I REFERENCE GROUP
POLLUTION
ACTMTIES
PB 296851
UNITED STATES
GREAT LAKES
TRIBUTARY LOADINGS
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UNITED STATES GREAT LAKES
TRIBUTARY LOADINGS
by
William C. Sonzogni
Timothy J. Monteich
William N. Bach
V. Gregory Hughes
Great Lakes Basin Commission Staff
Ann Arbor, Michigan
To be used as a portion of the Technical Reports of the
International Reference Croup on GREAT LAKES POLLUTION FROM
LAND USE ACTIVITIES of the International Joint Conanission—
prepared in partial fulfillment of U.S. Environmental
Production Agency Contract No. 68-01-1598 with the Great
Lakes Lisin Commission.
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ACKNOWLEDGEMENTS
The authors wish to acknowledge the support of members of the Great
Lakes Basin Commission staff, particularly William Sklmin, Thomas Heidtke,
Eugene Jarecki, end Leonard Crook. The secretarial support of Ruth Click
and Marie Murrell, as well as others, is much appreciated. The authors are
also indebted to the many individuals, most of whom are from agencies of the
eight Great Lakes states, who collected and analyzed samples from many
individual tributaries across the Basin, and without which this report
could not have been completed. In addition, we wish to acknowledge the
support of U. S. EPA, which sponsored this project. Mr. Merle Tellekson,
EPA's representative on PLUARG and the U. S. Task D Chairman, has been
particularly helpful and supportive in this as well as other PLUARG projects
we have undertaken.
A special thanks goes to those individuals who supplied specific
Information that was used in this report, especially those listed below:
Peter Anttila, U.S.G.S.
Roger Bat-merman, Wisconsin DNR
Bob Biebel, Southeastern Wisconsin Regional Planning Commission
Steve Buda, Michigan DNR
Raymond Canale, University of Michigan
Andy Carlson, New York State Department of Environmental Conservation
W. David Carpenter, U. S. Soil Conservation Service
John Clark, International Joint Commission
Dave Dolan, U. S. Environmental Protection Agency
Ron Drynan, International Joint Commission
Marty Harmless, Wendel Engineers, New York
James Kramer, McMastar University
Dave Krause, U. S. Environmental Protection Agency
Bruce Manny, U. S. Fish and Wildlife Service
Bill McCracken, Michigan DNR
Tom Mulr, Canada Centre for Inland Waters
Eugene Pinkstaff, U. S. Environmental Protection Agency
Bill Richardson, U. S. Environmental Protection Agency
David Rockwell, J. S. Environmentil Protection Agency
Hank Samide, New York State Department of Environmental Conservation
Keith Schmlde, U. S. Soil Conservation Service
John achroeter, Michigan DNR
Jerry Welch, U. S. Soil Conservation Service
Steve Yaksich, U. S. Army Corps of Engineers
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DISCLAIMER
The study discussed in this Report wad carried out as part of the
efforts of the Pollution from Land Use Activities Reference Group, an
organization of the International Joint Commission, established under the
Canada-U. S. Great Lakes Water Quality Agreement of 1972. Funding was
provided through the U. S. Environmental Protection Agency. Findings and
conclusions are those of the authors and do not necessarily reflect the
views of the Reference Group or its recommendations to the Commission.
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TABLE OF CONTENTS
PAGE NO.
LIST OF FIGURES vil
LIST OF TABLES ix
SUMMARY 1
CONCLUSIONS 3
INTRODUCTION 7
METHODOLOGY 9
lARAMETERS 9
TOTAL RIVER MOUTH LOAD CALCULATIONS 10
Data Sources 10
Base Years 11
Watershed Areas ] 1
Correcting Loads to the River Mouth ].5
Method of Calculating Loadings 13
POINT SOURCE LOADS ' • • 22
Data Sources 22
Location of Point Sources 24
Base Years 24
Estimation of Point Source Loads 25
Municipal Point Sources 25
Industrial Point Sources 27
DIFFUSE LOADS 28
Monitored Areas 28
Unmonitored Areas 29
RESULTS 31
DISCUSSION 71
ACCURACY OF TRIBUTARY LOADING ESTIMATES 71
IJC Sr.rveillence versus U.S. Task D Total Phosphorus Loads 72
EVALUATION OF U.S. TRIBUTARY LOAD ESTIMATES 74
Flow .74
Great Lakes Load Summary 80
Lake Superior 82
River Basin Group 1.1 82
River Basin Group 1.2 84
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TABLE OF CONTENTS (continued)
PACE NO.
Lake Michigan 85
River Basin Group 2.1 85
River Basin Group 2.2 87
River Basin Group 2.3 87
River Basin Group 2.4 89
Lake Huron 90
;iver Basin Group 3.1 90
River Basin Group 3.2 91
Lakt Erie 91
. Iver Basin Group 4.1 92
River Basin Group 4.2 92
River Basin Group 4.3 92
River Basin Group 4.4 93
Lake Ontario 93
River Basin Group 5.1 93
Fiver Basin Group 5.2 94
R.ver Basin Group 5.3 95
DIFFUSE LOADS 95
Transmission of Point Sources 96
Diffuse Unit Area Loads 97
T-'pes of Diffuse Sources 99
Control of Diffuse Sources 100
POINT SOURCE LOADS 100
Municipal Versus Industrial Point Sources 100
Effect of Small Point Sources 104
Effect of Reducing Municipal Loads 105
FLOW/CONCENTRATION RELATIONSHIPS 107
Variability of Flow 107
Variability of Concentration 110
Variability of Loads 112
Tributary Response Variations 112
Example of Stable Response Tributary - Grand River 117
Example of Event Response Tributary - Nemadji River 118
Watershed Characteristics Versus Tributary Response 121
Recommended Sampling Strategy for Stable Response vs.
Event Response Streams 124
Critical Erosion Period 126
REFERENCES 129
APPENDIX A - Individual Tributary River Mouth Loading Data 133
APPENDIX B - Haps Showing Regional Differences in the Total
Phosphorus and Suspended Solids Diffuse Unit
Area Loading Rates 157
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LIST OF FIGURES
NUMBER PAGE NO.
1 YEARLY FLUCTUATIONS IN FLOW 108
2 MONTHLY FLUCTUATIONS IN FLOW 109
3 MONTHLY CHANGES IN TOTAL P CONCENTRATIONS Ill
4 MAUMEE RIVER - FLOW VS TOTAL P CONCENTRATION 116
5 SOIL TEXTURE RIVER BASIN GROUP 1.1 122
6 SOIL TEXTURE RIVER BASIN GROUP 2.3 123
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LIST OF TABLES
NUMBER PAGE HO.
1 DRAINAGE AREA MEASUREMENT (HYDROLOGIC) 12
2 EXAMPLE OF LOAD CALCULATION USING THE RATION ESTIMATOR
PROGRAM 16
3 EXAMPLE OF RATIO ESTIMATOR RIVER MOUTH LOAD CALCULATION
USING STRATA 19
4 MEAN EFFLUENT CONC2NTRATION FOR GREAT LAKES MUNICIPAL
TREATMENT PIANTS 26
5 MUNICIPAL PLANT EFFLUENT CONCETNRATIONS 27
6 U.S. GREAT LAKES TRIBUTARY LOADINGS 32
7 HYDROLOGIC AREA LOADS 35
8 COMPARISON OF SURVEILLANCE SUBCOMMITTEE A?tt> U.S. TASK D
1976 TOTAi, PHOSPHORUS TRIBUTARY LOADS 73
9 ESTIMATED TOTAL ANNUAL MEAN DAILY TRIBUTARY FLOW TO
THE GREAT LAKES 74
10 TOTAL ANNUAL DAILY FLOW PER UNIT AREA OF WATERSHED 75
11 INDIVIDUAL ANNUAL MEAN FLOW FROM U.S. GREAT LAKES
TRIBUTARIES 76
12 RATIO OF SPRING (MARCH + APRIL + MAY) FLOWS FOR SEVERAL
GREAT LAKES TRIBUTARIES 79
13 RATIOS OF CHLORIDE LOAD AND ANNUAL FLOW BETWEEN WATER
YEARS 1975 and 1976 81
14 TOTAL PHOSPHORUS DIFFUSE LOADS ASSUMING 50 and 100 PERCENT
DELIVERY OF UPSTREAM POINT SOURCES 1975 96
15 EXAMPLE COMPUTER PRINTOUT OF UPSTREAM AND DOWNSTREAM
POINT SOURCE LOADS 98
16 1975 AND 1976 TOTAL TRIBUTARY POINT SOURCE LOADS
(MT/YR) FROM KUNICIPAL AND INDUSTRIAL PLANTS 102
17 COMPARISON OF POINT SOURCE PHOSPHORUS INPUTS TO LAKK ERIE
TRIBUTARIES COMPILED BY THE LAKE ERIE WASTEWATFR
MANAGEMENT STUDY AND GLBC (THIS STUDY) 105
18 U.S. TRIBUTARY TOTAL PHOSPHORUS LOADS ASSUMING
DIFFERENT MUNICIPAL EFFLUENT PHOSPHORUS CONCENTRATIONS 106
19 MANITOWOC RIVER (WISCONSIN) SUSPENDED SOLIDS LOADING DATA 113
20 LINEAR REGRESSION OF FLOW (cfs) VS CONCENTRATION (itigAO 114
21 GRAND RIVER TOTAL PHOSPHORUS AND SUSPENDED SOLIDS LOADS
CALCULATED BASED ON DAILY AND A MONTHLY SUBLET
OF THESE SAMPLES (DURING WATER YEAR 1976) 118
22 AVERAGE ANNUAL TOTAL PHOSPHORUS AND SUSPENDED SOLIDS
CONCENTRATION MEASURED NEAR THE MOUTH OF THE
GRAND RIVER SINCE 1963 119
23 NEMADJI RIVER (WISCONSIN) SUSPENDED SOLIDS DATA 120
24 LAKE HURON SOIL DATA 125
ix
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SUMMARY
Annual loads to rhe Great Lakes from U. S. tributaries were estimated
for total phosphorus, soluble ortho phosphorus, suspended solids, total
nitrogen, nitrate nitiogen, anmonia nitrogen, and chloride. Loads were
calculated for water years 1975 and 1976 using all available data. All
loads for monitored tributaries were calculated using the ratio-estimator
calculation method except for Lake Erie tributary loads which were obtained
from the Lake Erie Uastewater Management Study. In order to provide complete
coverage of the basin, loads from unmonitored watersheds were estimated
from unit area loads determined from similar and usually adjacent monitored
watersheds.
Lake Erie received the highest phosphorus and suspended solids
tributary loads during water year 1975, and Lake Superior the smallest.
Tributary loads of most parameters were higher during the 1976 water year
than the 1975 water year for all Lakes except Lake Superior. Differences in
loads generally corresponded with trends in flow. Tributary flows during
water years 1975 and 1976 were higher than the long-term average flows,
with the exception of Lake Superior tributaries.
Municipal and industrial point sources discharging to U. S. Great Lakes
tributaries were inventoried and their loading contribution estimated.
Emphasis was placed on phosphorus and suspended solids loads, with the most
complete information being available for municipal sources. When 100
percent transmission to the river mouth was assumed, identified point sources
accounted for a relatively small percent of the total tributary load.
Significantly reducing the assumed delivery of identified point source loads
generally resulted in only a slight increase in the proportion coming from
non-point sources. The non-point or diffuse unit area loading rate varied
widely from year-to-year as would be expected due to annual variations in
total tributary loads.
Two broad categories of Great Lakes tributaries were noted. Loads
from "event response" tributaries were greatly influenced by runoff events.
However, loads from "stable response" tributaries were not as greatly
influenced by runoff events, since concentrations did not usually vary
greatly with flow, and variations in flow with time tended to be more
moderate. Event response tributaries (such as many of the Lake Erie
tributaries) had high annual diffuse unit area loading rates for phosphorus
and suspended solids, while stable response tributaries (such as many found in
the eastern basin of Lake Michigan) had relatively small annual diffuse unit
area loading rates for these parameters. Although many factors probably
influence tributary response, the texture of surface soils in the watershed
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is thought to je very important. Event response tributaries tend to drain
watersheds whose soils have a high proportion of fine grained, clay particles.
while stable response tributaries have watersheds with relatively coarse-
grained, sandy soils.
Importantly, while the estimated loads are believed to be based on the
best available information, they are naturally subject to the limitations of
the data and must be interpreted with these limitations in mind. A major
source of < rror for the estimated loads of some tributaries is the lack
of representative data over different flow regimes during the annual cycle.
However, if the data are carefully interpreted with the limitations of specific
situations in mind, much useful Information can be obtained. Moreover,
the loading Information presented should serve as a foundation for expanding
and improving load estimates as more extensive and long-tern data become
available.
