of the past two years of monitor-
ing have impressed us with the changeable nature of Saginaw Bay and the conse-
quent need to extend the survey over several years in order to distinquish
genuine trends from annual fluctuations in water quality. In principle, at
least, the bay resembles a shallow estuary in which strong chemical gradients
and mixing occur, and where wind stress causes periodic tide-like changes in
water level. These features, combined with climatic variations from year to
year, greatly complicate the problem of defining "base-line" water quality in
Saginaw Bay.
We emphasize the fact that our field work has been coordinated whenever
practical with other concurrent studies on the bay. In particular, our sam-
pling coincided with satellite monitoring which was the subject of a separate
investigation on the use of remote sensing as a tool in water quality sur-
veying. While this scheduling created some problems with weather and per-
sonal convenience, it resulted in a body of correlated data that is available
for detailed study. Initial work on two sets of Landsat data has already
been published and the results were summarized briefly in this report (Co-
operative Studies, Section 8). Similar possibilities exist for correlated
studies of water chemistry and plankton populations which were sampled con-
currently by University of Michigan grantees.
A final comment concerning our presentation of the data is appropriate.
For reasons of economy and convenience we have grouped and averaged the data
somewhat arbitrarily (i.e., by quarter and segment), even though this process
confers some statistical bias on the results. Some such condensation of the
data was necessary, however, in order to view the results in a comprehensible
form. We readily admit that some other method of summarizing the data might
well support other interpretations of variance and distributional patterns
for certain parameters. At any rate, the raw data are available from the EPA
STORET system.
IV
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ABSTRACT
Water quality in Saginaw Bay, Michigan (western Lake Huron) was surveyed
during 32 cruises in 1974 and 1975, as part of the International Joint Com-
mission's Upper Lakes Reference Study co-sponsored by the United States and
Canada. Goals of the study were to establish a base of water quality infor-
mation and to provide data required to model biological and hydrological pro-
cesses in the bay. Sampling and in situ monitoring were conducted at 18-day
intervals during April - October (coinciding with Landsat satellite passes)
and approximately at monthly intervals during November - March. Samples were
collected from several depth levels at 59 stations in 1974 and at a 37-sta-
tion subset of these 59 stations in 1975. Measurements included: tempera-
ture, dissolved oxygen, conductivity, chloride, pH, alkalinity, Secchi depth,
chlorophylls, nitrate and phosphate, organic nitrogen, total phosphorus, or-
ganic carbon, total solids and major metals. Additional diurnal or daily
sampling was conducted at selected stations. Samples were analyzed aboard
ship or at the EPA Large Lakes Research Station at Grosse lie, Michigan.
Findings, based on statistical analyses of the data (filed in STORET),
indicate that highly eutrophic waters, in the inner part of Saginaw Bay
undergo complex mixing with oligotrophic Lake Huron waters in the outer bay.
Comparisons with 1956 data show diminished levels of certain parameters.
Remote sensing was shown to be useful for extrapolating water quality to
unsampled areas on a survey-by-survey basis.
The resulting data base will be used in formulating future policies for
pollution abatement in Saginaw Bay and adjoining waters.
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CONTENTS
Foreword iii
Preface iv
Abstract v
Figures viii
Tables xi
Abbreviations and Symbols xiv
Acknowledgements xvi
1. Introduction 1
2. Conclusions 2
3. Recommendations 3
4. Background 4
5. Objectives 18
6. Methods 19
Data acquisition 19
Data management and processing 26
7. Results 28
8. Evaluation and Discussion 118
Water quality variations 118
Water quality trends 126
Statistical relationships 134
Relation to water quality standards 135
Cooperative studies 137
References 140
vii
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FIGURES
Number Page
1 Lake Huron, including Saginaw River 5
2 Saginaw Bay and environs 6
3 Landsat-2 image (band 5) of February 2, 1975 8
4 Landsat-2 image (band 5) of March 9, 1975 9
5 Landsat-2 image (band 5) of April 14, 1975 10
6 Landsat-2 image (band 5) of May 20, 1975 11
7 Landsat-2 image (band 5) of July 31, 1975 12
8 Skylab S-190B photograph of September 18, 1974 13
9 Average monthly precipitation near Saginaw Bay,
1974 and 1975 16
10 Average monthly flows in lower Saginaw River
(Bay City), 1974-75 17
11 Segments (1-5) and stations sampled in 1974
(1-59) and 1975 22
12 Typical cruise tracks followed in 1974
(Cruise 9, June 18-22) 24
13 Flow diagram for data management 27
14 Temperature (°C) at selected stations 30
15 Data summary of temperature (°C) 32
16 Data summary of dissolved oxygen (mg Q~/H) 35
17 Data summary of specific conductivity (yS/cm) 37
18 Filtered chloride (mg Cl/£) at selected stations 39
viii
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19 Data summary of filtered chloride (mg Cl/£) 41
20 Data summary of pH 44
21 pH variation at Station 56 during a diurnal survey
(August 16-17, 1975) 45
22 Data summary of total alkalinity (mg CaCO^/SL) 47
23 Secchi disc depth (m) at selected stations 49
24 Data summary of Secchi disc depth (m) 51
25 Non-filterable chlorophyll a (yg chl. a/JO at
selected stations 54
26 Data summary of non-filterable chlorophyll a
(yg chl. a/JO 56
27 Non-filterable chlorophyll a (yg chl. a/JO variation
at Station 56 during a diurnal survey (August 16-17,
1975) 57
28 Non-filterable chlorophyll a (yg chl. a/JO in twice-weekly
samples from water intake plants 59
29 Data summary of unfiltered organic carbon (mg C/JO .... 61
30 Data summary of filtered organic carbon (mg C/JO 63
31 Data summary of unfiltered total solids (mg/JO 66
32 Data summary of filtered reactive silicate-silicon
(mg Si02/*0 68
33 Data summary of filtered total ammonia-nitrogen (mg N/JO • 70
34 Data summary of filtered nitrate + nitrite-nitrogen
(mg N/£) 73
35 Unfiltered Kjeldahl nitrogen (mg N/JO at selected
stations 75
36 Data summary of unfiltered Kjeldahl nitrogen (mg N/£) ... 77
37 Unfiltered Kjeldahl nitrogen (mg N/£) in twice-weekly
samples from water intake plants 79
38 Total nitrogen (mg N/JO at selected stations 81
39 Data summary of total nitrogen (mg N/£) 84
ix
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40 Data summary of filtered reactive phosphate-phosphorus
(mg P/£) 86
41 Data summary of filtered total phosphorus (mg P/£) 88
42 Unfiltered total phosphorus (mg P/£) at selected stations . . 91
43 Data summary of unfiltered total phosphorus (mg P/£) .... 93
44 Unfiltered total phosphorus (mg P/£) in twice-weekly
samples from water intake plants 95
45 Data summary of unfiltered sodium (mg Na/£) 97
46 Data summary of unfiltered potassium (mg K/£) 99
47 Data summary of unfiltered calcium (mg Ca/£) 102
48 Data summary of unfiltered magnesium (mg Mg/£) 104
49 Plot of correlation coefficients (Zr/Sz) of non-filterable
chlorophyll a with temperature 106
50 Plot of correlation coefficients (Zr/Sz) of non-filterable
chlorophyll a with filtered chloride 107
51 Plot of correlation coefficients (Zr/Sz) of non-filterable
chlorophyll a with Secchi disc depth 108
52 Plot of correlation coefficients (Zr/Sz) of non-filterable
chlorophyll a with total nitrogen 109
53 Plot of correlation coefficients (Zr/Sz) of non-filterable
chlorophyll a with unfiltered total phosphorus HO
54 Categorized Landsat image-map of water transparency on
June 3, 1974 (original in color) 116
55 Categorized Landsat image-map of water quality variables
on July 31, 1975 (original in color) 117
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TABLES
Number Page
Summary of Morphometric Data for Saginaw Bay
and Environs
2 Principle Water Quality and Biological Surveys of
Saginaw Bay ....................... 15
3 Schedule of Cruises and Diurnal Surveys ........... 20
4 Stations and Depths Sampled ................. 21
5 Methods and Equipment .................... 25
6 Temperature (°C) at Selected Stations ............ 29
7 Data Summary of Temperature (°C) .............. 31
8 Data Summary of Dissolved Oxygen (mg 0~/&) ......... 34
9 Data Summary of Specific Conductivity (yS/cm) ........ 36
10 Filtered Chloride (mg Cl/Jl) at Selected Stations ...... 38
11 Data Summary of Filtered Chloride (mg Cl/£) ......... 40
12 Data Summary of pH ..................... 43
13 Data Summary of Total Alkalinity (mg CaCO_/A) ........ 46
14 Secchi Disc Depth (m) at Selected Stations ......... 48
15 Data Summary of Secchi Disc Depth (m) ............ 50
16 Non-filterable chlorophyll a (yg chl. a/£) ......... 53
17 Data Summary of Non-filterable Chlorophyll a (yg chl. a/£) . 55
18 Mean Non-filterable chlorophyll a Values (yg chl.
From Cruise (SB) and Intake Plant (SBI) Samples ..... 58
19 Data Summary of Unfiltered Organic Carbon (mg C/H) ..... 60
xi
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20 Data Summary of Filtered Organic Carbon (mg C/£) 62
21 Data Summary of Unfiltered Total Solids (mg/£) 65
22 Data Summary of Filtered Reactive Silicate-Silicon
(mg Si02/£) 67
23 Data Summary of Filtered Total Ammonia-Nitrogen (mg N/£) . . 69
24 Data Summary of Filtered Nitrate + Nitrite-Nitrogen
(mg N/£) 72
25 Unfiltered Kjeldahl Nitrogen (mg N/£) at Selected
Stations 74
26 Data Summary of Unfiltered Kjeldahl Nitrogen (mg N/£) ... 76
27 Mean Unfiltered Kjeldahl Nitrogen (mg N/£) Values From
Cruise (SB) and Intake Plant (SBI) Samples 78
28 Total Nitrogen (mg N/£) at Selected Stations 80
29 Data Summary of Total Nitrogen (mg N/£) 83
30 Data Summary of Filtered Reactive Phosphate-Phosphorus
(mg P/£) 85
31 Data Summary of Filtered Total Phosphorus (mg P/£) 87
32 Unfiltered Total Phosphorus (mg P/£) at Selected Stations . 90
33 Data Summary of Unfiltered Total Phosphorus (mg P/£) .... 92
34 Mean Unfiltered Total Phosphorus (mg P/£) Values From
Cruise (SB) and Intake Plant (SBI) Samples 94
35 Data Summary of Unfiltered Sodium (mg Na/£) 96
36 Data Summary of Unfiltered Potassium (mg K/£) 98
37 Data Summary of Unfiltered Calcium (mg Ca/£) 101
38 Data Summary of Unfiltered Magnesium (mg Mg/£) 103
39 Correlation Coefficients for Selected Parameters. Data
From Total Bay, Year 1974 105
40 Multiple Regression Analysis of 1974 Data Using Non-
filterable Chlorophyll a as Dependent Variable Ill
41 Multiple Regression Analysis of 1975 Data Using Non-
filterable Chlorophyll a as Dependent Variable 112
xii
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42 Multiple Regression Analysis by Segments Using Non-
filterable Chlorophyll a as Dependent Variable 113
43 Concurrent Water Quality and Landsat Data for Saginaw Bay . . 115
44 Comparison of Annual Mean Data (Whole Bay) for
1974 and 1975 128
45 Water Quality Changes in Saginaw Bay During July -
October, 1935-1975 129
46 Comparison of 1965 (FWPCA) and 1974-75 (EPA) Data for
Inner Saginaw Bay 130
47 Comparison of 1965 (FWPCA) and 1974-75 (EPA) Data for
Middle Saginaw Bay 131
48 Comparison of 1965 (FWPCA) and 1974-75 (EPA) Data for
Outer Saginaw Bay 132
49 Comparison of 1965 (FWPCA) and 1974-75 (EPA Data for
Two Similar Locations in Inner Saginaw Bay 133
50 Water Quality Standards for Public Water Supplies 136
xiii
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
APHA
CCIW
CIS
ERTS
FWPCA
FWS
GLBC
GLRD
LLRS
LSC
MSCC
MWRC
NAS/NAE
NASA
NOAA
PAMILA
SPSS
STORET
d, 02
sp. cond.
f. Cl.
tot. alk.
nf. chl. a
u. org. C
f. org. C
u. tot. sol.
f. reac. Si02~Si
f. tot. NH3-N
f. NO3 + N02-N
u. Kjel. N
tot. N
f. reac.
f. tot. P
u. tot. P
u. Na
u. K
u. Ca
u. Mg
American Public Health Association
Canadian Centre for Inland Waters
Cranbrook Institute of Science
Earth Resources Technology Satellite (now Landsat)
Federal Water Pollution Control Administration
Fish and Wildlife Service
Great Lakes Basin Commission
Great Lakes Research Division of University of Michigan
Large Lakes Research Station of EPA at Grosse lie,
Michigan
Lake Survey Center
Michigan Stream Control Commission
Michigan Water Resources Commission, Department of
Natural Resources, State of Michigan
National Academies of Science/Engineering
National Aeronautics and Space Administration
National Oceanographic and Atmospheric Administration
Peak Analysis for Multi-Instrument Lab Automation
Statistical Package for the Social Sciences
EPA's computer data file
dissolved oxygen
specific conductivity
filtered chloride
total alkalinity
non-filterable chlorophyll a (corrected chlorophyll a)
unfiltered organic carbon
filtered organic carbon
unfiltered total solids
filtered reactive silicate-silicon
filtered total ammonia-nitrogen
filtered nitrate + nitrite-nitrogen
unfiltered Kjeldahl nitrogen
total nitrogen (u. Kjel. N + f. N03 + N02-N)
filtered reactive phosphate-phosphorus
filtered total phosphorus
unfiltered total phosphorus
unfiltered sodium
unfiltered potassium
unfiltered calcium
unfiltered magnesium
xiv
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calc. part. P — calculated particulate phosphorus (u. tot. P -
f. tot. P)
calc. f. inorg. N — calculated inorganic nitrogen (f. NC>3 + N02~ N +
f. tot. NH3)
calc. f. org. P — calculated organic phosphorus (f. tot. P - f. reac.
P04-P)
xv
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ACKNOWLEDGEMENTS
Other of our research technicians who had essential roles in various
stages of this project were John M. Spurr, Thomas J. Geyer, Judith A. Ott,
Thomas L. Chiotti and Thomas E. Imbrigiotta. Special thanks are due our
secretary, Debra L. Caudill, who typed the manuscript. We are indebted to
local representatives of Potomac Research, Inc., chiefly Mr. Ralph G. Allen,
for much computer support throughout the work. We are also grateful for much
assistance during cooperative field work from research technicians of the
University of Michigan's Great Lakes Research Division and Biological Station.
During 1974 excellent field support in the form of ships, equipment and
operators was provided by the NOAA Lake Survey Center in Detroit. The U.S.
Coast Guard Air Rescue Station also furnished helicopter support and in-
valuable assistance during midwinter sampling. We wish to thank the follow-
ing agencies for their cooperation in collecting and processing numerous
water intake samples: The Dow Chemical Company in Bay City, Bay City Water
Filtration Plant, Pinconning Water Works, Whitestone Point Water Filtration
Plant. Finally, throughout the project we have relied heavily on the support,
personnel and facilities of the EPA Large Lakes Research Station headed
successively by Drs. Tudor T. Davies and Wayland R. Swain. We express our
sincere thanks to numerous other individuals and agencies which have contri-
buted to this project from time to time.
xvi
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SECTION 1
INTRODUCTION
This survey was conducted as part of the International Joint Commis-
sion's (IJC) Upper Lakes Reference Study of Lake Huron and Lake Superior. Our
spatial coverage of Saginaw Bay overlapped slightly that of Southern Lake
Huron and Northern Lake Huron - Georgian Bay, areas surveyed respectively by
the University of Michigan and the Canada Centre for Inland Waters. U.S. and
Canadian interest in Saginaw Bay is related to the possible impact of bay
pollution on Lake Huron waters on both sides of the international boundary.
The work described here was closely coordinated with other related
studies of Saginaw Bay. Phytoplankton and zooplankton were surveyed con-
currently at the same stations by EPA grantees at the University of Michigan
(Great Lakes Research Division and Biological Station, respectively).
Current meter and drogue studies were conducted during summer 1974 by the
National Oceanic and Atmospheric Administration (Lake Survey Center). Experi-
ments on multispectral remote measurment of chlorophyll were carried out
during spring and summer 1974 by the National Aeronautics and Space Admini-
stration (Lewis Research Center). Finally, nearly all cruises coincided with
Landsat (ERTS) satellite passes over Saginaw Bay, to provide ground truth for
a NASA-supported study of remote sensing carried out by Bendix Aerospace
Systems Division.
Concurrent data on nutrient inputs from the bay's major tributaries were
collected by the Michigan Department of Natural Resources (Water Management
Division). Additional samples were collected at four stations by the Dow
Chemical Company (Bay City) and municipal water intake plants at Bay City,
Pinconning and Whitestone Point.
Most of these results are being incorporated in some fashion into mathe-
matical models under development at the EPA Large Lakes Research Station,
Grosse lie, Michigan. Our approaches to sampling the bay and organizing the
data throughout this study were designed primarily to support the modeling
programs. The statistical results presented here are not intended to provide
necessarily the most objective view of water quality in Saginaw Bay, but
rather are offered as a convenient summary of the data and their interrela-
tionships.
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SECTION 2
CONCLUSIONS
These results support the general findings of earlier studies that
Saginaw Bay is estuarine in character with pronounced gradients of water
quality between inner and outer bay, high primary production, active circula-
tion and frequent water level changes induced by wind stress. Water quality
ranges from eutrophic near the Saginaw River mouth to oligotrophic in the bay
mouth. The data suggest that thermal stratification occurs only briefly
during early spring, except in deep waters of the outer bay where a thermocline
persists throughout the summer.
Earlier assertions that the prevailing circulation of Saginaw Bay is
counterclockwise may be over-simplified, since current patterns are highly
dependent on wind stress. However, mean values of most parameters are
higher along the eastern side of the bay, suggesting that river water exits
the bay mainly on that side. Similar evidence points to a greater influx of
Lake Huron water along the western side of the bay. Additionally, nutrient
concentrations on the eastern side may be augmented to an important degree by
runoff and resuspension of sediments.
Saginaw River water is traceable throughout the bay by conservative
features such as chloride, conductivity, and major metals. Since concentra-
tions of these factors are related to overall turbidity and water color, it
is feasible to map their distribution (i.e., that of Saginaw River water)
using multispectral satellite (Landsat) data and correlation analysis.
However, the empirical relationships between satellite and water quality data
are influenced by atmospheric and other variables and therefore must be
re-defined on each occasion.
The data indicate a significant decrease in levels of most parameters
since 1965 surveys, especially within the inner bay. Presumeably, this is
due mainly to a decrease in nutrient input rates over this period. However,
a similar but smaller decrease in levels from 1974 to 1975 may be due to
climatic differences: e.g., more precipitation and runoff during 1974.
The Saginaw River system continues to have an adverse effect on water
quality in the bay, although no parameter values were consistently in viola-
tion of EPA or Michigan standards for ammonia, chloride, dissolved oxygen,
nitrate-nitrite or pH. An eightfold increase in chlorophyll a concentrations
from the outer to inner bay indicates the extent of nutrient enrichment,
largely from the Saginaw River.
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SECTION 3
RECOMMENDATIONS
In view of the difficulty of defining baseline conditions in a system as
variable as Saginaw Bay, another intensive survey of the present type should
be conducted after a 5-10 year interval. From a management standpoint, this
is all the more critical because waste treatment processes are being upgraded
throughout the Saginaw River basin and because productivity models currently
under development will require testing and verification on independent sets
of field data as water quality values change over time.
Future surveys in support of modeling efforts should include daily
monitoring of major nutrient inputs from the Saginaw River and other tribu-
taries. Other contributions of nutrients to bay waters from the atmosphere
and from resuspended sediments should be assessed more thoroughly than in
this study. Our results have indicated a need to take stock of infrequent
but substantial inputs of nutrients that may occur during storms or periods
of high runoff. The variability of some parameters at certain stations and
times is complex and should be investigated further as to cause and effect.
Survey vessels should carry out continuous monitoring of at least two
parameters, percent transmittance and specific conductivity, in order to
locate water mass boundaries and define the slope of chemical gradients.
This information, together with sample and satellite data, could be used to
map certain parameter distributions throughout the bay.
Other statistical relationships should be defined between chemical
parameters and such variables as phytoplankton and zooplankton biomass. Such
results would be informative as to the varying effects of these nutrients on
biota in the water column.
Since the selection of sampling stations on Saginaw Bay was not random,
the present mean data for each bay segment should be compared to random data
sets generated by contouring, or to data corrected for depth by volume aver-
aging.
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SECTION 4
BACKGROUND
Saginaw Bay is a broad estuary extending southwestward from Lake Huron's
western shore (Figure 1). The dimensions of the bay are approximately 42 x
82 km (26 x 51 mi); it covers an area of some 2,960 km2 (1,143 mi2). The
inner and outer halves of the bay, divided roughly by a line between Sand
Point and Point Lookout (Figure 2), have mean depths of 4.6 m (15 ft) and
14.6 m (48 ft), and each half contains some 30% and 70% of the total water
volume, respectively. The sediments are mainly glacial deposits of sand,
cobble, clay or silt. The shoreline topography is generally low and varies
from marsh to sand beaches and occasional rocky outcrops.
The Saginaw River and tributaries, which empty into the extreme south-
western end of the bay, drain a watershed of approximately 21,000 km2 (8,000
mi2). Land use in this area is dominated by agriculture and secondly, by
native forest. However, the basin had an estimated population in 1970 of
1,235,920, and includes four major urban-industrial centers: Bay City, Mid-
land, Saginaw and Flint. These have had a profound impact on water quality
of the Saginaw River system and thus on Saginaw Bay. These and other fea-
tures of the bay environment were reviewed by Freedman (1974). Table 1 gives
a summary of morphometric data for the bay, its watershed and areal sub-
divisions, as established in the present study. For purposes of this dis-
cussion the outer limits of the bay are defined on the map by a line con-
necting the base of Tawas Point on the west with the tip of Pointe aux Barques
on the east (see Figure 11).
Saginaw Bay, due to its high surface/volume ratio and broad communica-
tion with Lake Huron, is readily influenced by climatic variables including
temperature, light, wind and wave stress and by local currents in Lake
Huron. A typical sequence of seasonal changes in the bay, as occurred during
February - July 1975, is seen in Landsat (satellite) imagery, Figures 3-7.
Often there is active mixing of water masses having strikingly different
charateristics (Figure 8), especially during periods of high runoff. Al-
though circulation within the bay is rapid and highly variable, the pre-
dominant pattern has been reported to be counter-clockwise: oligotrophic
Lake Huron water enters along the northwestern shore and eutrophic bay water
exits along the northeastern side (Freedman, 1974). Rapid changes in water
level (i.e., seiches) of up to two meters are associated mainly with strong
southwest or northeast winds during summer and fall, respectively. The inner
bay is largely frozen over during January - February (Figure 3). Wave action
-------
LAKE
MICHIGAN
PORT
KUROWA
Figure 1. Lake Huron, including Saginaw Bay.
-------
STATUTE MILES
Figure 2. Saginaw Bay and environs (NOAA Chart No. 5, Lake Huron, 1974)
-------
TABLE 1. SUMMARY OF MORPHOMETRIC DATA FOR
SAGINAW BAY AND ENVIRONS
Watershed:
Total area (km2) 21,000
Tributaries, mean input (m^/sec) 153.7
Whole Bay:
Total area (km2) 2,960
Total volume (m3) 30 x 109
Lengh of shoreline (km) 240
Mean depth: inner bay (m) 4.6
outer bay (m) 14.6
Max. depth: inner bay (m) 14.0
outer bay (m) 40.5
Model Segments:
Surface Surface/
Mean Depth (m) Max. Depth (m) Area (m2) Volume (m^) Volume Ratio
Seg. 1 3.14 7.92 276 x 106 866 x 106 .32
Seg. 2 6.37 15.11 860 x 106 548 x 107 .16
Seg. 3 2.85 5.79 412 x 106 117 x 107 .35
Seg. 4 11.40 26.82 648 x 106 736 x 107 .09
Seg. 5 13.10 34.44 676 x 106 883 x 107 .08
-------
-001
-0152-N-I-N-D-2L NflSfl ERT
_ nun I U0@^ ~ 3@
82FEB75 C N4y-03/U08"-80 N Na3-03/U08a-0e rtSS 5
Figure 3. Landsat-2 image (band 5) of February 2, 1975.
Note: An unusually mild winter resulted in
broken ice cover (light areas) over the bay's
lower two-thirds. In 1974 the same area was
completely frozen at this time. A bar of
thinner ice stretches northward along the
Lake Huron shore.
-------
. ' ' ^r'- ^,- -*"v'.«:,.'"..„
.* Jf>,
,,^
. « -*i . *
' i
;/•
- J"
~ -fc.
•j~
& '••'-
'••'•£. ' ' ' •
f '• 1? . ~
j
'
•
' If
r •
&*e$
• .
.
-
•
•
--
S "'1
-
*,
,
itz-«m-n-i-n-D-2L
Figure 4. Landsat-2 image (band 5) of March 9, 1975.
Note: Fresh snow covers the ice pack, which
has shifted considerably since the previous
scene. The patch of open water near the
Saginaw River mouth (lower center) is main-
tained all winter by heated discharge from
the Karn-Weadock power plant (Consumers
Power Company).
-------
•1
IWR75 C
IU084-30 UB8<>-00i
J-VUeS^Se N N44-23/U083-22 flSS 5
U083-30I IN0«3-30 IU083-00
P SUN EI.47 RZI36 192- 1 H2-N- 1 -N-D-2L NflSfl ERTS E-2882- I
01
Figure 5. Landsat-2 image (band 5) of April 14, 1975.
Note: The bay is nearly ice-free by this
date except for shelfs along the eastern
shore. Turbidity plumes (lighter waters)
are seen emerging from the Saginaw River
during this period of thawing and high
runoff. A late snowfall covers the land.
10
-------
IU084-38
2flmY75 C fm-24/UBB3-23 N
i-19 HSS 5 D SUN
NRSfl
?l18-15482-5 01
Figure 6. Landsat-2 image (band 5) of May 20, 1975.
Note: Following the spring runoff, tur-
bidity has diminished except in inshore
areas. The bay's islands are clearly
outlined against the darker water.
11
-------
N N
-------
Figure 8. Skylab S-190B photograph of September 18, 1974.
Note: Details of turbidity patterns are readily
seen in a color photograph of lower Saginaw Bay.
Mixing of dark brown river water with clearer
with clearer blue waters of the open bay has
evidently resulted in these plumes of highly re-
flective (lighter) water. Some turbidity inshore
may be wind-generated.
13
-------
strongly affects the resuspension of shallow water sediments in the inner
bay. Dynamic features of the bay's hydrology as described by water quality
and circulation models will be discussed in detail elsewhere in this Research
Series.
The history of Saginaw Bay water quality has been documented by a number
of surveys, chiefly those listed in Table 2. Some results of these are
summarized in Freedman (1974). The present survey, begun in October 1973,
represents the most comprehensive study of water chemistry in Saginaw Bay to
date. Indications are that the study period embraces two years that are
significantly different as to climatic and hydrological factors (Figures 9,
10; Table 7). These conditions would be expected to create seasonal water
quality differences that are not necessarily related to long term trends.
Historically, pollution and eutrophication in Saginaw Bay have had an
adverse impact, direct or otherwise, on the bay's natural potential to sup-
port a diversified fishing industry, large populations of migratory water-
fowl, and to provide domestic water supplies as well as recreational and
esthetic uses (USFWS, 1969; GLBC, 1975; Freedman, 1974).
14
-------
TABLE 2. PRINCIPAL WATER QUALITY AND BIOLOGICAL SURVEYS
OF SAGINAW BAY
AGENCY
Michigan Stream
Cont. Commission
Great Lakes
Fish. Commission
Fed. Water Poll.
Cont. Adm.
U.S. Lake Survey
Center
Great Lakes Res.
Div. , Univ. of
Michigan
Beak Consultants
Dow Chem. Co.
NUMBER
OF
STATIONS
50
33
4
6
29
SURVEY TYPE
Water Quality
Water Quality
Water Quality,
Biology
Water Quality
Water Quality
Biology
Water Quality,
Biology
SURVEY PERIOD
Summer, 1935-36
June-Oct, 1956
July-Oct. 1965
1966
July, 1970
1970-71
Aug. -Sept. 1971
REFERENCES
MSCC (1937)
Beeton, et al.
(1967)
U.S. FWPCA
(1969)
U.S. Lake
Survey (1966)
Schelske and
Roth (1973)
Beak Consul-
tants (1971,
1972)
Batchelder
(1973)
15
-------
en
Ld
:r
o
o
<
O
S.0
4-. 0-
3.0-
»-• 2.0-
o
LoJ
1.0-
^ 0
1974
-— 1975
J" F M A
MJ"J"AS OND
Figure 9. Average monthly precipitation near Saginaw Bay, 1974 and 1975.
(Standish, Bay City and Sebewaing stations, U.S. Dept. of Commerce Climatological Data).
-------
0)
IL
0
LL
18000•
1S000-
1S000-
9000-
B000 -
3000H
0
1974
1975
I i T i i i » I i r r n i ii i i » i i i I i
J'FMA MJ"J"AS OND
Figure 10. Average monthly flows in lower Saginaw River (Bay City), 1974-75
(U.S. Geological Survey data).
-------
SECTION 5
OBJECTIVES
Three major objectives were addressed in this study:
• To establish a baseline of water quality for Saginaw Bay,
describing seasonal and spatial changes in bay parameters
over a two-year period.
• To provide data for modeling of hydrological
processes and plankton growth dynamics in the bay.
• To prepare a comprehensive water quality document on
Saginaw Bay for the International Joint Commission (Upper
Lakes Reference Group).
Minor objectives during the study included coordination of this work
with that of other agencies mentioned in the introduction.
18
-------
SECTION 6
METHODS
DATA ACQUISITION
General Approach
In 1974-1975 a total of 30 (plus 2 prior) survey cruises were conducted
on Saginaw Bay and in the lower Saginaw River. Most of the field work was
done by Institute personnel assisted at times by the U.S. Coast Guard, Air
Rescue Station at Selfridge Air National Guard Base, and by other grantees
from the University of Michigan, Great Lakes Research Division and Biological
Station. Ship support and operators were furnished in 1974 by the National
Oceanic and Atmospheric Administration, Lake Survey Center, and in 1975 by
the Environmental Protection Agency, Large Lakes Research Station (EPA/LLRS)
at Grosse lie.
During the April - October period most cruises were scheduled every 18
days to coincide with coverage by Landsat, formerly the Earth Resources
Technology Satellite (ERTS-1 and ERTS-2). During the winter a partial survey
by helicopter or ground team took place approximately once a month. Six
diurnal surveys at a single station were also completed in 1975. The cruise
and satellite dates, as well as the station coverage, are shown in Table 3.
Generally, field measurements and samples for laboratory analyses were
taken at selected stations and depth intervals throughout Saginaw Bay and in
the lower Saginaw River. In 1974 the cruises covered a maximum of 59 sta-
tions and 111 depth-levels; in 1975 a subset of 37 stations (including two
new ones) and 73 depth-levels were sampled. Only 1 meter samples were
collected by helicopter. The station coordinates and levels sampled are
given in Table 4. The location of all stations is shown on the map in
Figure 11, which also indicates a subdivision of the bay into 5 segments or
sub-areas. These were established by EPA modelers to provide spatial resolu-
tion within the bay. The presumed homogeneity of segments was based on 1974
water quality data and on the results of a current meter study (Richardson
amd Bierman, 1976). The segments are used in this report primarily for data
summation purposes.