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CONCLUSIONS
1. Annual loads from U. S. Great Lakes tributaries were estimates for
total phosphorus, soluble ortho phosphorus, suspended solids, total nitrogen,
nitrate nitrogen, ammonia nitrogen, and chloride. Loa-ls for all parameters
were calculated (except for Lake Erie loads, which were taken directly from
the Lake Erie Wastewater Management Study), using the ratio estimator method,
which was found to be a useful method for estimating loads on a comparable
basins. Individual loads were calculated for 43 to 110 (depending on the year
and parameter) U. S. tributaries. Loads from monitored tributaries account
for about 55 to 80 percent of the U. S. Great Lakes drainage basin.
2. Loads from monitored U. S. tributaries accounted for about 65 to 80
percent of the total U. S. tributary load on a lake basin basis during the
1975 water year. In some cases, the 1976 U. S. monitored tributary loads for
individual tributaries accounted for less than this amount, indicating less
extensive field sampling during the 1976 water year.
3. While the estimated loads are believed to be based on the bes*~
available information, they are subject to limitations of the data and must
be interpreted with these specific limitations in mind. A major source of
error in estimating river mouth loads for some (but not all) streams is the
lack of a representative temporal and spatial distribution of sample data over
the annual cycle.
4. For most parameters, loads were generally higher during the 1976
water year than during the 1975 water year. The one exception was Lake
Superior, where the opposite occurred. This pattern corresponds with general
trends in flow over the same period. Wide variation in loads from year to
year is not uncommon and, as is necessary in estimating representative flows,
long-term records are necessary to establish an "average" or "mean" load.
Nevertheless, a reasonable judgement on whether or not a load can be considered
typical can I-e reached by comparing historical flow information with current
flow conditions.
5. Annual mean daily discharge to each of the Great Lakes was generally
higher than the historical average in water years 1975 and 1976, except for
Lake Superior, where the 1976 flow was slightly less than the historical
average flow. Individual tributaries exhibited wide variations in mean
annual flow as compared to their historical averages, implying in certain
cases local climatological variations. Many streams had higher spring
(March, April and May) flows during 1976 than in 1975.
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6. Flow per unit area of watershed was highest for Lake Ontario. Unit
area flows for the other four Great Lakes were approximately equivalent.
7. Lake Erie received the largest U. S. tributary total phosphorus
and soluble ortho phosphorus loads, while Lake Superior received the smallest.
Suspended solids and nitrogen tributary loads were also highest to Lake Erie.
It appears that Lake Ontario receives the largest chloride tributary load.
Lake Erie again received the largest diffuse loads (total load minus point
source loads) per unit area of watershed.
8. Analysis of loadings during water year 1975 indicated that the Maumee
River, which drains into Lake Erie, contributes about twice as much total
phosphorus to the Great lakes as the Saginaw River, the next largest
tributary contributor. Other Lake Erie tributaries and the Grand River
in Michigan were also among the highest total phosphorus contributors.
Soluble ortho phosphorus loads followed a similar pattern, with the Grand
River (Michigan), Black-Rocky Complex (Lake Erie), and che Saginaw River
ranking behind the Maumee River as the largest contributors.
9. During water year 1975 the largest suspended solids load from any
tributary was also contributed by the Haumee River. The load from the
Maumee was about twice as great as the next largest contributors, which
included several other Lake Erie tributaries, the Genesee River (Lake
Ontario), and the Ontonagon River (Lake Superior). Excluding Lake Erie
tributaries, for which 1976 data were not available, the Genesee River was
the largest suspended solids contributor to the Great Lakes in water year
1976.
10. The diffuse load, which is defined as the total tributary load
minus the identified point sourt.e inputs, includes contributors from both
surface runoff and base flow. Diffuse sources accounted for a large percentage
of the total load for most parameters, assuming 100 percent transmission of
identified point source inputs. During 1975 about 70 percent of the total
phosphorus load and about 60 percent of the soluble ortho phosphorus
tributary load to the Great Lakes was classified as attributable to diffuse
sources. The 1975 water year suspended solids load to the Great Lakes
was attributable almost entirely to diffuse sources. Ammonia nitrogen
loads to the Great Lakes were least affected by diffuse sources, as less
than 50 percent were considered to be derived from diffuse sources. With
the exception of Lake Superior, the total phosphorus diffuse load contri-
buted to each of the Great Lakes was higher in water year 1976 than in water
year 1975, reflecting the general increase in total tributary loads. No
comparison can be made fur Lake Erie due to the lack of 1976 data.
11. Since assuming 100 percent delivery of point sources may overestimate
the tributary point source load to the Lakes (at leajt on a short-term basis),
loading estimates were alsc derived assuming 50 percent delivery of upstream
point sources and 100 percent delivery of downstream point sources. Generally,
the assumption of 50 percent upstream point source transmission increased the
diffuse load by only a small percentage when compared to the diffuse load
derived under the assumption of 100 percent delivery of both upstream and
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downstream sources. However, in some cases, the effect was significant.
Increasing the diffuse load by as much as 20 percent. Loading
data had been categorized in a format which facilitates the calculation of
the total diffuse load under a variety of delivery assumptions.
12. Aa might be expected, diffuse unit area loads calculated for
different watersheds varied widely from basln-to-basln and fro™ year-to-ye," r.
Phosphorus and suspended solids unit area loads varied somewhat analgously,
with estimates highest for the Lake Erie basin, the thumb area of the Lake
Huron basin, and parts of the Lake Ontario basin. A relatively low unit
area load was derived for a major portion of the eastern Lake Michigan basin.
13. Municipal sources accounted for most of the phosphorus point source
load to the Great Lakes. Municipal sources also accounted for most of the
nitrogen and a large part of the chloride load, although all of the industrial
point sources for each of these parameters may not have been Identified.
Point source inputs of suspended solids to tributaries appear to have little
impact on the total suspended solids tributary load. Several chloride point
sources associated with mining or industrial operations had major impacts on
the chloride load.
14. Analysis of available information indicates that municipal point
sources discharging less than 0.1 mgd (2.83 x 10 or/a), although numerous
in some areas, do not significantly affect loads, at least on a Lake basin
approach.
15. Under existing flow conditions found ftr municipal wastewater
treatment plants, discharging into U. S. tributaries floes not include direct
sources), a reduction of effluent total phosphorus concentrations from
1 mg/£ to 0.5 Dig/I would have a relatively minor effect on the total
tributary phosphorus load to the Great Lakes. This is particularly true
for Lake Superior and Lake Huron.
16. Although the relationship between flow and the concentration of
various flow sensitive parameters (e. g., phosphorus or suspended solids)
varies widely among tributaries, two broad groups of tributary responses
were noted. Certain tributaries seem to be greatly influenced by runoff
events. These are referred to as "event response" tributaries. However,
other tributaries are not dominated by runoff events because concentrations
do not vary greatly with flow, and the flow itself tends to be less eratic
(less flashy). These are referred to Aa "stable response" tributaries.
Event response tributaries, such as many of the Lake Erie U. 5. tributaries,
tend to have high annual diffuse unit area loads associated with flow
sensitive parameters, such as phosphorus and suspended solids. On the
other hand, stable response tributaries, such as Lake Michigan's Grand
River and many other Lake Michigan tributaries, tend '.o hove relatively
••all annual diffuse unit area loads associated with r.hese parameters.
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17. Although there are probably many factors vhich influence whether
a stream fits either an event response or tributary response classification,
the texture of the soil in the *>c»rcr?>>«>rt appears m be very important.
Those watersheds with surface soils containing considerable amounts of fine
clay-sized particles tend to contribute significantly higher unit area leads
of flow sensitive substances than watersheds that have more coarse-grained
sandy soils. Streams draining sand> soils generally had more stable chemical
concentrations and flows than streams fir fining clayey watersheds. The
differences in the chemical and physical characteristics of clay-sized particles
and coarse-grained particles and the infiltration capacity of sandy soils
versus clayey soils are major factors which cause a different loading response.
Detailed information on soil texture characteristics of U. S. Great Lakes
watersheds have been compiled, and further analysis of the effect of soil
texture on tributary loads will be conducted in Subactivity 3-4 of U. S.
Task D (PLUARG).
18. Because of the differences between stable response and event response
tributaries, it is felt that not every stream needs to be sampled routinely
during runoff events for the purpose of calculating loads. By examining
watershed characteristics, including but not limited to surface soil textures,
it may be possible to predict whether an event response or stable response
can be expected. Where possible, however, limited sampling during one or
more runoff events, particularly during the spring, would provide more
definitive information on whether routine event sampling is necessary to
characterize the annual load. Also, in many streams where concentration
remains fairly stable, sampling over several years on a monthly basis may
produce representative data which can be used to estimate loads in future
years. In other words, for certain rivers a knowledge of the daily flow
over a given year may be all that is necessary to reasonably estimate the
load, assuming no major changes occur in the characteristics of the watershed
or in the point source inputs.
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INTRODUCTION
Both Canada and United States define the major activities under Task D
of the Pollution from Land Use Activities Reference Croup (FLUARG) as
(1) assessment of shoreline erosion. (2) survey of river sediments and
associated water quality, and (3) assessment of the effects of river inputs
on Boundary waters. In April of 1975, a Plan of Study was developed to
further define the United States portion of Task D. This Plan of Study
posed the following general questions.
(1) Is shore erosion a significant pollutant source to the lake?
(2) What is the tributary loading to the lake that Is attributable
to land drainage, including the pollutant loading associated with
river sediments?
O) How have river inputs derived from land drainage affected the lake?
In order to help answer the second question, Subactivity 2-3 of Task D
was defined as indicated below:
"Based on existing data, a careful estimate of the
tributary output (input to the Great Lakes) of
pollutants, including total suspended solids and
chemical pollutants in particulate and soluble
forms, will be made. In recognition of the importance
if high flow conditions, particularly spring runoff,
cO the loading of many substances, the output from
river mouths during high flow and base flow (no surface
runoff) will be considered. Based on estimates of
point source inputs to the tributaries, estimates of the
pollutant output attributable to diffuse sources will
be made. In all cases, estimates of U. S. loading will
be delineated according to Individual major watersheds,
the IS planning subareas, and the 5 lake basins."
This report represents the completion of Subactivity 2-3 of U. S. Task D
by presenting estimations of U. S. tributary loads of selected chemicals
and solids, including both point and non-point tributary contributions.
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Two previous subactivitles of U. S. Task D provided essential background
Information for Subactivity 2-3, First, existing river mouth flow and
concentration data were Inventoried in Subactivity 2-1 of U. S. Task D.
The report from this task, entitled "Existing River Mouth Loading Data in
the C. S. Great Lak^s Basin" (Hall, et al., 1976) served as a major reference
for this work. Infoi-uacion on watershed demarkatlons, monitored tributaries,
parameters monitored, frequency of monitoring, and others, were used in sorting
out data useful for actual load calculations. Second, information from
Subactivity 2-2 of U. S. task D, which consisted of a detailed monitoring
pro gran of thu Grand River near the river's entrance into Lake Michigan,
was very useful to this study. This specialized monitoring program, which
was recommended as a result of an interim report of Subactivity 2-1 of
U. S. Task D, has provided some extremely valuable and unique information
of hasinwide application.
Subaccivity 2-3 also is intended to serve as baseline information for
other U. S. Task D studies, such as Subactivity 2-5 (phosphorus availability),
Subactivity 3-2 (biological impacts of loads), and Subactivity 3-4 (summary
of Task D). Importantly, this study is paramount to the central theme of
Task D, which is to determine the relative importance of non-point sources
of pollution with respect to other sources or other factors which affect
the water quality of the Great Lakes. This study will also be useful to
other Tasks in PLUARG, particularly the "overview modeling" integration
activity.
While much specific information is contained in this report, quite a
large amount of supplementary information, such as loads from Individual
point sources, were not included due to the volume of the material. This
supplemental information is available, however, and interested persons
should contact the authors at the Great Lakes Basin Commission offices for
further information.
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METHODOLOGY
PARAMETERS
Loadings have been calculated for total phosphorus, soluble ortho
phosphorus, suspended solids, total nitrogen, nitrate (+ nitrite)
nitrogen, ammonia i itrogen, and chloride. Phosphorus, nitrogen, and
suspended solids are all important non-point source pollutants which are
being emphasized in the PLUARG study. Suspended solids are of concern not
only as a non-point source pollutant, but. also because toxic trace
substances and nutr .ents are often associated with suspended material.
Chloride is importar.t because of its conservative nature and the fact that
it can be used as a "tracer" to provide general insight on loadings to the
lakes. Chloride can also be contributed by non-point sources, such as
runoff from urban or residential areas whers salt compounds have been
applied for road de- .cing purposes.