Typically, each survey-cruise was conducted over a 3-day period by two
boats: one was a 45-60 ft. vessel, usually equipped with some laboratory
facilities; the other was an 18-22 ft. outboard craft with only portable
monitoring equipment and sampling gear. In usual practice the small.boat
19
-------
TABLE 3. SCHEDULE OF CRUISES AND DIURNAL SURVEYS
CRUISE/ SURVEY
Cruise 1
Cruise 2
Cruise 3
Cruise 4
Cruise 5
Cruise 6
Cruise 7
Cruise 8
Cruise 9
Cruise 10
Cruise 11
Cruise 12
Cruise 13
Cruise 14
Cruise 15
Cruise 16
Cruise 17
Cruise 18
Cruise 19
Diurnal Survey
(Sta. 56)
Cruise 20
Cruise 21
Diurnal Survey
(Sta. 56)
Cruise 22
Cruise 23
Diurnal Survey
(Sta. 56)
Cruise 24
Cruise 25
Diurnal Survey
(Sta. 56)
Cruise 26
Cruise 27
Diurnal Survey
(Sta. 56)
Cruise 28
Cruise 29
Diurnal Survey
(Sta. 56)
Cruise 30
Cruise 31
Cruise 32
SAMPLING DATES
11/5-7/73
12/3-4/73
2/18-21/74
3/25/74
4/16-20/74
4/28-30/74
5/13-17/74
6/2-5/74
6/18-22/74
7/8-10/74
7/25-27/74
8/25-27/74
9/18-20/74
10/6-8/74
11/11-14/74
12/16-18/74
2/17-19/75
3/18/75
4/9-11/75
4/28-29/75
4/30-2/75
5/20-22/75
6/2-3/75
6/5-8/75
6/25-27/75
7/11-12/75
7/13-16/75
7/29-31/75
8/16-17/75
8/18-20/75
9/3-5/75
9/21/75
9/23/75
10/9-11/75
10/25-26/75
10/27-29/75
11/16-18/75
12/16/75
NO. STATIONS
SAMPLED
37
41
16
7
44
59
51
47
59
59
59
59
59
58
36
23
33
15
30
1
37
37
1
32
37
1
37
36
1
37
37
1
19
37
1
29
35
9
SATELLITE PASS DATES
10/31-11/1/73
12/5 & 6/73
2/15 & 16/74
3/23 & 24/74
4/10 & 11/74
4/28 & 29/74
5/16 & 17/74
6/3 & 4/74
6/21 & 22/74
7/9 & 10/74
7/27 & 28/74
9/1 & 2/74
9/19 & 20/74
10/7 & 8/74
11/12 & 13/74
12/18 & 19/74
2/20 & 21/75
3/27 & 28/75
4/1 & 2/75
5/1 & 2/75
5/19 & 20/75
6/6 & 7/75
6/24 & 25/75
7/12-13/75
7/30-31/75
8/17 & 18/75
9/4 & 5/75
9/22 & 23/75
10/10 & 11/75
10/28 & 29/75
11/15 & 16/75
12/21 & 22/75
20
-------
TABLE 4. STATIONS AND DEPTHS SAMPLED
Coordinates
Station
1
2
3
4
5
* 6
7
8
* 9
*10
*11
12
*13
*14
*15
*16
*17
18
*19
*20
*21
22
*23
*24
*25
26
27
*28
29
30
*31
32
*33
34
35
3G
37
38
*3y
*40
41
42
43
44
45
*46
47
43
49
50
51
52
53
54
55
56
*57
*58
*59
**60
**61
( * 1974
(** 1975
N. Latitude
43°
43°
43°
44°
43°
43"
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
43°
44°
44°
43°
44°
43°
43°
44°
44°
43°
44°
44"
44°
44°
44°
44°
44°
44°
44°
43*
43°
43°
44°
44°
43°
43°
43°
Only)
Only)
38'
43'
51'
06'
40'
40'
41'
40'
39'
41'
40'
38'
41'
42'
44'
46'
42'
44'
46'
49'
40'
49'
48'
47'
41'
45'
49'
51'
54'
58'
56'
54'
50'
53'
58'
01'
01'
58'
55'
04'
38'
03'
01'
sr
11'
00'
16'
14'
22'
10'
07'
04'
03'
36'
36'
43'
08'
03'
40'
58'
55'
10"
05"
25"
30"
50"
20"
05"
00"
20"
20"
00"
25"
05"
50"
50"
55"
10"
30"
55"
50"
15"
25"
35"
00"
40"
40"
10"
35"
50"
05"
10"
35"
20"
00"
45"
20"
05"
10"
40"
35"
55"
45"
25"
00"
15"
25''
30"
20"
40"
20"
25"
10"
20"
45"
20"
45"
05"
15"
50"
55"
40"
W.
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
S3
83
c!3
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
83
Longitude
51'
54'
54'
31'
52'
50'
50'
48'
50'
49'
44'
39'
46'
49'
51'
54'
44'
46'
48'
52'
52'
48'
44'
39'
35'
31'
37'
40'
44'
49'
40'
31'
30'
23'
34'
39'
32'
24'
19'
34'
50'
25'
20'
16'
33'
08'
29'
28'
22'
17'
10'
04'
00'
51'
53'
37'
23'
12'
53'
30'
26'
00"
US"
15"
45"
20"
00"
35"
25"
55"
10"
15"
40"
45"
15"
40"
45"
10"
25"
50"
00"
50"
40"
40"
20"
50"
35"
10"
25"
50"
15"
40"
40"
15"
35"
40"
45"
30"
55"
50"
25"
55''
50!l
2'j"
20"
00"
40"
25"
20"
40"
30"
15"
50"
15"
25"
25"
40"
45"
45"
45"
00"
25"
1m
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
V
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Depths
5m 10m 15m
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
A
X
X
XXX
XXX
XXX
XXX
X
X X
X X
Bo t . -1m
X
X
X
X
X
X
X
X
X
X
X
X
X
X
21
-------
Segment
1
2
3
4
5
River
Station Numbers
2,5,6,7,8,10,11,12,13,14,15,16,21,59
3,17,18,19,20,22,23,24,27,28,29,30
3k,32,35,36,60
25,26,33,34,55,61
4,37,40,42,45,47,48,49,50,57
38,39,43,44,46,51,52,53,58
1,9,41,54,55
No. Stations
14
17
6
10
9
5
TOTAL
61
Figure 11. Segments (1-5) and stations sampled in 1974 (1-59)
and 1975 (37 indicated byQand^).
22
-------
worked the inshore stations, delivering samples to the laboratory vessel
every few hours for processing. The tracks covered by both vessels on a
representative cruise are shown in Figure 12. Stations were located by using
a combination of timed runs from reference points, known depths and compass
bearings from shore features in some cases. Positioning for the larger
vessels and helicopters was assisted by radar and radio beacons, respectively.
Station-finding accuracy was considered to be generally within a quarter
mile.
Field Sampling
Water samples were collected using an all-plastic Kemmerer (4 liter) or
Niskin (5 liter) sampler, or by rubber hose and oil-free centrifugal pump.
All bottles used were of Nalgene (polypropylene), machine washed without
detergents, rinsed with 10% HC1 (nutrients) or 2% HNOs (metals), rinsed with
distilled water (Millipore Super-Q) and dried at 95°C. The small boat sam-
ples were kept temporarily in insulated chests (in darkness) at ambient water
temperatures; after receipt by the lab vessel they were refrigerated. For
filtered nutrient analysis, water was (in 1974) passed through 0.45 ym Milli-
pore type HA filters; later (1975), Whatman GF/F glass fiber filters were
used instead to reduce contamination (Filkins and Mullin, 1976). All non-
filterable chlorophyll samples were collected on Whatman GF/C filters. All
samples were transported on ice within 30 hours to EPA/LLRS where nutrient
analyses were generally completed within a further 24 hours. For some other
parameters samples were refrigerated or frozen longer (see Table 5). Filters
containing chlorophylls and all intake plant water samples were kept frozen
until analysis. The intake samples were analyzed for chloride, chlorophyll
a, total phosphorus and total Kjeldahl nitrogen only.
Field and Laboratory Analyses
Table 5 summarizes the methodology used for each parameter. Complete
descriptions of the methods and procedures, as modified in some cases (Table
5), are on file at EPA/LLRS, Grosse lie.
Quality Control
Quality control for automated nutrient and metals analyses involved
using replicate standards and samples, dilution of standards and samples,
addition of standards to samples, laboratory intercomparisons of samples and
analysis of EPA test standards. Two or more replicate samples for chloro-
phylls were run on some cruises. All carbon analyses were done in tripli-
cate. Any extreme value in each triplicate (i.e., 20% different from the
other two) was rejected, and the remaining two were averaged. Total solids
samples including some replicates were analyzed by a commercial laboratory.
Details of the quality control procedures are on file at EPA/LLRS, Grosse
He.
23
-------
Figure 12. Typical cruise tracks followed in 1974 (Cruise 9, June 18-22).
24
-------
TABLE 5. METHODS AND EQUIPMENT
PARAMETER
Temperature
Oxygen, dissoTved
Specific Conductivity
Chloride, filtered
pH
Akalinity, total
Secchi disc depth
Chlorophyll a, non-filterable
Carbon, filt. organic
Carbon, unfilt. organic
Solids, unfilt. total
Silicates, filt. reactive
Ammonia, filtered total
Nitrate + Nitrite, filt.
Nitrogen, unfilt. Kjeldahl
Phosphates, filt. reactive
Phosphorus, filt. total
Phosphorus, unfilt. total
Sodium, unfiltered
Potassium, unfiltered
Calcium, unfiltered
Magnesium, unfiltered
WHERE
MEASURED -
IN
SITU
X
X
X
X
ON
SHIP
X
X
X
X
AT
LLRS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
MAX. TIME
TO ANALYSIS
(in situ)
(in situ)
10 min.
48 hrs.
10 min.
10 min.
(in situ)
4 wks .
2 wks-sealed
7 mos-analyzec
2 wks-sealed
7 mos-analyzec
2 wks.
48 hrs.
48 hrs.
48 hrs.
48 hrs.
48 hrs.
48 hrs.
48 hrs.
6 mos .
6 mos .
6 mos .
6 mos.
METHODS
Submerged thermistor
probe; thermometry
Submerged KC1 probe
Electric conductance measurement
Ferric
Submerged combination pH probe
Sulfuric acid (0.02N)
titration to pH 4.5
Visual estimation
Extraction & spectrophntomet ry
(SCOR/UNESCO) '
Sealed ampuole wet
oxidation & IR analysis
Sealed ampuole wet
oxidation & IR analysis
Gravimetric measurement
"Molybdenum blue" color reaction
ierthelot color reaction
Sulf anilimide (diazo)
color reaction
Digestion &
autoanalysis for ammonia
"Phospho-molybdenuiri blue"
color reaction
)igestion &
autoanalysis for phosphate
Digestion &
autoanalysis for phosphate
Flame Atomic Absorption
Spec trophotomet ry (undigested)
Flame Atomic Absorption
Spectrophotometry (undigested)
Flame Atomic Absorption
Spectrophotometry (undigested )
rlame Atomic Absorption
Spec tropho tome try (undigested )
EQUIPMENT/
INSTRUMENTATION
Martek Mark II Monitor
Martek Mark II Monitor
Beckman RC19 Conductivity Bridge
Technicon AA2 Auto analyzer
Martek Mark 11 Monitor
Fisher 520 pH/Ion Meter
Burette S, Fisher 520 pH/Ion Meter
9 cm diam. B & W disc
P-E Coleman 124 Double
Beam Spectrophotomet er
Oceanography International 052413
6. MSA 300 IR analyzer
Oceanography International 052413
& MSA 300 IR analyzer
Mettler H10 Balance
Technicon AA2 Auto analyzer
Technicon AA2 Auto analyzer
Technicon AA2 Auto analyzer
Heating Block and
Technicon AA2 Auto analyzer
Technicon AA2 Auto analyzer
Heating Block &
Technicon AA2 Auto analyzer
Heating Block &
Technicon AA2 Auto analyzer
Instrumentation Laboratory 353
AA Spectrophotometry
Instrumentation Laboratory 353
AA Spectrophotometry
Instrumentation Laboratory 353
AA Spectrophotometry
Instrumentation Laboratory 353
AA Spectrophotometry
SOURCE OF METHOD
Martek Manual (1973)
Martek Manual (1973)
Beckman Manual (1973)
Technicon Industrial
Method No. 99-70W (1973)
Martek Manual (1973)
Standard Methods,
13th Ed. , (1971)
Welch (1948)
Strickland and Parsons (1968)
O.I. Proceedures
Modified (1974)
O.I. Proceedures
Modified (1974)
Standard Methods,
13th Ed. , (1971)
Technicon Industrial
Method No. 105-71W (1973)
Technicon Industrial
Method No. 154-71W (1973)
Technicon Industrial
Method No. 100-70W (1973)
LLRS modification of EPA
Corvallis method (1974)
Technicon Industrial
Method No. 155-71W (1973)
LLRS modification of EPA
Corvallis method (1974)
LLRS modification of EPA
Corvallis method (1974)
LLRS modification of EPA
Corvallis method (1974)
LLRS modification of EPA
Corvallis method (1974)
LLRS modification of EPA
Corvallis method (1974)
LLRS modification of EPA
Corvallis method (1974)
-------
Data Management and Processing
The management approach involved compiling all field and laboratory
data, editing and filing it in the EPA STORE! system. Processing included
retrieving and plotting the data in various spatial and temporal formats and
subjecting data to statistical analysis. These steps are outlined in Figure
13. For all parameters, field and laboratory data sheets were made compatible
with STORET punch card formats to streamline the transcription process.
Technicon nutrient Auto-Analyzers were interfaced with a PDP-8E mini-
computer (Digital Equipment Corp., DEC) to monitor analyses of up to eight
parameters simultaneously. Analog data from the colorimeters were recorded on
chart paper and digitized for peak analysis using a modified version of the
DEC "PAMILA" program (Peak Analysis for Multi-Instrument Lab Automation).
PAMILA performs digital filtering, peak detection, integration, and
baseline determination, and also generates punched paper tape. At the com-
pletion of a run, the paper tape is read into core memory, a permanent data
file is created on a magnetic disk, and a separate FORTRAN analysis program
operates on this data file. This FORTRAN program calculates a standard
least-squares calibration curve and converts the peaks to actual chemical
concentrations.
The SPSS program (Statistical Package for the Social Sciences), avail-
able from Optimum Systems, Inc., was used for both correlation and multiple
regression analyses of the retrieved data.
26
-------
INSTRUMENT DATA OUTPUT
LABORATORY BENCH SHEETS
(Data recorded on)
KEYPUNCH DATA SHEETS
(Data arranged in keypunch format)
KEYPUNCH CARDS
INTERMEDIATE LISTING PRINTOUT
(Raw bench sheet data in tabular
form- check data line by line)
POTOMAC RESEARCH INC.
STORET
Initial Data Storage
STORET RETRIEVAL OF DATA
(Verify line by line)
STORET
Final Data Storage
DATA RETRIEVAL/
STATISTICAL ANALYSIS
for study and public
use
Figure 13. Flow diagram for data management,
27
-------
SECTION 7
RESULTS
PARAMETER SUMMARIES
The following section summarizes, in tabular and graphical form, the
cumulative data for each parameter. An additional brief description high-
lights some aspects of the data that are not readily apparent from the tables
and figures. It is important to note that, for a given spatial or time
interval, data from all station-depths were combined and statistically treated
as a single data set. In other words, quarterly and annual means were deter-
mined directly from individual measurements and not from sets of cruise data
for the respective time periods.
Temperature
The highest mean temperature level of 17.9 °C during 1974-75 was recorded
at station 34 (segment 3). The lowest of 10.6 °C was at station 49 (segment
4). The 1974-75 mean value of 14.2 °C at station 59 was closest to the total
bay mean of 14.1 °C.
Mean values by segment ranged from 11.6 °C (segment 4, 1974) to 16.9 °C
(segment 1, 1975). The greatest annual range, 0.3 °C - 29.0 °C, occurred in
segment 5, 1974). In 1974 the mean value of 13.3 °C in segment 5 was closest
to the total bay mean of 13.6 °C. In 1975 the mean of 14.9 °C in segment 2
was closest to the bay mean of 14.1 °C.
Results showing the variation by cruise (at two depths) of temperature
at selected stations are given in Table 6 and Figure 14. Quarterly and an-
nual summaries of all temperature data compiled for each segment and the
total bay are shown in Table 7 and Figure 15.
Oxygen, dissolved (d. 02)
The highest mean dissolved oxygen level of 11.9 mg 02/£ during 1974-75
was recorded at station 50 (segment 4). The lowest of 6.7 mg 02/£ was at
station 55 (river). The 1974-75 mean value of 10.2 mg 02/£ at station 18 was
identical to the total bay mean.
Mean values by segment ranged from 9.4 mg 02/£ (segment 3, 1975) to 11.6
mg 02/& (segment 4, 1974). The greatest annual range, 3.0 mg 02/£ - 13.8 mg
02/£, occurred in segment 3 (1975). In 1974 the mean value of 11.0 mg 02/£ in
segment 4 was closest to the total bay mean of 10.6 mg 02/£. In 1975 the
28
-------
TABLE 6. TEMPERATURE (°C) AT SELECTED STATIONS PLOTTED IN FIGURE 14
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean * (Range)
17.5 (4.5-25.8)
17.3 (4.5-25.6)
16.3 (0.5-26.7)
16.3 (0.5-24.0)
14.6 (1.5-23.2)
11.8 (1.0-21.0)
17.0 (2.2-26.9)
19.4 (11.1-26.0)
13.0 (1.0-21.1)
7.7 (1.0-15.0)
13.2 (1.2-21.4)
6.3 (1.2-10.8)
Standard
Deviation
6.4
6.5
6.9
6.5
6.4
5.2
6.6
4.5
6.4
4.0
6.4
2.5
I
Minimum
Date
75-4-11
75-4-11
74-12-17
74-12-17
75-4-9
75-4-9
75-4-10
75-5-2
75-4-10
75-4-10
75-4-10
75-4-10
!
Maximum
Date
74-7-8
75-7-29
75-7-31
74-7-10
75-7-13
74-8-15
75-7-31
74-7-9
75-8-19
75-8-19
75-8-19
75-9-4
VO
*Mid-winter data included for 1 m depth only.
-------
STATION -4-3 (SEGMENT 4-
M A M J" J" A S O N D
1S75
j- p- M A M J~ J~ A S O N
STATION 3S < SEGMENT H>
•T F M A M T J~ A S O N D|J~ F M A M -J J~ A S O N D
1374- 1375
STATION 34- < SEQME.NT 3>
J"FMAMJ"TASON DJ" FMAMTJASOND
1374- 1375
I I I I I I I I I I I
j-FMAMTJ'ASON Dj J* FMAMJ"J"ASOND
1374-
1375
Figure 14. Temperature (°C) at selected stations (--).
-------
TABLE 7. DATA SUMMARY OF TEMPERATURE (°C),
PLOTTED IN FIGURE 15
r-.
cn
LO
r-.
en
I
Segment 1
Mean + s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
t of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
16.8 +6.7
.1 - 26.8
64
14.9 + 6.2
1.0 - 25.0
199
16.9 + 7.2
1.2 - 26.9
50
12.8 4- 6.0
1.0 - 21.9
230
13.1 + 6.3
1.2 - 25.1
182
14.1 -t- 6,5
.1 - 26.9
725
1
1.1 + 1.2
.1 - 2.5
3
1.0
1.0
1
2.1 + 1.3
1.2 - 3.0
2
-
-
-
-
-
1.4 * 1.0
.1 - 3.0
6
16.9 + 6.3
1.5 - ?4.6
23
32.7 + 6.7
1.0 - 23.0
80
14.7 + 7.3
1.3 - 23.5
23
9.2 + 6.0
1.0 - 20.3
90
9.3 -f 5.3
1.2 - 19.2
"
11.3 + 6.6
1.0 - 24.6
288 j
22.3 + 3.0
14.4 - 26.8
26
19.8 + 2.9
10.8 - 2B.O
75
22.1 + 2.3
19.0 - 26.9
20
17.9 + 4.1
5.5 - 21.9
83
19.4 ^ 4.0
5.1 - 25.1
64
19.4 -f 3.S
5.1-26.9 |
268 i
10. 9 + 2.7
7.0 - 13.4
12
10.7 + 2.7
5.8 - 13.6
43
11.8 ^ 2.2
8.0 - 13.0
5
11.1 jf 2.3
5.5 - 13.9
,,-j
10.5 ^ l.t.
5.8 - 1 3 . 7 1
4J? _ j
10.8 •* 2,6
5.5 - 13.9 |
163 1
31
-------
SEGMENT 4-
33.0-
30.0-
£ £0.0-
*
» 1S-0'
Q 10-0-
3.0-
0.0-
I
il
1 i
$
1 r
1 I
\\
\]
If
r!(
i
]
i a 3 4-v'R i~2 3 4-v'R
QUARTER QUARTER < 1SI7S >
SEGMENT
3o • 0 —
30.0-
U as 0-
w
M| ««( -u
«l
n is- 0-
O L0.0-1
3.0-
« 0
f
L
r[
]
J
fj
}
p
L [
•
1
J
[
]
m
" 1
T
123 4-VR 1 2 3 4-YR
QUARTER <137+> QUARTER <1.S7S>
LEGEND
MEAN
V
T 1
STAh/DARD 1
DEVIATION R*NOE-
1
J
t.
SEGMENT S
J^5 . ^J
30.0-
W £5.0-
VI
41
*• 13.0-
0)
Q 10.0-
3.0-
0.0-
f
1
1 Z
il
J .
i *-
],[
3 4-V
1 1
I
\\
\ •
^ 12:
1 [
i
3 4-V
)
J
R
QUARTER <1S7*> QUARTER < 1S7S )
SEGMENT 1
SEGMENT 3
33. 0-
30.0-
23. 0-
IS- 0-
1.0.0-
3.0-
&\ . ta —•
j
ffi
r
1 i
i
I
i
01
ni
i
i i
123 4-VR
QUARTER < 1B74-)
3 4-VR
QUARTER <107S>
30.0-
ij
as.0-
O 20.0-
5, is-0-
Q 10.0-
3.0-
0.0—^
(fi
J
ffi
| ffl
- f
1 \
\
0 .
yj
n
1
1
j
1 2 3 4-VR i 2. 3 4-VR
QUARTER < XS74-J QUARTER < 1373)
Figure 15. Data summary of temperature (°C).
-------
mean of 10.6 mg C>2/£ in segment 4 was identical to the bay mean.
Quarterly and annual summaries of all d. oxygen data compiled for each
segment and the total bay are shown in Table 8 and Figure 16.
Conductivity (sp. cond.)
The highest mean specific conductivity level of 702 yS/cm during 1974-75
was recorded at station 55 (river) . The lowest of 204 yS/cm was at station
49 (segment 4) . The 1974-75 mean value of 295 yS/cm at station 56 was identi-
cal to the total bay mean.
Mean values by segment ranged from 211 yS/cm (segment 4, 1974) to 334
yS/cm (segment 1, 1974). The greatest range, 230 yS/cm - 843 yS/cm, occurred
in segment 1 (1974) . In 1974 the mean value of 265 yS/cm in segment 2 was
closest to the total bay mean of 260 yS/cm. In 1975 the mean of 258 yS/cm
in segment 2 was closest to the bay mean of 248 yS/cm.
Quarterly and annual summaries of all sp. conductivity data compiled for
each segment and the total bay are shown in Table 9 and Figure 17 .
Chloride, filtered (f. Cl)
The highest mean filtered chloride level of 83.5 mg Cl/£ during 1974-75
was recorded at station 54 (river). The lowest of 5.9 mg Cl/£ was at station
50 (segment 4). The 1974-75 mean value of 18.8 mg Cl/£ at station 10 was
closest to the total bay mean of 18.7 mg C1/&.
Mean values by segment ranged from 7.0 mg C1/& (segment 4, 1974) to 23.2
mg Cl/£ (segment 1, 1974). The greatest annual range, 5.4 mg Cl/£ - 85.4 mg
CI/H, occurred in segment 1 (1974). In 1974 the mean value of 13.4 mg Cl/£ in
segment 2 was closest to the total bay mean of 13.2 mg C1/&. In 1975 the
mean of 12.2 mg Cl/£ in segment 2 was closest to the bay mean of 11.2 mg Cl/£.
Results showing the variation by cruise (at two depths) of f. chloride
at selected stations are given in Table 10 and Figure 18. Quarterly and an-
nual summaries of all chloride data compiled for each segment and the total
bay are shown in Table 11 and Figure 19 .
The highest mean pH level of 9.0 during 1974-75 was recorded at station
33 (segment 3). The lowest of 7.9 was at station 54 (river). The 1974-75
mean value of 8.4 at station 45 was identical to the total bay mean.
Mean values by segment ranged from 8.2 (segment 4, 1974) to 8.8 (segment
3, 1974 and 1975). The greatest annual range, 6.9 - 9.4 occurred in segment
2 (1974). In 1974 the mean value of 8.4 in segment 5 was closest to the
bay mean.
33
-------
TABLE 8. DATA SUMMARY OF DISSOLVED OXYGEN
(mg 02/£), PLOTTED IN FIGURE 16
CTl
Segment 1
Mean + s.d.
Range
*f of Samples
Mean + s.d.
Range
# of Samples
Segment 1 11^
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
it of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
10. 1 + 1.6
4.7 - 16.0
156
10.1 + 2.0
1.8 - 14.0
205
10.1 + 1.7
7.6 - 14.8
50
11.6 + 1.8
8.8 - 15.5
175
11.0 -r 1.6
R..1 - 15.0
119
10.6 + 1.9
1.8 - 16.0
705
Quarters
Ist(J-M)
16.0
16.0
1
_
_
14.3 + .6
13.4 - 14.8
4
_
_
_
13.0
n n
1
14.3 + 1.1
13.0 - 16.0
6
2nd(A-J)
10.4 + 1.6
5.2 - 13.9
75
10.9 + 1.8
5.6 - 14.0
107
9.8 + 1.4
8.0 - 12.6
17
12.4 + 1.5
8.9 - 14.8
110
11.9 + 1.6
3.7 - 15-0
56
11.3 + 1.8
5.2 - 15.0
365
3rd (J-A)
9.40 + 1.4
4.7 - 11.9
61
9.2 + 1.8
1.8 - 13.6
89
9.3 + .9
7.6 - 11.3
21
10.3 -t- 1.4
8.8 - 15.5
61
10.1 + 1.2
8.3 - 13.6
54
9.7 + 1.5
1.8 - 15.5
286
4th(S-D)
10.7 -t- .-5
9.5 - 11. 5
19
10.4 + .3
9.9 - 10.7
9
10.7 + .5
10.2 - 11.8
8
10.3 + .2
10.1 - 10.6
4
10.3 + .2
10.0 - 10.5
8
10.5 + .48
9.5 - 11.8
48
un
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
» of Samples
Segment IV
Mean + s.d.
Range
ff of Samples
Mean + s.d.
Range
# of Samples
Total Bay
Mean -t- s.d.
Range
# of Samples
9.9 + 2.0
5.8 - 14.0
58
10.5 -f 1.4
6.4 - 14.3
140
9.4 + 2.3
3.0 - 13.8
49
11.0 + 1.5
7.9 - 14.2
181
10.6 + 1.6
7.1 - 14.0
159
10.6 ^ 1.7
3.0 - 14.3
587
11.2
11.2
1
-
-
-
4.4
4.4
1
-
-
-
-
-
-
7.8 jt 4.6
2
10.7 + 1.7
7.8 - 14.0
20
10.8 + 1.2
8.0 - 14.3
38
10.8 + 1.9
7. a - 13.8
23
12.0 + 1.4
9.8 - 14.2
53
11.9 + 1.3
9.6 - 14.0
54
11.5 + 1.5
7.8 - 14.3
188
8.7 + 1.8
5.8 - 13.5
25
9.5 + 1.3
6.4 - 11.9
61
7.9 -V 1.6
3.0 - 10.0
20
9.9 + 1.2
7.9 - 13.6
71
9.2 + 1.3
7.1 - 13.6
59
9.4 i 1.5
3.0 - 13.6
236
11.1 i 1.0
10.0 - 13.2
12
11.6 + .7
9.8 - 12.8
41
9.9 + 1.3
8.7 - 12.0
5
11.3 + .8
9.9 - 12.8
57
11.0 + .7
9.6 - 12.2
46
11.2 + .9
8.7 - 13.2
161
34
-------
SEGMENT 4-
IB-
IS-
O 10-
o>
E
123 4-VR
QUARTER
123 4-VR
QUARTER
SEGMENT 2
U>
le-
- l*-
« ia-
O IB-
1° s-
4.-
a-
T T T
'[
*•
r [
I f ra5[
c
1
123 4-VR 1 2 3 4-VR
QUARTER QUARTER < ISI73>
LEGEND
V
T
T
STANIVKRD
DEVIATION f
i
•J
r-
ANOC
b
SEGMENT S
1B-
L8-
^\ 1*-
« I
O i0-|
123 4-VR 123 4-VR
QUARTER (SUARTER < 1S7S) QUARTER < !S74-> QUARTER < ia73>
Figure 16. Data summary of dissolved oxygen (mg 02/H).
-------
TABLE 9. DATA SUMMARY OF SPECIFIC CONDUCTIVITY (yS/cm),
PLOTTED IN FIGURE 17
01
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
t of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean A s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
$ of Samples
Yearly
Gross
334.5^104.1
230 - 843
190
265 + 38
130 - 423
260
313 +_ 53
236 - 440
64
211 + 24
102 - 365
260
230 + 34
182 - 389
207
260 + 72
102 - 843
-981
Quarters
Ist(J-M)
413.5 + 74.3
301 - 490
6
324 + 23
307 - 340
2
364 + 77
269 - 427
5
229 +_ 37
201 - 290
5
223 + 12
206 - 234
4
318 + 97
201 - 490
22
2nd(A-j)
370.9 + 112.7
258 - 828
81
293 £ 36
222 - 423
102
342 +_ 56
236 - 440
24
216 + 31
102 - 365
114 •
245 + 41
186 - 389
90
280 + 83
102 - 828
411
3rd(J-A)
293.3 + 78.1
231 - 843
68
250 + 22
130 - 305
111
285 + 21
251 - 324
25
210 + 14
188 - 253
95
221 + 23
182 - 288
79
244 + 49
130 - 843
378
4th (S-D)
316.6 + 98.1
230 - 609
35
233 +_ 21
164 - 274
45
284 + 28
256 - 345
10
199 + 9
178 - 223
46
214 +_ 22
182 - 282
34
240 -f 64
164 - 609
170
LO
t^
CTl
Mean + s.d.
Range
(t of Samples
Mean + s.d.
Range
ft of samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of samples
Segment V
Mean + s.d.
Range
ft of Samples
Total Bay
Mean + s.d.
Range
t of Samples
341 jf 74
230 - 569
72
258 + 36
205 - 400
213
290 + 43
222 - 429
56
215 + 18
189 - 262
236
222 + 22
184 - 331
186
248 + 54
184 - 569
763
377 + 34
302 - 425
10
277 + 45
205 - 400
12
347 + 56
275 - 429
5
214 + 10
205 - 233
7
209 +11
194 - 221
6
292 *_ 75
194 - 429
40
382 + 75
283 - 569
23
284 + 35
214 - 400
79
296 + 42
222 - 362
23
222 + 23
189 - 222
90
222 -f 23
184 - 324
72
259 + 60
184 - 569
287
304 + 56
230 - 439
25
237 + 21
205 - 307
75
264 + 22
225 - 298
20
212 +_ 12
192 - 262
81
221 + 16
197 - 274
62
236 + 39
192 - 439
263
315 + 80
232 - 528
14
244 + 24
209 - 311
47
299 + 35
252 - 355
8
208 + 15
196 - 273
58
224 + 28
200 - 331
46
236 £ 47
196 - 528
173
36
-------
SEGMENT 4-
E
<,
IA
a.
• e i
i 2 3 4-YR123 4-YR
QUARTER (1874.) OUARTER < 1S73>
SEGMENT 2
GJ
»~J
i i i i I
i 2 3 4-YR 1 2 3 4-YR
QUARTER
SEC3MENT I
A
SEGMENT 3
ffi I
1 a 3 4-YR 1 a 3 4-VR
QUARTER <1O74-) QUARTER (137S)
123 4-YR 1 2 3 4-YR
QUARTER < 1S7*O QUARTER < 1S7S>
Figure 17. Data summary of specific conductivity (yS/cm).