There are other substances for which it would be useful to have
loading information. For example, detailed annual loads to the Great Lakes
of certain toxic heav/ mm which loading may be calculated. It is likely
that more information will be available in the near future on these
parameters from which Great Lakes loadings can be calculated (loads of
certain toxic substances will likely be estimated or projected as part of
the Great Lakes Basin Plan planning process of the Great Lakes Basin
Commission). For a discussion of the availability of river mouth data for
a number of parameters that were not discussed in this report, such as
total solids, particle size, silica, total soluble phosphorus, chloric**,
manganese, iron, total and dissolved heavy metals, pesticides, and
industrial organics, refer to Hall et al. (1976).
All loadings were calculated based on existing data and no attempt was
made to determine the quality of the data used. No determinations were
made, for example, on the adequacy of the analytical techniques used to
generate the data or the quality control employed in the analysis. Further,
the statistical validity of the data was not critiqued. Since any one
parameter could be determined by a variety of methods, many of which are
operationally defined and not always directly comparable, a certain amount
of judgement was used in determining whether the data found for a certai.i
tributary were reasonable. For example, In the case of dissolved reactive
phosphorus, the type of filter paper used may have a bearing on the results
reported. Soluble phosphorus data obtained using a glass fiber filter
•ay not correlate exactly with data obtained using a 0.45 micron nembrane
filter. However, where results from two operationally defined techniques
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define approximately the same form or fraction of a given pollutant,
for the purposes of these loading estimations, they were generally
considered as the same parameter. For the purposes of these river mouth
loading estimates, slight modifications in methodology were not assumed
to have any significant bearing on the results.
There were some problems (although rare) associated with the terminology
used for certain parameters, especially in the case of phosphorus. A
variety of terms have been used for different phosphorus fractions, and it
is sometimes difficult to determine which form of phosphorus is actually
implied. For example, the term "phosphate P" could mean several different
fractions, including total inorganic phosphorus or soluble reactive
phosphorus. In cases such as these, it was sometimes necessary to look at
the analytical methods used to see what form of phosphorus was actually
implied. Again, even if slight differences in techniques were determined to
have occurred, the effect on the loading estimates would generally be
very small, if not undetectable. In order to get a better understanding of
the different types of phosphorus forms and how they are analyzed &ut! thus
operationally defined, the reader is referred to Figure 4 pagp 25 In
Hall et al. (1976).
Nitrogen data used in the calculations generally caused few problems.
Nitrate nitrogen was often measured in combination with nitrite nitrogen.
Since nitrite is absent or present only in minute quantities in most the
waters due to its instability in the presence of oxygen, no distinction was
made between nitrate loads and nitrate + nitrite loads.
Total nitrogen loads were calculated based on reported total nitrogen
values whenever possible. When total nitrogen was not reported, the sum of
inorganic plus organic nitrogen concentrations or total KJeldahl nitrogen
plus nitrate (+ nitrite) nitrogen was used.
TOTAL RIVER M3UTH LOAD CALCULATIONS
All river mouth loads that were calculated and used in this report are
presented in Appendix A. These loads, calculated for individual tributaries,
serve as the basis for other calculations such as the computation of unit
area loadings.
Data Sources
River mouth loads vcre calculated using the best available concentration
and flow information. Every effort was made to utilize all data available
for any given tributary, since the confidence in a loading estimate is
generally Improved as the number of data points is increased. Primary
sources of data include State water surveillance programs, U. S. Geological
Survey programs, International Joint Commission PLUARG and Upper Lakes
Reference Group studies, the U. S. Army Corps of Engineers Lake Erie
Wastewater Management Study, and other work done by universities and
special State or Federal projects.
10
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In general, data on the seven parameters considered weie available on
all major IK S. Great Lakes tlrbutaries. Appendix A indicates the number
of flow and concentration data pairs that were used in each loading
calculation.
The primary source of daily and mtan avimal flow information was II. S.
Geological £ irvey Water Resources Data Reports. Some State surveillance
programs also collected flow data (generally at the time of the sample
collection) which were used where appropriate.
Base Years
All loadings were calculated according to the water year as standardized
by the U. S. Geological Survey. In an effort to make this report as current
as possible and compatible with other PLUARG work, water years 1975
(October 1, 1974-September 30, 3975) and 1976 (October 1, 1975-September 30,
1976) were chosen as the base periods for annual load calculations. For
many tributaries the mean annual daily flow during water year 1975 was
nimilar to the mean annual daily flow for the historical period of record.
Although it would be improper to call water year 1975 a "typical" year,
since no year is "typical," water year 1975 does provide a good base for
comparison with other years.
Watershed Areas
In this report tributaries and their watersheds have been organized
according to individual tributaries, hydrologic areas, river basin
groups, and lake basins following the procedure used in Subactivity 2-1
of U. S. Task D, PLUARG (Hall et al.. 1976). Each of the 72 hydrologic
areas consists of a single major watershed or a complex of small watersheds
draining individual tributaries. Hydrologic areas are grouped into 15
larger river basin groups which contain anywhere from one to eight
hydrologic areas. Each lake basin consists of two or more river basin
groups. A description of the U. S. tributaries, their organization and
maps of their drainage basins, have been previously recorded in Hall et al,
(1976).
Table 1 shows the watershed areas used in this study. Watershed area
measurements were obtained primarily from the Great Lakes Basin Framework
Study, Appendix 1, Alternative Frameworks. Additional drainage area
information, especially for areas containing £he smaller rivers, was
obtained from a computerized list of watershed areas compiled for the
Conservation Needs Inventory by the U. S. Soil Conservation Service.
11
-------
Table 1
DRAINAGE AREA MEASUREMENT (HYDROLOGIC)
LAKE SUPERIOR BASIN
Rivet Basin Group 1.1
1. Superior Slop* Complex (Minnesota)
2. Saint Louis River
3. Apostle Island Complex
4. Bad River (Wisconsin)
S. Montreal River Complex
River Basin Group 1.2
1. Porcupine Mountains Complex
2. Ontonagon River
3. Keweenaw Peninsula Coop lex (Michigan)
4. Sturgeon River (Michigan)
5. Huron Mountain Complex (Michigan)
6. Grand Harais Complex (Michigan)
7. Tahquamenon River (Michigan)
8. Sault Complex (Michigan)
LAKE MICHIGAN BASIN
River Basin Group 2.1
1. Menomlnee Complex (Michigan)
2. Menominee River
3. Peshtigc River (Wisconsin)
U. Oconto River (Wisconsin)
5. Suamico Complex (Wisconsin)
6. Fox River (Wisconsin)
7. Green Bay Complex (Wisconsin)
River Bat- in Group 2.2
1. Chicago-Milwaukee Complex
River Basin Group 2.3
1. Saint Joseph River
2. Black River (South Haven) Complex (Michigan)
3. Kalamazoo River (Michigan)
4. Black River (Ottawa Co.) Complex (Michigan)
5. Grand River (Michigan)
River Basin Group 2.4
1. Muskegon River (Michigan)
2. Sable Complex (Michigan)
AREA
1.000 Hectares
4,400
2,391
595
944
514
258
80
2.009
272
353
350
183
252
311
216
70
11,741
4,367
273
1,061
298
275
125
1,710
625
563
563
3,356
1,211
93
520
66
1,466
3,455
685
503
1,000 Acres
10, m
5,907
1,470
2,334
1,269
637
197
4.964
672
872
865
452
622
768
540
173
29,011
10,791
674
2,621
737
680
310
4,225
1,544
1,392
1,392
8,292
2,992
229
1,285
163
3,623
8,536
1,692
1,242
'Area measurements also include small watersheds, streams, and land
areas that drain directly into Basin Lakes. Source:
Great Lakes
Basin Framework Study. Appendix 13, Laud Use and Management. Does
not Include major inland water.
12
-------
Table 1 (Continued)
DRAINAGE AREA MEASUREMENT (HYDROLOCIC)
3. Manistee River (Michigan)
4. Traverse Complex (Michigan)
5. Seul Choix-Groscap Coop lex (Michigan)
6. Manistlque River (Michigan)
7. Bay De Hoc Complex (Michigan)
8. Eseanaba River (Michigan)
AREA
1.000 Hectare*
520
683
142
375
310
237
1,000 Acres
1,284
1,689
352
926
765
586
LAKE HURON BASIN 4,192 10,358
River Basin Group 3.1 2,108 5,208
1. Les Cheneaux Complex (Michigan) 364 901
2. Cheboygan River (Michigan) 409 1,010
3. Presque Isle Complex (Michigan) 145 358
4. Thunder Bay River (Michigan) 327 808
5. Au Sable and Alcona Complex (Michigan) 576 1,422
6. Rifle-Au Cres Complex (Michigan) 287 709
River Basin Group 3.2 2,084 5,150
1. Kavkawlin Complex (Michigan) 100 248
2. Saginaw River (Michigan) 1,617 ^.995
3. Thumb Complex (Michigan) 367 90?
LAKE ERIE BASIN 5,559 13,735
River Basin Group 4.1 1,347 3.328
1. Black River (Michigan) 180 «6
2. St. Clair Complex (Michigan) 155 383
3. Clinton River (Michigan) 203 301
4. Rouge Complex (Michigan) 189 468
5. Huron River (Michigan) 220 543
6. Swan Creek Complex (Michigan) 7>t 182
7. Raisin River 326 805
River Basin Group 4.2 2,685 6,635
1. Ottawa River 44 109
2. Maumee River 1,711 4,229
3. Toussaint-Portage Complex (Ohio) 266 656
4. Sandusky River (Ohio) 397 980
5. Huron-Vermilion Complex (Ohio) 267 661
River Basin Group 4.3 843 2,082
1. Black-Rocky Complex (Ohio) 230 568
2. Cuyahoga River (Ohio) 234 578
3. Chagrin Complex (Ohio) 77 189
4. Grand River (Ohio) 212 525
5. Asheabula-Conneaut Complex 90 222
13
-------
Table 1 (Continued)
DRAINAGE AREA MEASUREMENT (HYDROLOGIC)
AREA
River Basin Group 4.4
1. Erie-Chautauqua Complex
2. Cattaraugus Creek (New York)
3. Tonavanda Complex (New York)
LAKE ONTARIO BASIN
1.000 Hectares
684
169
144
371
4,577
1.000 Acres
1,690
418
355
917
11,309
River Basin Group 5.1
1. Niagara-Orleans Complex (New York)
2. Genesee River
River Basin Group 5.2
1. Wayne-Cay uga Complex (New York)
2. Oswego River (New York)
3. Salmon Complex (New York)
River Basin Group 5.3
1. Black River (New York)
2. Perch Complex (New York)
3. Oswagatchie River (New York)
4. Grass-Raquette-St. Regis Complex (New York)
To Convert From To
Hectares (ha) Acres (ae)
911
269
642
1,766
177
1,316
273
1.900
521
126
430
823
Multiply By
2.471
2,250
664
1,586
4,363
437
3,252
674
4,696
1,289
311
1,0&2
2,034
Table 1
DRAINAGE AREA MEASUREMENT (HYDROLOGIC)
AREA
AREA
1.000 Hectares
1.000 Hectares
STATE SUMMARY
Illinois
Indiana
Michigan
Minnesota
16
944
15,030
1,591
New York
Ohio
Pennsylvania
Wisconsin
GREAT LAKES TOTAL
5.146
3,027
156
4,558
30,468
To Convert Proa
Hectares (ha)
To
Acres (ac)
Multiply By
2.471
-------
Correcting Loads to the River Mouth
Not all chemical stations and flow gaging stations are located at the
river mouth. In order to present a total river mouth load in these
situations, it was necessary to adjust flow and some concentrations to
account for the area below monitoring stations.
In order to adjust flow measurements to the river mouth, gape flow
was multiplied by the ratio of the total drainage area over the g^ged
drainage area. For example, if a river drains a total area of 1,000 square
kilometers, but the farthest downstream flow gage is located 15 river
kilometers upstream from the mouth and accounts for only 900 square kilometers,
the gaged flow would be multiplied by 1,000/900 or 1.11 to provide a
corrected flow. All flows used in loading calculations in this report
were corrected in this matter, if not already reported as accounting for the
total watershed drainage area.
In most cases, chemical monitoring stations were located at or very
near the river mouth. Consequently, no concentration adjustments were made,
and it was assumed that concentrations at the mouth were the same as those
measured at the monitoring station. An exception to this procedure occurred
if the monitoring station were above a major impoundment. In these few
cases, the load was calculated at the s'at ion above the impoundment, and the
remaining area was considered to be unmonitored and treated in a manner
similar to those streams that have no chemical or flow information on them
(as will be discussed in a later section).