-------
TABLE 10. FILTERED CHLORIDE (mg Cl/£) AT SELECTED STATIONS, PLOTTED IN FIGURE 18
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean * (Range)
81 (25-175)
80 (15-180)
24 (8-40)
22 (8-38)
10 (6-15)
9 (6-17)
19 (10-29)
20 (13-30)
8 (5-40)
6 (4-6)
7 (4-25)
6 (3-7)
Standard
Deviation
39
40
9
9
3
3
5
4
7
1
4
1
Minimum
Date
75-9-3
74-2-21
75-12-16
74-12-17
74-10-6
74-10-6
74-2-18
75-5-22
74-4-29
74-6-19
74-6-19
74-7-26
Maximum
Date
74-10-6
74-10-6
74-12-17
74-12-17
74-6-3
75-4-30
74-5-16
75-6-27
74-2-20
74-4-20
74-2-20
75-4-10
CO
oo
*Mid-winter data included for 1 m depth only.
-------
STATION 4-a (SEGMENT 4.)
STATION SI (SEGMENT S>
33 -,
1—I—|—I—I I I \ ! I
T F M A M 0" J~ A S O N D|J~ F M A M 0" .J A S O N D
1975
1374-
1075
ASOND
1975
Figure 18. Filtered chloride (mg Cl/£) at selected stations (-•-).
-------
TABLE 11. DATA SUMMARY OF FILTERED CHLORIDE (rag Cl/£),
PLOTTED IN FIGURE 19
Mean + s.d.
Range
1 of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
S egment y
Mean + s.d.
Range
# of Samples
Total Bay
Range
tt of Samples
Yearly
Gross
22.9 + 12.9
5.4 - 85.4
201
13.4 +_ 5.6
2.7 - 67.0
260
20.0 + 7.7
6.1 - 40.3
68
7.0 + 4.0
2.9 - 40.0
254
3.3 - 26.2
208
2.7 - 85.4
991
Quarters
Ist(J-M)
13.8 ^ 11.9
5.4 - 29.3
6
21.0 + 1.1
20.2 - 21.8
2
8.7 +_ 3.1
6.1 - 13.5
5
28.6 + 9.8
14.4 - 40.0
5
9.9 - 25.2
4
5.4 - 40.0
22
2nd(A-J)
24.8 + 11.8
10.4 - 71.0
89
15.5 + 4.1
6.9 - 25.6
102
24.4 + 8.5
10.7 - 40.3
26
6.9 + 2.9
2.9 - 20.5
110
10.1 -t- 4.7
4.4 - 26.2
85
2.9 - 71.0
412 .
3rd(J-A)
19.4 + 8.1
10.1 - 43.7
70
12.5 -f 6.8
2.7 - 67.0
109
18.8 + 4.5
10.2 - 26.4
26
6.4 +_ 1.6
3.0 - 11.4
91
7.8 -t- 3.8
3.3 - 20.8
83
2.7 - 67.0
379
4th (S-D)
26.4 + 19.7
9.7 - 85.4
36
10.4 + 3.1
5.9 - 18.5
47
17.5 + 5.7
8.7 - 26.0
11
6.0 + .9
4.6 - 9.7
48
8.2 + 3.6
4.9 - 21.2
36
4,6 - 85.4
178
un
Mean + s.d.
Range
1 of Samples
Mean + s.d.
Range -
i of Samples
Mean + s.d.
Range
ft of Samples
Segment IV
Mean + s.d.
ft of Samples
Segment V
Mean + s.d.
ft of Samples
Total Bay
Mean + s.d.
t of Samples
23.2 + 8.4
8.3 - 41.8
73
12.2 + 4.3
6.2 - 31.9
214
17.4 + 5.5
8.2 - 30.5
56
7.1 + 2.3
5.1 - 19.0
238
8.1 * 2.8
5.2 - 21.5
188
11.2 + 6.6
5.1 - 41.8
769
25.5 + 4.8
4.1 - 32.9
10
13.3 + 6.3
8.6 - 31.9
12
22.7 + 7.6
10.6 - 30.5
5
6.2 ^ 1.3
5.4 - 8.9
7
6.1 + .6
55-6.9
6
15.4 + 9.2
4.1 - 32.9
40
27.1 + 7.3
15.8 - 41.8
23
15.3 +4.2
7.0 - 24.0
80
17.5 + 5.9
8.2 - 30.0
23
7.9 + 3.1
5.3 - 19.0
90
7.8 + 2.5
5.2 - 19.1
72
12.4 + 7.2
5.2 - 41.8
288
21.3 •* 8.4
10.5 - 35.4
26
10.0 + 2.5
6.2 - 18.3
75
16.0 + 3.9
10.4 - 24.1
20
6.8 + 1.3
5.1 - 10.9
83
8.5 t 2.6
5.4 - 18.2
64
10.4 + 5.8
5.1 - 35.4
268
18.6 i 9.2
8.3 - 40.0
14
10.3 + 2.8
7.0 - 18.5
47
17.2 + 4.9
11.0 - 25.2
8
6.5 + 1.5
5.4 - 13.7
58
8.3 + 3.5
5.5 - 21.5
46
9.7 ^ 5.4
5.4 - 40.0
173
40
-------
SEGMENT
ee>-
\ w-
w
o> «-
E
20.
ffl
*i
1 2
QUAF
•
i * i A i &
3 4-VR 1 2 3
!TER (1874-) QUARTE
± £
4-v'R
* < 1S7S>
LEGEND
SEGMENT 2
N.
o>
E
QUART
] 4 i
3 4-VR
ER (1S74.)
ii..I
123 4-VR
(ftUARTER < 1S73>
JN
Si
T
3TAI
DEV
STANDARD
DEVIATION
SEGMENT S
_ CD IB
L 2 3 4-VR 123 4-VR
QUARTER ( lS74-> QUARTER < 1Q73)
SEGMENT 1
SEGMENT -3
J.OT0-
80-
_
>X» O8I-
^m
w
0)
E
n=n
i 2
QU,
It
i 3 .
^RTER
1
^
QUARTER < 13735
11010-
eo-
-
\ SB-
U
4e-
0)
E
20-
^ f L|J IjJ L[J IJJ
123 4-VR 123 4-VR
QUARTER < IQ74-) QUARTER C 1.S73)
Figure 19. Data summary of filtered chloride (mg Cl/£).
-------
Quarterly and annual summaries of all pH data compiled for each segment
and the total bay are shown in Table 12 and Figure 20.
Figure 21 shows typical variation of pH during a 24-hour period at one
station (56) in the inner bay.
Alkalinity, total (tot, alk.)
The highest mean total alkalinity level of 183 mg CaC03/£ during 1974-75
was recorded at station 55 (river). The lowest of 78 mg CaC03/£ was at sta-
tion 49 (segment 4). The 1974-75 mean value of 99 mg CaC03/£ at station 14
was identical to the total bay mean.
Mean values by segment ranged from 81 mg CaC03/£ (segment 4, 1974) to
118 mg CaC03/£ (segment 1, 1975). The greatest annual range, 77 mg CaC03/£ -
173 mg CaC03/£, occurred in segment 1 (1974). In 1974 the mean value of 95
mg CaC03/£ in segment 2 was closest to the total bay mean of 92 mg CaC03/£.
In 1975 the mean of 98 mg CaC03/£, in segment 2 was closest to the bay mean of
92 mg CaC03/£.
Quarterly and annual summaries of all tot. alkalinity data compiled for
each segment and the total bay are shown in Table 13 and Figure 22.
Secchi Disc Depth
The highest mean Secchi depth level of 5.3 m during 1974-75 was recorded
at station 51 (segment 5). The lowest of 0.4 m was at station 54 (river).
The 1974-75 mean value of 1.6 m at station 61 was closest to the total bay
mean of 1.8 m.
Mean values by segment ranged from 0.87 m (segment 1, 1974) to 3.6 m (seg-
ment 4, 1975). The greatest annual range, 0.5 m - 9.0 m, occurred in segment
5 (1974). In 1974 the mean value of 1.3 m in segment 2 was closest to the
total bay mean of 1.8 m. In 1975 the mean of 1.5 m in segment 2 was closest
to the bay mean of 2.1 m.
Results showing the variation by cruise (at two depths) of Secchi depth
at selected stations are given in Table 14 and Figure 23. Quarterly and an-
nual summaries of all Secchi depth data compiled for each segment and the
total bay are shown in Table 15 and Figure 24.
Chlorophyll a, non-filterable (nf. chl. a)
The highest mean non-filterable chlorophyll a level of 42.87 yg chl. a/£
during 1974-75 was recorded at station 21 (segment 1). The lowest of 2.25 yg
chl. a/H was at station 50 (segment 4). The 1974-75 mean value of 15.25 yg
chl. all at station 32 was closest to the total bay mean of 15.37 yg chl. a/A.
Mean values by segment ranged from 3.5 yg chl. a/H (segment 4, 1974) to
33.3 yg chl. a/£ (segment 1, 1975). The greatest annual range, 4.2 yg chl.
a/H - 87.9 yg chl. a/a, occurred in segment 1 (1975). In 1974 the mean value
42
-------
TABLE 12. DATA SUMMARY OF pH PLOTTED IN FIGURE 20
Mean + s.d.
Range
# of samples
Segment II
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
)t of samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
yearly
Gross
8.60 + .42
7.21 - 9.58
164
8.58 + .35
6.88 - 9.40
240
8.80 -t- .28
7.93 - 9.33
50
8.22 ^ .33
7.34 - 9.3C
248
8.4 + .4
7.5 - 9.3
190
8.45 +_ .40
6.88 - 9.58
892
Quarters
Ist(J-M)
8.25 + .30
7.90 - 8.80
6
8. 03 + .14
7.98 - 8.18
2
8.56 + .40
7.93 - 8.86
5
7.97 + .04
7.9 - 8.0
5
8.0 + .4
7.8 - 8.6
4
8.21 + .35
7.80 - 8.86
22
2nd(A-J)
8.61 + .50
7.21 - 9.58
77
8.65 + .38
6.88 - 9.40
118
8.87 + .23
8.30 - 9.33
23
8.12 + .43
7.34 - 9.30
110
8.3 + .5
7.5 - 9.3
78
8.45 ^ .50
6.88 - 9.58
406
3rd(J-A)
8.74 ^ .30
7.86 - 9.22
50
8.58 + .31
7.78 - 9.18
82
8.88 + .23
8.48 - 9.18
14
8.35 + .18
7.77 - 8.75
87
8.5 + .2
8.0 - 9.1
74
8.53 +_ .29
7.77 - 9.22
307
4th(S-D)
8.43 + .29
7.88 - 9.02
31
8.38 + .28
7.96 - 8.92
38
8.58 + .27
8.24 - 8.85
8
8.20 + .17
8.04 - 8.79
46
8.3 + .2
8.0 - 8.9
34
8.33 + .26
7.88 - 9.02
157
LO
Segment 1
Mean -f s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Moan + s.d.
Range
» of Samples
Total Bay
Mean -t- s.d.
Range
# of Samples
8.7 +- .4
7.6 - 9.4
57
8.5 + .3
7.9 - 9.1
198
8.8 -f .3
8.1 - 9.4
45
8.3 + .2
7.7 - 8.9
228
8.4 +- .3
7.6 - 9.1
182
8.5 + .3
7.6 - 9.4
710
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
8.7 + .4
8.0 - 9.3
23
8.4 + .3
7.9 - 9.1
80
8.7 + .3
8.1 - 9.1
23
8.3 ;f .3
7.8 - 8.9
88
8.4 + .3
7.9 - 9.0
72
8.4 + .3
7.8 - 9.3
286
8.8 + .4
7.6 - 9.4
22
8.6 + .2
8.0 - 9.0
73
8.9 + .2
8.5 - 9.4
17
8.5 + .2
8.0 - 8.8
83
•8.6 + .2
8.0 - 9.1
64
8.6 + .3
7.6 - 9.4
259
8.5 + .3
8.1 - 8.9
12
8.3 + .2
8.1 - 8.9
45
8.5 + .3
8.1 - 8.9
5
8.2 + .2
7.6 - 8.5
57
8.2 + .2
7.6 - 8.7
46
8.3 + .2
7.6 - 8.9
165
43
-------
SEGMENT 4-
- i
123 4-VR
QUARTER (IS7*>
123 4-VR
QUARTER 11B73>
SEGMENT 2
e
3
i 2 3 4-YR
QUARTER «IB7*>
i 2 3 4-VR
QUARTER < 1079)
LEGEND
r »-
e »-
= 3-
w 3-
9TAI
3EV
STANIVKRD
DEVIATION
RANQC
SEGMENT S
4
123 4-VR 123 4-VR
QUARTER < 1874.) QUARTER < 1O73>
SEGMENT 1
4 T $
I f 0 f
e-
w 7-
^
I -H
123 4-VR 123 4-VR
QUARTER dUARTER < L87S}
SEGMENT 3
1 e 3 4-VR 123 4-VR
QUARTER <1S7*> QUARTER < 1S73>
Figure 20. Data summary of pH.
-------
STATION SB
< SEGMENT 3 >
Q . S
8.
1 MSTSR
4. METERS
i i 1 i r I r i i T i i r i i I r i i i r
8 12 IS e0
HOUR
Figure 21. pH variation at station 56 during a diurnal survey
(August 16-17, 1975).
45
-------
TABLE 13. DATA SUMMARY OF TOTAL ALKALINITY (mg CaC03/£),
PLOTTED IN FIGURE 22
Segment 1
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of samples
Segment III
Mean + s.d.
Range
(t of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
tt of Samples
Total Bay
Mean + s.d.
Range
« of Samples
Yearly
Gross
107 ;+ 18
77 - 173
174
95 +_ 10
75 - 145
246
102 -f 12
83 - 142
56
81 + 5
70 - 104
234
84 + 7
74 - 115
178
92 + 15
70 - 173
888
Quarters
Ist(J-M)
112.5 + 9.6
102.0 - 127. <
6
95 +_ 1
94 - 96
2
110 jt 15
86 - 122
5
83 + 5
77 - 91
5
84 + 2
81 - 86
4
99 ± 16
77 - 127
22
2nd(A-J)
119.1 j+ 20.5
91.0 - 173.0
69
100 + 11
82 - 145
101
113 + 10
90 - 142
21
83+7
70 - 104
90
84 + 8
75 - 115
68
97 + 19
70 - 173
349
3rd(J-A)
98.01 + 9.3
77.0 - 129.0
68
91 + 5
75 - 103
105
94 ^ 5
83 - 104
23
81 + 4
72 - 93
93
82 + 4
75 - 96
72
88 ± 9
72 - 129
361
4th (S-D)
100.6 + 13.!
88 - 142
31
89 + 4
80 - 95
38
94 + 5
89 - 101
7
80 + 2
75 - 86
46
86 + 8
74 - 102
34
88 + il
74 - 142
156
LD
r«.
en
Mean + s.d.
Range
« of samples
Mean + s.d.
Range
tt of Samples
Segment III
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
B of Samples
Total Bay
Mean + s.d.
Range
fl of Samples
118 ±_ 27
89 - 173
22
98 + 13
80 - 131
96
106 + 18
82 - 136
60
83 + 8
67 + 102
107
85 t_ 9
63 - 111
86
92 + 16
63 - 173
371
_
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
141 + 16
108 - 173
11
108 + 12
85 - 131
48
116 + 14
98 - 136
10
86 + 8
67 - 102
57
85 + 10
63 - 111
46
97 j+ 19
• 63 - 173
172
92 + 3
89 - 94
4
85 ;+ .5
85 - 86
5
88 + 7
82 - 96
5
-
-
-
84 + 2
81 - 86
5
87+4
81 - 96
19
96 J+ 8
89 - 111
7
89 + 6
80 - 107
43
94
94
1
79+5
74 - 98
50
84 + 9
75 - 111
35
86 + 9
74 - 111
136
46
-------
SEGMENT 4-
O L22I-
n
E
LEGEND
1 2 3 4-VR 123 4-VR
QUARTER ClSI7-4-> QUARTER (ia?S>
SEGMENT
~ e*3i
^\. 1Q0-
« !«,-
S 120-
O 100-
U
O> sizi .
E «-
20-
1
1
1
T T \
1 1 ',
- 31 f ® $ :
i
i
i
i
i
1 2 3 4-VR
QUARTER < 1S74O
m X
^ x, tt\
T _ 4 I|J
~~1 1 I 1 1
1 2 3 4-VR
aUARTER < 1O73)
N.
"»
T
STANTW5D
DEVIATION f
1
.*
••
ANQE
£•
SEGMENT S
O
u
0
u
j
J-i
i 2. 3 4-VR
QUARTER ( L874->
1 e 3 4-VR
QUARTER ! 1B73)
SEGMENT
SEGMENT 3
130-
v^^ ia0-
n 1*0-
Q 120-
0 lta0"'
U 60-
O) ^^
£ 4«J-
«E
!{i;
J
fi 1
' J
rD III I
1
L 2 3 4-YR 123 4-VR
QUARTER GlUARTER < 1.373)
200-
130-
^ 1S0-
n lJ***~
O 120-
0
en Q0-I
£ 442H
0-
i*4»i *B i
1 2. 3 4-VR 1 2. 3 4-VR
QUARTER < !S74-> QUARTER < 1S73>
Figure 22. Data summary of total alkalinity (mg CaC03/£).
-------
TABLE 14. SECCHI DISC DEPTH (m) AT SELECTED STATIONS, PLOTTED IN FIGURE 23
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean * (Range)
0.5 (0.2-1.5)
0.9 (0.5-1.6)
2.0 (1.0-3.5)
0.9 (0.5-2.3)
5.1 (1.0-7.5)
5.3 (1.7-8.5)
Standard
Deviation
0.3
0.3
0.6
0.6
1.5
1.8
Minimum
Date
74-6-18
74-4-17
74-10-6
74-6-19
75-6-26
75-4-10
Maximum
Date
74-2-21
75-7-31
75-7-29
75-2-19
75-5-1
74-6-19
oo
*Mid-winter data included for 1 m depth only.
-------
STATION 4-s
J"FMAMTTASOND|J'FMAMTJ'ASOND
g.0 i I 1 I I I I I I I I I I I I I 1 i I I
J~FMAr-1J~-JASON D|J" Ff-lAM-TTASOND
1374-
1375
Figure 23. Secchi disc depth (m) at selected stations (-•-).
-------
TABLE 15. DATA SUMMARY OF SECCHI DISC DEPTH (m),
PLOTTED IN FIGURE 24
CTi
Mean + s.d.
Range
ft of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
S of Samples
Yearly
Gross
.87 + .35
.10 - 3.00
131
1.3 + .5
.3 - 3.0
156
1.0 ^ .7
.4 - 4.0
57
3.4 + 1.6
1.0 - 7.5
100
2.7 + 1.9
.5 - 9.0
82
1.8 t_ 1.5
.1 - 9.0
526
Quarters
Ist(J-M)
3.00
3.00
1
'
3.2 + 1.4
1.5 - 4.0
3
3.1 t_ 1.2
1.5 - 4.0
4
2nd(A-J)
.82 + .30
.10 - 1.80
59
1.4 ^ .6
.3 - 3.0
73
.8 + .3
.5 - 1.4
25
3.5 +_ 1.6
1.0 - 7.5
43
2.8 + 1.8
.5 - 8.5
36
1.8 + 1.5
.1 - 8.5
236.
3rd (J-A5
.80 + .29
.30 - 1.70
46
1.2 + .4
.4 - 2.7
59
1.0 + .4
.5 - 2.0
19
3.2 + 1.5
1.0 - 7.0
40
2.9 ^ 2.0
.7 - 9.0
35
1.8 + 1.5
.3 - 9.0
199
4th(S-D)
1.02 + .27
.60 - 1.50
25
1.1 + .4
.5 - 1.5
24
.7 + .3
.4 - 1.3
10
3.6 + 1.8
1.2 - 7.0
17
2.1 + 1.7
.7 - 7.0
11
1.7 + 1.4
.4 - 7.0
87
in
r^.
CTi
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
tt of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
f of Samples
.9 + .4
.3 - 3.0
50
1.5 + .7
.3 - 5.0
115
1.4 ^ .7
.5 - 3.0
42
3.6 i 1.5
1.0 - 8.0
86
3.0 + 1.6
.8 - 8.0
67
2.1 ^ 1.5
.3 - 8.0
360
1.5 + .8
.5 - 3.0
7
2.6 + .2
2.4 - 2.7
2
2.5 + .4
2.3 - 3.0
3
4.5
4.5
1
-
-
-
2.1 + 1.0
.5 - 4.5
13
.8 ± .3
.5 - 1.3
17
1.5 + .6
.4 - 2.7
45
1.6 -t- .6
.6 - 2.6
19
3.8 + 1.5
1.0 - 7.5
34
3.6 + 1.4
.9 - 6.8
27
2.3 ^ 1.5
.4 - 7.5
142
.e + .3
.3 - 1.6
18
1.5 ^ .8
.3 - 5.0
43
1.0 + .5
.5 - 2.2
16
3.7 + 1.7
1.2 - 8.0
31
2.7 + 1.9
.8 - 8.0
23
2.0 + 1.6
.3 - 8.0
131
.8 + .2
.5 - 1.0
8
1.3 + .5
.6 - 2.1
25
.9 jf .2
.6 - 1.1
4
3.2 t_ 1.3
1.3 - 5.3
20
2.4 + 1.3
.9 - 5.5
17
1.9 ^ 1.3
.5 - 5.5
74
50
-------
SEGMENT 4-
e.szs-
a.0-
• !
II
1
II
1 1
1!
11
•
|i
i
i 2 3 4-VR 123 4-YR
QUARTER < 19740 QUARTER < 1S73>
SEGMENT 2
J i 1 1
"i!
]ffi[
]
1234-VR 1234-YR
QUARTER <1974-> GtUARTER
SEGMENT 3
Xlt* • 10 —
9
s *•-
TJ
II
4 4 i [
& :L I
123 4-YR 123 4-YR
QUARTER <1074-> QUARTER <197S>
Figure 24. Data summary of Secchi disc depth (m).
-------
of 16.26 yg chl. a/£ in segment 2 was closest to the total bay mean of 15.7
yg chl. a/£. In 1975 the mean of 12.9 yg chl. a/£ in segment 2 was closest
to the bay mean of 11.9 yg chl. a/£.
Results showing the variation by cruise (at two depths) of nf. chloro-
phyll a at selected stations are given in Table 16 and Figure 25. Quarterly
and annual summaries of all chlorophyll a data compiled for each segment and
the total bay are shown in Table 17 and Figure 26.
Figure 27 shows typical variation of nf. chlorophyll a during a 24-hour
period at one station (56) in the inner bay. Twice-weekly chlorophyll a data
from four intake plants (plotted in Figure 28) are compared in Table 18 to
regular cruise data for the same sites.
Carbon, unfiltered organic (u. org. C)
The highest mean unfiltered organic carbon level of 13.2 mg C/£ during
1974-75 was recorded at station 55 (river). The lowest of 2.4 mg C/£ was at
station 57 (segment 4). The 1974-74 mean value of 5.9 mg C/£ at station 22
was closest to the total bay mean of 6.1 mg C/£.
Mean values by segment ranged from 3.5 mg C/£ (segment 4, 1974) to 8.1
mg C/£ (segment 1, 1974). The greatest annual range, 3.6 mg C/£ - 34.5 mg
C/£, occurred in segmnet 1 (1974). In 1974 the mean value of 5.8 mg C/£ in
segment 2 was closest to the total bay mean of 5.6 mg C/£. In 1975 the mean
of 5.4 mg C/£ in segment 2 was closest to the bay mean of 5.1 mg C/£.
Quarterly and annual summaries of all u. org. carbon data compiled for
each segment and the total bay are shown in Table 19 and Figure 29.
Carbon, filtered organic (f. org. C)
The highest mean filtered organic carbon level of 11.4 mg C/£ during
1974-75 was recorded at station 55 (river). The lowest of 2.3 mg C/£ was at
station 57 (segment 4). The 1974-75 mean value of 4.9 mg C/£ at station 21
was identical to the total bay mean of 4.9 mg C/£.
Mean values by segment ranged from 3.3 mg C/£ (segment 4, 1975) to 6.3
mg C/£ (segment 3, 1974, and segment 1, 1975). The greatest annual range,
3.5 mg C/£ - 16.7 mg C/£, occurred in segment 1 (1975). In 1974 the mean
value of 4.5 mg C/£ in segment 2 was closest to the total bay mean of 4.4 mg
C/£. In 1975 the mean of 4.5 mg C/£ in segment 2 was closest to the bay mean
of 4.3 mg C/£.
Quarterly and annual summaries of all f. org. carbon data compiled for
each segment and the total bay are shown in Table 20 and Figure 30.
Solids, unfiltered total (u. tot, sol.)
The highest mean unfiltered total solids level of 456.8 mg/£ during 1974-
75 was recorded at station 55 (river). The lowest of 125.3 mg/£ was at sta-
52
-------
TABLE 16. NON-FILTERABLE CHLOROPHYLL a (ug chl. a/£) AT SELECTED STATIONS, PLOTTED IN FIGURE 25
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean * (Range)
26.64 (.67-65.10)
23.73 (4.01-46.50)
33.24 (9.38-76.30)
29.02 (7.46-57.40)
8.24 (2.25-25.50)
8.96 (3.37-27.60)
25.86 (4.25-68.50)
33.17 (11.20-50.70)
2.27 (0.64-12.00)
3.04 (1.34-5.93)
1.91 (0.72-6.01)
2.92 (1.04-5.53)
Standard
Deviation
16.62
14.02
17.01
15.05
5.08
6.44
16.22
12.74
2.24
1.33
1.19
1.58
1
Minimum
Date
74-2-21
75-9-3
75-7-31
75-7-31
75-10-27
75-9-23
75-2-19
75-5-22
74-7-9
75-5-21
74-7-9
75-10-10
Maximum
Date
74-7-8
75-10-27
75-7-16
75-7-16
75-9-3
75-9-3
75-7-31
75-7-31
75-6-26
75-7-15
75-10-10
75-7-15
*Mid-winter data included for 1 m depth only.
-------
STATION 4-S ( SE.GME.NT 4- J
70
60
S0
-------
TABLE 17. DATA SUMMARY OF NON-FILTERABLE CHLOROPHYLL a (yg chl. a/£),
PLOTTED IN FIGURE 26
cr>
Segment 1
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
ft of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Range
ft of Samples
Yearly
Gross
1.07-74.40
152
178
24.85+13.4
4.41-58. 50
54
3.52 + 2. 34
.40 - 11.50
138
7.69 + 8.81
.32 - 57.40
128
15.7+14.3
.32 - 74.4
650
Quarters
Ist(J-M)
4.33 - 31.40
3
2
9.25 ^ 5.85
4.41 - 18.9
5
3.71 -f 4.23
.88 - 8.58
3
3.42 + 1.76
2.25 - 5.45
3
.88 - 31.4
16
2nd(A-J)
1.07 - 74.40
68
75
22.30 ^ 11.53
9.78 - 44.7
22
3.21 t 2.12
.88 - 10.90
54
7.30 -f 5.87
.88 - 25.70
55
.88 - 74.4
274
3rd(J-A)
9.71 - 68.30
50
64
32.8 + 12.8
12.8 - 58.5
16
3.59 +_ 2.52
.40 - 11.50
47
7.68 + 11.09
.64 - 57.40
46
18.0 + 16.4
.40 - 68. 3
223
4th (S-D)
9.31 - 52. 3(
31
37
25.5 + 13.4
8.12 - 43.1
11
3.89 i 2.28
1.28 - 9.38
34
9.16 + 10.11
.32 - 36.60
24
14.7 + 12.2
.32 - 52.3
137
in
t-*
CD
Segment 1
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
« of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
-
4.2 - 87.9
74
12.9 + 7.4
1.4 - 41.1
209
24.0 + 14.8
4.1 - 68.5
53
" - '
.3 - 25.3
228
6.5 + 6.7
.6 - 38.8
186
11.9 + 13.4
.3 - 87.9
750
-
10
6.7 + 5.7
1.4 - 20.1
12
8.6 + 3.8
4.3 - 13.6
5
" - '
.3 - 3.9
6
1.3+ .6
.6 - 2.3
6
8.5 + 8.3
.3 - 35.4
39
-
23
11.3 + 6.5
3.0 - 41.1
78
19.4 + 14.0
4.0 - 46.8
21
' - '
.8 - 19.7
90
4.1 + 2.9
1.0 - 16.5
71
10.5 + 13.0
.8 - 77.9
283
-
27
15.2 + 8.8
1.8 - 39.8
73
32.5 + 15.0
6.0 - 68.5
19
• _ -1
.9 - 25.3
75
9.0 + 9.5
.8 - 38.8
63
14.8 + 16.2
.8 - 87.9
257
14.4 - 45.4
14
13.5 + 5.2
2.3 - 28.6
46
25.4 + 6.2
17.3 - 36.4
8
-
1.4 - 15.1
57
7.4 + 5.0
1.0 - 21.5
46
10.6 + 8.7
1.0 - 45.4
171
55
-------
SEGMENT 4-
B0-
0)
^^
o\
miiii * i IB i ill
3 4-YR 1 S 3 4-YR
QUARTER (1374O QUARTER <1B73>
SEGMENT 2
Ul
eei-
^- SEJ-
Ol
a- *0-
C»1 —
OB L
][
lil
1 i!
]1
]T[
]
123 4-VR 123 4-VR
QUARTER < L374-) QUARTER < LB73)
SEGMENT S
. [p f
If
If
1 _if
lt[
1
123 4-VR 123 4-VR
QUARTER < 1.37*0 QUARTER < 1S73 )
SEGMENT I
1 £ 3 4-VR 1 £ 3 4-VR
QUARTER < 1S74-) QUARTER < LS73>
SEC3MENT 3
.
12 3 4-VR 123 4-VR
QUARTER
Figure 26. Data summary of non-filterable chlorophyll a (yg chl.
-------
STATION SB (SEGMENT 3>
14-.0
CD
-------
TABLE 18. MEAN NON-FILTERABLE CHLOROPHYLL a VALUES (yg chl. a/£)
FROM CRUISE (SB) AND INTAKE PLANT (SBI) SAMPLES, PLOTTED IN FIGURE 28
Month
-------
INTAKE STATION -4-
•0.0-
1S74-
INTAKE STATION 3
1375
80.0-
B0.0-
40.0-
20.0-
Ul
1S74-
1S7S
INTAKE STATION
INTAKE STATION
60-0-
-
\ so. 0-
-**^ ^*
*• 40.0-
S0.0-
0.0-
1
1
1
1
1
1
1
1
^_, 1
A f\ '
A/ VK
___/ V v p-
197S
XFr-lAMJ"J"A3O NDjJ'F'r-lAf! JJ" ASO N D
1Q74- 1375
Figure 28. Non-filterable chlorophyll a (yg chl. a/£) in twice-weekly samples
from water intake plants (equivalent to stations 1, 2, 3, 4).
-------
TABLE 19. DATA SUMMARY OF UNFILTERED ORGANIC
CARBON (mg C/H) PLOTTED IN FIGURE 29
Segment 1
Mean + s.d.
Range
t of Samples
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean +• s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
i of Samples
Gross
8.1 + 5.3
3.6 - 34.5
61
5.8 + 2.5
2.6 - 16.3
76
8.6 + 3.3
2.8 - 16.4
18
3.5 + 1.6
1.9- 10.0
63
4.4 + 2.5
2.2 - 14.9
50
5.6 + 3.6
1.9 - 34.5
268
Ist(J-M)
_
-
-
_
-
_
.
.
-
-
_
-
.
-
-
Quar
2nd(A-J>
12.4 + 6.3
5.5 - 34.5
23
7.8 + 2.6
5.1 - 16.3
28
11. 5 +- 2.6
9.1 - 16.4
7
4.5 + 1.7
2.7 - 7.5
21
5.5 + 3.3
2.9 - 14.9
20
7.9 + 4.7
2.7 - 34.5
99
-ers
3rd(J-A)
-
-
_
-
-
_
-
-
-
-
-
-
4th (S-D)
5.4 -f 1.6
3.6 - 11.5
38
4.6 + 1.5
2.6 - 9.1
48
6.7 + 2.1
2.8 - 9.2
11
.3.0+1.4
1.9 - 10.0
42
3.7 <- 1.6
2.2 - 9.8
30
4.3 + 1.8
1.9 - 11.5
169
LO
1-^
CTi
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment III
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
* of Samples
7.9 + 2.7
4.1 - 15.7
76
2.6 - 14.0
142
1.8 - 12.9
47
3.6 + 1.5
2.1 - 13.1
130
4.0 + 1.6
2.2 - 10.2
92
5.1 + 2.4
1.8 - 15.7
487
6,0 + 0.8
4,1 - 7.0
10
3.2 - 6.0
13
4.8 - 11.0
5
2.8 + .41
2.2 - 3.4
6
3.0 + 0.4
2.4 - 3.3
5
4.5 + 1.8
2.2 - 11.0
39
8.5 + 1.9
4.8 - 11.4
24
5,6 + 1.6
2.6 - 10.2
56
5.4 + 2.0
1.8 - 8.8
19
3.4 -t 1.1
2.1 - 7.7
55
3.2 + 0.9
2.2 - 6.6
39
4.8 + 2.2
1.8 - 11.4
193
9.4 + 3.4
4.1 - 15.7
24
6.1 -f 2.4
3.1 - 14.0
42
8.3 + 2.3
5.4 - 12.9
16
4.3 + 2.1
2.3 - 13.1
39
5.0 + 1.6
2.6 - 8.4
27
6.2 + 3.0
2.3 - 15.7
148
6.3 +_ 1.4
4.3 - 9.8
18
4.8 + 1.3
2.8 - 8.6
31
6.6 -1- 1.8
4.7 - 9.8
7
3.1 -t- 0.7
2.3 - 6.1
30
4.3 + 1.8
2.4 - 10.2
21
4.6 + 1.8
2.3 - 10.2
107
60
-------
SEGMENT
C10 . 10-
18.0-
18.0-
— 14.0-
\ 12.0-
• I
w 10.0-
01 e.0-
E e.0-
4.0-
a.0-
oi.n-
i ,
][
1
] .ill
"
III
1
LEGEND
1234-YR 123 4-YR
QUARTER (1S74J QUARTER <1S73)
SEGMENT 2
Kta • K» —
18.0-
ie.0-
_ 14.0-
\ 12.0-
W 10.0-
O> B.0-
4.0-
2.0-
•
r
[
1 2
QU
1 |l
i 3 4-Y
IKRTER <16
1
R i 2 :
r?4) QUART
IJl
3 4-Y
ER (IE
]
R
175 >
3TA(
DEV
1
9TANTVM53D
DEVIATION
RANOE
SEGMENT S
Cjo . 10 ~
18.0-
ie.0-
— 14.0-
X 12. BI-
ii
10.0-
0) 8.0-
E e.0-
4.0-
2.0-
0.0-
1
]
][
i .lilt
1234-YR ia34-V
i
R
QUARTER <1Q74> QUARTER <1O7S>
SEGMENT
SEGMENT 3
KiO.JO-
18.0-
18.0-
14.0-
12.0-
10.0-
8.0-
e.0-
4.0-
£.0-
_
' A
1
1
1
1
! x f
i rti 1
mil
1
T r
1
t
20.0-
18.0-
ie.0-
— 14.. 0-
\^ 12.0-
U 10.0-
9 B.0-
E e.0-
2.0-
S'
f
|l
1 1 1 T
IPi!
1
123 4-VR 1H34-YR 1S3 4-YR 123 4-YR
QUARTER (1S74) QUARTER (1S73) QUARTER <1S74> QUARTER < 187S)
Figure 29. Data summary of unfiltered organic carbon (mg C/fc).
-------
TABLE 20. DATA SUMMARY OF FILTERED ORGANIC
CARBON (mg C/£) PLOTTED IN FIGURE 30
CTi
Mean +_ s.d.
Range
# of Samples
Mean + s.d.
Range
H of Samples
Segment III
Mean + s.d.
Range
t of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
ft of Samples
To t_a 1 Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
5.6 + 2.2
1.0 - 12.6
61
4.5 + 1.7
2.4 - 12.1
76
6.3 + 2.7
2.7 - 13.0
18
3.4 -h 1.5
2.3 - 9.3
62
3.7 + 1.6
2.2 - 10.0
50
4.4 + 2.0
1.0 - 13.0
267
Quarters
Ist(J-M)
-
-
-
-
.
.
_
_
_
_
_
-
-
-
2nd(A-j)
7.3 + 2.5
1.0 - 12.6
23
6.1 + 1.8
3.8 - 12.1
28
8.9 + 2.5
5.6 - 13
7
4.6 + 2.0
2.4 - 9.3
20
4.6 + 2.1
2.2 - 10.0
20
5.9 + 2.5
1.0 - 13.0
98
3rd(J-A)
-
-
-
-
_
-
-
_
-
_
-
-
-
-
4th (S-D)
4.5 + 0.9
2.9 - 7.0
38
3.6 -f 0.6
2.4 - 4.8
48
4.6 + 0.9
2.7 - 5.7
11
2.8 + 0.4
2.3 - 3.7
42
3.2 + 0.7
2.2 - 5.1
30
3.6 + 1.0
2.2 - 7.3
169
Mean + s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range
# of Samples
Segment _II_I
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
ft of Samples
Total Bay
Mean + s.d.
Range
f of Samples
6.3 + 2.8
3.5 - 16.7
75
2.4 - 12.3
140
5.0 + 1.6
3.0 - 10.6
45
3.3 + 1.1
1.8 - 7.9
130
3.5 -*- 1.1
1.9 - 7.1
92
4.3 + 1.9
1.8 - 16.7
482
5.0 + 0.6
3.6 - 5.5
10
3.1 - 5.6
13
4.7 -t- 1.0
3.3 - 6.1
5
2.7 + 0.6
2.2 - 3.8
6
2.8 + 0.3
2.5 - 3.2
5
3.9 + 1.1
2.2 - 6.1
39
6.6 + 1.6
4.1 - 9.9
24
3.0 - 6.6
55
4.3 + 1.0
3.0 - 6.1
19
3.0 + 0.7
1.8 - 4.8
56
3.0 + 0.7
1.9 - 4.7
39
4.0 + 1.5
1.8 - 9.9
193
7.8 + 4.1
3.7 - 16.7
23
2.4 - 12.3
41
6.2 + 2.1
3.9 - 10.6
14
4.2 + 1.4
2.5 - 7.9
39
4.4 + 1.2
2.6 - 7.1
27
5.2 + 2.6
2.4 - 16.7
144
4.7 + 1.1
3.5 - 7.7
18
— '
2.5 - 6.4
31
4.4 + 1.0
3.6 - 5.9
7
2.9 + 0.4
2.1 - 4.2
29
3.5 + 0.9
2.6 - 6.2
21
3.7 +_ 1.0
2.1 - 7.7
106
62
-------
SEGMENT
f^O
IB
15
— 14-
\^ i2
\j
10
O> _
* :
4-
01
.0-
.0-
.0-
. 0 -
.0-
.0-
-0-
.0-
.0-
1
1
I
1
1
1
I
T '
T '
I J. ill ' rT1! l"fl I Jl fl
yj 1 m ty QUARTER <1B7S>
SEGMENT 2
U>
1B.0-
1B.0-
L0.0-
B.0-
4--0-
0.0-
|
1 .1
] ill
lit
1
123 4-VR
QUARTER
123 4-VR
QUARTER < 1073)
LEGEND
T
STAl
DEV
STANtVsRD
DEVIATION
SEGMENT S
L8.0-
LB.0-
— 1.4..B-
\ 1E.0-
<-' 10.0-
o> e.Ei-
£ e.0-
•4-.0-
0.0-
1
[
|
1 2
1 ii .jit!
i 3 4-YR 1 2 3 4-YR
QUARTER
SEGMENT 1
SEGMENT 3
18.0-
XS.0-
_ 14-.0-
\^ ia . 0-
*J 10 . 0-
0) 8-0-
E e-0-
4--0-
E..0-
[
'
1 it
1
i J
i
lit
]
1 2 3 4- VR
QUARTER <1S7*
1 a 3 4-VR
QUARTER <1S7S>
_
\
u
0)
E
^'-^j
IB
IB
14-
ia
10
8
6
4-
a
d
.0-
.0-
-0-
.0-
.0-
.0-
.0-
.0-
.0-
1
1
1
J
1
i
' IP;
• i
i
I T T
1 i m
1 __ _ I ] r
r
]
i
i
1 £ 3 4-VR L 2 3 4-YR
QUARTER < 1S74O tiUARTER < 1S7S >
Figure 30. Data summary of filtered organic carbon (mg
-------
tion 50 (segment 4). The 1974-75 mean value of 202.8 mg/£ at station 3 was
closest to the total bay mean of 206.9 mg/£.
Mean values by segment ranged from 85.4 mg/£ (segment 2, 1974) to 262.3
mg/£ (segment 1, 1975). The greatest annual range, 74 mg/£ - 330 mg/£, oc-
curred in segment 4 (1975). In 1974 the mean value of 167.2 mg/£ in segment
1 was closest to the total bay mean of 127.4 mg/£. In 1975 the mean of 189.3
mg/£ in segment 2 was closest to the bay mean of 182.5 mg/£.
Quarterly and annual summaries of all u. tot. solids data compiled for
each segment and the total bay are shown in Table 21 and Figure 31.
Silicate-silicon, filtered reactive (f. reac. SiO^-Si)
The highest mean filtered reactive silicate-silicon level of 3.99 mg
Si02/£ during 1974-75 was recorded at station 54 (river). The lowest of
0.27 mg Si02/£ was at station 60 (segment 2). The 1974-75 mean value of 1.08
mg Si02/£ at station 58 was closest to the total bay mean of 1.06 mg
Mean values by segment ranged from 0.44 mg Si02/£ (segment 3, 1975) to
1.08 mg Si02/£ (segment 4, 1974). The greatest annual range, 0.08 mg Si02/£ -
7.49 mg Si02/£, occurred in segment 1 (1975). In 1974 the mean value of 0.98
mg Si02/£ in segment 5 was closest to the total bay mean of 0.99 mg Si02/£.
In 1975 the mean of 0.54 mg Si02/£ in segment 5 was closest to the bay mean
of 0.55 mg Si02/£.
Quarterly and annual summaries of all f. reac. silicate-silicon data
compiled for each segment and the total bay are shown in Table 22 and Figure
32.
Ammonia-nitrogen, filtered total (f . tot. NH^-N)
The highest mean filtered total ammonia-nitrogen level of 0.354 mg N/£
during 1974-75 was recorded at station 1 (river). The lowest of 0.010 mg
N/£ was at station 60 (segment 2). The 1974-75 mean value of 0.052 mg N/£
at station 15 was closest to the total bay mean of 0.061 mg N/£.
Mean values by segment ranged from 0.014 mg N/£ (segment 4, 1975) to
0.059 mg N/£ (segment 1, 1974). The greatest annual range, 0.001 mg N/£ -
2.14 mg N/£, occurred in segment 1 (1974). In 1974 the mean value of 0.039
mg N/£ in segment 2 was closest to the total bay mean of 0.037 mg N/£. In
1975 the mean of 0.015 mg N/£ in segments 2, 3, 5 was closest to the bay
mean of 0.018 mg N/£.
Quarterly and annual summaries of all f. tot. ammonia-N data compiled
for each segment and the total bay are shown in Table 23 and Figure 33.
Nitrate + nitrite-nitrogen, filtered (f . NOa + N02-N)
The highest mean filtered nitrate + nitrite-N level of 0.816 mg N/£ dur-
ing 1974-75 was recorded at station 55 (river). The lowest of 0.123 mg
64
-------
TABLE 21. DATA SUMMARY OF UNFILTERED TOTAL
SOLIDS (mg/£) PLOTTED IN FIGURE 31
Mean + s.d.
Range
« of Samples
Segment II
Mean + s.d.
Range
$ of Samples
Segment III
Mean + s.d.
Range
t* of Samples
Mean + s.d.
Range
tt of Samples
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s-d.
Range
tt of Samples
Gross
161 .2 + 90.6
80 - 310
8S.4 + 17.4
f.fi - 114
7
L7'j. 0 + 4.2
172 - 178
2
.
_
L27.4 + f7.6
66 - .310
14
Ist(J-M)
_
-
-
_
_
.
_
_
_
_
_
Quar
2nd(A-J)
_
-
"_
_
.
_
_
.
_
_
_
_
_
.
_
_
_er s
3rd(J-A)
.
_
-
-
_
_
.
_
_
_
_
_
_
_
4th (S-D)
.67.2 + 90.6
80 - 310
5
85.4 +• 17.4
66 - 114
7
L75.0 + 4.2
17.' - 178
2
_
_
_
_
_
127.4 + 67.6
66 - 310
14
LD
Mean + s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
d of Samples
Total__Bay
Mean + s.d.
Range
# of Samples
262.3 + 56.
172 - 376
30
189.3 + 29.:
126 - 254
54
193.4 +32.!
120 - 270
25
146.3 + 37.8
74 - 330
49
151.3 + 29.2
104 - 212
36
182. 5 + 53.2
74 - 376
194
-
-
-
-
-
-
-
-
_
_
-
-
-
-
-
-
289.3 + 42.9
220 - 346
11
195,6 + 34.2
126 - 254
25
194.0 -t- 44.3
120 - 270
11
146.8 + 52.2
74 - 330
21
132.8 + 21.9
104 - 172
12
185.0 + 62.0
74 - 346
80
241.5 + 59.3
172 - 376
16
186.2 + 22.4
158 - 242
27
194.5 + 21.5
178 - 244
11
146.9 + 22.8
108 - 182
27
160.6 + 28.3
104 - 212
24
179.0 + 44.1
104 - 376
105
274.0 + 51.0
236 - 332
3
151.0 + 4.2
148 - 154
2
187.3 + 22.5
168 - 212
3
120
120
1
_
_
_
200.7 + 65.5
120 - 332
9
65
-------
SEGMENT 4-
[
]i.|
l
1234-YR 1234-YR
QUARTER <1S7*> QUARTER < 1H73>
SEGMENT 2
a
E
Sffi
123 4-YR 1 2 3 4-YR
QUARTER (1S7*> QUARTER (1S7SJ
o>
E
UEQEND
N
T 1
STANUM5D
DEVIATION
i
_A
ANQC
t.
SEGMENT S
1 2 3 4-YR
QUARTER <1.S7*>
1234- YR
QUARTER <1Q73>
SEGMENT 1
SEGMENT 3
4-CKJ
-
„„.
300-
-
a»-
-
IBB-
_
1
JL
r
r
?
1
[f| r
1
1
J 1
1 2 3 4-YR 1 2 3 4-YR
l»l»l ™
~
300-
X.
CD 200-
E
100-
-
03—1
1
1
1
l
1
- - i [] i ffl [
i
1
i
i
i
i
1234- YR 123 4-YR
QUARTER
-------
TABLE 22. DATA SUMMARY OF FILTERED REACTIVE SILICATE-SILICON
(mg Si02/£), PLOTTED IN FIGURE 32
Mean + s.d.
Range
# of Samples
Segment' 1 1
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
(t of Samples
Mean + s.d.
Range
It of Samples
Total Bay
Mean + s.d.
Range
» of Samples
Yearly
Gross
.88 -h .70
.07 - 3.94
200
1.05 + .65
.05 - 3.69
275
.72 + .39
.05 - 1.87
68
1.08 + .33
.070 - 2.03
256
.98 -t- .42
.040 - 3.17
209
.99 + .55
.05 - 3.94
1,011
Quarters
Ist(J-M)
1.96 +_ 1.74
.30 - 3.94
6
1.38 + .64
.92 - 1.83
2
.54 + .28
.10 - .85
5
1.06 + .06
1.01 - 1.13
5
.89 + .10
.81 - 1.03
4
1.14 + .03
.10 - 3.94
23
2nd(A-J)
.65 + .70
.07 - 3.0
89
.71 i .58
.05 - 3.69
117
.57 ^ .39
.05 - 1.87
26
1.03 + .35
.07 - 1.94
109
.92 + .57
.04 - 3.17
86
.62 + .57
.05 - 3.69
429
3rd(J-a)
.95 ^ .50
.32 - 2.16
69
1.25 + .54
.50 - 3.21
109
.89 -t- .37
.45 - 1.72
26
1.03 + .29
.64 - 1.98
94
1.03 + .30
.52 - 2.10
S3
1.07 -f .44
.32 - 3.21
381
4th(S-D)
1.15 i .51
.24 - 1.94
36
1.44 + .65
.13 - 2.91
47
.73 + .33
.08 - 1.29
11
1.27 + .33
.75 - 2.03
48
.97 + .20
.53 - 1.29
36
1.20 + .50
.08 - 2.91
178
in
Mean + s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range
# of samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
jt of Samples
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
» of Samples
.69 +_ 1.32
.08 - 7.49
73
.47 ;f .41
.08 - 3.67
214
.44 + .39
.08 - 1.68
56
.64 + .55
.08 - 2.29
238
54 ;f .51
08 - 2.24
189
55 t_ .63
08 - 7.49
770
.74 + .44
.09 - 1.33
10
.33 ^ .27
.09 - 1.09
12
.27 ^ .16
.09 - .45
5
1.33 + .25
.89 - 1.55
7
1.16 i .38
.48 - 1.50
6
.73 + .52
.09 - 1.55
40
.49 + .68
.08 - 2.60
23
.44 ^ .30
.08 - 1.43
80
.38 +_ .26
.08 - 1.10
23
1.02 -t- .55
.09 - 2.29
90
.81 ^ .51
.08 - 1.62
72
.70 + .54
.08 - 2.60
288
.99 + 2.00
.08 - 7.49
26
.61 + .55
.08 - 3.67
75
.67 + .51
.16 - 1.68
20
.37 + .36
.08 - 1.56
83
.32 + .36
.08 - 1.50
65
.51 + .79
.08 - 7.49
269
.41 + .85
.08 - 3.33
14
.30 + .26
.08 - 1.05
47
.19 + .18
.08 - .49
8
.34 + .35
.08 - 1.81
58
.34 + .44
.08 - 2.24
46
.33 + .42
.08 - 3.33
173
67
-------
SEGMENT 4-
\ *'""!
« 3.001-
o _
" z. .ta-
li
6 i.»:
-iiif «hl|
^ X • U-l •• • I f I
1 2 ^ 4-VR 1 2 3 4-VR
QUARTER dXJARTER < L07S>
/Vx
f rf. \
/ °"
1 0» N
. r * - /\
A °" / o,. \
SEGMENT 2
00
^ • n^^ —
4.. 80-
\ 3ge-
0* 3'ee>[
" 2.«,-
0)
E 1.20-
01 . 0m -
|
I
ra
1,
)l
, r
]l
i
ii
i
|
j
l!ii[
Hi
i
123 4-VR 123 4-VR
QUARTER < 1B74O QUARTER ( !Sf7S>
LEGEND
\.
T I
STANDARD 1
DEVIATION fwK"=-
i
.4
t.
3 4-VR i 2 3 4-VR
QUARTER < LS74-) QUARTER < 1B7S>
SEGMENT 1
SEGMENT -3
_ ' 4-.BC3-
2
Vt
B
E
1 .20-
l[
1 2
JT
a ii
i 3 4-V
/
! ii
=; i 2
].
3 *-
.[
r
1
3 4-V
a-iop q
4--ee>-
\
«* 3.ao-
0
" 2.«,-
B>
1 .ZCJ-
s|i|l m j j I
ta.taa i T — T t •• i T i- i - r i
R 1 E 3 4-VR 1 S 3 4-VR
QUARTER < 1074-) OlUARTElR <1973J QUARTER aUARTER C187S>
Figure 32. Data summary of filtered reactive silicate-silicon (mg Si02/£).
-------
TABLE 23. DATA SUMMARY OF FILTERED TOTAL AMMONIA-NITROGEN
(mg N/£), PLOTTED IN FIGURE 33
01
Segment 1
Mean + s.d.
Range
ft of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
(t of Samples
Segment^ IV
Mean + s.d.
Range
S of Samples
Mean + s.d.
Range
ft of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
.059 + .157
.001-2.140
208
.039 + .030
.005 - .144
277
.032 + .037
.005 - .239
65
.024 + .016
.005 - .128
254
.026 + .02C
.005 - .135
208
.037 + .076
.001 - 2.14
1?015
Quarters
Ist(J-M)
.409 + .850
.001 - 2.140
6
.076 + .034
.052 - .100
2
.016 + .008
.007 - .029
5
.011 + .004
.007 - .015
5
.012 + .004
.009 - 018
4
.122 + .442
.001 - 2.14
22
2nd(A-J)
.041 + .044
.005 - .150
97
.032 + .027
.005 - .144
120
.023 + .018
.005 - .073
23
.015 + .010
.005 - .061
107
.024 + .026
.005 - .135
85
.028 + .030
.005 - .150
434
3rd (J-A)
.046 + .033
.005 - .144
69
.050 + .034
.008 - .144
108
.047 + .053
.008 - .239
26
.033 + .019
.005 - .128
94
.031 + .016
.005 - .086
83
.041 + .030
.005 - .239
380
4th(S-D)
.078 + .114
.010 - .620
36
.032 + .018
.016 - .127
47
.024 + .006
.016 - .035
11
.028 + .010
.017 - .084
48
.023 +_ .008
.010 - .036
36
.038 + .056
.010 -.620
178
IT)
1^.
CT>
Segment 1
Mean + s.d.
Range
# of Samples
Segment II
Mean + s.d.
Range •
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
H of Samples
.032 + .036
.003 - .153
34
.015 + .015
.003 - .115
79
015 + .011
003 - .041
23
014 + .011
003 - .048
61
015 + .009
006 - .038
56
018 + .020
003 - .153
253
.041 + .027
.011 - .108
10
.040 + .026
.007 - .115
12
.032 + .006
.024 - .041
5
.025 +_ .010
.007 - .036
7
.029 + .005
.025 - .037
6
.037 4- .025
.007 - .115
40
.025 + .033
.007 - .117
10
.014 + .006
.007 - .035
32
.011 + .005
.007 - .021
10
.015 + .012
.007 - .048
28
.011 + .007
.007 - .032
19
.014 + .013
.007 - .117
99
.153
.153
1
.006 + .007
.003 - .023
7
-
-
-
-
-
-
-
.035 + .059
.003 - .153
8
.022 + .029
.003 - .095
13
.008 + .004
.003 - .022
28
.009 + .003
.003 - .012
8
.010 + .006
.003 - .031
26
.016 + .009
.006 - .038
31
012 + .013
003 - .095
106
69
-------
SEGMENT 4-
0. ISjZI-
0.080-
0.04O-
0 . 000-
.ll
T
|1J
1 ii ii
1234- YR 1234- VR
QUARTER (1374-5 QUARTER Cla7S>
SEGMENT 2
w • ufciKJ —
a. ie«a-
^^ 0. 120-
z
0) 0 . 0B0-
0- 04-0-
17) . ddOl -
H
m
1,
.
i
i[
] I
U±±[
i
4-VR 123 4-VR
UUARTE.R < iaT7*> QUARTER < iaT7S>
LEGEND
DEVIATION
SEGMENT S
_~" 0. 120H
z
a 0.C9B0-
E
0-040-
0.000-
[
^U \
, — U
T
liffil
1 T . u
J s £ i 4
123 4-YR 1 2 3 4-YR
QUARTER C19740 QUARTER < 1ST7»>
SEGMENT 1
SEGMENT 3
0 * LOCI —
0. 120-
0.0B0-
0.040-
0.000-
1 [
{
} r
T r
1
I
r
1
]
1234- YR 1^34^ YR
\ 0.120-
01 0.080-
0.040-
0.000-
T
J
i 2 c
ffi
ffl s « J
3 4-YR 1 2 3 4-YR
GIUARTER (1974O QUARTER <19y5> QUARTER C 137* > QUARTER (1973)
Figure 33. Data summary of filtered total ammonia-nitrogen (mg
-------
N/£ was at station 30 (segment 2). The 1974-75 mean value of 0.316 mg N/£ at
station 59 was closest to the total bay mean of 0.312 mg N/£.
Mean values by segment ranged from 0.200 mg N/£ (segment 2, 1975) to
0.498 mg N/£ (segment 3, 1974). The greatest annual range, 0.05 mg N/£ -
4.2 mg N/£, occurred in segment 3 (1974). In 1974 the mean value of 0.277 mg
N/£ in segment 2 was closest to the total bay mean of 0.295 mg N/£. In 1975
the mean of 0.215 mg N/£ in segment 5 was closest to the bay mean of 0.225
mg N/£ .
Quarterly and annual summaries of all f. nitrate + nitrite-N data com-
piled for each segment and the total bay are shown in Table 24 and Figure 34.
Nitrogen, unfiltered Kjeldahl (u. Kjel. N)
The highest mean unfiltered Kjeldahl nitrogen level of 1.293 mg N/£
during 1974-75 was recorded at station 54 (river). The lowest of 0.155 mg
N/£ was at station 50 (segment 4). The 1974-75 mean value of 0.425 mg N/£
at station 15 was closest to the total bay mean of 0.426 mg N/£.
Mean values by segment ranged from 0.201 mg N/£ (segment 4, 1974) to 0.64
mg N/£ (segment 1, 1975). The greatest annual range, 0.22 mg N/£ - 1.97 mg
N/£, occurred in segment 1 (1975). In 1974 the mean value of 0.338 mg N/£ in
segment 2 was closest to the total bay mean of 0.326 mg N/£. In 1975 the mean
of 0.36 mg N/£ in segment 2 was closest to the bay mean of 0.33 mg 'N/£.
Results showing the variation by cruise (at two depths) of u. Kjel.
nitrogen at selected stations are given in Table 25 and Figure 35. Quarterly
and annual summaries of all u. Kjel. N data compiled for each segment and
the total bay are shown in Table 26 and Figure 36.
Twice-weekly u. Kjel. N data from four intake plants (plotted in Figure
37) are compared in Table 27 to regular cruise data for the same sites.
Nitrogen, total (tot. N, computed as u. Kjel. N + f. NOs + N02-N)
The highest mean total nitrogen level of 2.121 mg N/£ during 1974-75 was
recorded at station 54 (river). The lowest of 0.383 mg N/£ was at station 50
(segment 4). The 1974-75 mean value of 0.719 mg N/£ at station 10 was closest
to the total bay mean of 0.706 mg N/£.
Mean values by segment ranged from 0.418 mg N/£ (segment 4, 1975) to
0.968 mg N/£ (segment 1, 1975). The greatest annual range, 0.31 mg N/£ -
2.87 mg N/£, occurred in segment 3 (1975). In 1974 the mean value of 0.474
mg N/£ in segment 5 was closest to the total bay mean of 0.544 mg N/£. In
1975 the mean of 0.574 mg N/£ in segment 2 was closest to the bay mean of
0.557 mg N/£.
Results showing the variation by cruise (at two depths) of total nitrogen
at selected stations are given in Table 28 and Figure 38. Quarterly and an-
71
-------
TABLE 24. DATA SUMMARY OF FILTERED NITRATE + NITRITE-NITROGEN
(rag N/£), PLOTTED IN FIGURE 34
en
Mean + s.d.
Range
# of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean •+ s.d.
Range
# of Samples
Gross
.348 + .437
.050-3.250
208
.277 + .282
.050-1.600
279
.496 + .680
.050-4.199
70
.232 + .070
.060 - .490
261
-249 jf .164
.050-1. 326
198
.295 + .344
.050-4.199
1,019
Ist(J-M)
1.824 -t- 1.239
.282 - 3.250
6
1.105 + .018
1.092 - 1. 117
2
1.331 + 1.617
.340 - 4.199
5
.314 + .068
.259 - .431
5
.321 +_ .037
.295 - .37f,
4
1.168 + 1 .289
JrO - 4.199
Quar
2nd(A~j)
.528 + .301
.174 - 1.600
97
.485 + .296
.050 - 1.600
121
.887 -f .532
.050 - 1.684
28
.288 + .049
.164 - .490
114
.379 4- .195
.074 - 1.326
75
.450 + .301
.050 - 1.684
437
ers
3rd(j-A)
.090 + .045
.050 - .268
69
.110 + .054
.050 - .361
109
.084 + .020
.050 - .116
26
. 186 + .047
.072 - . 298
94
. 170 + .056
.066 - .311
83
.137 + . 064
. OJO - . 361
381
4th (S-D)
0.111 + .083
.050 - .318
36
.094 + .056
.050 - .258
47
.111 + .061
.050 - .244
11
.180 ^ .038
.060 - .-: '^
48
.149 + .050
.050 - -27C
36
. i.jj - .Gt,y
.Ob - .318
178
Lf)
Segment 1
Mean + s.d.
Range
« of Samples
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
.336 + .379
.050 - 1.58;
73
.200 + .163
.050 - .798
214
.299 + .400
.050 - 1.96:
56
.209 + .068
.050 - .678
238
.215 +_ .187
.050 - 2.261
189
.225 + .214
.050 - 2.261
770
.553 + .133
.248 - .740
10
.345 + .116
.195 - .644
12
.827 + .665
.286 - 1.963
5
.287 •*• .018
.263 - .317
7
.619 + .804
.279 - 2.261
6
.485 + .402
.195 - 2.261
40
.503 + .434
.076 - 1.582
23
.332 + .165
.050 - .798
80
.471 + .393
.050 - 1.548
23
.249 + .069
.091 - .678
90
.294 -f .105
.182 - .805
72
.321 + .215
.050 - 1.582
288
.161 -f .265
.050 - .970
26
.097 + .060
.050 - .335
75
.051 + .006
.050 - .075
20
.172 + .053
.050 - .274
83
.140 -*- .070
.050 - .294
65
.135 + .119
.050 - .970
269
.231 + .412
.050 - 1.291
14
.088 + .043
.050 - .184
47
.095 JH .050
.050 - .159
8
.189 + .045
.050 - .295
58
.144 + .073
.050 -__-316
46
.149 + .140
.050 - 1.291
175
72
-------
SEGMENT 4-
0)
E
LEJ3END
1 2 3 4-VR 12 3 4-VR
QUARTER < J.974-) QUARTER ( L87S)
SEGMENT 2
a.eew-
X
Z Z.SMW-
a
E
01 . O*0tM —
_
[
!* * [
} * if -J
123 4-VR i 2 3 4-YR
QUARTER <1S740 QUARTER
s.
T
L~.
DEVIATION f
1
_i
f
ANQE
t.
SEGMENT S
i
- i * * 1
i 2 3 4-VR
QUARTER <1S74O
™ S <£ [
J i i — i — 1
C 2 3 4-V
aUARTER (IS
|
=?
73 >
SEGMENT 3
3.eee-
X
o>
E
1 .£00-
iz.cxziei-
-,
1
1 , [
T
1 I [] I m [
]
1 2 3 4- YR i 2 3 ^ YR
^ . 000 ~
01
E
i . 000-
0.000 J
Dr
L _ ffi I
r
,
i
1
,
\\
J 2 3 4-YR i J
•i 3 4-Y
)
R
QUARTER <1974-> QUARTE.R C197S> QUARTER
Figure 34. Data summary of filtered nitrate + nitrite-nitrogen (mg N/£).
-------
TABLE 25. UNFILTERED KJELDAHL NITROGEN (nig N/£) AT SELECTED
STATIONS, PLOTTED IN FIGURE 35
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean* (Range)
1.290 (0.730-2.350)
1.250 (0.680-2.150)
0.630 (0.190-1.240)
0.540 (0.210-1.300)
0.280 (0.080-0.630)
0.250 (0.090-0.690)
0.620 (0.280-1.030)
0.720 (0.430-1.120)
0.180 (0.080-0.360)
0.150 (0.050-0.410)
0.170 (0.050-0.340)
0.130 (0.060-0.250)
Standard
Deviation
0.460
0.400
0.310
0.280
0.110
0.130
0.260
0.230
0.080
0.080
0.080
0.060
Minimum
Date
74-6-3
74-4-29
74-6-20
74-6-20
75-7-29
75-7-29
75-2-19
75-5-22
75-10-10
75-5-21
75-5-21
74-9-19
Maximum
Date
75-10-27
75-10-27
74-7-27
74-7-27
75-9-3
75-4-30
74-7-26
74-7-26
75-6-26
74-10-7
75-6-6
74-7-26
*Mid-winter data included for 1 m depth only.
-------
STATION
-------
TABLE 26. DATA SUMMARY OF UNFILTERED KJELDAHL NITROGEN
(mg N/£), PLOTTED IN FIGURE 36
Mean + s.d.
Range
# of Samples
Segment' II
Mean + s.d.