Loads determined by the U. S. Army Coips of Engineers Lake Erie
Wastewater Management Study (U. S. Army Corps of Engineers, 1975) were
used in determining Lake Erie tributary inputs. These loads were not
corrected for the distance between the gage and the lake. Consequently,
for this study the Corps river loads were extrapolated from the gage to the
river mouth using the area ratio approach for flow outlined above.
Method of Calculating Loadings
Loadings calculated for this report, other than those to Lake Erie,
were done using the ratio estimator method, employing a computer program
developed specifically for applying the calculation method (Clark, 1976).
This method has been widely reviewed and Is generally accepted by the Great
Lakes research and surveillance community as the preferred and, importantly,
standard method for calculating tributary loads. Table 2 illustrates a
sample calculation of load using the ratio estimator program.
The ratio estimator method calculates an average daily load at the
river mouth adjusted to some extent for the variability of flow over an
annual cycle. For example, monitoring programs that employ monthly sampling
may miss high flow events. If a mean daily flow were calculated based on
the days sampled, an improper estimate of the total annual load would result.
However, if the mean daily load is adjusted by multiplying it by the ratio
of the mean daily flow for the year over the mean daily sample flow, some
of the bias can be removed from the calculated load. It is also desirable
15
-------
T'.BLE 2
t AMPLE 0 LOAD CALCULATION USING
THE RATIO ESTIMATOR PROGRAM
TRIB: FOX
-------
ro provide an error statement associated with the calculations based on the
variability of the data, such as a nean square error tern. The ratio
i!3t tutor method provides auch an error estimate.
The following equations summarize how the ratio estimator, as well a.<
how the mean square error tern. Is calculated.
The ratio estimator, "ti , is defined in International Joint Commission
(1976) as
^'
where
1 -»• -
a
y x
V • mean daily flow for the water year
m - nean daily loading for the days concentration*
* were determined
IB • mean daily flow for the days concentrations
were determined
n " number of days ooncer :rj.tions were determined
i-l
X..Y, - n
i i
m -m
y x
n-1
n
i-l
n-1
and the X. and Y. are the individual measured flow and
calculated loading, respectively, for each day concentrations
were determined .
17
-------
The iMan-square-error of this estimator may be estimated to terms
of the order n"2, assuming the population size is very large by,
E} - .
Where S IB calculated analogously to S
J" ™
For a further explanation of the ratio estimator used , see Menominee
River Pilot Watershed Study (1977).
If the mean annual daily flow la not known, loadings are estimated
using the sample mean of the calculated dally loadings. Also, in some
cases the sampling program was designed to collect data during high flow
events. For situations such as this, the data were divided into two or
three flow strata and a separate load and error were calculated for each
strata. Table 3 illustrates the use of the ratio estimator program
using two strata.
All loads and the mean square error terms derived from the ratio
estimator approach are presented in Appendix A. It is important to note
that error statements generated by this procedure do not necessarily
reflect the accuracy of the calculated load. This point will be discussed
in detail in a later section.
In order to avoid duplicating work, some loading estimates were not
calculated from concentration and flow data, but were obtained directly
from other reports. U. S. Army Corps of Engineers have developed a flow
interval calculation method for use in the Lake Erie Wastewater Management
Study. This approach is analagous to the ratio estimator method in that
it uses additional flow information for the year to weight the loads. It
also provides an error statement. In our report all Lake Erie mean annual
loads were obtained directly from the Lake Erie Wastewater Management Study,
and no attempt was made to recalculate loads using the ratio estimator
approach.
-------
TABLE 3
EXAMPLE OF RATIO ESTIMATOR RIVER MOUTH
LOAD CALCULATION USING STRATA
TRIB: BAD RIVER BASIN: SUPERIOR
WATER YEAR: 1975 PARAMETER: SUSPENDED SOLIDS
STRATUM 1 UPPER FLOW CUTOFF - 1000.0000 * DAYS: 342
LOADINGS FLOWS
RBG: 1
kg/day
m3/sec cfs
CONCENTRATIONS
mg/liter
3.000
2.000
14.000
13.000
4.000
5.000
25.000
13.000
24.000
14.000
12.000
16.000
14.000
15.000
16.000
31.000
5.000
7.000
9.000
5.000
10.000
17.000
7.000
22.000
15.000
14.000
16.000
MEAN SAMPLE LOG - 11419.9 kg/day
MEAN STRATUM FLOW - 15.631 m3/sec or 552 cfs
THE BIASED RATIO ESTIMATE - 17650.3 kg/day
APPROX. UNBIASED RATIO EST. - 17707.8 kg/day
CORRECTION FOR BIAS OF EST. - 57.5 kg/day
RATIO OF MEAN STRATUM FLOW TO MEAN SAMPLE FLOW IS 1.55
BASED ON VALUES OF 15.63 and 10.11 m3/sec, respectively
2334
1620
10036
13486
3190
4392
31928
24363
47209
14009
8573
11470
5926
6275
6068
11528
2496
6028
14004
4587
11377
17136
7724
24275
4551
9214
4541
MEAN SAMPLE
9.0
9.4
8.3
12.0
9.2
10.2
14.8
21.7
22.8
11.6
8.3
8.3
4.9
4.8
4.4
4.3
5.8
10.0
18.0
10.6
13.2
11.7
12.8
12.8
3.5
7.6
3.3
FLOW - 10.1
318.0
331.0
293.0
424.0
326.0
359.0
522.0
766.3
804.0
409.0
292.0
293.0
173.0
171.0
155.0
152.0
204.0
352.0
636.0
375.0
465.0
412.0
451.0
451.0
124.0
269.0
116.0
.1 m3/sec
EST. MEAN STRATUM LOADING IS THEREFORE 17707.8 kg
-------
TABLE 3 CONTINUED.. .
EST. MEAN ERROR OF THIS EST. IS 1368.2 kg
EST. ARE BASED ON 26 DEGREES OF FREEDOM.
SUM-OF-SQUARES-ERROR - 50544992.(kg/d)**2 or 6733851.(t/year}**2
TRIB: BAD RIVER BASIN: SUPERIOR
WATER YEAR: 1975 PARAMETER: SUSPENDED SOLIDS
RBG: I
STRATUM 2 #DAYS: 23
LOADINGS FLOWS
kg/day m3/sec cfs
19930. 67.8 2396.0
53990PA 173.1 6113.0
83453' ' 173.1 6113.0
1824u6 48.0 1695.0
740314 66.9 2364.0
140140 101.4 3580.0
6597989 178.4 6301.0
2756731 185.5 6551.0
10959018 332.0 11726.0
127144 46.0 1624.0
MEAN SAMPLE FLOW - 137.23 m3/sec
CONCENTRATIONS
mg/liter
34.000
361.000
558.000
44.000
128.000
16.000
428.000
172.000
382.000
32.000
MEAN SAMPLE LDC = 3544755.0 kg/day
MEAN STRATUM FLOW = 156.366 m3/sec or 5522 cfs
THE BIASED RATIO ESTIMATE - 4038986.0 kg/day
APPROX. UNBIASED RATIO EST. - 4134327.0 kg/day
CORRECTION FOR BIAS OF EST. - 95341.0 kg/day
RATIO OF MEAN STRATUM FLOW TO MEAN SAMPLE FLOW IS 1.14
BASED ON VALUES OF 156.37 and 137.23 m3/sec, RESPECTIVELY
EST. MEAN STRATUM LOADING IS THEREFORE 4134327.0 kg
EST MEAN ERROR OF THIS EST IS 698087.4 kg
EST. ARE BASED ON 9 DEGREES OF FREEDOM.
SUM-OF-SQUARES-ERROR - 4873259057152 (kg/d)**2 or 649239461888, (t/year)**2
SUMMARY FOR THE BAD RIVER
OVER 2 STRATA:
EST. MEAN DAILY LOADING IS THEREFORE 277111.1 kg/day
EST. MEAN ERROR OF THIS EST. IS 44007.7 kg
EST. LOADING FOR YEAR - 101145552 kg, or 101145.5 METRIC TONS
EST. MEAN ERROR FOR THIS TOTAL - 16062825 kg, or 16062.8 METRIC TONS
EST ARE BASED ON 9.02 EFFECTIVE DECREES OF F
ARE THE DATA CORRECT FOR ENTRY TO THE FILE??
1
BAD RIVER SUPE 1 101145.5 258014192.0 10
DATA HAS BEEN ENTERED.
20
-------
The Upper Lakes Reference Gr~>up (ULRG) also calculated mean dally
river loads (Upper Lakes Reference Group, 1976) for Lake Superior and
Huron tributaries. Their sampling program was monthly with extra samples
taken in the spring. To calculate a mean daily load, a load for each day
that samples were taken was generated and then averaged- This procedure
is shown mathematically below:
S QiXCi
L • mean daily river load
Qi • river flow for any g^ven day 1
Ci - concentration for day i
n • total number of days sampled
At first it was thought that these loads could be used directly in this
report. However, a significant difficulty was observed with this
calculation technique in that it is strongly biased toward the springtime
(and generally high flow events) sampling. For example, if 16 samples
were taken over the year, one in each month except for the month of April
where five samples were taken, the mean daily load calculated from these
data would be biased toward the April samples. If the April data were
obtained during high flows (and higher concentrations for some parameters),
the annual load for some parameters could have been over-estimated.
Because of this problem, mean annual loads reported by ULRG were not used
in this report except where no mean annual daily flow data were available
for recalculation of the loads using the ratio estimator method. In many
cases significant differences were observed between the mean annual load
calculated by the ratio estimator method and the ULRG method, despite the
fact the same data were used.
In calculating river mouth loads, an understanding of the influence
of high flow events is crucial. For example, for tributaries draining
into parts of Lake Erie it is clear that high flow events have a major
Impact on the total load of sediment and certain chemical substances.
However, the relationship between.flow and concentration varies widely
over the U. S. Great Lakes Basin. The importance of high flow events will
be discussed in a later section, but it should be noted here that all
data, including high flow event data that were available, were used in
calculating river mouth loads.
21
-------
POINT SOURCE LOADS
In order to determine the relative Importance of non-point or diffuse
sources to the total river mouth load, municipal and industrial discharges
which potentially contribute to river mouth loadings have been determined.
The difference between total load and point source inputs delivered to the
river mouth provides an estiirate of non-point or diffuse load to the Great
Lakes from a tributary.
Data Sources
Point source dischargers within the U. S. Great. Lakes Basin were
identified from a number of different sources. Summaries or computerized
files of point source information were consulted whenever possible. A
brief description of the major sources of information used is discussed
below:
National Pollution Discharge Elimination System
(NPDES) - Thia system was the basis for much of the information used
in this report. The U. S. Environmental Protection Agency (EPA)
maintains this file. Region V of U. S. EPA supplied most of
the information which was in turn collected and supplied to EPA
from the Great Lakes States.
International Joint Commission
The 1975 and 1976 Water Quality Board reports provided information
on phosphorus discharges for municipal plants with discharges
greater than one million gallons per day. Appendices B and C
of the Water Quality Board reports (the Surveillance Subcommittee
and the Remedial Programs Subcommittee Reports) alsc provided
information, particularly with regard to municipal and industrial
discharges in defined problem areas. Industrial point source
information compiled for the Upper Lakes Reference Groun, which
was for the most part deriveH from NPDES permit information,
formed the basis of industrial point source information for
Lakes Huron and Superior. Other information compiled by the
IJC Great Lakes Regional Office, such as a computerised list of
municipal facilities with design flow and type of treatment,
was also used to supplement this information.
New York
The New York Department of Environmental Conservation supplied
most of the Mew York State point source information through a
computer printout from the State's Pollution Discharge
Elimination System. The Department of Environmental Conservation's
"Water Quality Management Plan fcr the St. Lawrence Basin" (1975)
and "St. Lawrence River Basin PLln for Pollution Abatement" (1971)
also were used, particularly for noint sources affecting the
International section of the St. Lawrence.
22
-------
Wisconsin
The Wisconsin Department cf Natural Resources' "Water Quality
Management Basin Plan for the Rivers of the Northwest Shore of
Lake Michigan" (1975) provided location of nost point sources
in the area as well as United discharge information for municipal
plants. "Southeast Wisconsin River Basins - A Drainage Basin
Report" (Southeast Wisconsin Regional Planning Commission, 1976)
provided poinc source information on the southern part of the
state. The "Manitowoc River Basin Report" (Wisconsin Department
of Natural Resources, 1977) was used to obtain information on the
Kanitowoc River Basin. The Southeast Wisconsin Regional Basin
Commission kindly provided preliminary information on municipal
and Industrial point sources identified In their area. Finally,
while some NPDES summaries of Wisconsin were used, complete
and extensive computerized NPDES list of point source dischargers
provided by the state was received too late to be reviewed in
detail for this report. However, preliminary examination
indicated that most of the point sources were accounted for
through other sources of information.
Michigan
A listing of Industrial and municipal point source discharges
was obtained from the Michigan Department of Natural Resources.
Available DNR files in Lansing were also surveyed to obtain
additional details on point source inputs. Information on point
sources was also partially derived from the East Central Michigan
Planning and Development Region (Chester Engineers, 1977).
Lake Erie Wastewater Management Study
The Lake Erie Wastewater Management Study (U. S. Army Corps of
Engineers, 1975) provided a large amount of Information on point
source discharges to Lake Eric. Information available included
a detailed listing of non-Industrial point source loads. No
data were available on industrial inputs to the Lake Erie Basin
except for Information provided by the New York Department of
Environmental Conservation.
U. S. EPA Special Reports
Special reports, particularly the Water Pollution Investigation
Series (Sargent, 1975; Patterson et al.. 1975) were used to
gain supplemental point source information.
23
-------
lu compiling point source information, NPDES records and IJC information
(supplied basically by the states) were the primary information sources
used. Other information was used to supplement this data. In some cases,
a combination of information sources uas used to obtain the required
information (for example, the receiving water of the discharger may have
been obtained from one source and the load of certain parameters from
another).
Location of Point Sources
A great deal of effort was expended in locating where a point source
enters a tributary to the Great Lakes. Obviously, many physio-chemical
and biological factors may affect the delivery of point source discharges
to the river mouth of a tributary. Consequently, all point source inputs
to a Great Lakes tributary were classified as an "upstream" or "downstream"
source. The cut-off between upstream and downstream was arbitrarily
chosen as approximately 50 river kilometers upstream from the river mouth
or at the outlet oi an impoundment or lake-like widening of the river
where such occurs within 50 river kilometers of the mouth. Grouping data
into these upstream and downstream categories permits calculations of
different point source deliveries to the river mouth when different
delivery or transmission ratios are known or assumed.
Base Years
As discussed previously, water years 1975 and 1976 were chosen as
base years for loading calculations. Consequently, point source annual
loads for these periods were also sought.
In many instances, point source discharges were not available for all
parameters for both base years. When an annual load was available for only
one year, that load was assumed to apply to the ether year. If data were
not available for either year in question, but were presented for another
year previous to 1975, then the most recent data were used to calculate
an annual pollutant discharge, on the assumption that these data are
typical of the two base years. If known upgrading of the point source
wastewater treatment facility had occurred between the year of available
data and the base year, such as often occurred in the case of phosphorus
removal at municipal treatment plants, non-base year data were not used
and a load estimated as described below.
Some point source annual loads are reported according to the calendar
year instead of the water year. However, since annual loads are often
determined from a few samples per year (or even less), no attempt was made
to adjust annual point source inputs to the water year. Any annual
discharges reported or calculated for the calendar year were assumed to
apply to the water year (if loads for the water year were not available).
-------
Estimation of Point Source Loads
Point source loads were estimated for both municipal and industrial
dischargers. Because of the differences in available data, municipal
loads were determined somewhat differently than industrial loads.
Municipal Point Smrcea. For each municipal discharger identified
(over 800), information was collected on the name of the discharger, the
receiving tributary, the water year in which the data were collected, the
data source, «-he load for that year for available parameters of interest,
whether the source was discharged Into an upstream or downstream segment,
the effluent flow per day. aiid the plant's location in relation to the
river mouth water quality sampling station. In terms of loading information,
data on phosphorus and suspended solids were most often found. Actual
loading figures for the other five parameters considered in this study
were often not readily available from the various data sources.
In cases where phosphorus and suspended solids data were not available
for loading calculation work, an average phosphorus concentration obtained
from an analysis of those municipal plants with existing loading information
was multiplied by the known flow to obtain a load. Actual flow data, or in
some cases design flow, was found for all municipal discha-gers identified
as a contributor. In a few of the more obscure plants, where only a load
was found, the flow was back-calculated using average concentrations as
described below.
In determining an "average" phosphorus and suspended solids concentration,
known municipal concentration data were grouped according to treatment type
as shown in Table 4. The combined average of primary and secondary
treatment plants and the average of tertiary plants given In Table 4
were used in estimating loads for primary and secondary plants and for
tertiary plants, respectively, for which concentration information was
not available.
In gathering information for Table 4, it was noticed that several
plants that were listed as having tertiary treatment (phosphorus removal)
had relatively high phosphorus concentrations in their effluents. While
these concentrations or the actual treatment were suspect, they were still
used for calculating an average concentration. Consequently, the average
effluent phosphorus concentration from tertiary plants (1.3 ng/l P)
could be slightly high.
Table 4 also shows the average phosphorus concentration for those
plants that have a flow of between 0.1 mgd and 1 mgd. The average
concentration obtained for these small plants compares very closely with
the average concentration calculated for primary treatment plants. This
indicates that while the small plants may be insignificant as far a- total
flow is concerned because of their higher concentration, they may indeed
provide a significant phosphorus load.
25
-------
TABLE 4
MEAN EFF: EHT Cl*CASTRATIONS FOR GREAT LAKES
MUNICIPAL TREATMENT PLANTS
(Plants generally 1 mgd >r greater except as noted)
Number of
Type of^ Treatment Paraueter S&IA Plants Standard Deviation
Primary ? ic'vhorus (as P) 5.5 9 1.8
Secondary " 3.9 57 2.2
Primary +
Secondary " 4.1 66 2.2
Tertiary
CP removal) " 1.3 94 0.7
Small Plants " 5.2 12 3.4
Primary S j.spended Solids 59.3 7 26.9
Secondary " 31.6 30 20.7
Primary +
Secondary " 36.8 37 24.2
Tertiary " 24.8 63 16.7
All Plants
(Primary +
beconary +
Tertiary) " 29.2 100 20.5
12 plants considered with flow between 0.1 and 1.0 mgd. Data from Lake
Erie Wastewater Management Study (Preliminary Feasibility Report,
Volume 11, Appendix A, 1975)
Only very limited Information was available on the parameters of
interest other than phosphorus and suspended solids. To estimate point
source loadings for these other parameters, average effluent concentrations
determined by the U. S. Army Corps of Engineers Lake Erie Wastewater
Management Study, as shown in Table 5, were used as representative
concentrations for all Great Lakes municipal point sources. Note that
soluble ortho phosphorus concentrations we»-e estimated to be fifty percent
of the total phosphorus concentration reported or derived from Table 4.
26
-------
TABLE 5
MUNICIPAL PLANT EFFLUENT CONCENTRATIONS
Soluble Ortho Phosphorus (as P)
Nitrate (Nitrite) Nitrogen
Anaemia Nitrogen
Organic Nitrogen
Chloride
0.5 x Total Phosphorus Concentration
6.6 mg/£
7.9 rag/£
2.33 ng/1
160 mg/£
Provided by u'. S. Army Corps of Engineers Lake Erie Wastewater
Management Study (1975)
Only those municipal plants that had a continuous discharge were
considered as a pollutant point source. Further, facilities with a
discharge less than 0.1 mgd were not considered. Any plants that
discharged to a lagoon or th.it discharged very infrequently were not
considered when calculating total point source loads. It was felt that
there was no accurate way to assess the annual pollutant impact of a
lagoon, which may discharge only one or two times a year. Lagoon treatment
systems were identified and located, however, so information is available
on lagoons for further analysis oeyond this report.
Industrial Point Sources. Of the 700 industrial point sources
identified as possible contributors of the pollutants under consideration,
loads were determined for about 200 dischargers. These dischargers were
thought to represent most of the major industrial point sources contributing
to U. S. streams draining into the Great Lakes. Industries identified
but for which no loads were estimated, had no or insufficient data
available on the pollutants of concern to permit estimating an annual
load. A special effort was made, however, to include all dischargers
that might be significant, particularly in terms of dischargers of
phosphorus and suspended solids. For industrial dischargers it was not
possible to estimate the output of all seven pollutants considered, but
if annual outputs of some parameters were available or computable, they
were used.
27
-------
In a few cases special assumptions were made with regard to point
sources that are worth mentioning. Point source contributions to the
Indiana Harbor Canal and Burns Ditch, although located in a major urban
area on the south shore of Lake Michigan, were not considered as part of
the tributary load. Due to the unusual hydrology involved, these waters
were considered direct dischargers (direct dischargers will be compiled
in Subactivity 3-4 of U. S. Task D). In the Lake Ontario watershed, the
New York Barge Canal intersects (through a lock system) with the Genesee
and Oswego Rivers. Point source inputs to the canal were thus assigned
either to the Genesee or Oswego River. Point sources entering the
Barge Canal east of the Genesee were assigned to the Oswego. Otherwise,
Che point sources were considered to contribute to the Genesee system.
Also, since Tonawanda Creek (located in the western part of the Lake
Ontario basin) flows into the Niagara River (ultimately) about fifty
percent of the year and into the Barge Canal the rest of the year, half
of the annual point source load was assigned to Tonawanda Creek and half
to the Genesee River.
Any point source that was found below the river mouth water quality
station was considered to be a direct discharge to the lake and was not
included in the total river mouth load. These direct sources, along with
other point sources discharging directly to a lake rather than to a
tributary, were not included in the river mouth or diffuse loading
calculations as they do not influence tributary water quality within the
monitored areas.
DIFFUSE LOADS
For the purposes of this report, diffuse loads were considered to be
that portion of the total tributary load not attributable to a point source.
Examples of diffuse pollutant sources are agricultural runoff, highway
deicing activities, sheet and gully erosion and streambank erosion.
Another source included in the diffuse category is base flow or groundwater
input to streams, which for some tributaries and parameters, contributes
a large fraction of the total d.ffuse load.
Two methods of calculating difruse loads were utilized. One method
was applicable to river basins for which river mouth monitoring data
(1. e., field data) were available. The second, more indirect method,
was used to estimate diffuse loads from areas where no river mouth
monitoring data were found. The following section explains these two methods.
Monitored Areas
Diffuse loads from monitored areas were calculated by subtracting
point source inputs from the total river mouth loada. However, since all
point sources discharged may not actually reach the- Great Lakes, subtracting
all point source inputs from the total tributary load, regardless of
where they entered the tributary system (far upstream or near the mouth),
may result In an underestimation of the diffuse or non-point source load.
Since the actual ratio of point source Inputs contributed to a tributary
-------
Co that delivered to the river mouth is unknown, the point source data
were aggregated in such a way that permits varying assunptions on point
source transmission.
For the purposes of this report, two transmission assumptions were
made and used to calculate point source loads delivered to the river mouth.
The first assumption was simply that all relevant point source pollutants
discharged into watershed reached the river mouth. The second assumption
was that only fifty percent of the upstream sources but all of the
downstream sources reached the river mouth (the definition of upstream and
downstream : ources wast presenter* earlier). Comparison of the diffuse
loads calculated with these two scenarios providi insight into how
point source transmission may affect the distribution of point and
non-point conti buttons to the total tributary load. While only two point
source transr Ission scenarios have been calculated for this report, the
methodology was designed to permit the effect of other assumptions of
point source transmissions on the diffuse/point source load ratio to be
readily calculated.
Unmonitored Areas
Unmonitored areas were those hydrologic areas and Individual
tributaries which were Insufficiently monitored so as to prevent a loading
calculation using the ratio estimator method. In order to estimate a load
from these areas, an annual diffuse unit area load (kg/ha/year) from a
monitored area with similar basin characteristics was multiplied by the
watershed area to provide an annual loading.
Unit area loads for monitored areas were calculated by dividing the
diffuse load (total load minus point source load) by the area of drainage.
Because of the two different point source transmission scenarios used,
two different unit area loads were calculated for each monitored area.
Consequently, two different estimates of loads for unmonitoved areas were
generally calculated for each water year.
In applying a diffuse unit area load factor froa a monitored area
to an unmonitored area, care was taken to be sure the unit area load applied
was a reasonable representation of actual conditions. For example, the
comparability of watersheds with respect to soil texture, soil credibility,
surficlal geology, and runoff characteristics were considered in the
application of diffuse unit area annual loads to unmonitored areas. In
addition, an attempt was uade to consider the effects of geographic
variations in rainfall, atmospheric inputs, and land use practices.
Whenever feasible, adjacent or nearly adjacent areas with calculated
diffuse unit area loads were used to estimate unmonitored diffuse loads.