Range
0 of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
jf of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
.506 + .308
.120-1.380
110
.338 •* .187
.110-1.800
180
.494 + .199
.140-1.120
47
.201 + .186
.050-2.000
157
.256 + .138
.060 - .750
142
.326 + .233
.050 - 2.00
636
Quarters
1st (J-M)
-
-
-
-
-
-
-
-
-
-
-
-
-
2nd(A-J)
.314 + .114
.160 - .620
32
.259 jf .120
.110 - .790
58
.373 + .145
.140 - .760
16
.142 + .090
.050 - .530
48
.21 -f .11
.07 - .60
48
.238 + .131
.050 - .790
202
3rd(J-A)
.627 -1- .408
.120 - 1.380
42
.387 + .168
.120 - 1.190
75
.592 +- .222
.340 - 1.120
20
.229 + .128
.080 - .640
61
.28 + .15
.06 - .75
58
.318 -1- .262
.060 - 1.380
256
4th(S-D)
.536 + .191
.260 - 1.060
36
.357 + .247
.120 - 1.800
47
.491 + .119
.230 - .650
11
.223 + .285
.070 - 2.00
48
.27 + .14
.10 - .65
36
.347 + .20
.070 - 2.00
178
LO
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# Of Samples
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
(t of Samples
.64 + .30
.22 - 1.97
72
.36 + .14
.06 - .85
214
.53 + .22
.10 - 1.08
54
.21 + .13
.05 - 1.11
240
.24 + .14
.05 - .75
189
.33 + .22
.05 - 1.97
769
.45 -f .13
.22 - .67
10
.29 + .09
.13 - .44
12
.49 + .26
.28 -.87
4
.17 + .05
.13 - .23
7
.16 + .02
.13 - .19
6
.32 + .18
.13 - .87
39
.78 ^ .35
.37 - 1.97
23
.40 + .14
.14 - .82
80
.47 + .20
.10 - .84
22
.22 + .17
.05 - 1.11
90
.24 + .15
.05 - .75
71
.35 + .24
.05 - 1.97
286
.65 + .29
.35 - 1.41
25
.36 + .15
.06 - .85
74
.61 + .25
.26 - 1.08
20
.21 + .10
.06 - .72
85
.25 + .14
.07 - .73
66
.34 + .23
.06 - 1.41
270
.50 + .17
.26 - .90
14
.34 ^ .11
.19 - .71
48
.52 + .16
.28 - .77
8
.19 + .11
.050 - .60C
58
.24 + .13
.09 - .72
46
.29 + .17
.09 - .90
174
76
-------
SEGMENT 4-
i.a00-
L .200-
-
0.000-
-r
m
\\
i
i
i
i .i
i
. Ac
i
1 2 3 4-YR 1 2 3 4-YR
QUARTER <1S74-) GlUARTER (1373)
SEGMENT 2
[
][
1[
][
] §[
y | T
_
][
lit
]
1 £ 3 4-YR 123 4-YR
UUARTELR
LEGEND
V
T
L~,
DEVIATION f
L
^
w*
ANoe
(•
SEGMENT 3
D> 0.
E
1234- VR
QUARTER QUARTER < I.S7S >
e>
E
]f[
i ii
j!
lii
i
1234-YR 1234-YR
QUARTER < 1S74-) QUARTER < 1S73)
Figure 36. Data summary of unfiltered Kjeldahl nitrogen (mg N/&).
-------
TABLE 27. MEAN UNFILTERED KJELDAHL NITROGEN VALUES (mg N/£) FROM CRUISE (SB)
AND INTAKE PLANT (SBI) SAMPLES, PLOTTED IN FIGURE 37
Month
i-H
in
r^
O1
tM
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
Station
Saginaw River
SB 1
—
—
—
0.760
0.750
0.815
0.733
—
—
1.355
—
2.070
—
1.895
1.920
1.390
0.950
0.935
1.548
1.225
0.985
1.843
1.280
—
SBI 1
1.034
0.843
0.636
0.598
0.928
0.815
1.526
1.613
1.420
1.203
1.470
1.433
1.280
1.716
1.204
1.094
1.439
1.508
1.109
0.776
1.184
1.220
1.045
1.241
Kawkawlin
SB 2
—
—
—
0.430
0.300
0.263
0.555
0.380
—
0.470
—
0.320
—
—
0.750
1.120
0.570
0.450
0.720
0.470
0.990
0.490
0.290
0.640
SBI 2
—
—
—
—
—
—
—
—
—
—
—
0.340
0.310
0.155
0.458
0.538
0.765
0.606
0.450
0.398
0.621
0.505
—
—
Pinconning
SB 3
—
—
—
—
—
0.360
0.460
—
—
0.670
—
—
—
0.220
—
0.640
0.560
0.570
0.590
0.460
0.760
0.640
0.260
—
SBI 3
—
—
—
—
—
—
—
—
—
—
—
—
—
0.303
0.417
0.608
0.658
0.714
0.864
0.578
0.797
0.700
—
—
Whitestone Point
SB 4
—
—
—
—
—
0.077
0.278
—
—
0.105
0.130
—
—
—
—
0.150
0.115
0.183
0.235
0.295
0.178
0.235
0.110
—
SBI 4
0.147
0.196
0.187
0.154
0.155
0.213
0.203
0.211
0.210
0.195
—
0.225
0.103
0.133
0.156
0.264
0.143
0.201
0.245
0.166
0.205
0.225
—
—
78
-------
INTAKE STATION
0)
E
0. e»0ia I i i i i i i i i i r i i i i i i i i i i i i .
J'FriAMJ'J'ASON D|T FnAt-lXJ-ASOND
1.974-
INTAKE STATION 3
197S
O)
E 0.000
JTriAMJ'J'ASON DpT FMAnJ
1974- 1975
INTAKE STATION 2
INTAKE STATION 1
. saxa
j. -
z ^.aa
E 0.aee-
J"F"MAM-T.rASON DfJ" F'MADJ'J'ASOND
1O74- 197S
1S74-
Figure 37. Unfiltered Kjeldahl nitrogen (mg N/&) in twice-weekly samples
from water intake plants (equivalent to stations 1, 2, 3, 4).
-------
TABLE 28. TOTAL NITROGEN (mg N/£) AT SELECTED STATIONS,
PLOTTED IN FIGURE 38
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
I
8
I
3
I
10
1
3
I
20
I
28
Mean* (Range)
2.082 (1.340-3.120)
2.048 (1.290-3.040)
0.963 (0.330-2.740)
0.709 (0.340-1.350)
0.477 (0.180-0.730)
0.457 (0.250-1.090)
0.852 (0.370-1.730)
0.924 (0.550-1.900)
0.409 (0.280-0.600)
0.413 (0.280-0.610)
0.390 (0.220-0.600)
0.399 (0.260-0.510)
Standard
Deviation
0.511
0.427
0.630
0.300
0.144
0.179
0.328
0.380
0.080
0.083
0.096
0.060
Minimum
Date
74-06-03
74-04-29
74-06-20
74-06-20
75-07-29
75-07-29
75-02-19
75-05-22
75-10-10
75-05-21
75-05-21
74-09-19
Maximum
Date
75-10-27
75-10-27
74-07-27
74-07-27
75-09-03
75-04-30
74-07-26
74-07-26
75-06-26
75-10-07
75-06-06
74-07-26
00
o
*Mid-winter data included for 1 m depth only.
-------
TAT ION 4-3 SEGMEN
-JFMAMTJ'ASON DjJ~ FMAMJT.TASOND
1374- 1975
STATION 35 SEGMENT 2
00
1974-
STATION 0S SEGMENT 1
1375
STATION SI SEGMENT 5
0.600•
0 . 4-00
0.200-
0. 000
.TFMAM.JJ'ASONDJ'FMAMJ'J'ASOND
1374- 137S
STATION 34- SEGMENT 3
STATION 55
1374-
1375
3.S00'
3.000-
2.500-
2.000-
0.500-
0.000
J~FMAMJJ"ASON D|-T RMAMTJASOND
1374- 1975
0.S00-
0. 000
-JFMAM.TJ'ASOND.JFMAM.T.TASOND
1374- 1375
Figure 38, Total nitrogen (mg N/£) at selected stations (-•-).
-------
nual summaries of all tot. nitrogen data compiled for each segment and the
total bay are shown in Table 29 and Figure 39.
Phosphate-phosphorus, filtered reactive (f. reac. POi^-P)
The highest mean filtered reactive phosphate-phosphorus level of 0.095
mg P/£ during 1974-75 was recorded at station 54 (river). The lowest of
0.002 mg P/£ was at station 60 (segment 2). The 1974-75 mean value of 0.012
mg P/£ at stations 5 and 56 was closest to the total bay mean of 0.013 mg
P/£.
Mean values by segment ranged from 0.002 mg P/£ (segments 2, 3, 4, 5,
1975) to 0.011 mg P/£ (segment 1, 1974). The greatest annual range, 0.001
mg P/£ - 2.1 mg P/£, occurred in segments 1, 3 (1974). In 1974 the mean
value of 0.005 mg P/£ in segment 5 was closest to the total bay mean of
0.006 mg P/£. In 1975 the mean of 0.002 mg P/£ in segments 2, 3, 4, 5 was
identical to the bay mean.
Quarterly and annual summaries of all f. reac. PO^-phosphorus data com-
piled for each segment and the total bay are shown in Table 30 and Figure 40.
Phosphorus, filtered total (f. tot. P)
The highest mean filtered total phosphorus level of 0.131 mg P/£ during
1974-75 was recorded at station 1 (river). The lowest of 0.003 mg P/£ was at
station 45 (segment 4). The 1974-75 mean value of 0.021 mg P/£ at station 59
was identical to the total bay mean.
Mean values by segment ranged from 0.004 mg P/& (segment 4, 1975 and
segment 5, 1974) to 0.014 mg P/£ (segment 1, 1975). The greatest annual
range, 0.002 mg P/£ - 0.125 mg P/£, occurred in segment 1 (1974). In 1974
the mean value of 0.006 mg P/£ in segment 2 was identical to the total bay
mean. In 1975 the mean of 0.007 mg P/£ in segment 2 was identical to the bay
mean.
Quarterly and annual summaries of all f. tot. phosphorus data compiled
for each segment and the total bay are shown in Table 31 and Figure 41.
Phosphorus, unfiltered total (u. tot. P)
The highest mean unfiltered total phosphorus level of 0.267 mg P/£
during 1974-75 was recorded at station 55 (river). The lowest of 0.005 mg
P/£ was at station 51 (segment 5). The 1974-75 mean value of 0.046 mg P/£
at station 11 was closest to the total bay mean of 0.045 mg P/£.
Mean values by segment ranged from 0.008 mg P/£ (segment 4, 1975) to
0.58 mg P/£ (segment 1, 1974 and 1975). The greatest annual range, 0.002
mg P/£ - 0.290 mg P/£, occurred in segment 1 (1974). In 1974 the mean value
of 0.026 mg P/£ in segment 2 was closest to the total bay mean of 0.025 mg
P/£. In 1975 the mean of 0.024 mg P/£ in segment 2 was closest to the bay
mean of 0.020 mg P/£.
82
-------
TABLE 29. DATA SUMMARY OF TOTAL NITROGEN (ing N/£) ,
PLOTTED IN FIGURE 39
01
Segment 1
Mean + s.d.
Range
ft of Samples
Segment II
Mean + s.d.
Range
ft of Samples
Segment III
Mean + s.d.
Range
ft of Samples
Segment IV
Mean + s.d.
Range
tt of Samples
Mean + s.d.
Range
Jf of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Vearly
Gross
.684 + .293
.32 - 1.43
126
.535 + .219
.250- .185
182
.789 + .408
.37 - 2.25
47
.428 + .183
19 - 2.20
156
474 + .142
24 - .94
136
544 + .258
19 - 2.25
647
Quarters
Ist(J-M)
-
-
-
-
-
-
-
-
-
-
-
-
2nd(A-J)
.706 + .273
.370 - 1.420
39
.629 + .254
.320 - 1.39
58
1.051 + .576
.37 - 2.25
16
.444 + .103
.34 - .83
48
.535 + .156
.34 - .94
42
.614 + .299
.320 - 2.25
203
3rd(J-A)
.713 + .352
.32 - 1.43
47
.509 + .146
.300 - 1.29
76
.685 + .210
.440 - 1.170
20
.433 + .106
.28 - .74
60
.469 + .118
.26 - .85
58
.533 + .219
.26 - 1.43
261
4th(S-D)
.629 + .23
.33 - 1.36
40
.462 + .236
.2 0 - 1.85
48
.595 + .111
.410 - .750
11
.405 + .290
.190 - 2.20
48
.410 + .133
.24 - .75
36
.481 + .245
.19 - 2.20
183
IT)
r-*.
Segment 1
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
t of Samples
Total Bay
Mean -f s.d.
Range
# of Samples
.968 + .589
.34 - 2.74
84
.574 + .245
.18 - 1.49
216
.877 + .492
.31 - 2.87
44
.418 4- .138
.20 - 1.31
247
.461 + .224
.18 - 2.48
187
.557 + .343
.18 - 2.87
778
1.035 + .254
.42 - 1.35
11
.628 + .173
.42 - 1.04
13
1.36 + 1.041
.66 - 2-. 87
4
.474 + .046
.43 - .53
7
.795 + .826
.43 - 2.48
6
.807 + .516
.42 - 2.87
41
1.289 + .701
.52 - 2.74
26
.739 + .270
.35 - 1.49
80
1.04 + .477
.40 - 2.03
17
.473 + .169
.24 - 1.31
94
.539 + .211
.35 - 1.53
71
.67 + .396
.24 - 2.74
288
.830 + .508
.40 - 2.67
30
.474 + .174
.180 - 1.01
75
.701 + .258
.31 - 1.13
16
.38 + .104
.20 - .92
87
.395 + .107
.23 - .78
64
.478 + .259
.18 - 2.67
272
.68 + .477
.34 - 2.00
17
.439 + .119
.25 - .81
43
.609 + .164
.38 - .87
7
.378 + .099
.25 - .70
59
.388 + .102
.18 - .77
46
.435 + .20
.18 - 2.00
177
83
-------
SEGMENT 4-
o>
E
-3 • WV>~
2.300-
2.000-
I.S00-
l .000-
0.300-
0. 000-
1
II
1
J .[
r— * 1 — -1
j i i t
p— — 1 I 1
1
1
LEGEND
11111 r i i i i
123 4-YR 123 4-YR
QUARTER <1S7*> QUARTER < IB73>
SEGMENT 2
3.000 -
2. 300 -
\ 2-000 -
1 . 300 -
0)
E L.000-
oo e'-sa*a;
"^** 0. asauzi -
[
T
I i(
][
— i
l
it
liiE
i
1 a 3 4-YR L 2 3 4-YR
QUARTER QUARTER ( IQ73)
s.
-f
I*~
••
DEVIATION RAN°E
1
SEGMENT S
a . 000 -
0) L.30CJ-
E
0.300-
0. 000-
i Ji J
i 5 t
\
123 4-YR 1 a 3 4-YR
QUARTER QUARTER (1873)
SEGMENT 3
3 . 000 -
2.0001
1 . 300 -
1 . 000 -
0 . 300 -
itig
123 4-Y
QUARTER < LS
i f
R 12
f?A- > QUv
1|
3 ^
\RT
ll
3 '
ER
]l
^Y
(IE
^
R
373!
3.000-
E.300-
v^ 2 . 000 -
1.300-
0)
E i . 000 -
0 . 300 -
1 J
QU
J(h [
= 3 4-Y
ARTER <1E
1 1
R
37* >
-
i :
QU
S 3 4-xr
IARTER
-------
TABLE 30. DATA SUMMARY OF FILTERED REACTIVE PHOSPHATE-PHOSPHORUS
(mg P/£), PLOTTED IN FIGURE 40
CTi
Mean + s.d.
Range
fl of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Total Bay^
Mean + s.d.
Range
# of Samples
Yearly
Gross
.011 + .015
.001 - .100
208
.007 + .010
.002 - .099
280
.008 + .017
.001 - .100
67
.004 -1- .002
.001 - .026
257
.005 + .005
001 - .061
209
.006 + .009
001 - .100
1,024
Quarters
Ist(J-M)
.014 +_ .013
.001 - .028
6
.010 + .005
.006 - .013
2
002 + .002
.001 - .005
5
002 + .001
001 - .004
5
002 + .001
001 - .004
4
006 + .009
001 - .028
23
2nd(A-J)
.013 + .018
.002 - .100
97
.007 -f .011
.002 - .077
122
.014 + .027
.002 - .100
25
.004 + .001
.002 - .008
110
.005 -f .007
.002 - .061
86
.007 + .013
.002 - .100
442
3rd(J-A)
.006 + .003
.003 - .015
69
.007 -f .010
.003 - .099
109
.005 + .002
.003 - .011
26
.005 + .003
.003 - .026
94
.004 +_ .002
.003 - .01.3
83
.005 + .003
.003 - .099
381
4th(S-D)
.012 + .017
.002 - .093
36
.004 + .001
.002 - .009
47
.004 + .001
.002 - .005
11
.003 + .001
.003 - .006
48
.004 + 001
.003 - .006
36
.005 + .008
.002 - .093
178
Lf>
r--.
Mean + s.d.
Range
(t of Samples
Mean + s.d.
Range
ft of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
ft of Samples
Segment V
Mean + s.d.
Range
tt of Samples
Total Bay
Mean + s.d.
Range
If of Samples
.005 + .008
.001 - .047
73
.002 + .001
.001 - .009
214
.002 + .001
.001 - .007
56
.002 + .001
.001 - .019
238
.002 + .001
.001 - .010
189
.002 + .003
.001 - .047
770
.003 -f .001
.002 - .007
10
.002 -i- .002
.001 - .009
12
.003 + .002
.001 - .007
5
.002 + .002
.001 - .005
7
.001 + .0005
.001 - .002
6
.002 + .002
.001 - .009
40
.006 + .006
.001 - .022
23
.002 + .001
.001 - .006
80
.002 + .001
.001 - .004
23
.002 +• .001
.001 - .005
90
.002 + .002
.001 - .010
72
.002 + .002
.001 - .022
z!88
.005 -f .011
.001 - .047
26
.002 + .001
.001 - .004
75
.002 + .001
.001 - .003
20
.002 + .002
.001 - .019
83
.001 + . OOO'j
.001 - .004
65
.002 + .004
.001 - .04?
.'69
.002 -f .001
.001 - .003
14
.002 + .001
.001 - .003
47
.002 + .0005
.001 - .002
8
.001 + .0004
.001 - .002
58
i
.001 + .0006
.001 - .003
46
.002 + .001
. •• >1 - . i'U3
. ' i j
85
-------
SEGMENT 4-
k3 . Ik^U? -
0. JZtS(Z>-
0 . 030-
0,0+0-
0.020-
1
i
i
i
i
i
i
i
i
i
II' T T
.iBJidi'fflii-l
i a 3 4-VR
QUARTER
1 2 3 4-YR
QUARTER < 1S7S>
SEGMENT 2
00
0 . J. UM0 -
0. 080-
\ 0.0e0-
O> 0^3-
E
0.020-
^1
i I
QU/
] r
i :
^RT
3 4-V
ER QUARTER t 1O7S)
UEQ6>JD
J\
V
T
3TAI
DEV
I
STANtVKRD
DEVIATION
SEGMENT S
1 £
QU>
] i . [
i 3 4-Y
^RTER (IS
— -1
1
T" \ "T" "^ T
R 123 4-YR
I7*> QUARTER ( IS7S>
SEGMENT
SEGMENT 3
0.080-
^ 0.0B0-
O)
£ CJ-O-MZl-
0 .020-
I
i z
jl
=! 3 H
I
JYJ
1 4[
i ill
]T[
4 HYU
3
R
QUARTER WUARTER <1ET7S>
Figure 40. Data summary of filtered reactive phosphate-phosphorus (mg P/£)
-------
TABLE 31. DATA SUMMARY OF FILTERED TOTAL PHOSPHORUS
(mg P/&), PLOTTED IN FIGURE 41
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
S of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
.012 + .016
.002 - .125
115
.006 + .003
.002 - .018
183
.007 + .005
.002 - .033
54
.005 + .009
.002 - .072
159
.004 + .003
.002 - .035
145
.006 + .009
002 - .125
656
Quarters
Ist(J-M)
.002 + 0
.002
4
.006 + .006
.002 - .010
2
.002 + 0
.002
5
.037 + .039
.002 - .072
4
.002 + .0006
.002 - .003
3
.010 + .022
002 -.072
18
2nd(A-J)
.016 -1- .018
.002 - .070
33
.005 + .002
.002 - .010
60
.007 + .003
.003 - .016
18
.003 ± .002
.002 - .018
47
.005 + .005
.002 - .035
48
.006 + .009
.002 - .070
206
3rd(J-A)
.008 + .006
.002 - .037
42
.006 + .003
.002 - .018
74
.008 + .006
.004 - .033
20
.005 + .006
.002 - .044
60
.004 + .002
.002 - .013
58
.006 + .005
4th(S-D)
.016 + .022
.002 - .125
36
.006 + .003
.003 - .015
47
.007 + .003
.004 - .013
11
.004 + .002
.002 - .009
48
.005 + .003
.003 - .014
36
.007 4- .011
.002 - .044 .002 - .125
254 | 178
un
r~-
CTl
Segment 1
Mean + s.d.
Range
ft of Samples
Segment II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
.014 + .014
.002 - .083
73
.007 + .005
.002 - .048
215
.006 + .003
.002 - .016
55
.004 + .004
.002 - .044
239
.005 + .003
.002 - .034
190
.007 + .004
.002 - .083
772
.007 + .003
.002 - .011
10
.004 + .003
.002 - .012
12
.005 + .003
.002 - .009
4
.003 + .002
.002 - .006
7
.003 + .001
.002 - .004
6
.004 + .003
.002 - .012
39
.016 + .010
.003 - .048
23
.007 + .006
.002 - .048
80
.006 + .003
.002 - .011
23
.004 + .003
.002 - .032
90
.005 + .003
.002 - .032
72
.006 + .004
.002 - .048
288
.CIS -v .019
.004 - .083
26
.006 + .004
.002 - .021
75
.006 + .003
.002 - .012
20
.005 + .005
.002 - .044
84
.004 + .002
.002 - .012
66
.006 + .008
.002 - .083
271
.010 + .011
.002 - .045
14
r
.008 + .006
.002 - .022
48
.009 •*• .004
.005 - .016
8
.004 + .003
.002 - .016
58
.006 + .006
.002 - .034
46
.006 + .006
.002 - .045
174
87
-------
SEGMENT 4-
Ifer • -blfc'l*-' —
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\0.Ejee-
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QUARTER (19"74-> QUARTER C19VS>
LEGEND
SEGMENT
00
00
4-YR
QUARTER
123 4- YR
QUARTER ( ie7S
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DEV
1
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DEVIATION
SEGMENT S
1234-VR 1S34-VR
QUARTER C137t> QUARTER <19T5
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QUARTER ( 137^-) QUARTER ( L973J
123 4- YR 1234-^
QUARTER < 1374-> QUARTER C ]
Figure 41. Data summary of filtered total phosphorus (mg P/£).
-------
Results showing the variation by cruise (at two depths) of u. tot. phos-
phorus at selected stations are given in Table 32 and Figure 42. Quarterly
and annual summaries of all u. tot. P data compiled for each segment and the
total bay are shown in Table 33 and Figure 43.
Twice-weekly u. tot. P data from four intake plants (plotted in Figure
44) are compared in Table 34 to regular cruise data for the same sites.
Sodium, unfiltered (u. Na)
The highest mean unfiltered sodium level of 46.64 mg Na/£ during 1974-
75 was recorded at station 55 (river). The lowest of 3.20 mg Na/£ was at
station 50 (segment 4). The 1974-75 mean value of 9.00 mg Na/£ at station
20 and 29 was closest to the total bay mean of 9.74 mg Na/£.
Mean values by segment ranged from 3.6 mg Na/£ (segment 4, 1974) to
11.7 mg Na/£ (segment 1, 1974). The greatest annual range, 5,0 mg Na/£ -
50.0 mg Na/£, occurred in segment 1 (1974), In 1974 the mean value of 7.9
mg Na/£ in segment 2 was closest to the total bay of 7.0 mg Na/£.
Quarterly and annual summaries of all u. sodium data compiled for each
segment and the total bay are shown in Table 35 and Figure 45.
Potassium, unfiltered (u, K)
The highest mean unfiltered potassium level of 4.32 mg K/£ during 1974-
75 was recorded at station 55 (river). The lowest of 0.87 mg K/£ was at sta-
tion 51 (segment 5). The 1974-75 mean value of 1.60 mg K/£ at station 20
was closest to the total bay mean of 1.58 mg K/£.
Mean values by segment ranged from 0.9 mg K/£ (segment 4, 1974) to 1.9
mg K/£ (segments 1 and 3, 1974). The greatest annual range, 1.1. mg K/£ -
5.6 mg K/£, occurred in segment 1 (1974). In 1974 the mean value of 1.5 mg
K/£ in segment 2 was closest to the total bay mean of 1.4 mg K/£.
Quarterly and annual summaries of all u. potassium data compiled for
each segment and the total bay are shown in Table 36 and Figure 46.
Calcium, unfiltered (u. Ca)
The highest mean unfiltered calcium level of 89.86 mg Ca/£ during 1974-
75 was recorded at station 55 (river). The lowest of 27.9 mg Ca/£ was at
station 51 (segment 5). The 1974-75 mean value of 40.92 mg Ca/£ at station
2 was closest to the total bay mean of 40.89 mg Ca/£.
Mean values by segment ranged from 29.8 mg Ca/£ (segment 4, 1974) to
46.3 mg Ca/£ (segment 1, 1974). The greatest annual range, 28.0 mg Ca/£ -
104.0 mg Ca/£, occurred in segment 1 (1974). In 1974 the mean value of 40.5
mg Ca/£ in segment 2 was closest to the total bay mean of 37.0 mg Ca/£.
89
-------
TABLE 32. UNFILTERED TOTAL PHOSPHORUS (rag P/£) AT SELECTED STATIONS,
PLOTTED IN FIGURE 42
Station
Number
55
8
35
34
49
51
Location
River
Segment I
Segment II
Segment III
Segment IV
Segment V
Depth
In Meters
1
8
1
3
1
10
1
3
1
20
1
28
Mean* (Range)
0.251 (0.185-0.341)
0.283 (0.121-0.665)
0.060 (0.017-0.110)
0.044 (0.006-0.078)
0.014 (0.002-0.059)
0.013 (0.004-0.032)
0.034 (0.008-0.048)
0.037 (0.026-0.052)
0.005 (0.002-0.017)
0.008 (0.002-0.089)
0.006 (0.002-0.048)
0.004 (0.003-0.008)
Standard
Deviation
0.050
0.111
0.030
0.021
0.011
0.008
0.013
0.009
0.003
0.019
0.009
0.002
Minimum
Date
75-11-16
75-4-11
75-7-31
75-10-11
75-9-23
74-7-8
75-2-19
75-5-22
74-12-18
74-4-20
75-7-30
74-8-14
Maximum
Date
75-4-11
75-7-29
75-12-16
74-12-17
75-9-3
75-9-3
75-8-20
75-6-8
75-6-26
74-10-7
74-2-20
75-8-19
VD
O
*Mid-winter data included for 1 m depth only.
-------
STATION -4-a
0- 100 -
\ 0.075
a
a
£ 0.050
0.0as
1374-
STATION 06 (SEGMENT 1>
0"FM AM J" J" A
1974-
STATION 3-*- fSE.GME.NT 3 >
0 . 125-
0. 100-
~\ 0 . 075 —
o.
D)
£ 0.050^
0 . 025 -
/H /[
\\ fv/A/j
'•'<
J'F'MAMJ'J'ASONDJ'Fr-lAr^J"
1374- 13
- > n.TU
^ \
i 1 ^
ii\|
y ^
III!
J" ASO N E
7S
0.BCKZI-
0.S00-
a. 0. 4^0-
E 0.300-
0.200'
0. 100-
0.000-
STATION SS
.^r^^
IT i'T' i i i i i i i i
1974-
----fc» |->CT*B»
h
l'i
1 '
1 i
,\ 1 i
Cr^V\
s. ^/
j-p"r-l>\MJ"J'ASOND
1375
0. 100-
\ 0.075-
(L
E 0.050-
0 • 000 —
• i ntTtn
i i i i t i — i i i i "i — FT • i T r • i i i i r i "i—
1974- 1975
Figure 42. Unfiltered total phosphorus (mg P/&) at selected stations (-•-)•
-------
TABLE 33. DATA SUMMARY OF UNFILTERED TOTAL PHOSPHORUS
(mg P/£), PLOTTED IN FIGURE 43
Mean + s.d.
Range
ft of Samples
Segment' 1 1
Mean + s.d.
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Yearly
Gross
.058 + .039
.002 - .290
109
.026 + .013
.003 - .069
180
.037 + .015
.011 - .081
47
.009 + .010
.002 - .089
157
.013 + .016
.002 - .Q48
142
.025 + .027
.002 - .290
635
Quarters
Ist(J-M)
-
-
-
-
-
-
_
-
-
-
.
_
-
2nd(A-J)
.071 + .052
.002 - .290
32
.024 + .013
.003 - .057
58
.046 + .018
.021 - .081
16
.008 + .009
.002 - .042
48
.016 + .013
.002 - .048
48
.028 + .033
.002 - .290
202
3rd(J-A)
.054 + , 028
.013 - .118
42
.027 + .014
.004 - .069
75
.030 + .010
.012 - .050
20
.007 + .008
.002 - .050
61
.009 + .007
.002 - .031
58
.023 + .022
.002 - .118
256
4th(S-D)
.050 + ,034
.004 - .160
35
.026 + .012
.007 - .069
47
.038 + .013
.011 - .059
11
.010 + .013
.002 - .089
48
.011 + .009
.003 - .038
36
.024 + .024
.002 - .160
177
Segment 1
Mean + s.d.
Range
« of Samples
Segment II
Mean + s.d.
Range •
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Mean + s.d.
# of Samples
Total Bay
Mean + s.d.
Range
ft of Samples
.058 + .029
.006 - .160
72
.024 + .014
.002 - .077
214
.032 + .013
.005 - .055
54
.008 + .008
.002 - .050
237
.011 + .009
.002 - .071
190
.020 + .021
.002 - .160
767
.040 + .013
.008 - .056
10
.015 + .012
.002 - .043
12
.024 + .014
.008 - .038
4
.004 + .002
.002 - .008
7
.004 + .002
.002 - .007
6
.019 + .018
.002 - .056
39
.069 + .025
.034 - .140
23
.026 + .015
.007 - .077
80
.028 + .013
.005 - .052
22
.008 + .007
.002 - .050
87
.009 + .007
.002 - .032
72
.020 + .021
.002 - .140
284
.060 + .035
.017 - .160
25
.023 + .013
.002 - .062
74
.034 + .011
.014 - .048
20
.009 + .008
.002 - .040
85
.012 + .011
.002 - .071
66
.02.1 + .022
.002 - .160
272
.047 + .023
.006 - .110
14
.026 + .010
.006 - .043
48
.041 + .009
.028 - .055
8
.008 + .007
.002 - .033
58
.012 + .009
.003 - .040
46
.020 + .017
.002 - .110
174
92
-------
SEGMENT 4.
0.e*0
0. LB0
9 0.120
E
T T I1 $ V
i2 3 iYR 1 2 3 4-YR
QUARTER <1974-> QUARTER < 1S73>
SEGMENT 2
0.
n
E
1234-YR 1234. YR
QUARTER <1S74O QUARTER C1B73)
LEGEND
DEVIATION
SEGMENT
1 2 3 4-YR 1 2 3 4-YR
QUARTER <1874-> QUARTER < 1S73)
SEGMENT 1
SEGMENT 3
0.2*0-
0. 1B0-
0. 120-
1 2
,
III
; 3 •<
][
t-Y
T
1 ,1;
l{i
]
=5 1 2 3 4-YR
QUARTER QUARTER <1B73>
1 1
1234-YR 123 4-YR
QUARTER <1S74.) QUARTER (1B7S>
Figure 43. Data summary of unfiltered total phosphorus (mg P/£).