Once a diffuse load was calculated for an unmonitored area,
Identified point i-L-rce Inputs were added to give a total load for a given
year. Two different total loads were thus calculated for each water year,
one assuming 100 percent delivery of point source inputs to the river
•oath and the other assuming delivery of SO percent of upstream point
source inputs and 100 percent of the downstream point source inputs.
29
-------
In most cases mmoiitoreH areas had few If any point sources in their
watersheds.
30
-------
RESULTS
Tables 6 and 7 present tributary and land runoff loading information
for the entire V. S. Great Lakes drainage baain. Table £ gives
information on by Lake and total U. S. Great Lakes Basin, while Table 7
gives Information on an individual hydrologic area and river basin group
basis. All values presented in these tables are based upon analysis of
point and non-point inputs tr. individual rivers draining in the U. S.
Basin. The numbers for the hydrologic areas have been rounded to two
significant figures. The river basin group totals, lake totals, and U. S.
Great Lakes Basin totals are r-ummatlons of The hydrologic area numbers.
Data are presented for seven parameters for both 1975 and 1976,
except for Lake Trie, for which 1976 data are not yet available. The
"Total Load" column represents the total diffuse and point source load
coming into the Lakes from the tributaries within a given area. The
"Monitored Load" column gives that portior of the total load that was
calculated from existing flow and concentration field data on individual
tributaries within a particular area. An estimated load was also made
for the unmo-.-itored areas based on a best judgement application on unit
area loads to unmonltored areas. The estimated unnonitored load plus
the monitored load equals the total load. The "Percent Diffuse" column
represent--, that p< r^lon of the total load which is non-point or from
diffuse sources (/ icludes base flow, see page 100). Tills value is obtained by
subtracting all known point source loads contributing to the area in
question. It was assumed that 100 percent of all point source inputs
within a siven basin are delivered to the Lake in calculating this
diffuse load (point source loads assuming a 50 percent delivery of upstream
source:, have also been calculated but are not presented hern). The
"Unit Area" column presents the total (monitored plus unmonitored area)
diffuse unit area load. This value was obtained by dividing the total
diffuse load by the given area.
Values presented in the U. S. Greet Lakee Tributary Loading Summary
table for total load and monitored load are summations of the river basin
group information. The percent diffuse and unit area loads are calculated
for each Lake based on the diffuse load and the diffuse load divided
by the drainage area of the given *^ake, respectively. All values
presented in these tables are based upon the best available data for both
river mouth and point source loading information.
•u
-------
Table 6
U.S. GREAT LAKES
TRIBUTARY LOADINGS
Lake
Number
1
2
3
it
5
Lake
Lake
Lake
Lake
Lake
Name
Superior
Michigan
Huron
Erie
Ontario
TOTAL
Lake
1
2
3
4
5
Lake
Lake
Lake
Lake
Lake
Superior
Michigan
Hurc.i
Erie*
Ontario
TOTAL*
Lake
1
2
3
4
5
Lake
Lake
Lake
Lake
Lake
Superior
Michigan
Huron
Erie*
Ontario
TOTAL*
Total Phosphorus 1975
Total1
Load
1.M9
3,190
1,720
8,639
1,966
16,904
Soluble
464
1,224
456
2,070
522
4,736
2
Monitored
Load
999
2,772
1,472
6,899
1,424
13,566
%3
Dif-
fuse
90
55
66
81
S3
71
Ortho Phosphorus
133
1,055
365
1,320
374
3,247
Suspended Solids
1,380,500
608,800
467,300
6,054,900
1,054,000
9,565,500
1,011,200
455,700
256,300
3,822,000
779,000
6,324,200
B8
56
45
62
45
60
1975
96
93
98
99 1
95
98
Unit4
Area
.28
.15
.27
1.3
.23
.40
1975
.09
.06
.05
.23
.05
.10
300
49
110
,100
220
310
Total1
Load
964
3,596
1,954
NA
3,513
-
Total Phosphorus
1976
2 *3
Monitored Dif-
Load
464
3,062
1,563
NA
2.580
-
fuse
86
63
83
MA
72
-
Soluble Ortho Phosphorus
361
1,153
843
NA
549
-
720,800
742,400
765,100
NA
1,545,000
86
933
663
NA
416
-
Suspended Solids
447,030
602,100
424,100
NA
1,316,000
86
55
83
NA
32
-
1976
93
95
99
NA
96
Unit
Area
.20
.19
.40
NA
.56
-
1976
.07
.05
.17
NA
.04
-
150
57
180
NA
330
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tona/yr)
1976 Lake Erie data not available (NA)
Percent of total load from diffuse aources (nonpoint)
^
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km /yr)
-------
Table 6
U.S. GREAT LAKES
TRIBUTARY LOADINGS
Lake
Nunfcer Name
1 Lake Superior
2 Lake Michigan
3 Lake Huron
4 Lake Erie*
5 Lake Ontario
TOTAL
Lake
1 Lake Superior
2 Lake Michigan
3 Lake Huron
4 Lake Erie*
5 Lake Ontario
TOTAL*
Lake
1 Lake Superior
2 Lake Michigan
3 Lake Huron
4 Lake Erie*
5 Lake Ontario
TOTAL*
Total Nitrogen 19
Total1
Load
13,530
47,410
29,130
111,670
24 .970
226,710
Monitored
Load
9,830
39,940
23,772
79,550
19.220
172,292
2 Dif-
96
79
88
92
66
85
Nitrate (Nitrite) N
3,118
20,050
18,250
85,918
13.500
140,836
1,565
5 961
2,423
6,236
3.419
19,604
2,381
16,950
14,873
63,650
10,210
108.064
Ammonia N
1,061
4,761
2,236
3,551
2,350
13,959
94
81
94
96
82
92
1975
87
49
32
40
35
44
75
Unit4
Area
2.9
3.2
6.4
19.
3.6
6.4
1975
.66
1.4
4.1
15.
2.4
4.3
.31
.24
.19
.82
.26
.28
Total
Total1
Load
10,900
54,530
27,470
NA
35.260
Nitrogen 1976
Monitored
Load
4.440
44,930
20,130
NA
26.300
Nitrate (Nitrite)
2,145
22,697
15,011
NA
17J920
395
5,160
1,740
NA
3.844
830
18,717
10,154
NA
13,160
Animonia N
443
4,321
1,517
NA
2,826
Dif-
fuse
94
82
86
NA
76
-
N 1976
91
84
93
NA
86
-
19 '6
75
33
25
NA
26
Unit.
Area
2.3
3.6
5.9
NA
6.0
-
.44
1.6
3.4
HA
3.4
-
.15
.15
.10
NA
.22
Total load from Hydrologlc Area (metric tons/yr)
Portion of total load that was nonltored (metric tons/yr)
1976 Lake Erie data not available (NA)
Percent of total load from diffuse sources (nonpoint)
4
Total diffuse unit area load (kg/hectare/yr or
10'1 metric tonn/kmz/yr)
-------
Table 6
U.S. GREAT LAKES
TRIBUTARY LOADINGS
Lake
Number Name
1 Lake Superior
2 Lake Michigan
3 Lake Huron
4 take Erie*
5 Lake Ontario
*
Total
ChlAride 1975
1 2 ^ 4
Total Monitored DI f- Unit
Load Load fuse Area
92..680 50,520 61 13
775,500 636,960 65 43
377,400 351,290 66 60
855,600 577,800 90 31
1,199,900 1,149,200 52 140
3,301,080 2,765,770 66 74
Chloride 1976
Total1 Monitored2 Dif- Unit4
Load Load fuse Area
81,600 26,680 55 10
711,600 563,650 72 42
422,100 359,030 70 74
NA NA NA NA
1,607,800 1,553,300 64 220
Total load from Hydrologic Area (metric tona/yr)
2
Portion of total load that was oonitored (necric tons/yr)
*1976 Lake Erie data not available (NA)
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectare/yr or
10~1 metric tons/k»^/yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKE SUPERIOR
Hydrologic Area
Humber
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
Mane
Superior Slope Complex
Saint Louis River
Apostle Island Complex
Bad River
Montreal River Complex
River Basin Group 1.1 Total
Porcupine (fountains Complex
Ontonagon River
Keweenav Peninsula Complex
Sturgeon River
Huron Mountain Complex
Grand Mara Is Complex
Tahquanenon River
Sault Complex
River Basin Group 1.2 Total
Total
Total1
Load
180
260
420
160
33
1,053
26
160
22
19
46
31
13
19
336
Phosphorus
Monitored
Load
140
260
140
160
27
727
20
160
0
19
38
12
13
10
272
1975
t3
Dif-
fuse
100
67
100
100
81
91
79
100
97
100
28
100
64
100
87
Unit*
Area
.30
.18
.80
.60
.33
.39
.07
.45
.06
.10
.05
.10
.04
.27
.14
Total
Total1
Load
180
120
280
52
22
654
28
100
22
39
51
31
20
19
310
Phosphorus
Monitored
Load
0
120
95
52
-13-
286
0
100
0
39
0
0
20
.12-
178
1976
t3
Dif-
fuse
100
58
100
100
71
91
80
99
97
100
25
100
77
100
77
Unit*
Area
.30
.08
.54
.20
.20
.25
.08
.28
.06
.21
.05
.10
.07
.27
.13
1
Total load from Hydrologic Area (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
2 L.
Portion of total load that was monitored (metric tons/yr) Total diffuse unit area load (kg/hectare/yr or
10-1 metric tona/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydrologlc Area
Number
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Name
MenoBlnee Complex
Menomi.iee River
Peshtlgo River
Oconto River
Sua«lco Complex
Fax River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex*
Saint Joseph River 450
Black River (S. Haven) Coop lex
Kalamazoo River
Black River (Ottawa Co.) Comp.
Grand River
River Basin Group 2.3 Total
Muakegon River
Sable Complex
ManlBtee River
Traverse Coaplex
Seul Cholx-GroBcap Complex
Maniatique River
Bay De Hoc Complex
Escanaba River
River Basin Group 2.4 Total
Total
Total1
Load
11
87
59
51
44
500
220
972
300
450
14
230
78
760
1,532
81
94
53
51
11
46
13
37
386
Phosphorus
Monitored
Load
5
87
59
51
16
500
150
868
160
450
0
230
0
760
1,440
79
64
53
12
0
46
13
37
304
1975
z3
Dif-
fuse
100
83
100
99
100
24
52
56
81
44
100
34
16
46
42
90
99
61
84
IOC
85
100
99
88
Unit*
Area
.04
.05
.20
.19
.35
.07
.32
.12
.42
.16
.15
.15
.19
.24
.19
.10
.20
.06
.06
.08
.10
.04
.15
.10
Total
Total1
Load
35
73
39
57
92
520
200
1,016
470
490
18
230
81
840
1,659
100
130
61
51
13
51
13
32
451
Phosphorus
Monitored
Load
15
73
39
57
32
520
120
856
300
490
0
230
0
840
1,560
100
91
56
12
0
51
3.6
32
346
1976
Z3
Dif-
fuse
100
66
100
98
100
31
83
59
86
56
100
35
19
55
51
92
99
66
84
100
86
100
98
90
Unit4
Area
.13
.05
.13
.22
.73
.09
.26
.14
.73
.23
.19
.15
.23
.31
.25
.13
.29
.08
.06
.09
.12
.04
.13
.12
Total load from Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; set page 87.
Percent of total load from diffuse sources (nnnpolnt)
Total diffuse unlr area load (kg/hectare/yr or
10"1 metric tons/km /yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKE HURON
Hydrologlc Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.7
3.2.3
Nane
Lea Cheneaux Complex
Cheboygan River
Presque Isle Complex
Thunder Bay River
Au Sable and Alcona Complex
Rlfle-Au Ores Complex
River Basin Group 3.1 Total
Kawkawllr Complex
Saglnav River
Thumb Complex
River Basin Group 3.2 Total
Total
Total1
Load
78
30
5.7
33
33
58
238
42
1,200
240
1,482
Phosphorus
2
Monitored
Load
18
29
2.5
33
30
54
166
18
1,200
88
1,306
1975
23
Dif-
fuse
100
100
100
100
100
84
96
73
53
99
61
Unit*
Area
.26
.07
.04
.10
.06
.17
.11
.31
.39
.64
.43
Total
Total1
Load
94
24
15
15
40
45
233
41
1,400
280
1,721
Phosphorus
Monitored
Load
22
23
6.6
15
36
24
127
0
1,400
36
1,436
1976
x*
Dlf-
flMft
100
99
100
100
100
80
96
73
77
99
81
Unit*
Area
.31
.06
.10
.05
.07
.13
.11
.03
.68
,78
.68
Total load from H>drologlc Area (metric tona/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint)
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ERIE
Hydrologic Area
Number
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clair Complex
Clinton River
Rouge Complex
Huron River
Swan Creek Complex
Raisin River
River Basin Group 4.1 Total
Ottawa River
Maumee River
Toussaint-Portage Complex
Sandusky River
Huron-Verm* lion Complex
River Basin Croup 4.2 Total
Black-Rocky Complex
Cuyahoga River
Chagrin Complex
Grand River
Aahtabula-Conneaut Complex
River Ba?in Group 4.3 Total
Erie-Chautauqua Complex
Cattaraugus Creek
Tonawanda Complex
River Basin Group 4.4 Total
Total Phosphorus
Total1
Load
46
64
260
320
250
60
310
1'n°
69
2,600
240
620
310
3,839
750
790
160
380
190
2,270
300
180
740
1,220
Monitored
Load
46
23
260
200
250
0
280
1,059
0
2,600
150
600
220
3,570
660
790
140
330
170
2,090
0
180
0
180
1975
,3
Z
DJf-
fuse
86
92
58
96
60
\00
72
76
95
86
85
81
86
85
76
65
96
100
97
79
92
94
63
75
Unit4
Area
.22
.40
.76
1.6
.70
.70
.70
.74
1.0
1.3
.77
1.3
1.0
1.2
2.5
2.2
2.0
1.8
2.0
2.1
1.6
1.2
1.6
1.5
Total Phosphorus 1976
_3
1 2 It
Total Monitored Dlf- Unit
Lrad Load fuse Area
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolni
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/km2/yr)
-------
Table 7
HYDRULOGIC AREA LOADS
LAKE ONTARIO
Hydrologlc Area
Huaber
5.1.