-------
TABLE 34. MEAN DNFILTERED TOTAL PHOSPHORUS VALUES (mg/X.) FROM CRUISE (SB)
AND INTAKE PLANT (SBI) SAMPLES, PLOTTED IN FIGURE 44
Month
~a-
r^
CT\
rH
in
r-
O">
rH
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
Station
Saginaw River
SB 1
—
—
—
0.244
0.233
0.222
0.205
—
—
0.220
—
0.294
—
0.274
0.240
0.204
0.213
0.230
0.271
0.213
0.179
0.271
0.240
—
SBI 1
0.226
0.159
0.131
0.171
0.184
0.227
0.214
0.234
0.243
0.186
0.215
0.242
0.220
0.250
0.198
0.183
0.164
0.176
0.149
0.096
0.165
0.178
0.184
0.180
Kawkawlin
SB 2
—
—
—
0.040
0.040
0.032
0.047
0.037
—
0.042
—
0.026
—
—
0.065
0.094
0.056
0.039
0.046
0.039
0.100
0.042
0.036
0.071
SBI 2
—
—
—
—
—
—
—
—
—
—
—
0.023
0.014
0.013
0.049
0.078
0.074
0.047
0.040
0.031
0.046
0.041
—
—
Pinconning
SB 3
—
—
—
—
—
0.037
0.039
—
—
0.043
—
—
0.008
—
0.026
0.046
0.036
0.028
0.031
0.057
0.059
0.020
—
SBI 3
—
—
—
—
—
—
—
—
—
—
—
—
0.013
0.026
0.045
0.036
0.043
0.046
0.050
0.053
0.044
—
—
Whitestone Point
SB 4
—
—
—
—
—
0.028
0.007
—
—
0.004
0.007
—
—
—
0.006
0.003
0.007
0.007
0.010
0.010
0.005
0.004
—
SBI 4
0.004
0.006
0.008
0.006
0.003
0.004
0.008
0.011
0.008
0.008
—
0.006
0.004
0.004
0.006
0.011
0.006
0.008
0.009
0.008
0.005
0.004
—
—
94
-------
INTAKE STATION
0.
a
0.Z30
0.200-
. 1S0-
0.0se>-
I iliTi l i i I i I i i i i i i I i I I i
T r M A M J" J" A S O N D|J F M A M -T J" A 3 O N D
1374-
INTAKE STATION 3
lays
. S30
01
£
0.Z00-
0. 1.30-
. L00-
VO
i i i i i i i l
1974-
M I I I I I
1S7S
INTAKE STATION
INTAKE STATION 1
as. 130-
£21. 100-
co . e>30-
/
•J
.TF"MAMJ"XASQN DjJ" F'MAMJ'J'ASDND
1974- 197S
tzi.aazi -
^^ 0.130-
a
O)
g 0 . 100 ~
0.0S0 ~
\ f^V\
V ^
1974- 197S
Figure 44. Unfiltered total phosphorus (mg P/£) in twice-weekly samples
from water intake plants (equivalent to stations 1, 2, 3, 4).
-------
TABLE 35. DATA SUMMARY OF UNFILTERED SODIUM (rag Na/£),
PLOTTED IN FIGURE 45
•=*•
r—
Segment 1
Range
# of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
» of Samples
Segment V
Range
ft of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Gross
5.0 - 50.0
134
7.9 + 2.0
5.0 - 13.0
43
11.0 + 2.7
7.0 - 18.0
37
3.6 + 1.1
3.0 - 11.0
163
3.0 - 10.0
87
7.0 + 5.5
3-50
464
Ist(J-M)
6.0 - 1' .0
4
9.0 + o
9.0
2
10.3 ^ 3.2
8.0 - 14.0
3
4.8 + 1.7
3.0 - 7.0
4
4.0 - 5.0
4
7.2 + 3.2
3-14
17
Quar
2nd(A-J)
6.0 - 50.0
64
9.0 + 1.6
6.0 - 13.0
18
12.1 -f 3.5
7.0 - 18.0
15
3.8 + 1.4
3.0 - 11.0
76
4.5 + 2.1
3.0 - 10.0
32
7.7 ^ 6.2
3-50
205
ers
3rd(J-fl)
5.0 - 20.0
46
6.8 ^ 2.0
5.0 - 11.0
18
10.5 + 1.3
8.0 - 13.0
14
3.5 +_ .6
3.0 - 5.0
55
4.0 + 1.4
3.0 - 8.0
35
6.5 t_ 4.0
3-20
168
4th (S-D)
12.4 + 1.0.4
5.0 - 45.0
20
7.2 + 1.6
6.0 - 9.0
5
9.6 + 2.1
7.0 - 12.0
5
3.2 ^ .4
3.0 - 4.0
28
4.1 <- 1.3
3.0 - 7.0
16
6.6 * 6.7
3-45
74
96
-------
SEGMENT 4-
0 30 . 2J-
z
1 £ 3 4- VR 1234- YR
QUARTER < 1374-) QUARTER
SEGMENT 2
D 30.0-
z
VO
123 4-VR 123 4-VR
QUARTER (1374.) QUARTER
LEGEND
Si
*•
T
STANDARD
DEVIATION F
1
j
i-
ANQE
u
SEGMENT S
- j 4 a j:
1 2 3 4-YR L 2 3 4-YR
QUARTER QUARTER <1.S73>
SEGMENT
SEGMENT 3
\4-i0 . EJ
o
Z 30 • 0 H
0)
C E0 . 0 -
10.0-
0. 0-
f
L
ii
II
1 r
J
1
J
i 1 1 1 ' ! 1 — | 1 1 '
1 £ 3 4- VR 1 S 3 4- YR
QUARTER
4-0.0-
O 30 . 13 -
0) £0 . 0 -
E
10. 0-
0.0-
rn 1
I Ij] $ Q] ffi
1234- YR 1234- YR
QUARTER QUARTER <1S7S>
Figure 45. Data summary of unfiltered sodium (mg Na/£).
-------
TABLE 36. DATA SUMMARY OF UNFILTERED POTASSIUM (mg K/£),
PLOTTED IN FIGURE 46
cr>
Mean + s.d.
Range
# of Samples
Segment' II
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean +• s.d.
Range
# of Samples
Total Bay
Mean + s.d.
Range
tt of Samples
Yearly
Gross
1.9 + 0.7
1.1 - 5.6
134
1.5 + .3
.9 - 2.2
43
1.9 + .5
1.2 - 3.1
37
.9 + .1
.7 - 1.7
163
1.0 -f .2
.7 - 1.6
87
1.4 + .6
.7 - 5.6
464
Quarters
Ist(J-M)
2.2 + .5
1.6 - 2.7
4
1.9 ^ .4
1.6 - 2.2
2
1.8 + .4
1.4 - 2.2
3
1.1 + .1
1.0 - 1.2
4
1.0 + 0
1.0
4
1.5 + .6
1.0 - 2.7
17
2nd(A-J)
2.1 + .9
1.2 - 5.6
64
1.7 +_ .3
1.2 - 2.2
18
2.2 + .6
1.2 - 3.1
15
.9 + .2
.7 - 1.7
76
1.1 + .3
.7 - 1.6
32
1.5 + .8
.7 - 5.6
205
3rd{J-A)
1.7 + .3
1.2 - 2.3
46
1.3 + .2
.9 - 1.8
18
1.8 + .2
1.2 - 2.1
14
.9 +_ .1
.7 - 1.4
55
1.0 + .2
.8 - 1.4
35
1.3 + .4
.7 - 2.3
168
4th (S-D)
'
!.&-*- .a
i. 1 - 4.0
20
1.3 •*- .1
1.2 - 1.4
5
1.5 + .2
1.3 - 1.7
5
.9 + .1
.8 - 1.2
28
.9 + .1
.8 - 1.2
16
1.2 + .6
.8 - 4.0
74
98
-------
SEGMENT 4-
7.0-
e-0-
_ s.0-
^ 4-.Bl-
lP 3.0-
J 4 J
1 2 3 4-YR
QUARTER < 1.S74-
QUARTER ( 1S7S)
SEGME.NT 2
_ s.0-
O) 3.0-
E ,.0H
VO
VD
123 4-YR
QUARTER < laT74->
123 4-YR
QUARTER ( L87S)
LEGEND
S.0-
4..B-
DEVIATION
SEGMENT S
4
1 2 3 4-YR
QUARTER <1S7«O
1 2 3 4-YR
QUARTER <1S73>
SEGMENT
SEGMENT 3
B.0-
— 3.0-
\
^ 4-.0-
O) 3.0-
E «...
1 .0-
0.0-
1
ij
1
1
L 2. 3 4-VR L H 3 4-VR
QUARTER QUARTER <1S7S)
7 .0-
e.et-
S.0-
\
^ ..0-
L .0-
0.0-
ml? ml
i. H 3 4-YR 1 S 3 4-VR
QUARTER QUARTER
Figure 46. Data summary of unfiltered potassium (mg K/£).
-------
Quarterly and annual summaries of all u. calcium data compiled for each
segment and the total bay are shown in Table 37 and Figure 47.
Magnesium, unfiltered
The highest mean unfiltered magnesium level of 21.27 mg Mg/£ during
1974-75 was recorded at station 55 (river). The lowest level of 7.00 mg
Mg/£ was at station 47 (segment 4). The 1974-75 mean value of 9.90 mg Mg/£
at station 16 was closest to the total bay mean of 9.95 mg Mg/£.
Mean values by segment ranged from 7.4 mg Mg/£ (segment 4, 1974) to 12.1
mg Mg/£ (segment 3, 1974). The greatest annual range, 8.0 mg Mg/£ - 35.0 mg
Mg/£, occurred in segment 3 (1974). In 1974 the mean value of 9.6 mg Mg/£
in segment 2 was closest to the total bay mean of 9.1 mg Mg/£.
Quarterly and annual summaries of all u, magnesium data compiled for each
segment and the total bay are shown in Table 38 and Figure 48.
PARAMETER CORRELATIONS
The following show some results of correlation and multiple regression
analyses of the data. As a first step, matrices of correlation coefficients
were generated using all combinations of parameter pairs. This was done for
all the data groupings described earlier as well as for the total aggregate
of data. One example is shown in Table 39. In this matrix the only coeffi-
cients shown are those significant at the 99% level, all representing a high
degree of correlation.
Selected results of the correlation analysis are also shown in Figures
49-53, in which the variations of Zr/Sz for chlorophyll a vs. other key
parameters are plotted against time in each bay segment. In this format the
time and place of significant correlations are readily apparent.
Multiple regression analysis was also used to examine the "dependence"
of chlorophyll a levels on phosphorus and nitrogen species, as shown in
Tables 40 and 41. Table 42 shows how these relationships varied in each of
the bay segments during 1974 and 1975.
Cooperative Studies
Remote Sensing —
These results also have been used to support a study conducted by Bendix
Aerospace Systems Division in Ann Arbor, Michigan. The project, entitled
"Application of Landsat to the Surveillance and Control of Lake Eutrophica-
tion in the Great Lakes Basin", was supported by Contract NAS 5-20942 from
the National Aeronautics and Space Administration (NASA). The objectives of
that part of the study related to Saginaw Bay were to use satellite multi-
spectral data to estimate levels of various water quality factors and to map
their distribution throughout the bay. Thus, Landsat surveillance was in-
100
-------
TABLE 37. DATA SUMMARY OF UNFILTERED CALCIUM (rag Ca/£),
PLOTTED IN FIGURE 47
en
Segment . ±
Mean + s.d.
Range
# of Samples
Segment' II
Range
# of Samples
Segment III
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Range
# of Samples
Total Bay
Mean + s.d.
Range
# of Samples
Gross
46.3 + 13.3
28.0-104.0
134
30.0 - 58.0
43
46.2 + 10.4
33.0 - 72.0
37
29.8 + 3.7
24.0 - 46.0
163
25.0 - 43.0
87
37.0 +_ 11.5
24 - 104
464
1st (J-M)
54.8 + 10.7
44.0 - 69.0
4
47.0 - 48.0
2
56.7 + 12.1
44.0 - 68.0
3
36.3 +_ 6.1
32.0 - 45.0
4
34.0 - 38.0
4
45.3 +_ 11.8
32 - 69
17
Quar
2nd(A-J)
53.2 + 14.4
35.0 - 104.0
64
38.0 - 58.0
18
54.2 + 8.5
36.0 - 72.0
15
31.3 + 3.7
26.0 - 46.0
76
26.0 - 43.0
32
41.3 +_ 13.7
26 - 104
2Q5
_ers
3rd fj-/0
38.8 + 4.4
31.0 - 53.0
46
30.0 - 48.0
18
38.6 + 2.8
33.0 - 42.0
14
28.9 ^ 2.5
24.0 - 36.0
55
25.0 - 40.0
35
33.3 + 5.8
24 - 53
168
4th (S-D)
39.7 + 11.3
28.0 - 69.0
20
32.0 - 35.0
5
37.4 + 1.1
36.0 - 39.0
5
26.3 + 1.0
25.0 - 29.0
28
27.4 + 2.0
26.0 - 32.0
16
31.4 + 8.4
25 - 69
74
101
-------
SEGMENT 4-
0> 40.0-
E
1234-YR 1234-YR
QUARTER <1S7*> QUARTER
SEGMENT 2
a 4«.
E
O
to
123 4-YR 123 4-YR
QUARTER 9UARTER <1S7S)
LEGEND
'N
STAl
36V
1
STANtVKRD
DEVIATION
SEGMENT S
s
i 2 3 4-YR [ 2 i 4-Y'R
QUARTER <1874O QUARTER <1Q7S)
SEGMENT 3
a
u
.SB-
.0)-
.0-
II
111!
]
•0.0-
u
a 40.0-
E
20.0-
01 . I
1
1234- YR 1234- YR 1234- YR 1234- YR
QUARTER QUARTER C1B7S) QUARTER < 1S74-) QUARTER < IS7S)
Figure 47. Data summary of unfiltered calcium (mg Ca/£).
-------
TABLE 38. DATA SUMMARY OF UNFILTERED MAGNESIUM (mg Mg/£),
PLOTTED IN FIGURE 48
Segment 1
Mean +; s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Mean + s.d.
Range
# of Samples
Segment IV
Mean + s.d.
Range
# of Samples
Segment V
Mean + s.d.
Range
fr of Samples
Total Bay
Mean + s.d.
Range
H of Samples
Yearly
Gross
11,0 + 2,5
6.0 - 20,0
134
9.6 + 1.1
8,0 - 13.0
43
8.0 - 35.0
37
7.4 + .9
6.0 - 14.0
163
7.7 +• .9
6.0 - 10.0
87
9.1 + 2.6
6-35
464.
Quarters
Ist(J-M)
11.5 + 1.7
10.0 - 13,0
4
9.5 + .7
9.0 - 10.0
2
9.0 - 14.0
3
7.0 + 1.4
6.0 - 9.0
4
8.0 + 0
8.0
4
9.4 +_ 2.4
6-14
17
2nd(A-J)
11.7 +_ 2.8
6.0 - 20.0
64
10.3 + 1.3
9.0 - 13.0
18
8.0 - 16.0
15
7.4 + .8
6.0 - 11.0
76
7.9 + 1.1
6.0 - 10.0
32
9.5 + 2.8
6-20
205
3rdfJ-A)
10.3 + 1.4
8.0 - 14.0
46
9.1 + .7
8.0 - 10.0
18
9.0 - 12.0
14
7.5 +_ .5
7.0 -9.0
55
7.8 + .9
7.0 - 10.0
35
8.8 + 1.6
7-14
168
4th (S-D)
10.1 -f 2.6
8.0 - 16.0
20
8.6 + .5
8.0 - 9.0
5
14.8 + 11.3
9.0 - 35.0
5
7.2 + 1.3
6.0 - 14.0
28
7.4 + .7
7.0 - 9.0
16
8.6 + 3.7
6-35
74
103
-------
SEGMENT 4-
01 e0.0-
13.0-
O)
£ 10.0-
3.0-
0.121
123 4-YR 1 23 4-YR
QUARTER <1ST740 QUARTER 11B73)
SEGMENT 2.
ffl
1234- YR
QUARTER
1234- YR
QUARTER
LEGEND
MEAN
v
•»
T
STANTVKRD
DEVIATION F
1
_i
I-
ANQE
SEGMENT S
4 4 [J
1 2 3 4-YR
QUARTER <1S7*>
~T 1 1 1 1
1 2 3 4-YR
QUARTER ( 1SF73>
SEGMENT
SEGMENT 3
33.0-
30.0 J
— 23.0-1
0) 20.0-
13.0-
01
£ 10.0-
3.0-
• dull
1234- YR 123 4-YR
QUARTER <187-4-> QUARTER (1373)
30.0-
^ 23.0-
01 2B.0-
13.0-
m
£ ' 10.0-
S.0-
0 0 —
fflf t
i a 3 ^
QUARTER
[
I- V
< IE
1
R 1 a 3 4-VR
r74-> QUARTER < 1.073)
Figure 48. Data summary of unfiltered magnesium (mg Mg/£).
-------
TABLE 39. CORRELATION COEFFICIENTS FOR SELECTED PARAMETERS.
DATA FROM TOTAL BAY, YEAR 1974
o
Temperature
Dissolved Oxygen
Secchi Depth
PH
Tot. Alkalinity
Sp. Conductivity
F. Chloride
Nf. Chlorophyll a
U. Sodium
U. Potassium
U, Magnesium
U. Calcium
F, Tot. Ammonia
F. Reac. Phosphorus
F. Reac. Silicates
F. NO +NO Nitrogen
F. Tot. Phosphorus
U. Kjel. Nitrogen
U. Tot. Phosphorus
1.0000
-.6356
(725)
.0957
(964)
.1262
(969)
.2572
(793)
.2191
(476)
.1854
(476)
.2141
(476)
.1887
(888)
-. 3661
(758)
.3100
(622)
.1659
(575)
1.0000
.1624
-.2131
(668)
-.2019
(690)
-.2015
(629)
-.3737
(334)
-.3785
(334)
-.3612
(334)
-.3055
(334)
-.2921
(616)
- 1524
(453)
.2279
(561)
-.1536
(409)
-.2084
(382)
1.0000
.5973 1.0000
(450)
.5005 .4651
(468) (825)
-.3309
(506)
-.3541
(512)
-.4174
(439)
-.4576 .1424
(229) (424)
-.4943 .1369
(229) (424)
-.4744 .2009
(229) (424)
-.4606 .1444
(229) (424)
-.1682
(374)
-.3199
(323)
-.3392
(308)
1.0000
.3081
(872)
.2626
(860)
.1767
(682)
.3689
(425)
.4147
(425)
.3656
(425)
.4052
(425)
.1387
(587)
.1690
(658)
.2094
(465)
1.0000
.7889
(945)
.5764
(760)
.9091
(473)
.9172
(473)
.7919
(473)
.8896
(473)
.1851
(871)
.3848
(647)
-.1860
(951)
.4703
(735)
.4037
(456)
.4425
(610)
.6359
(564)
1.0000
.6483
(780)
.9279
(486)
.8811
(486)
.7565
(486)
.7932
(486)
.1911
(887)
.3600
(647)
.2340
(954)
.3206
(744)
.4729
(460)
.4998
(616)
.6507
(571)
1.0000
.6658
(379)
.6484
(379)
.6817
(379)
.5192
(379)
-.1345
(763)
.3245
(635)
.7330
(444)
.5604
(407)
1.0000
.9218
(496)
.7892
(496)
.8258
(496)
.2100
(429)
.5494
(315)
-.2550
(473)
.3353
(379)
.5679
(218)
.5866
(307)
.7263
(268)
1.0000
.8266
(496)
.9095
(496)
.2489
(429)
.5802
(315)
-.2195
(473)
.4944
(379)
.4665
(218)
.5312
(307)
.7326
(268)
1.0000
.7827
(496)
.1712
(429)
.3763
(315)
-.2153
(473)
.4786
(379)
.2739
(218)
.4992
(307)
.6151
(268)
1.0000
.1838
(838)
.5122
(654)
-.2539
(965)
.5512
(758)
.4333
(460)
.3913
(622)
.7181
(575)
j
1.0000
.2501 1.0000
(453)
.1066 1.0000
(683)
.1243 .2172 1.0000
(561) (374)
.5274 .5301 1.0000
(322) (270)
.1372 .2573 1.0000
(409) (616)
.3355 .3432 -.1862 .3569 .5031 .4990 1.0000
(382) (308) (477) (465) (571) (407)
-------
CHLOROPHYLL A WITH TEMPERATURE
SEGMENT *
a -
8 -
7 -
if! e~
\ s -
g
N 4- -
3 -
2 -
1 -
tTl —
fc 1
|
**• + * *
. 1
I
1 •
1 .
.... .. I
*A X i H
iVu ' ii.
1 P\/\ i / \A
CO
III
-20 W
(L
t
-15 <
L
o
-10
ul
z
- 0
SIGNIFICANCE AT 1 PERCENT LEVEL.
2./S.
+ NUMBER OF SAMPLES
1974-
1975
CHLOROPHYLL A WITH TEMPERATURE
SEGMENT S.
A/A.
CHLOROPHYLL A WITH TEMPERATURE
SEGMENT 5
& B1
\ sJ
k s 5
1974-
1975
CHLOROPHYLL A WITH TEMPERATURE
SEGMENT 1
J"FMAMJ"JASON DjT FMAMJ'O'ASOND
1974- 1975
CHLOROPHYLL A WITH TEMPERATURE
SEGMENT 3
10 -
9 -
8 -
7 -
,K e -
UJ
\ S -
K
N 4- -
3 -
a -
i -
ct -
1
1
1
i
* 4- 1
* ** ** I
* f
*. 1
1 * * ** *
l\ A I * **
f vy \ /ts" ^
i y y ' ^^^ / v y i
- es
01
-20 |5
p.
E
-is £
It
-121°
H
u
(D
-5 §
z
- 0
J.VLJ —
9 -
8 -
7 -|
in" e-
\ S -
N 4- -
3 -
£ -
1 -
0 -
7
4.
*
* . * *
\\/^^ ^y
""T"l~r TT r TVT"T~T~T'T~r'f I'T'Tl T^T T" T T
J"FMAMJTASONDj.JFMAMJ"J"ASOND
1974- 1975
1974-
Figure 49. Plot of correlation coefficients (Zr/Sz) of non-filterable chlorophyll a with temperature.
Dotted line, 99% significance level.
-------
CHLOROPHYLL A WITH CHLORIDE
SEGMENT 4-
SIGNIFICANCE AT 1 PERCENT LEVEL
2./S.
•»• NUMBER OF SAMPLES
CHLOROPHVLL A UITH CHLORIDE
SEGMENT 5
CHLOROPHYLL A WITH CHLORIDE
SEGMENT 2
1974-
-lAMJJASOND
1975
T I II1 1—!—1—I—I—I—I—1—1—I—1—1—!—1—1—T~
J"FMAMXJ"ASON DiJ" FMAM.TJASOND
1374-
CHLOROPHYLL A WITH CHLORIDE
SEGMENT 1
CHLOROPHYLL A WITH CHLORIDE
SEGMENT
I I I I I | I I I 1 I I
JFMAMJ"J"ASON D|J~ FMAMJ"J"ASOND
1974-
1975
1974-
1375
Figure 50. Plot of correlation coefficients (Zr/Sz) of non-filterable chlorophyll a with filtered chloride.
Dotted line, 99% significance level.
-------
CHLOROPHYLL A WITH SECCHI DEPTH
SEGMENT
CHLOROPHYLL A WITH SECCHI DEPTH
SEGMENT 2
\ S
N" *
3
2
25
SIGNIFICANCE AT 1 PERCENT LEVEL
Z./S*
••• NUMBER OF SAMPLES
CHLOROPHYLL A WITH SECCHI DEPTH
SEGMENT S
in
\ s
N •*• -
3 •
2 -
-20 U
1974-
1975
1974-
"MAMXTASOND
1375
CHLOROPHYLL A WITH SECCHI DEPTH
SEGMENT 1
Lie -
a -
8 -
7 -
H S —
m
\ S -J
K
N 4- -
3 -
2 -
1 -
d — i
*-•*•* ^
* *
^
4. f.
-
A . ...
Trfi fi *
/ ^\ ^/\ I \f\
- £L^>
01
-20 3
P-
Z
<
-is m
lL
0
-10 K
ul
-------
o
VO
CHLOROPHYLL A WITH TOTAL NITROGEN
SEGMENT 4-
i.io —
S3 -
8 -
7 -
di B~
VI
\ S -
N 4--
3 -
2 -
1 -
*
*
"*-
*
t
• ^
/\ J
s\ / \f\ ' ,
• / \ / i/ w "A
/ \ y \ f\
- £LC3
tn
-H0 ^
(L
n
<
-15 ff)
u.
0
-10 K
ul
(D
-5 5
z
® ~i— T i i r~r T T i ~i i r i i T i i T i ~n r~i *-"
1974- 1975
CHLOROPHYLL, A WITH TOTAL NITROGEN ^^
/•"Xx^J**1
J O«
SEGMENT 2 /
i n "** *
L^ — r
3 -
8 -
*i:
M 4- -
N ^
3 -
2 -
1 -
r?i -
.„ ^ ^ „... . . ^
-/\ A A
^ \ A *• /~ A ^" k^L / \
m i \ / *\ i^ ^^ 1 \
\j Vvl/ v W 1
r 0~
en 1
-- 3 L 2
1 1 °- 0"
~1S S Jk o,. °"
I". (f \
-10 ° V 0>\ 0,
s V «• i -x,./
-5 ? V«of »• X
D Xg"jrt/O- O-
z ^v^
- (3 ^^J ^^^.
J
x
/N
/*y
I O"
/ 0»
" ' *
U' "
s-~r\ 0"
/CX,, 0 /,
4 \ - /
°" *V-
O" / N
O../ 0-ie;
v / ll—
* O-
°" / ox
o/ °"&V
/i 7
•-,/J
/
°^/
SIGNIFICANCE AT 1 PERCENT LEVEL
+• NUMBER OF SAMPLES
/N
\
JFr-lAMTTASON D| J" FMAM-T-TASOND
CHLOROPHYLL A WITH TOTAL NITROGEN
SEGMENT S
25
1974-
1975
1974-
1975
CHLOROPHYLL A WITH TOT
SEGMENT 1
10
NITROGEN
CHLOROPHYLL A WITH
NITROGEN
SEGMENT 3
±x-t
a -
8 -
7 -
in B-
\ 5 -
K
|Sj 4- -
3 -
£ -
1 -
S3
^_
* A,
/ \
*/ V * *
. . S^r^ / vL.
\ /
J"FMAMTJ"ASONDT^MAMJ"TASOND
C—^J
tn
-20^
P-
E
L-15 If]
U.
O
-10
K
bJ
(D
- s 5
z
23
1374-
Figure 52. Plot of correlation coefficients (Zr/Sz) of non-filterable chlorophyll a with total nitrogen.
Dotted line, 99% significance level.
-------
CHLOROPHYLL A WITH TOTAL PHOSPHORUS
SEGMENT 4-
121
SIGNIFICANCE AT 1 PERCENT LEVEL
Zii/Sc
+• NUMBER OF SAMPLES
CHLOROPHYLL A WITH TOTAL PHOSPHORUS
SEGMENT 2
10
CHLOROPHYLL A WITH TOTAL PHOSPHORUS
2S
1374-
1075
CHLOROPHYLL A WITH TOTAL PHOSPHORUS
SEGMENT 1
10
1374-
1375
CHLOROPHYLL A WITH TOTAL PHOSPHORUS
SEGMENT 3
10
1374-
1375
1374-
1375
Figure 53. Plot of correlation coefficients (Zr/Sz) of non-filterable chlorophyll o. with unfiltered
total phosphorus. Dotted line, 99% significance level.
-------
TABLE 40. MULTIPLE REGRESSION ANALYSIS OF 1974 DATA USING NON-FILTERABLE
CHLOROPHYLL a AS DEPENDENT VARIABLE
Analysis
Multiple r 0.654 Of Variance
r Square 0.428 Regression
Standard Error 11.42 Residual
Variables in the Equation
Regression
Variable Coefficient (B)
Particulate Phosphorus 380.49
F. Reac. Phosphate-P -160.62
F. Nitrate + Nitrite-N -11.34
Constant 15.76
DF SS
3 24748.3
151 19695.6
Standard
Error of B
37.02
51.14
3.97
MS F
4926.1 37.69*
230.4
F
105.6*
10.8*
8.1
*Significant at the 1% level.
-------
TABLE 41. MULTIPLE REGRESSION ANALYSIS OF 1975 DATA USING NON-FILTERABLE
CHLOROPHYLL a AS DEPENDENT VARIABLE
N3
Analysis
Multiple r 0.593 Of Variance
r Square 0.352 Regression
Standard Error 11.18 Residual
Variables in the Equation
Regression
Variable Coefficient (B)
Particulate Phosphorus 221.09
E. Reac. Phosphate-P -83.07
F. Nitrate + Nitrite-N 2.78
Constant 8.71
DF SS
3 9708.0
143 17886.5
Standard
Error of B
37.21
41.93
1.92
MS F
3236.0 25.9*
125.1
F
35.30*
3.92*
2.10
*Significant at the 1% level.
-------
TABLE 42. MULTIPLE REGRESSION ANALYSIS BY SEGMENTS USING NON-FILTERABLE
CHLOROPHYLL a AS DEPENDENT VARIABLE
YEAR
1974
1975
SEGMENT
I
2
3
4
5
1
2
3
4
5
MULTIPLE r
0.846*
0.779*
0.257*
0.888*
0.934*
0.713*
0.840*
0.915*
0.814*
0.965*
MOST IMPORTANT INDEPENDENT VARIABLE
1st
part. P
part. P
f. reac. PO^-P
u. tot. P
f. inorg. N
part. P
u. tot. P
u. tot. P
u. tot. P
u. tot. P
2nd
f . inorg . N
f . inorg . N
f. org. P
f. org. P
tot. N
tot. N
f. inorg. N
f. inorg. N
part. P
f. org. P
3rd
tot. N
f. reac. PO^- P
tot. N
f . inorg . N
f. reac. PO^-P
f . inorg . N
f. org. P
part. P
f. inorg. N
f. tot. P
*Significant at 99% level
-------
tended to supplement mapping of nutrient distributions based on conventional
sampling from ships. Data from the bi-weekly cruises, which were scheduled
to coincide with Landsat passes over Saginaw Bay, were correlated with re-
flectance measurements recorded by satellite sensors in four regions of the
visible to near-infrared spectrum. This approach was designed to show empir-
ical relationships between remote and direct measurements that could be used
to predict values in unsampled areas.
The satellite data that Bendix chose to process were recorded on two
occasions, June 3, 1974 and July 31, 1975, coinciding with cruises 8 and 25,
respectively (Table 43). In applying a step-wise linear regression analysis
to the data, the water quality measurements were each considered as dependent
variables; Landsat reflectance measurements were regressed against these as
independent variables. The results indicate which sensor band., band ratio or
combination of bands is most useful for predicting levels of each water qual-
ity parameter. Correlation coefficients and prediction accuracy were eval-
uated in each case. The processed Landsat data were used finally to generate
a color-coded image or map of water quality categories throughout the bay.
Examples are shown in Figures 54 and 55.
Results of the Bendix study suggest that such water quality maps based
on calibrated satellite data can be used with fair reliability to estimate
ranges of concentration for certain parameters, even for those variables
(e.g., total phosphorus, chloride) which are not directly detectable by re-
mote sensors. This is true because water masses with a varying content of
Saginaw River water are enriched correspondingly with nutrients and salts.
The same river water is characterized also by its color and particle content,
which are markedly different from those of Lake Huron water. As a result,
river water in various stages of dilution can be identified by visible charac-
teristics which are correlated with other conservative but invisible features
of water quality.
However, the relationships between turbidity and other variables, such
as chloride or temperature, are strictly empirical and are subject to change,
perhaps even on a daily basis. Moreover, the Landsat data, even on apparently
clear days, are subject to atmospheric effects that may vary in each spectral
band. In summary, it is apparent that regular Landsat mapping of water qual-
ity in the bay is feasible with the following provisions: that sampling is
conducted within a few hours of Landsat passage; that such concurrent measure-
ments are used to "re-calibrate" the satellite data on each occasion; that the
errors of estimation for each parameter (based on comparison of actual and
predicted values) are within acceptable limits. The advantages of using Land-
sat monitoring as an adjunct to conventional point-sampling are that it pro-
vides an economical basis for extrapolating water quality parameters from
point samples to unsampled areas, and it provides a synoptic view of water
mass boundaries that no reasonable amount of point sampling could duplicate.
The methodologies, results and conclusions of this study are discussed
in more detail elsewhere (Rogers, et^ al., 1975a; Rogers, et a^. , 1975b;
Rogers, et al., 1976).
114
-------
TABLE 43. CONCURRENT WATER QUALITY AND LANDSAT DATA FOR SAGINAW BAY
•J
CT*
tH
n
W
§
*n
in
r^
o\
1-1
rH
<"1
SM
hJ
£3
>->
On Site Measurements
Laboratory Analysis
sta.
no.
7
8
12
18
26
27
32
34
38
42
43
44
52
56
60
61
Mean
Std.Dev
1
2
3
5
6
7
9
10
14
15
16
18
19
20
21
22
23
28
29
30
31
35
36
41
54
55
59
Mean
Std.Dev
temp.
°c
26.1
26.7
26.8
23.6
26.0
23.7
24.8
26.9
25.1
20.4
23.5
24.4
21.5
23.7
22.5
25.7
24.46
1.92
19.8
17.5
19.2
18.0
18.7
17.0
19.0
18.0
18.4
17.0
18.2
17.7
16.2
17.5
17.8
16.3
17.0
15.4
16.6
18.7
16.2
15.8
17.8
18.8
19.0
19.2
18.0
17.73
1.15
Secchl
depth
m
1.9
1.6
1.3
2.0
1.6
2.0
1.8
10.6
1.4
5.5
1.5
1.0
2.1
2.2
5.0
1.2
2.0
1.3
0.3
1.0
0.6
0.6
0.4
0.6
0.3
0.7
0.8
1.3
0.8
1.3
1.7
1.5
0.5
1.4
1.7
1.7
1.8
1.2
2.2
2.2
1.8
0.4
0.3
0.3
0.8
1.04
0.62
sp.
cond.
uS/cm
243.
258.
277.
237.
251.
239.
235.
294.
244.
211.
246.
281.
238.
244.
215.
252.
247.8
21.8
772.
320.
330.
492.
828.
425.
827.
381.
309.
323.
315.
293.
303.
268.
466.
283.
286.
329.
269.
285.
274.
283.
262.
764.
736.
659.
359.
423.7
196.0
f. Cl.
mg/1
10.9
11.1
18.8
9.8
13.8
10.1
10.1
24.1
11.7
6.6
12.1
20.1
10.4
10.6
6.9
12.7
12.5
4.7
L118.
200.
207.
485.
364.
1070.
287.
196.
160.
190.
170.
157.
159.
465.
163.
172.
194.
140.
153.
137.
147.
124.
950.
882.
759.
265.
358.2
316.6
nf.
chl. £
ug/1
20.70
9.38
10.70
5.61
11.60
7.38
7.38
68.50
13.60
1.84
15.60
37.10
10.00
6.58
1.84
18.00
15.36
16.53
36.20
17.00
3.74
59.70
27.90
50.80
38.20
53.90
29.00
6.17
12.10
9.46
2.73
5.93
69.30
4.41
5.93
5.85
5.69
6.74
3.93
5.13
6.17
55.50
26.80
22.80
36.60
22.507
20.651
Major Metals
Na
mg/1
41.
10.
11.
20.
42.
12.
7.
9.
9.
8.
33.
12.
17.83
13.15
K
mg/1
5.3
1.7
1.8
2.9
5.2
2.1
1.2
1.7
1.5
1.5
4.0
2.1
2.58
1.45
Mg
mg/1
19.
10.
11.
16.
19.
13.
9.
10.
10.
10.
19.
12.
13.17
3.97
Ca
mg/1
101.
44.
50.
70.
104.
55.
39.
46.
45.
42.
93.
52.
61.75
24.12
Nutrients
f .
tot. P
mg/1
0.054
0.010
0.070
0.006
0.004
0.010
0.004
0.043
0.071
0.071
0.0343
0.0303
u.
Kjel. N
mg/1
0.37
0.41
0.65
0.38
0.35
0.29
0.33
1.00
0.29
0.14
0.42
0.72
0.33
0.26
0.17
0.42
0.41
0.22
0.81
0.27
0.52
0.19
0.24
0.23
0.20
1.00
0.94
0.73
0.513
0.328
u .
tot. P
mg/1
0.012
0.017
0.027
0.012
0.018
0.012
0.010
0.039
0.014
0.002
0.013
0.027
0.009
0.014
0.004
0.020
0.016
0.009
0.200
0.029
0.145
0.029
0.016
0.014
0.018
0.185
0.213
0.196
0.1045
0.0896
Computer Processing of CCTs
LANDSAT Digital Data
mean reflectance for
station area
Bands: 4567
Max:254 254 254 252
40.6 27.5 14.8 1.4
44.0 29.5 16.3 1.5
42.8 29.5 16.2 1.7
38.1 24.7 13.8 0.5
42.7 28.3 14.7 0.4
38.1 24.5 12.2 0.3
37.2 23.2 11.7 0.1
38.6 29.1 16.4 0.9
40.4 26.1 12.3 0.1
32.3 20.3 9.8 0.3
36.0 23.1 10.9 0.2
35.6 25.5 14.5 0.8
32.3 21.1 11.0 0.4
39.5 25.2 12.8 0.6
34.0 21.0 10.1 0.1
43.7 28.7 14.1 0.6
38.5 25.4 13.2 0.6
3.8 3.1 2.2 0.5
50.2 38.0 23.8 6.8
47.0 27.2 14.2 3.2
62.8 42.0 18.6 4.3
43.6 27.4 17.1 4.7
46.1 32.3 19.6 4.3
43.1 25.8 15.3 2.7
46.5 32.5 19.9 4.1
42.8 25.3 15.0 3.6
45.1 27.4 14.0 2.9
46.7 25.8 13.0 2.8
56.9 37.2 17.5 4.2
47.0 26.3 12.8 2.7
45.9 25.0 12.5 2.8
45.8 23.5 12.4 2.4
44.9 29.5 18.5 5.0
44.1 23.1 11.3 2.3
44.1 23.4 11.9 3.1
43.6 23.7 11.6 3.0
43.5 22.7 11.3 2.2
52.5 29.1 15.8 5.4
43.5 22.2 11.5 2.2
44.8 23.8 13.4 4.7
48.2 27.1 16.3 5.7
46.8 32.1 21.9 7.1
53.0 40.7 27.2 9.0
53.7 41.3 27.3 8.3
46.8 29.5 16.7 3.9
47.37 29.03 16.31 4.20
4.73 6.03 4.61 1.85
no . ot
pixels
to sta.
area
56
63
72
72
64
90
100
100
121
72
72
72
72
72
110
99
81.7
10
49
56
81
81
90
27
67
63
42
49
56
72
49
72
42
64
64
42
64
49
80
64
17
8
12
64
-------
Image produced by
Bendix Aerospace
Systems Division
Secchi Depth
, (meters)
0,3
0.6
0.8
1,0
1.3
1.5
1.7 to 1.8
2.2
3 to 3.3
Uncategorized
Map covers area approximately
25 by 40 nautical miles.
RESULTS OF STEPWISE REGRESSION ANALYSIS
Variable
Temperature
Secchi disc depth
Specific conductivity
filtered Chloride
Non-filterable
chlorophyll a
Unfiltered sodium
Unflltered Potassium
Unfiltered magnesium
Unfiltered calcium
Filtered total
phosphorus
Unfiltered Kjeldahl
nitrogen
Unfiltered total
phosphorus
Units
°C
•
US/cm
mg Cl/i
us
chl. a/I
mg Da/1
«g K/l
mg Mg/I
mg Ca/t
mg til
mg N/l
mg P/l
Regrss-
Step
1
1
2
1
1
1
2
1
1
2
1
2
1
2
1
1
1
2
Independent
CLANDSAT Band)
5
6
7
6
6
6
4
6
6
4
6
4
6
4
6
6
6
4
Regression
CLANDSAT Bands)
5
6
6,7
6
6
6
6,4
6
6
6,4
6
6,4
6
6,4
6
6
6
6,4
Standard
Estimate
0.6759
0.3839
0.2890
115.130
180.578
18.715
14.905
8.5521
0.9698
0.7737
2.4170
1.4331
14.9092
11.0980
0.0121
0.1429
0.0225
0.0155
Inaccuracy
3.8
36.9
27.7
27.2
50.4
83.2
66.2
48.0
37.6
30.0
18.4
10.9
24.1
18.0
35.3
27.9
21.5
14.8
Regression
Coefficient
0.819
0.791
0.892
0.817
0.829
0.450
0.721
0.785
0.772
0.876
0.815
0.945
0.808
0.909
0.926
0.912
0.972
0.988
Figure 54. Categorized Landsat image-map of water transparency
on June 3, 1974 (original in color).
116
-------
- ••..., • •
I" • '•: :
-
!;Vr <$$
• i • . • .-
. : ••-., . -
'.:~
'::4vi:: "••
A
31.6*
<0.4*
37.5*
363*
1.55*
.066*
99.1*
290*
17.6*
B
27.3
0.4
19.7
284
.71
.032
37.5
217
8.1
C
25.2
1.9
10.4
243
.28
.014
5.0
179
3.2
D
23.3
2.7
9.9
235
.,27
.012
7.6
174
2.7
E
20.6
3.9
8.2
221
.22
.005
7.6
164
1.6
Standard
Error of
Estimate
1.6
1.1
1.9
8.9
.08
.004
8.5
15
2.2
Temperature ( C)
Secchi Depth (m)
Chloride (mg/£)
Conductivity (micromhos)
Total Kjeldahl Nitrogen (mg/£
Total Phosphorus (mg/&)
Chlorophyll a (yg/£)
Total Solids (mg/£)
Suspended Solids (mg/£)
*Values are beyond the range of sample data and may not occur in nature.
Image produced by Bendix Aerospace Systems Division.
Figure 55. Categorized Landsat image-map of water quality variables
on July 31, 1975 (original in color).
117
-------
SECTION 8
EVALUATION AND DISCUSSION
WATER QUALITY VARIATIONS
The following discussion, by parameter, deals with the data presented in
Tables 6-38 and Figures 4-48. The results are considered, first, from the
standpoint of six key parameters (temperature, chloride, Secchi depth,
chlorophyll a, Kjeldahl nitrogen and total phosphorus monitored at six sta-
tions. The latter were chosen to represent two years of sampling on the bay
and Saginaw River. Data for one meter depth and near the bottom show the
occurrence of stratification as well as seasonal variability at each point.
Diurnal variations at station 56 are also represented for six occasions during
1975.
Secondly, all of the results are considered in terms of spatial (segment
and total bay) and temporal (quarterly and annual) averages. These segments,
established for modeling purposes, represent areas of generally distinctive
water quality (Richardson and Bierman, 1976). Some statistical differences
between the 1974 and 1975 data sets may have resulted from the sampling of
fewer stations in each segment during 1975. However, the station sub-sets
sampled in 1975 were those which, on statistical analysis of the 1974 results,
were found to best represent average water quality in each of the segments.
Temperature
Annual mean temperatures were highest in relatively stagnant inshore
waters of the inner bay (Sta. 34) and lowest where Lake Huron waters usually
intrude along the northern side of the bay mouth (Sta. 49). In most areas
two temperature maxima occurred in July and in August (Figure 14). Water
temperatures rose earlier during spring 1975 and were generally warmer all
year (Table 7) .
Evidence of thermal stratification is seen in the comparison of surface
(1 m) and bottom waters in Figure 14. A thermocline occurred in the inner
bay during calm periods, chiefly in May. Generally, however, a combination
of wind and wave action caused complete mixing in all but protected or deeper
areas. In the outer bay a thermocline persisted at the 15 - 20 m level
throughout the May - October period.
Annual mean temperature by segment decreased in order of segments 1, 3,
2, 5 and 4. This pattern shows that the dominant influx of cooler Lake Huron
water is along the northwestern side of the bay. Consequently, the outflow
118
-------
of bay water is mainly along the southeastern side. As expected, the strong-
est thermal gradients and barriers occurred in the transitional zone toward
the western side of the mid-bay area. These often corresponded with turbid-
ity and chemical boundaries, as subsequent data show.
Occasional instances of thermal inversion were noted near the Saginaw
River mouth when warmer but denser, chloride-rich water lay near the bottom.
For some stations, temperature means at measured depth are biased toward
higher values because only surface (1 m) waters were sampled by helicopter
during midwinter (i.e., Sta. 34, Table 6).
Studies by Consumers Power Company (cited in Freedman, 1974) have shown
that thermal discharges from their plant at the Saginaw River mouth have been
detectible for some 2 miles offshore. Although no such effects were noted in
the present survey, Landsat (satellite) imagery recorded during winter (1975)
shows a persistent area of open water adjacent to the plant (Figure 4) .
Oxygen, dissolved (d. 02)
In general dissolved oxygen remained at near-saturation levels year-
round throughout the bay. Thus, the observed ranges in dissolved oxygen
content were mainly a function of water temperature variations. The lowest
mean value (i.e., 6.7 mg 02/£ at Sta. 55) show some tendency toward oxygen
depletion in the lower Saginaw River. There, the lowest single value, re-
corded at 6 m, was 3.3 mg 02/&. Otherwise, unusually high oxygen levels in
the inner bay were noted only occasionally, as in July 1975 during a calm
period which accompanied a heavy algal bloom. At that time, d. 02 values at
Station 8, for example, were 13.5 mg 02/& and 8.4 mg 02/£ at 1 m and 3 m,
respectively. The latter value represents the saturation level of d. 02 at
ambient temperature, while the former represents super-saturation due to phy-
toplankton photosynthesis .
Three d. 02 values were recorded through the ice in the inner bay during
February 18-19, 1975:
Station mg d. 02/£ Temperature % Saturation
3 12.0 1.0 86.8
16 11.2 .8 81.2
26 4.4 1.2 31.9
The minimum value of 4.4 mg 02/£ was from station 26 near the Sebewaing River
mouth. The other two are from similar nearshore areas on the opposite side
of the bay.
Specific Conductivity (sp. cond.)
Extremes of conductivity were measured in the Saginaw River (highest)
and in the outer bay (lowest) toward the western shore. By far the greatest
fluctuations in conductivity occurred in segment 1, the area most affected
by river inputs of salts and nutrients. Segment 1 was much less subject to
119
-------
conductivity variations in 1975 than in 1974. Throughout the bay conduc-
tivity varied most during the spring and summer quarters. Like chloride,
conductivity serves generally as a label for the component of Saginaw River
water that occurs in any part of the bay. However, conductivity is less
conservative since it is affected by ions, other than chloride, that are
biologically active.
Chloride, filtered (f. Cl)
Mean concentrations of chloride were highest in the Saginaw River (Sta.
54) and lowest in the extreme outer bay (Sta. 50). Chloride values were con-
sistently much higher and more variable in the inner bay (Seg. 1-3). The
variations were particularly large along the entire western half of the bay
where, apparently, there is more frequent mixing of Lake Huron and bay water
during the spring. At outer bay stations 49 and 51 occasional higher chloride
values at the surface indicate layering of bay waters over colder Lake Huron
water. This is confirmed by temperature (Table 6). These "peaks" of sur-
face chloride concentration in the outer bay, that occurred during the May -
July period, may result from periodic wind stress (mainly southwesterly) on
surface waters of the inner bay. Within the inner bay, chloride values
fluctuated without any such clear pattern.
Variations in mean pH were relatively small among bay segments . Indivi-
dual values ranged from 6.9 to 9.4, with most of the lower levels occurring
in the Saginaw River and river mouth, and in Lake Huron waters in the outer
bay (e.g., Sta. 49, 50). Occasionally, a high pH (>9) was recorded in sur-
face waters during phytoplankton blooms, when dissolved C02 may have been de-
pleted by photosynthesis. Such an effect was seen, for example, at several
inshore stations of the inner bay during July 13-16, 1975*. In most cases
the pH of underlying (poorly-lighted) water was several tenths lower. Pre-
sumably the lower (<8) mean pH of Saginaw River water results either from
acidic pollutants and/or additional C02 generated by organic decay.
Alkalinity, total (tot, alk.)
Alkalinity values were relatively high (ca. 180 mg CaC03/Jl) in the Sagi-
naw River and lowest (ca. 80 mg CaC03/£) in the extreme outer bay. Between
these extremes the distribution of alkalinity generally followed that of Sagi-
naw River water throughout the bay. This is evidenced by the positive cor-
relation (based on regression analysis) of alkalinity and chloride values,
particularly within the inner bay. Freedman (1974) noted that slightly higher
alkalinity values in the summer hypolimnion, as reported in Lake Survey data
(1966), may result from sinking and re-solution of precipitated CaCO^. How-
ever, there was no such clear evidence of vertical variations in alkalinity
in the present data. Throughout the bay alkalinity values were generally
highest and most variable during the spring quarter.
*The eastern side, and in particular Station 26, showed high pH values
during May - July in 1974 and 1975.
120
-------
Secchi Disc Depth
Mean Secchi depth values were lowest, indicating extreme turbidity, in
the Saginaw River (Sta. 55) and highest in the mid-outer bay (Sta. 51). In
the river water clarity was lowest during the May - August period, but with
only minor fluctuations. This indicates a continuously high loading of
pariculate matter. In the inner bay (Seg. 1, 2, 3) greater clarity and more
variation occurred. An exception was Station 34 in Wildfowl Bay which, be-
cause of its protected status and low clarity, resembled the river stations.
Much higher mean values and variability were seen in the outer bay, particul-
arly in segment 5.
It is apparent from Figure 24 that there is considerable overlap in the
ranges of Secchi depth between the inner and outer bay. This and the great
variations of clarity that occurred in the outer bay indicate that active mix-
ing of clear (Lake Huron) and turbid (bay) water takes place there. Such
intermittant mixing (cf; Fig. 23) may occur mainly as a function of wind-
generated circulation. Sharp turbidity boundaries were observed frequently
in segments 4 and 5 where greatly different water masses were in contact.
In the inner bay, however, clarity variations probably were affected to a
greater extent by wave-resuspension of sediments in shallow water as well as
by the mixing of river and bay water. Turbidity boundaries were much less
evident in this area. Where available, first quarter data (Fig. 24, seg. 1,
3) show that water clarity under ice cover is significantly greater.
Chlorophyll a, non-filterable (nf. chl. a)
Concentrations of particulate chlorophyll a were higher in the inner bay
(seg. 1) than in the outer bay (seg. 4) by a factor of 10. Variability was
also high in segment 1, the upper extreme being approximately 20-fold greater
than the lower. Mean values in the Saginaw River were considerably lower
(by 1/3) than those in segment 1, possibly due to extreme turbidity and other
pollution in the river. When the water column was stratified, chlorophyll
levels were usually higher near the surface. However, the 1 meter mean values
in Table 16 (except for Sta. 55) are biased downward by mid-winter samples of
low chlorophyll content. Otherwise, this table shows that chlorophyll a on
the western side of the inner bay (seg. 2) is markedly less abundant than on
the eastern side (seg. 3) where there is less influx of Lake Huron water.
Temporal variations of chlorophyll a followed a reverse pattern to that
of turbidity (i.e., Secchi depth). The amount of chlorophyll variation was
smallest in the outer bay and greatest in the river. The opposite was true
of Secchi depth. This indicates that extreme variations in the particle con-
tent of bay water need not represent similar changes in the crop of algal
chlorophyll. In short, much of the particulate matter is probably not algal
in nature.
Mean values by segment were generally highest in the third quarter. Wide
ranges Qf chlorophyll concentration, especially in the inner bay, indicated
the occurrence of algal blooms. In fact, such blooms were observed frequently
during the growing season.
121
-------
Carbon, unfiltered organic (u. org. C)
Extreme levels of u. org. carbon were highest in the Saginaw River
(Sta. 55) and lowest in the outer bay (Sta. 57). Segment means followed a
similar pattarn, ranging from lowest in segment 4 to double that value in
segment 1. In segment 1 the greatest variations also occurred during the
spring (2nd) quarter in 1974, but not in 1975. No first or third quarter
data were obtained for 1974 due to experimental problems. However, the com-
plete data set for 1975 indicated a u. org. C peak occurring in all segments
during the summer (3rd) quarter. That is consistent with the observed peak
in chlorophyll a during the same period. The next highest segment means in
1975 were in the second quarter in all areas except for segment 3 where win-
ter (1st) quarter values were relatively higher. It is interesting to note
that, although chlorophyll a levels were not unusual at that time, high u.
Kjel. N and low d. 02 values (even relative to segment 1) suggest a signifi-
cant winter input of organic matter to segment 3. A possible source is the
Michigan Sugar Company beet processing plant on the Sebewaing River.
Carbon, filtered organic (f. org. C)
Concentrations of f. org. carbon followed similar distributional and
seasonal patterns as those of u. org. C. With regard to 1975 segment means,
the u./f. org. C ratios ranged from 1.34 in segment 3 to 1.09 in segment 4.
This suggests again that loadings of particulate carbon were relatively high
in the Sebewaing area, particularly during mid-winter. The range of f. org.
C values was on the whole less than that of u. org. C, especially in the outer
bay (seg. 4 and 5). This indicates a wider fluctuation of particulate carbon
levels, including cellular biomass, than of dissolved and colloidal forms. A
similar relationship was seen between particulate (unfiltered minus filtered)
and dissolved forms of nitrogen (Figs. 34 and 39).
Solids, unfiltered total (u. tot, sol.)
Concentrations of u. tot. solids were predictably highest in the Saginaw
River (Sta. 55) and lowest in the extreme outer bay (Sta. 50), Although sam-
pling coverage was incomplete and mainly limited to 1975, the data indicate
that u. tot. solids levels in the inner bay were approximately 2-fold higher
than in the outer bay. Quarterly mean values were fairly constant within
each segment, suggesting that observed summer increases of non-filterable
chlorophyll occurred at the expense of dissolved solutes and colloids in the
water column.
Silicate-silicon, filtered reactive (f. reac. SiOz-Si)
Extreme values of f. reac. silicates were highest in the Saginaw River
(Sta. 54) and lowest in the mid-bay area (Sta. 60). However, the segment
means were highest in the outer bay (seg. 4) and lowest in the eastern inner
bay (seg. 3). The greatest variability occurred in segment 1. This distri-
bution suggests that inputs to the bay of silicate-rich water come intermit-
tantly from the Saginaw River and more regularly from Lake Huron. Dissolved
silicate is probably depleted within the inner bay due to heavy diatom growth
122
-------
in these eutrophic waters. The data In Figure 32 show, in fact, that sili-
cate depletion in the inner bay (seg. 1, 2, 3) was generally strongest during
the spring and fall quarters when active diatom growth occurs. In the low-
productivity waters of Lake Huron (i.e., seg. 4), this effect is not notice-
able.
Ammonia-nitrogen, filtered total (f. tot. NHg-N)
Ammonia, like dissolved oxygen, is subject to diffusion and biological
uptake and therefore is a highly labile feature of water quality. Data in
Figure 33 indicate the variable nature of ammonia values during 1974, even
in the outer bay.
Levels of dissolved ammonia, which results mainly from organic decay,
were highly variable throughout Saginaw Bay during 1974 (Figure 33). This
appears to be real since in segment 1, at least, variability was great during
both years. The highest mean values were in the Saginaw River and in segment
1. Mean values for all segments were generally highest in the summer (3rd)
quarter during 1974 and in the winter (1st) quarter during 1975. This sug-
gests that generation of ammonia by decay and biological uptake of ammonia
were dominant respectively in 1974 and 1975. However, the reasons for this
difference in 1974 and 1975 levels are not clear.
Nitrate + nitrite-nitrogen, filtered (f. NOs + N02~N)
Extreme values of f. nitrate + nitrite occurred in the Saginaw River,
Station 55 (highest) and the western inner bay, Station 50 (lowest). The
segment means are more informative, showing a narrow range from 0.200 to 0.498
mg N/£ in segments 2 and 3, respectively. From the Figure 34 data it is ob-
vious that inputs of nitrate + nitrite from the Saginaw River to segment 1
during 1974 were very high in the first quarter (1.824 mg N/£) and declined
to a low of 0.090 mg N/£ during the third quarter. This pattern diminished
progressively toward the outer bay (seg. 4), and was less pronounced alto-
gether during 1975. This seasonal decline of nitrate + nitrite levels was
likely due to a combination of decreasing input rates (after the spring run-
off) and increasing consumption by phytoplankton as the growing season ad-
vanced.
Nitrogen, unfiltered Kjeldahl (u. Kjel. N)
Total Kjeldahl nitrogen values ranged from a high of 1.293 mg N/£ in
the Saginaw River to the low of 0.155 mg N/£ in the outer bay (Sta. 50). Seg-
ment means also show the high and low values in segments 1 and 4, respectively,
In all segments during 1974, u. Kjel. nitrogen values rose from a relatively
low level in winter-spring (quarters 1 and 2) to a maximum in summer, followed
by a decline to an intermediate fall value (quarter 4). In 1975, the pattern
was similar but less definite. Variability also was highest during the spring
in segment 1; but in segments 2 and 4 it was highest in the fall, perhaps due
to increased wind-induced mixing of inner bay and Lake Huron water coupled
with the fall overturn.
123
-------
The relative increase in Kjel. nitrogen from the second to the third
quarter was accompanied by decreases in total phosphorus (Fig. 43) and con-
servative factors, such as chloride (Fig. 19). The latter changes are a
function of decreasing inputs via the Saginaw River, but the Kjel. N increase
over this interval was possibly due to nitrogen fixation by the abundant
crops of blue-green algae observed during the summer. Concurrent changes in
chlorophyll a concentration (Fig. 26) closely parallel those of u. Kjel. N.
Nitrogen, total (tot. N)
These values were calculated for most samples by simple addition of f.
nitrate + nitrite-N and u. Kjeldahl N measurements in order to furnish a
counterpart for unfiltered total phosphorus data.
Extreme levels of tot. nitrogen were highest in the Saginaw River (Sta.
54) and lowest in the outer bay (Sta. 50). Segment means varied only 2-fold
from the low in segment 4 to the high in segment 1. Variability of tot. N
was on the whole greater during 1975 in segments 1, 3 and 5, especially in
the winter and spring quarters.
Segment means show a general decline of tot. N from spring to fall,
suggesting a steady depletion of all forms of nitrogen after initial high in-
puts from the Saginaw River in early spring. This pattern is also evident
but less obvious in the outer bay (seg. 4 and 5).
The data in Table 28 do not suggest any consistent differences between
tot. N values at 1 m and near the bottom.
Phosphate-phosphorus, filtered reactive (f. reac. PO^-P)
Levels of f. reac. phosphates ("ortho-phosphates") were highest in the
Saginaw River (Sta. 45) and lowest in mid-bay (Sta. 60). Segment means
ranged from near-detection limits over most of the bay to a high of 0.011 mg
P/Jl in segment 1. Although these mean values were low and relatively uniform
throughout the year, periodic higher levels during the 2nd quarter are indi-
cated by the much greater range of values then, particularly in the inner bay
(Fig. 40). On the western side (seg. 2 and 4) the greater range occurred
during the 3rd quarter. These periodic high levels appear to have been much
less prominant during 1975. This may reflect a difference in the volume or
quality of spring inputs of phosphates between 1974 and 1975. However, it
is not possible to distinguish between the effects of inputs, losses and phy-
toplankton uptake in interpreting these PO^-P data.
Phosphorus, filtered total (f. tot. P)
The f. tot. phosphorus maximum occurred in the Saginaw River (Sta. 1) and
the minimum in the outer bay (Sta. 45). The corresponding high and low seg-
ment means were in segments 1 and 4, respectively. Variability was also high-
est in segment 1 where the quarterly mean values were relatively high, espe-
cially during the spring. Quarterly means in all other segments were fairly
124
-------
constant In the 0.002 - 0.010 mg P/£ range during both years. The observed
ranges of individual values, however, were notably different from segment to
segment and year to year. Periodically, high values of f. tot. P were seen
(Fig. 41) in the western outer bay (seg. 4), an area that was poorest in f.
reac. P and u. tot. P.
Phosphorus, unfiltered total (u. tot. P)
Extreme values of u. tot. phosphorus were highest in the Saginaw River
(Sta. 55) and lowest in the outer bay (Sta. 51). The highest and lowest seg-
ment means were seen in segments 1 and 4, respectively. In general, u. tot.
P inputs from the Saginaw River to segment 1 were highest in the spring quar-
ter (Fig. 43), and diminished through summer and fall. This pattern was pro-
gressively weaker toward the outer bay; in segment 4 mean u. tot. P was al-
most constant throughout the year.
The data in Table 32 suggest that there was no consistent difference
between u. tot. P concentrations at 1 meter and near the bottom. In view of
the normally high levels of dissolved oxygen throughout the bay, there is no
reason to expect that the rate of net phosphorus flux from sediments is
unusually high. However, wind stress may cause resuspension of particulate
phosphorus in shallow areas and a temporary increase in u. tot. P.
Sodium, unfiltered (u. Na)
Concentrations of sodium were highest in the Saginaw River (Sta. 55) and
lowest in the extreme outer bay (Sta. 50). Segment means followed the same
pattern, with the high and low occurring in segments 1 and 4, respectively.
Variability of sodium levels was by far greatest in segment 1, especially
during the spring and fall quarters (2 and 4). This indicates a sizeable
input via the Saginaw River during the peak runoff periods (see Fig. 10).
Since sodium behaves conservatively, it serves to label river water in the
course of its movement and dilution throughout the bay. The distribution of
sodium was highly correlated with that of chloride, another conservative fac-
tor (Table 39).
Sodium levels were highest during the second quarter in those segments
(1, 3 and 5) that seem to be most influenced by the flow of Saginaw River
water. In other areas (seg. 2 and 4) more affected by periodic intrusions of
Lake Huron water, the sodium level was highest in the first quarter and
tapered off gradually throughout the rest of the year. This difference may
reflect some weakening of Lake Huron water flows into Saginaw Bay during mid-
winter, or a correspondingly greater movement of sodium-rich river water into
those areas under the ice.
Potassium, unfiltered (u. K)
Extreme levels of potassium were distributed like those of sodium. An
important difference is that the annual segment mean for potassium was as high
in segment 3 as in segment 1. This indicates a significant input of potassium
to segment 3, other than from segment 1, since neither chloride, conductivity
nor sodium were conserved to that extent. Potassium and chloride distribu-
125
-------
tions were correlated (r = 0«88) throughout the bay, but less so than sodium
and chloride (Table 39). Moreover, potassium levels were highest during
the first quarter in segments 1, 2 and 4, but peaked during the second quar-
ter in segment 3 (and possibly segment 5, although only one measurement was
available then). Variability was greatest during the second quarter through-
out the bay.
Since fertilizers are typically an important source of potassium in
runoff from agricultural land, it is possible that such runoff enters the
bay every spring from numerous canals which drain the rich farming areas
bordering segment 3.
Calcium, unfiltered (u. Ca)
Like sodium and potassium, calcium was most concentrated in the Saginaw
River (Sta. 55) and rarest in the outer bay (Sta. 51). Seasonal levels in
all segments were highest in the first quarter and declined generally through-
out the year. In the inner bay, notably segment 1, variability was greatest
during the period of high runoff (quarter 2). Otherwise, the seasonal de-
cline of calcium levels may be related also to decreased solubility of cal-
cium salts (e.g., calcium carbonate) at higher water temperatures, and to
biological uptake. Alkalinity values followed a similar pattern, at least
within the inner bay. In the outer bay (segments 4 and 5) calcium was more
highly correlated in its distribution with chloride than were the other major
metals.
Magnesium, unfiltered (u. Mg)
Magnesium concentrations were highest in the Saginaw River (Sta. 55) and
lowest in a nearshore area of the outer bay (Sta. 47, seg. 4). However, the
highest segment mean was in segment 3, rather than in segment 1. The segment
mean for magnesium in segment 1 was slightly lower than that of sodium, but
the former values were much higher in the outer bay (segments 4 and 5). This
suggests that magnesium levels in the bay are influenced less by inputs from
the Saginaw River than those of sodium, potassium or calcium.
The relatively high level of magnesium in segment 3 occurred during the
fourth quarter when levels elsewhere in the bay were declining. This points
to a significant input from some artificial source, possibly connected with
sugar beet processing in the Sebewaing area. Sampling for major metals in
segment 3 was confined to Station 26 at the mouth of the Sebewaing River.