5.1.
5.2.
5.2.
5.2.
5.3.
5.3.
5.3.
5.3.
1
2
1
2
3
1
2
3
4
Name
Niagara-Orleans Coup lex
Genesee River
River Basin Group 5.1 Total
Wayne-Cayuga Complex
Oawego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Oswagatchie River
Grass-Raquette-St. Regis Coop.
River Basin Group 5.3 Total
Total Phosphorus
Total1
Load
290
590
880
83
510
66
659
154
33
130
110
427
Monitored
Load
0
530
530
0
510
0
510
154
0
130
100
384
1975
X3
Dif-
fuse
56
71
66
92
0
93
21
85
100
91
42
77
Unit4
Area
.61
.61
.61
.61
.25
.08
.25
.27
.27
.06
.17
Total1
Load
360
800
1,160
120
920
190
1,230
410
83
290
340
1,123
Total Phosphorus
Monitored
Load
0
720
720
0
920
0
920
410
0
290
240
940
1976
X3
Dlf-
fuae
68
78
75
95
39
98
53
96
100
96
//
90
Unit*
Area
.90
.90
.90
.90
.27
.76
.39
.76
.66
.67
.32
.54
Total load froa Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint)
Total diffuse unit area load (kg/hectare/yr or
10
,-1
stric tann/km'/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE SUPERIOR
Hydrologic Area
Number
1.1.1
J.I. 2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
Hame
Superior Slope Complex
Saint Louia River
Apostle Island Complex
Bad River
Montreal River Complex
River Basin Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keweenaw Peninsula Complex
Sturgeon River
Huron Mountain Complex
Grand Marals Complex
Tahquamenon River
Sault Complex
River Basin Group 1.2 Total
Soluble
I
Total
Load
60
120
140
32
6.2
358—
16
19
7.3
4.7
24
21
7.9
6.6
106
Ortho Phosphorus
Monitored
Load
0
0
48
32
5.6
86
0
19
0
4.7
2.8
7.9
7.9
4.4
47
Z3
Dif-
fuse
100
78
100
100
48
92
38
99
96
100
36
100
71
100
74
1975
A
Unit
Area
.10
.10
.27
.12
.04
.14
.02
.05
.02
.03
.04
.07
.03
.07
.04
Soluble
1
Total*
Load
60
73
94
11
11
249
4.1
39
7.0
8.2
25
20
4.1
4.6
112
Ortho Phosphorus 1976
2
Monitored
Load
0
0
0
0
9.4
9.4
1.4
39
0
8.2
24
0
4.1
0
77
I3
Dif-
fuse
100
65
100
100
71
88
100
99
100
100
35
100
44
100
'83
4
Unit
Area
.10
.05
.18
.04
.01
.09
.01
.11
.02
.04
.04
.07
.01
.07
.05
Total load from Hydrologic Area (metric tons/yr)
Portion of tota1 load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoln
4Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km2/yr)
-------
Table I
HYDROLOCIC AREA LOADS
LAKE MICHIGAN
Hydrologic Are*
Number
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Name
Menomlnee Complex
Menomlnee River
Peahtlgo River
Oconto River
Suamlco Complex
Fox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex**
Saint Joseph River
Black River (S. Haves) Complex
Kalauzoo River
Black River (Ottawa Co.) Comp.
Grand River
River Basin Group 2.3 Total
Huskegon River
Sable Complex
Manistee River
Traverse Complex
Seul Cholx-Groacap Complex
Hanlstlque River
Bay De Hoc Complex
Kscanaba River
River Basin Group 2.4 Total
Soluble
Total1
Load
6.4
37
34
15
21
220
140
473
68
96
3.9
95
14
320
529
29
24
19
23
6.7
26
2.5
24
154
Ortho Phosphorus
2
Monitored
Load
2.8
37
34
15
7.5
220
80
396
45
96
0
95
0
320
511
29
0
19
k.i
0
£O
0
24
103
Z3
Dif-
fuse
100
61
100
96
100
65
88
77
64
0
100
23
61
36
"28
87
95
8
83
100
100
100
100
83
1975
Unit*
Area
.02
.02
.11
.06
.17
.08
.20
.08
.08
_
.0<
.04
.13
.08
.05
.04
.05
.03
.02
.05
.07
.01
.10
.04
Soluble
Total1
Load
7.3
23
10
9.4
20
110
110
293
99
160
4.2
87
11
340
602
38
34
18
74
5.9
20
2.5
14
157
Ortho Phosphorus 1976
Monitored2
Load
3.2
23
10
9.4
7.0
110
64
227
24
160
0
87
0
340
587
37
0
18
5.4
0
20
.7
14
95
Z3
Dif-
fuse
100
37
100
94
100
41
85
66
74
32
100
30
48
46
41
67
97
4
80
99
100
100
100
77
Unit*
Area
.03
.01
.03
.03
.16
.03
.15
.04
.13
.04
.04
.05
.08
.11
.06
.04
.07
.OIK*
.03
.04
.05
.01
.06
.04
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric to.is/yr)
*
K • leas than
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; see page 87.
Percent of total load from diffuse sources (nonpolnt
i
Total diffuse unlr area load (kg/hectare/yr or
10"1 metric tons/km/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE HURON
Hydrologlc Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.3.6
3.2.1
3.2.2
3.2.3
Name
Les Cheneaux Complex
Cheboygan River
Fresque Isle Complex
Thunder Bay River
Au Sable and Alcona Complex
Rifle-Au Cres Complex
River Basin Group 3.1 Total
Kavkavlin Complex
Saglnaw River
Thumb Complex
River Basin Group 3.2 Total
Soluble
Total1
Load
36
13
8.6
10
21
22
111
15
260
70
345
Ortho Phosphorus 1975
2
Monitored
Load
8.5
12
2.2
10
20
21
74
5.1
260
26
291
Dif-
fuse
100
100
100
100
100
82
96
61
7
99
28
Dnlt4
Area
.12
.03
.06
.03
.04
.06
.05
.09
.01
.19
.05
Soluble
Total1
Load
28
5.9
4.3
2.7
13
.14
68
15
620
140
775
Ortho Phosphorus 1976
Monitored
Load
6.5
5.7
0
2.7
12
6.8
23
0
620
20
640
ZJ
Dif-
fua«
100
100
100
100
100
73
94
61
78
9?
82
Unit*
Area
.09
.01
.03
.01
.02
.04
.03
.09
.30
.38
.30
Total load from Hydrologlc Area (metric tons/yr)
2
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse aourcea (nonpolntj
j
Total diffuse unit area load (kg/hectare/yr or
10~1 metric tona/km^/yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKF ERIE
Hydrologic Area
Number
••.1.1
4.1.2
4.1.3
4.1.4
4.1.3
4.1,6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clair Complex
Clinton River
Rouge Complex
Huron River
SWOT. Creek Coiijilex
Raisin River
River Basin Group 4.1 Total
Ottawa River
Haunee River
Toussaint-Portage Complex
Sanduaky ?.l >°r
Huron-Vermilion Complex
River Basin Group 4.2 Total
Black-Rocky Complex
Cuyahogd R: ve r
Chagrin Complex
Grand River
Ashtabula-Conneaut Complex
River Basin Group 4.3 Total
Erle-Chautauqua Conplex
Cattaraugus Creek
Tonavanda Complex
River Basin Group 4.4 Total
Soluble
i
Total1
Load
26
21
78
170
40
11
100
446
17
610
77
85
55
844
320
180
24
57
27
608
39
13
120
172
Ortho Phosphorus
2
Monitored
Load
26
0
0
110
40
0
0
176
0
610
52
33
44
789
140
180
22
0
0
342
0
13
0
13
3
A
Dif-
fuse
87
89
32
96
0
10°
58
67
90
68
75
31
59
64
72
32
85
99
89
64
67
54
12
28
1975
4
Unit
Area
.12
.12
.12
.86
-
.12
.18
.22
.24
.24
.22
.07
.12
720
1.0
.25
.26
.26
.26
.47
.16
.05
.05
.07
Soluble Ortho Phosphorus 1976
3
1 2 4
Total1 Monitored Dlf- Unit
Load Load fuse Area
^Total load from Hydrologic Area (metric tons/yv)
2
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoii
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/knZ/yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKE ONTARIO
Hydrologlc Area
Number
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Name
Niagara-Orleans Complex
Cenesee River
River Baa In Oroup 5.1 Total
Wayne-Cayuga Complex
Osvego River
Salmon Complex
River Basin Croup 5.2 Total
Black River
Perch Complex
Oawagatchie River
Graas-Raquette-St. Regis Comp.
River Basin Group 5.3 Total
Soluble
i
Total
Load
58
86
144
7.2
120
49
176
-i 10
7.5
31
54
202
Ortho Phosphorus
2
Monitored
Load
0
68
68
0
120
0
120
110
0
31
45
185
t3
Dif-
fuse
15
25
21
56
0
9?
29
90
100
82
42
76
1975
/
Unit
Area
.03
.03
.03
.03
_
.20
.03
.20
.06
.06
.03
.08
Soluble
i
Total
Load
68
110
l^e
11
200
21
232
50
8.0
33
48
139
Ortho Phosphorus 1976
2
Monitored
Load
0
89
89
0
200
0
200
50
0
33
44
127
X3
Dif-
fuse
25
40
34
72
0
92
12
83
100
83
19
62
A
Unit
Area
.06
.06
.06
.06
_
.08
.02
.08
.06
.06
.01
.04
Total load from Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent: of total load fro* diffuse sources (nonpolnt
Total diffuse unit area load (kg/hectare/yr or
UT1 metric tons/km2/yr)
-------
Table ^
HYDROLOCIC AREA LOADS
LAKE SUPERIOR
Hydrologlc Area
Number
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
*
Over
Name
Superior Slope Complex
Saint Louis River
Apostle Island Complex
Bad River
Montreal River Coirplex
River Basin Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keweenaw Peninsula Complex
Sturgeon River
Huron Mountain Complex
Grand Marais Complex
Tahquamenon River
Sault Complex
River Baa In Group 1.2 Total
46,000 MT/yr from point sources
Drains a large clay are.a
Susf ended Solids
Total1
Load
43,000
70,000
470,000
100,000
5,900
688,900
36,000
580,000
17,000
20,000
12,000
9,900
7,400
9,300
691,600
Monitored
Load
35,000
70,000*
160,000
100,000
4,700
369,700
17,000
580,000
0
27,000
5,100
3,800
7,400
8,200
641,500
1975
Z3
Dif-
fuse
100
32*
100
100
90
93
66
100
100
100
100
100
100
100
98
Unit*
Area
72
24
900
390
75
270
38
1600**
41
110
48
32
34
130
330
Total1
Load
61,000
27,000
220,000
150,000
3,400
461,400
34,000
150,000
12,000
26,000
8,700
11,000
7,900
9,800
259,400
Suspended Solids
2
Monitored
Load
3,800
27,000*
74,000
150,000
2,700
257,500
4,700
150,000
0
26,000
930
0
7,900
0
189,530
1976
X3
Dif-
fuse
100
0*
100
100
99
94
35
100
100
100
100
100
100
100
91
Unit*
Area
100
-
420
590
43
180
50
410**
35
140
35
35
36
140
120
Total load tram Hydrologlc Area (metric tona/yr)
Portion >{ total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint)
Total diffuse unit »r«a load (kg/hectare/yr or
10"1 metric tons/V«2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydrologic Area
Humker
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2,4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
1
Nane
Mencminee Complex
Henjalnee River
Peshtlgo River
Oconto River
Suamlco Complex
Fox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex *
Saint Joseph River
Black River (S. Haven) Complex
Kalamazoo River
Black River (Ottawa Co.) Coop.