WATER QUALITY TRENDS
Periodic surveys of Saginaw Bay waters since 1935 have provided some
basis for assessing long-term changes or trends in water quality during the
past 40 years. Such trends reflect real changes in the quality of loadings,
chiefly from the Saginaw River system. They also reflect, to an uncertain
degree, changes in climate, lake levels, and other natural cycles. Further-
more, in comparing data from different surveys, allowances must be made for
126
-------
discrepancies due to different methodologies, station locations and sampling
dates. A comparison of all the mean data for 1974 and 1975 (Table 44) shows
how much variation might be expected from year to year on a whole bay basis.
The climatic and flow data already referred to in Figures 9 and 10, and in
Table 7, indicate natural causes for at least some of this variation.
The data show clearly that 1974 was generally a cooler, wetter year than
1975; apparently, enrichment of the bay (via tributaries) and consequent al-
gal production were greater in 1974. There is little reason to suspect that
the observed differences relate to a change in human impact on water quality.
Rather, it appears to have resulted from a short-term climatic change, and
therefore does not constitute a trend.
In our experience, water quality conditions almost anywhere in the bay
are subject to great variation on a seasonal or even weekly basis. This is
due to the often turbulent nature of the open bay and its estuarine charac-
ter; i.e., large chemical gradients frequently occur within the space of a
few kilometers. These variations, imposed on normal seasonal differences
from year to year, complicate the problems of establishing "baseline" water
quality and detecting genuine trends. The point is that no two-year survey
of Saginaw Bay would be adequate to establish any real trends of water qual-
ity such as might result from a gradual change in nutrient loadings; natural
yearly variations are manifestly too great.
Over the 40-year time span, more evidence of any long-term changes in
the human impact on Saginaw Bay waters should be apparent. Unfortunately,
data are scarce for most parameters. In Table 45, data representing three
key parameters are compared: chloride (a conservative tracer); chlorophyll
a (indicating primary production); total phosphorus (a major nutrient). To
compensate in part for differences in sampling coverage and timing among
surveys, the data have been averaged (or expressed as a range) over compar-
able portions of the river and bay. The results suggest a trend, at least
with regard to the history of chloride and chlorophyll a levels.
Chloride concentrations in the Saginaw River during 1935 and 1956 sur-
veys were higher than current values by a factor of 5. This trend is less
pronounced in data for the inner bay and diminishes further in the outer
bay data. It is noteworthy that inputs of chloride to the Saginaw River at
Midland from Dow Chemical Company alone were reduced from 2.70 million pounds/
day in 1965 to 0.89 million pounds/day in 1972 (MWRC, 1974). Similar data
on chlorophyll a and total phosphorus are not available from the earlier sur-
veys. However, the observed changes since 1965 do not suggest any strong
trends during that period.
The 1965 data set is the most suitable for a more detailed comparison
with the 1974-75 survey results. Tables 46-49 show the means and ranges of
data for three subdivisions of the bay and for two comparable stations.
Since 1965 chloride concentrations and conductivity appear to have de-
creased in the inner and middle bay areas by a factor of 2 or 3. Chlorophyll
a levels seem to have increased slightly throughout the bay. Total phos-
127
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TABLE 44. COMPARISON OF ANNUAL MEAN DATA (WHOLE BAY) FOR 1974 AND 1975
PARAMETER
Temperature (°C)
Oxygen, diss. (rag 02/&)
Conductivity, spec. (yS/cm)
Chloride, filt. (rag C1/&)
pH (s.u.)
Alkalinity, tot. (mg CaC03/£)
Secchi disc depth (m)
Chlorophyll a, non-filt.
(yg chl. a/£)
Carbon, unfilt. org. (mg C/£)
Carbon, filt. org. (mg C/£)
Solids, unfilt. tot. (mg/£)
Silicate-silicon, filt. reac.
(mg Si02/£)
Ammonia, filt. (mg N/&)
Nitrate + nitrite-nitrogen, filt.
(mg N/£)
Nitrogen, unfilt. Kjel. (mg N/&)
Nitrogen, tot. (mg N/Jl)
Phosphate-phosphorus, filt. reac.
(mg P/£)
Phosphorus, filt. tot. (mg P/£)
Phosphorus, unfilt. tot. (mg P/£)
Sodium, unfilt. (mg Na/£)
Potassium, unfilt. (mg K/&)
Calcium, unfilt. (mg Ca/£)
Magnesium, unfilt. (mg Mg/£)
ANNUAL MEAN + DEV.
1974
13.6 + 5.9
10.6 + 1.9
260 + 72
13.2 + 9.5
8.45 + .40
92 + 15
1.8 + 1.5
15.7 + 14.3
5.6 + 3.6
4.4 + 2.0
127.4 + 67.6
.99 + .55
.037 + .076
.295 + .344
.326 + .233
.544 + .258
.006 + .009
.006 + .009
.025 + .027
7.0 + 5.5
1.4 + .6
37.0 + 11.5
9.1 + 2.6
1975
14.1+6.5
10.6 + 1.7
248 +_ 54
11.2 + 6.6
8.5 + .3
92 + 16
2.1 + 1.5
11.9 +_ 13.4
5.1 + 2.4
4.3 + 1.9
182.5 + 53.2
.55 + .63
.018 + .020
.225 + .214
.33 + .22
.557 +_ .343
.002 + .003
.007 + .004
.020 + .021
-
-
-
-
128
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TABLE 45. WATER QUALITY CHANGES IN SAGINAW BAY DURING
JULY-OCTOBER, 1935-1975
PARAMETER
Chloride
(ing/ JO
Chlorophyll a
(Mg/JO
Total Phosphorus
(mg/£)
LOCATION1"
SAGINAW
RIVER
50-300
280
170
99.3
62.9
18.0
41.7
34.7
.17
.221
.237
INNER AND
MIDDLE BAY
(SEGMENTS
1,2,3)
25-40
60
47
17.9
16.9
20.7
17.2
21.3
.041
.01 - .07
.038
.037
OUTER BAY
(SEGMENTS
4,5)
10
11
8
2-20
10
7.9
7.9
2.5
5.4
7.2
.018
.01-. 17
.01-. 03
.011
.013
YEAR
1935-36
1956
1965
1966
1970
1974
1975
1965
1974
1975
1956
1965
1971
1974
1975
DATA
SOURCE*
1
2
3
4
5
6
6
3
6
6
2
3
7
6
6
*l-Mich. Stream Cont. Comm. (1937)
2-Beeton, et_ al. (1967)
3-U.S. Fed. Water Poll. Contr. Adm. (1969)
4-U.S. Lake Survey Ctr. (1966)
5-Schelske and Roth (1973)
6-Present report (1977)
7-Canadian Cetr. for Inland
Waters (1971)
tOne meter samples only.
129
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TABLE 46. COMPARISON OF 1965 (FWPCA) and 1974-75 (EPA) DATA* FOR INNER SAGINAW BAY
PARAMETER
Temperature, °C
Dissolved Oxygen
pH
Conductivity, pS/cm
Chloride (f. Cl)
Ammonia-N (f. NH3-N)
Nitrate + Nitrite-N
(f. N03 + N02-N)
Total N (tot. N)
Dissolved P (f. tot. P)
Total P (u. tot. P)
Calcium (u. Ca)
Magnesium (u. Mg)
Sodium (u. Na)
Potassium (u. K)
Chlorophyll a, yg/A
(n-f. chl. a)
1965 - (4 STA.)
MEAN
15.5
9.8
8.0
430
62
.36
.3
-
-
49
16
20
5.5
24.4
RANGE
3.5 - 22.0
6.2 - 12.7
7.1 - 8.5
270 - 720
25 - 130
.10 - 1.60
<.l - 1.2
<.01 - .07
<.01 - .17
26 - 72
10 - 33
9-31
2.3 - 9.5
—
1974 - SEGMENT 1
(13 STA.)
MEAN
19.1
9.96
8.78
294
20.8
.039
.091
.664
.008
.048
38.8
10.3
11.7
1.7
33.5
RANGE
11.0 - 24.0
6.8 - 11.9
8.2 - 9.2
227 - 843
10.0 - 49.0
.009 - .138
.050 - .300
.330 - 1.43
.002 - .020
.004 - .116
31.0 - 53.0
8.0 - 14.0
5.0 - 50.0
1.2 - 2.3
8.0 - 68.3
1975 - SEGMENT 1
(5 STA.)
MEAN
18.9
9.97
8.72
308
20.1
.039
.168
.968
.017
.060
-
-
-
-
34.4
RANGE
10.6 - 26.8
6.0 - 13.5
7.6 - 9.4
230 - 492
11.0 - 44.0
.003 - .153
.050 - 1.10
.340 - 2.74
.004 - .083
.017 - .160
-
-
-
-
5.7 - 87.9
* All values in mg/£ unless otherwise indicated,
-------
TABLE 47. COMPARISON OF 1965 (FWPCA) AND 1974-75 (EPA) DATA* FOR MIDDLE SAGINAW BAY
PARAMETER
Temperature, °C
Dissolved Oxygen
pH
Conductivity, yS/cm
Chloride (f. Cl)
Ammonia-N (f. NH3-N)
Nitrate + Nitrite-N
(f . N03 + N02-N)
Total N (tot. N)
Dissolved P (f. tot. P)
Total P (u. tot. P)
Calcium (u. Ca)
Magnesium (u. Mg)
Sodium (u. Na)
Potassium (u. K)
Chlorophyll a, pg/£
(n-f. chl. a)
1965 - (9 STA.)
MEAN
15.5
9.8
8.0
324
36
.19
.1
.46
-
-
41
14
15
4.0
16.9
RANGE
3.5 - 21.5
8.0 - 12.6
7.1 - 8.4
180 - 540
4 - 100
<.05 - .94
<.l - 1.0
<.l - 1.0
<.01 - .07
<.01 - .07
27 -54
8-25
3-37
.9 - 5.5
—
1974 - SEGMENTS 2 & 3
(23 STA.)
MEAN
19.3
9.88
8.7
258
14.1
.044
.099
.623
.007
.031
37.1
9.6
8.5
1.5
24.6
RANGE
10.0 - 26.4
5.1 - 12.2
7.8 - 9.2
169 - 321
3.0 - 46.0
.008 - .239
.050 - .400
.280 - 2.250
.002 - .033
.004 - .069
30.0 - 48.0
8.0 - 12.0
5.0 - 13.0
1.2 - 2.1
2.3 - 58.5
1975 - SEGMENTS 2 & 3
(13 STA.)
MEAN
18.9
9.8
8.7
253
12.5
.007
.077
.625
.007
.029
-
-
-
-
19.4
RANGE
10.2 - 26.9
6.3 - 12.9
8.1 - 9.4
209 - 367
6.0 - 28.0
.003 - .023
.050 - .300
.180 - 2.70
.002 - .021
.002 - .078
-
-
-
-
1.8 - 68.5
u>
* All values in mg/£ unless otherwise indicated.
-------
TABLE 48. COMPARISON OF 1965 (FWPCA) AND 1974-75 (EPA) DATA* FOR OUTER SAGINAW BAY
PARAMETER
Temperature, °C
Dissolved Oxygen
pH
Conductivity, yS/cm
Chloride (f. Cl)
Ammonia-N (f. NH3-N)
Nitrate + Nitrite-N
(f. N03 + N02-N)
Total N (tot. N)
Dissolved P (f. tot. P)
Total P (u. tot. P)
Calcium (u. Ca)
Magnesium (u. Mg)
Sodium (u. Na)
Potassium (u. K)
Chlorophyll a, yg/fc
(n-f. chl. a )
1965 - (10 STA.)
MEAN
13.0
10.3
7.9
210
8
.14
.2
.47
-
-
27
11
4
1.5
2.5
RANGE
3.0 - 20.0
8.2 - 12.5
6.9 - 8.3
120 - 340
4 -18
<.05 - .49
<.l - .5
<.l - 1.38
<.01 - .13
<.01 - .17
22 - 35
8-19
3-7
.9 - 2.2
—
1974 - SEGMENTS 4 & 5
(19 STA.)
MEAN
17.8
9.9
8.5
219
8.2
.031
.161
.466
.004
.012
29.2
7.6
3.7
.9
7.1
RANGE
7.0 - 29.0
8.3 - 11.6
7.9 - 9.1
186 - 288
3.0 - 21.0
.005 - .128
.050 - .300
.190 - .940
.002 - .014
.002 - .050
24 - 36.0
7.0 - 10.0
3.0 - 8.0
0.7 - 1.4
0.4 - 57.4
1975 - SEGMENTS 4 & 5
(14 STA.)
MEAN
17.7
9.9
8.5
219
7.9
'.013
.147
.422
.005
.012
-
-
-
-
7.2
RANGE
10.6 - 25.1
7.4 - 12.8
8.0 - 9.1
192 - 323
5.0 - 21.0
.003 - .034
.050 - .200
.180 - 2.48
.002 - .025
.002 - .071
-
-
-
-
0.9 - 38.8
* All values in rag/A unless otherwise indicated.
-------
TABLE 49. COMPARISON OF 1965 (FWPCA) AND 1974-75 (EPA) DATA*
FOR TWO SIMILAR LOCATIONS IN INNER SAGINAW BAY
Parameter
Temperature, °C
Dissolved Oxygen
PH
Conductivity, yS/cm
Chloride (f. Cl)
Ammonia-N (f. NH-j-N)
Nitrate + Nitrite-N
(f . N03 + N02-N)
Total N (tot. N)
Dissolved P
(f. tot. P)
Total P (u. tot. P)
Calcium (u. Ca)
Magnesium (u. Mg)
Sodium (u. Na)
Potassium (u. K)
Chlorophyll a, yg/£
(n-f. chl. a)
1965
Sta. X100
17.0
8.0
7.7
820
170
.55
.74
1.53
.10
.17
87
26
52
13.6
-
1974-75
Sta. 9
16.3
8.3
8.3
525
59.1
.211
.528
1.475
.068
.163
-
25t
35t
4.4t
31.8
1965
Sta. H232
15.5
9.8
8.0
320
35
.16
.20
.48
-
-
40
13
13
3.6
18.2
1974-75
Sta. 24
15.5
9.3
8.7
273
13.5
.045
.318
.424
.004
.028
34t
8t
4t
l.lt
18.7
*Mean values in mg/£, except as indicated.
t!974 data only.
133
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phorus data are inconclusive, as are mean values for the various forms of
nitrogen. Concentrations of major metals have decreased throughout the bay
since 1965; the percentage decrease was least for calcium and greatest for
potassium.
STATISTICAL RELATIONSHIPS
Correlation analyses and multiple regression analyses were undertaken
to define statistical relationships among the chemical and physical para-
meters studied. First, simple Pearson correlation coefficients (Pearson's r),
which represent the degree of association between two variables, were com-
puted for all combinations of parameters. The sample matrix of Pearson's r,
shown in Table 39, includes only those values significant at the 99% level.
Among the relationships between parameters, those of chloride, Secchi disc
depth and various nutrients with chlorophyll a are informative since chloro-
phyll a has long been used as an indicator of algal biomass. Although the
correlations alone do not establish causality, they still should reflect the
dependence of algal biomass on "limiting" nutrients, including nitrogen and
phosphorus species. To that extent the statistical results may suggest cause-
and-effect relationships that warrant closer study.
Since the number of samples (parameter pairs) used in the correlations
was different for each cruise, an attempt was made to normalize Pearson's r
by using the Z transformation with each standard deviation. In Figures 49-
53 each value of Pearson's r, plotted against time, has been normalized for
variation in sample numbers by the use of the Z transformation divided by its
standard deviation (Zr/Sz). Thus, the significant values of Zr/Sz can be
considered as corrected for variations in sample numbers.
The resulting plot of the correlation of chlorophyll a with temperature
is shown in Figure 49. In segments 1, 4 and 5, significant correlations are
shown for some cruises. This is due to the fact that warmer waters and/or
greater runoff, particularly in the spring, were associated with higher pri-
mary production both in the inner and outer bay.
Correlations of chlorophyll a with chlorides were significant mainly
during the spring and fall and especially in the outer bay (Figure 50).
While chloride itself has little importance as a plant nutrient, it serves to
label Saginaw River water which is enriched with respect to many nutrients.
Some of these may stimulate algal production in the outer bay.
Secchi disc depth was correlated sometimes with chlorophyll a (Figure
51) in part because some reduction in water transparency is caused by algal
cells, especially during periodic blooms. However, it is apparent that tur-
bidity or decreased Secchi depth is not strongly correlated with algal popu-
lation (i.e., chlorophyll), particularly in segment 1 where sediment loadings
from the Saginaw River strongly affect water clarity.
In all areas but segment 3 chlorophyll a and total nitrogen levels appear
to be correlated best (Figure 52) during three separate periods in the spring,
summer and fall. These may correspond to bloom situations when the rates of
134
-------
either nitrogen input or fixation (by blue-green algae) were relatively high.
However, this pattern was less noticeable during 1974 than in 1975.
The correlations of chlorophyll a with total phosphorus (Figure 53) were
remarkably similar to those with chloride (Figure 49). This suggests that
the phosphorus content of Saginaw River water (labelled by chloride) stimu-
lates algal production throughout the bay.
In all cases the correlation of chlorophyll a with the above parameters
was probably least variable in segment 3. This may be due in part to the
stabilizing effect of nutrient loadings other than those from Saginaw River
waters. This has already been mentioned in relation to total carbon levels
in segment 3. Secondly, there is notable difference in these correlations
between 1974 and 1975, which suggests a variation in cause and effect rela-
tionships with climatic or other circumstances.
The results of multiple regression analysis shown in Tables 40 and 41
indicate that chlorophyll a levels (as the dependent variables) were largely
predictable on the basis of "particulate" phosphorus levels; the latter data
were calculated by subtracting filtered total P from unfiltered total P. Pre-
dictability was improved only slightly by addition of f. reac. phosphate and
f. nitrate + nitrite-N data to the equation. This was especially true in
1974. Such strong correlations between chlorophyll a and particulate forms
of phosphours and nitrogen are to be expected since these are important con-
stituents of phytoplankton. Soluble forms of these nutrients, however, may
vary inversely with chlorophyll concentration since they tend to be depleted
from bay waters during algal blooms.
In Table 42 similar results are presented for each segment. These show
that chlorophyll a varies primarily as a function of total or particulate
phosphorus. Secondarily important are dissolved forms of nitrogen and phos-
phorus as well as total nitrogen. On the whole, predictability of chlorophyll
a levels from nutrient data appeared to be most reliable in the outer bay,
segments 4 and 5.
RELATION TO WATER QUALITY STANDARDS
Results for only a few of the parameters surveyed can be considered in
the context of EPA and Michigan standards for public water supplies. Current
standards are shown in Table 50.
Although a few ammonia values recorded in the Saginaw River and at seg-
ment 1 stations (up to 2.14 mg N/£) exceeded the EPA standards, nearly all
mean values for each station and segment were well below 0.5 mg N/£. Most
segment means were less than 0.05 mg N/£. No single value for nitrate +
nitrite reached 10 mg N/£; the highest value was 3.6 mg N/£. Most mean values
for stations and segments were below 0.5 mg N/£. All chloride values (maxi-
mum, 185 mg Cl/£) were below the EPA standard of 250 mg/£. Annual means for
four stations in the Saginaw River mouth exceeded the Michigan standard of
50 mg Cl/£ (monthly average). However, no quarterly mean for segment 1 was
135
-------
TABLE 50. WATER QUALITY STANDARDS FOR PUBLIC WATER SUPPLIES*
Parameter
EPA Standard
(1972)
Michigan Standard for
Great Lakes (1977)
Ammonia - N
Chloride
Dissolved Oxygen
Nitrate + Nitrite
PH
0.5
250.0
10.0
5.0 - 9.0
50.0**
6.0
6.5 - 8.8
* All values except pILin mg/£.
** Based on monthly average.
136
-------
greater than 26.4 mg Cl/£. A number of dissolved oxygen values in the Saginaw
River were less than the Michigan standard of 6 mg C>2/£; the minimum was 2.7.
However, the lowest mean values were 6.7 mg 02/£ for a river station (54) and
9.4 mg 02/£ for segment 3. Some pH values in all segments and in the river
exceeded the upper limits of 9.0 (Michigan) and 8.8 (EPA standard). The full
range of pH recorded during both years was 6.88 - 9.58. Five station mean
values were slightly above 8.8. Segment means, except in two quarters, were
below the EPA upper limit of 8.8.
The standards for nutrients (other than nitrate + nitrite) required to
protect water supplies, wildlife and recreational waters are not defined
quantitatively. Michigan regulations state:
Rule 1060. Nutrients originating from domestic, industrial,
municipal or domestic animal sources shall be limited to the extent
necessary to prevent stimulation of growths of aquatic rooted, at-
tached and floating plants, fungi or bacteria which are or may be-
come injurious to the designated uses of the waters of the state
(MWRC, 1974).
It is clear that current levels of phosphorus, nitrogen and other nutrients
in Saginaw Bay do stimulate rich algal growths, but whether to an "injurious"
degree remains to be established.
Sawyer (1947) has defined critical springtime levels of inorganic nitro-
gen and phosphorus (reactive phosphates) that he considered sufficient to
cause algal blooms and which therefore characterize eutrophic waters. These
thresholds are:
Inorganic N — 0.300 mg N/£
Inorganic P — 0.010 mg P/£
Yearly averages of inorganic nitrogen (nitrate, nitrite and ammonia) in Sagi-
naw Bay indicate that segments 1, 2 and 3 were above Sawyer's critcial con-
centration of 0.300 mg N/£. On the basis of yearly averages of inorganic re-
active phosphates (orthophosphates), only segment 1 (1974) was above the
critical level of 0.010 mg P/£. However, on the basis of 2nd quarter con-
centrations, both segments 1 and 3 were above the critical level. Segments
4 and 5 were well below it.
Clearly, these values alone are not reliable as indicators of trophic
condition in Saginaw Bay. Frequently, the lowest levels of reactive phos-
phate in the inner bay, for instance, may simply reflect algal uptake during
blooms rather than a decrease in the input rate. Turnover rates of available
nitrogen and phosphorus are the crucial factors not apparent in these results.
Cooperative Studies
Remote Sensing —
These results also have been used in a study conducted by Bendix Aero-
space Systems Division in Ann Arbor, Michigan. The project, entitled "Appli-
137
-------
cation of Landsat to the Surveillance and Control of Lake Eutrophication in
the Great Lakes Basin", was supported by Contract NAS 5-20942 from the
National Aeronautics and Space Administration (NASA). The objectives of that
part of the study related to Saginaw Bay were to use satellite multispectral
data to estimate levels of various water quality factors and to map their
distribution throughout the bay. Thus, Landsat surveillance was intended to
supplement mapping of nutrient distributions based on conventional sampling
from ships. Data from the bi-weekly cruises, which were scheduled to coin-
cide with Landsat passes over Saginaw Bay, were correlated with reflectance
measurements recorded by satellite sensors in four regions of the visible to
near-infrared spectrum. This approach was designed to show empirical rela-
tionships between remote and direct measurements that could be used to pre-
dict concentrations in unsampled areas.
The satellite data that Bendix chose to process were recorded on two
occasions, June 3, 1974 and July 31, 1975, coinciding with cruises 8 and 25,
respectively (Table 43). In applying a step-wise linear regression analysis
to the data, the water quality measurements were each considered as depend-
ent variables; Landsat reflectance measurements were regressed against these
as independent variables. The results indicate which sensor band, band
ratio or combination of bands was most useful for predicting levels of each
water quality parameter. Correlation coefficients and prediction accuracy
were evaluated in each case. The processed Landsat data were used finally
to generate a color-coded image or map of water quality categories through-
out the bay. Examples are shown in Figures 54 and 55.
Results of the Bendix study suggest that such water quality maps based
on calibrated satellite data can be used with fair reliability to estimate
ranges of concentration for certain parameters, even for those variables
(e.g., total phosphorus, chloride) which are not directly detectable by re-
mote sensors. This is true because water masses with a varying content of
Saginaw River water are enriched correspondingly with nutrients and salts.
The same river water is characterized also by its color and particle con-
tent, which are markedly different from those of Lake Huron water. As a
result, river water in various stages of dilution can be identified by vis-
ible characteristics which are correlated with other conservative but in-
visible features of water quality.
However, the results showed that relationships between turbidity and
other variables, such as chloride or temperature, are strictly empirical and
are subject to change, perhaps even on a daily basis. Moreover, the Landsat
data, even on apparently clear days, are affected by atmospheric losses that
may differ in each spectral band. In summary, it is apparent that regular
Landsat mapping of water quality in the bay is feasible with the following
provisions: that sampling is conducted within a few hours of Landsat passage;
that such concurrent measurements are used to "re-calibrate" the satellite
data on each occasion; that the errors of estimation for each parameter (based
on comparison of actual and predicted values) are within acceptable limits.
The advantages of using Landsat monitoring, as an adjunct to conventional
point-sampling are that is provides an economical basis for extrapolating
water quality parameters from point samples to unsampled areas, and it pro-
138
-------
vides a synoptic view of water mass boundaries that no reasonable amount of
point sampling could duplicate.
The methodologies, results and conclusions of this study are discussed
in more detail elsewhere (Rogers, at a.1., 1975a; Rogers, .et al, 1975b;
Rogers, jit al., 1976).
139
-------
REFERENCES
American Public Health Association (APHA), American Water Works Association
and Water Pollution Control Federation. 1971. Standard Methods for
the Examination of Water and Waste Water, 13th Ed. American Public
Health Assoc., Washington, D.C. 874 p.
Batchelder, T.L. 1973. Saginaw Bay baseline ecological survey. 1971.
Waste Control Department, Dow Chemical Co., Midland, Michigan. 56 p.
Beak Consultants. 1974. Site ecology, Sect. 2.7. In: V. 1-2, Environ-
mental Report, Quanicassee Plant Units 1 and 2. Consumers Power Co.,
Jackson, Michigan (n.p.)
Beeton, A.M., S.H. Smith and F.H. Hooper. 1967. Physical limnology of
Saginaw Bay, Lake Huron. Tech. Rep. No. 12, Great Lakes Fishery
Commission, Ann Arbor, Michigan. 56 p.
Canadian Centre for Inland Waters (CCIW). 1971. Limnological data on Lake
Huron (unpublished). Filed at CCIW, Burlington, Ontario.
Filkins, J.C. and M.D. Mullin. 1976. Potential interference from filter
media in nutrient chemical analysis. Presented at 19th Conf. on Great
Lakes Res., Internat. Assoc. Great Lakes Res. (May 4-6, 1976), Guelph,
Ontario.
Freedman, P.L. 1974. Saginaw Bay: An Evaluation of Existing and Historical
Conditions. EPA-905/9-74-003, U.S. Environmental Protection Agency
(Region V), Chicago, Illinois. 137 p.
Great Lakes Basin Commission (GLBC). 1975. Great Lakes Basin Framework
Study, Appendices 6, 8, 17, 21 and 22. Great Lakes Basin Commission,
Ann Arbor, Michigan.
Michigan Stream Control Commission (MSCC). 1937. Saginaw Valley Report.
State of Michigan, Dept. of Natural Resources, Lansing, Michigan. 156 p.
Michigan Water Resources Commission (MWRC). 1974. Water Quality Management
Plan for Lower Lake Huron Basin. State of Michigan, Dept. of Natural
Resources, Lansing, Michigan. (n.p.)
140
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Richardson, W.L. and V.J. Bierman, Jr. 1976. A mathematical model of pollu-
tant cause and effect in Saginaw Bay, Lake Huron, p. 138-158. In:
Water Quality Criteria Research of U.S. Environmental Protection Agency.
Proc. of Symp. on Marine, Estuaries and Freshwater Quality, AIBS 26th
Ann. Mtng. (August 1975), Corvallis, Oregon. 207 p.
Rogers, R.H., L.E. Reed and V.E. Smith. 1975a. Computer mapping of turbidity
and circulation patterns in Saginaw Bay, Michigan (Lake Huron) from ERTS
data, p. 415-429. In; Proc. of American Congress of Surveyors and
Mappers, and American Society of Photogrammetry (ACSM-ASP) Convention,
(March 9-14, 1975), Washington, D.C. 799 p.
Rogers, R.H., N.J. Shah, J.B. McKeon, D. Wilson, L.E. Reed, V.E. Smith and
N.A. Thomas. 1975b. Application of Landsat to the surveillance and con-
trol of eutrophication in Saginaw Bay, p. 437-446. In: Proc. of Tenth
International Symposium on Remote Sensing of Environment, Ann Arbor,
Michigan. V.-2, 1456 p.
Rogers, R.H., N.J. Shah, J.B. McKeon and V.E. Smith. 1976. Computer mapping
of water quality in Saginaw Bay with Landsat digital data, p. 584-596.
In: Proc. of American Congress of Surveyors and Mappers, and American
Society of Photogrammetry (ACSM-ASP) Convention (Feb. 22-28, 1976).
Washington, D.C. 621 p.
Sawyer, C.N. 1947. Fertilization of lakes by agricultural and urban drain-
age. J. New England Water Works Assoc. 61:109-127.
Schelske, C.L. and R.C. Roth. 1973. Limnological survey of Lakes Michigan,
Superior, Huron and Erie. Publ. No. 17, Great Lakes Research Div.,
Univ. of Michigan, Ann Arbor, Michigan. 108 p.
Strickland, J.D.H. and T.R. Parsons. 1968. A Practical Handbook of Seawater
Analysis. Bull. 167, Fish. Res. Brd. of Canada, Ottawa. 311 p.
U.S. Environmental Protection Agency (EPA). 1971. Methods for Chemical
Analysis of Water and Waste Water. Water Quality Off., Analytical
Quality Control Lab., Cincinnati, Ohio. 312 p.
U.S. Environmental Protection Agency (EPA). 1976. Quality Criteria for
Water. EPA-440/9-76-023. Washington, D.C. 501 p.
U.S. Lake Survey Center (LSC). 1966. Lake Huron limnological data (unpub-
lished). Filed at Great Lakes Environmental Research Lab. (GLERL), U.S.
Dept. of Commerce, Ann Arbor, Michigan.
U.S. Federal Water Pollution Control Administration (FWPCA). 1969. Lake
Huron, Michigan Water Quality Data, 1965 Survey. Clean Water Series:
LHBO-17-A. Dept. of the Interior, Washington, D.C. 331 p.
U.S. Fish and Wildlife Service (FWS). 1969. Fish and Wildlife as Related
to Water Quality of the Lake Huron Basin. Dept. of the Interior,
Washington, D.C. 134 p.
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U.S National Academies of Science and Engineering (NAS/NAE). 1972. Water
Quality Criteria, 1972. Environmental Studies Board, National Academy
of Science and National Academy of Engineering, Washington, D.C. 594 p.
Welch, P.S. 1948. Limnological Methods. McGraw-Hill Book Co., New York.
381 p.
142
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-77-125
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Survey of Chemical Factors in
Saginaw Bay (Lake Huron)
5. REPORT DATE
October 1977
issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
V.E. Smith, K.W. Lee, J.C. Pilkins, K.W. Hartwell,
K.R. Rygwelski, J.M. Townsend
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Cranbrook Institute of Science
Bloomfield Hills, Michigan 48013
10. PROGRAM ELEMENT NO.
1BA608
11. CONTRACT/GRANT NO.
R802685
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory - Duluth, MN
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
13. TYPE OF REPORT AND PERIOD COVERED
Final - 1974 - 1975
14. SPONSORING AGENCY CODE
EPA/600/03
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Water quality in Saginaw Bay, Michigan (western Lake Huron) was surveyed
during 32 cruises in 1974 and 1975. as part of the International Joint Commission's
Upper Lakes Reference Study co-sponsored by the United States and Canada. Goals
of the study were to establish a base of water quality information and to
provide data required to model biological and hydrological processes in the bay.
Sampling and in situ monitoring were conducted at 18-day intervals during April -
October (coinciding with Landsat satellite passes) and approximately at monthly
intervals during November - March. Samples were collected from several depth levels
at 59 stations in 1974 and at 37-station subset of these 59 stations in 1975.
Measurements included: temperature, dissolved oxygen, conductivity, chloride, PH
alkalinity, Secchi depth, chlorophylls, nitrate and phosphate, organic nitrogen,
total phosphorus, organic carbon, total solids and major metals. Additional
diurnal or daily sampling was conducted at selected stations.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Nutrients
Chlorophylls
Water Chemistry
Lake Huron
Saginaw Bay
Eutrophication
Chlorophyll a
08/H
13/B
13. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (This Report)
unclassified
21. NO. OF PAGES
159
20. SECURITY CLASS (This page)
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
143
* U.S. GOVERNMENT PRINTING OFFICE: 1977— 757-140/6594
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