Grand River
River Basin Group 2.3 Total
Muskegon River
Sable Complex
Mania tee River
Traverse Complex
Seul Choix-Groscap Complex
Hanlstlque River
Bay De Hoc Complex
Eacanaba River
River Baaln Group 2.4 Total
Suspended Solids
Total1
Load
5,700
13,000
4,000
7,300
26,000
60,000
78,000
194,000
100,000
82,000
3,600
27,000
2,700
76.000
191,300
'.1,000
16,000
20,000
21,000
4,800
12,000
4,900
4,100
123,800
Monitored
Load
2,500
13,000
4,000
7,300
9,300
60,000
41,000
137,100
50,000
82,000
2,800
27,000
0
76.000
187,800
40,000
0
20,000
4,700
0
12,000
0
4,100
80,800
1975
z3
Dif-
fuse
100
R8
100
83
100
65
110
88
96
97
100
82
93
94
94
100
99
91
99
100
100
100
96
98
Unit*
Area ,
21
11
13
24
210
23
120
38
isr>
66
39
43
39
49
54
57
36
36
32
33
33
16
16
36
Total1
Load
17;000
16,000
6,000
10,000
52,000
100,000
24,000
225,000
67,000
110,000
4,900
37,000
3,700
150.000
305,600
63,000
14,000
18,000
19,000
5,900
16,000
4,900
4.000
144,800
Suspended Solids.
Monitored2
Load
7,500
16,000
6,000
10,000
18,000
100,000
13.000
170,500
32,000
110,000
J
37,000
0
150.000
297,000
61,000
0
16,000
4,200
0
16,000
1,400
4.000
102,600
1976
z3
Dif-
fuse
100
91
100
88
100
87
100
93
94
98
100
82
95
97
96
100
99
90
99
100
100
100
96
98
Unit4
Area
63
14
20
36
42
52
39
38
110
91
53
59
53
98
87
89
31
31
28
41
41
16
16
42
Total load from Hydrologic Area (metric tons/yr)
^Portion of total load that was monitored (metric tcms/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; see page 87.
4
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit, area load (kg/hectare/yr or
10"1 metric tons/km /yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE HURON
Hydrologlc Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.2
3.2.3
Name
Lea Cheneaux Complex
Cheboygan River
Presque Isle Complex
Thunder Bay River
Au Sable and Alcona Coupler
Rifle- Au Gres Complex
River Basin Group 3.1 Total
Kawkawlin Complex
Saglnav River
Thumb Complex
River Baaln Group 3.2 Total
Suspended Solids 1975
Total1
Load
ISO, 000
7,200
8,700
6,000
12,000
30,000
243,900
3,400
120,000
100,000
223,400
Monitored
Load
43,000
6,900
2,200
6,000
11,000
27,000
96,100
2,200
120,000
38,000
160,200
*3
Dif-
fuse
100
100
100
100
100
100
ICO
98
91
100
95
Unit4
Area
600
17
60
18
21
103
120
33
68
280
100
Suspended Solids 1976
Total1
Load
57,000
8,800
11,000
6,900
16,000
22,000
121,700
3,400
360,000
280.000
643,400
Monitored2
Load
13,000
8,400
0
6,900
15,000
13,000
56,300
0
360,000
8,800
368,800
*3
Dif-
fuse
100
100
100
100
100
100
100
98
97
100
98
Unit4
Area
190
21
74
21
28
77
60
33
220
850
300
Total load from Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km2/yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKE ERIE
Hydrologlc Area
Number
4.1.1
6.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clalr Complex
Clinton River
Rouge Complex
Huron River
Swan Creek Complex
RMain River
River Basin Group 4.1 Total
Ottawa River
Maunee River
TouBsalnt-Portage Complex
Sanduaky River
Huron-Verallion Complex
River Baain Group 4.Z Total
Black- Rocky Complex
Cuyahoga River
Chagrin Complex
Grand River
Ashtabula-Conneaut Complex
River Baali Group 4.3 Total
Erie-Chautauqua Complex
Cattaraugus Creek
Tonawanda Complex
River Basin Group 4.4 Total
Suspended Solids
Total1
Load
16,000
13,000
18,000
23,000
23,000
7,900
150,000
250,900
54,000
1,400,000
110,000
340,000
280,000
2,184,000
460,000
630,000
270,000
570,000
240,000
2,170,000
450,000
680,000
320,000
1,450,000
2
Monitored
Load
16,000
0
0
17,000
23,000
0
0
56,000
0
1,400,000
66,000
320,000
180,000
1,966,000
240,000
630,000
250,000
0
0
1,120,000
0
680,000
0
680,000
1975
z3
4
Dlf- Unit
fuse Area
100 86
100 86
96 86
26 86
82 92
100 U2
99 460
91 177
100 840
100 840
100 420
100 860
100 1,000
100 817
100 2,000
99 2,700
100 3,600
100 2,700
100 2,700
100 2,600
100 2,700
100 4,800
S8 1,100
100 2 , 300
Suspended Solids 1976
2 *3
Total Monitored Oil- Unit
Load Load fuse Area
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
4
Percent of total load from diffuse sources (nonpoii
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ONTARIO
Hydrologlc Area
Number
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Mane
Niagara-Orleans Complex
Genesee River
River Basin Group 5.1 Total
Wayne-Cayuga Complex
Oswego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Oswagatchie River
Grass-Raquette-St. Regis Coup.
River Basin Group 5.3 Total
Suspended Solids
Total1
Load
75,000
590^,000
665,000
45,000
100,000
49.000
194,000
73,000
4 4, 'cOO
25.000
195.000
2
Monitored
Load
0
540.000
540,000
0
100,000
0
100,000
73.000
0
44,000
22.000
139,000
1975
Z3
Dif-
fuse
96
99
99
7*
76
100
78
94
100
100
.11
98
Unit*
Area
270
840
680
270
56
200
93
130
420
100
30
100
Suspended Solids
Total1 Monitored
Load Load
75,000 0
1,100,000 IjlOOfOOO
1,175,000 1.100,000
40,000 0
141,000 141,000
52,000 0
233,000 141,1/00
41,000 41,000
53,000 0
20,000 20,000
23.000 14.000
137,000 75,000
19/6
Z3
Dif-
fuse
96
100
99
86
77
80
79
88
100
100
98
96
Unit*
Area
270
1.600
1,2CO
270
82
170
:.io
70
420
45
28
69
Total load fro* Hydrcloglc Area (Metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectare/yr or
10~* metric tons/km'/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE SUPERIOP
Hydrologic Area
Number
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.S
1.2.6
1.2.7
1.2.8
Name
Superior Slope Complex
Saint Louis River
Apostle Island Complex
Bad River
Montreal River Complex
River Basin Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keweenaw Peninsula Complex
Sturgeon River
Huron Mountain Complex
Grand Marala Complex
Tahquamenon River
Sault Complex
River Basin Group 1.2 Total
Total Nitrogen
Total1
Load
3,100
2,500
1,400
640
400
8.040
700
1,100
940
490
810
700
500
250
5,490
Monitored
Load
2,500
2,500
490
640
320
6,450
420
1,100
0
490
420
270
500
180
3,380
1975
Z3
Dif-
fuse
100
91
100
100
89
97
82
100
100
100
83
100
96
100
95
Unit*
Area
5.2
2.4
2.8
2.5
4.5
3.3
2.1
3.1
2.7
2.6
2.7
2.2
2.2
2.2
2.5
Total
Load
2,600
1,200
1,300
650
280
6,030
580
740
1,000
360
880
640
470
200
4,870
Total Nitrogen
Monitored
Load
0
1,200
430
650
230
2,510
150
740
0
360
210
0
470
0
1,910
1976
%3
Dif-
fuse
100
81
100
100
85
95
76
100
100
100
84
100
96
100
94
Unit*
Area
4.4
3..0
2.4
2.5
3.0
2.4
1.6
2.1
2.9
1.9
2.9
2.0
2.0
2.9
2.2
Jl
o
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint]
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydro logic Area
Hurter
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Nave
Menomlnee Complex
Menomlnee River
Peahtlgo River
Oconto River
Suaaico Complex
Fox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex*
Saint Joseph River
Black River (S. Haven) Complex
Kalamazoo River
Black River (Ottawa Co.) Coup.
Grand River
River Basin Group 2.3 Total
Muskegon River
Sable Complex
Manlstee River
Traverse Complex
Seul Cholx-GroBcap Complex
Manlstlque River
Bay De Hoc Coup lex
Eacanaba River
River Basin Group 2.4 Total
Total
Tctal1
Load
450
1,600
600
1,400
450
4,700
2,400
11,600
4,000
7,700
940
3,800
710
11,000
24,150
1,600
1,000
1,200
1,100
420
1,100
690
550
7,660
Nitrogen
Monitored
Load
200
1,600
600
1,400
160
4,700
1,300
9,960
2,000
7,700
750
3,800
0
11,000
23,250
1,600
0
1,200
1,100
0
1,100
0
550
4,730
1975
Dif-
fuse
100
94
100
100
100
63
94
83
88
70
100
57
45
73
70
96
96
95
92
100
100
100
100
97
Unit*
Area
1.6
1.5
2.0
5.5
3.6
1.7
3.7
2.2
6.2
4.5
10
4.2
4.8
5.4
5.0
2.2
2.2
2.3
1.5
2.9
2.9
2.3
2.3
2.2
Total1
Load
560
1,600
840
1,700
410
4,600
3,400
13,110
4,200
10,000
940
3,600
730
13,000
28,270
2,200
1,400
1,300
1,400
430
1,100
590
530
8,950
Total Nitrogen
Monitored2
Load
250
1,600
840
1,700
140
4,600
1,800
10.930
2,100
10,000
0
3.600
0
13,000
26,600
2,100
0
1,100
360
0
1,100
110
530
5,300
1976
X3
Dif-
fuse
100
94
100
100
100
65
95
86
88
77
100
52
46
77
lit
96
97
95
94
100
100
100
100
97
Unit4
Area
2.1
1.4
?..8
6.7
3.2
1.8
5.2
2.6
6.5
6.4
10
3.6
5.2
6.7
5.2
3.0
3.0
2.3
2.0
3.0
3.0
2.2
2.2
2.5
Total load from Hydrologlc Area (netric tona/yr)
Portion of total .load that was monitored (metric tons/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; see page 87.
Percent of total load from diffuse sources (nnnpoint)
H
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km /yr)
-------
Table 7
HYUROLOGIC AREA LOADS
LAKE HURON
Hydrologic Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.2
3.2.3
Name
Les Cheneaux Complex
Cheboygan River
Presque Isle Complex
Thunder Bay River
Au Sable and Alcona Conplex
Rifle-Au Gres Complex
River Basin Group 3.1 Total
Kavkawlln Complex
Saglna-4 River
Thuiib Complex
River Basin Group 3.2 Total
Total Nitrogen 1975
Total1
Load
1,100
590
360
530
750
1,000
4,330
1,100
18,000
5,800
24,800
Monitored
Load
250
560
92
530
690
970
3,092
580
18,000
2,100
20,680
Z3
Dif-
fuse
100
100
100
100
100
98
99
96
81
100
86
Unit*
Area
3.6
1.4
2.5
1.6
1.3
3.6
2.1
10
9.3
16
10
Total
Load
440
520
290
380
770
1,000
3,400
970
17,000
6,100
24,070
Total Nitrogen
1 Monitored2
Load
100
500
0
380
700
580
2,260
0
.17,000
870
17,870
1976
Z3
Dif-
fiwe
100
100
100
100
100
99
100
95
79
100
85
Unit*
Ana
1.5
1.3
2.0
1.2
1.3
1^5
1.7
9.2
8.1
17
9.7
J>
•J
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint)
Total diffuse unit area load (kg/hectare/yr or
10~l metric tons/k«2/yr)
-------
Table 7
HVDROLOGIC AREA LOADS
LAKE ERIE
Hydrologic Area
Number
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clair Complex
Clinton River
Rouge Couple x
Huron River
Stun Creek Complex
Raisin River
River Basin Group 4.1 Total
Ottawa River
Haunee River
Toussaint-Portage Complex
San dusky River
Huron- Vermilion Complex
River Basin Group 4.2 Total
Black- Rocky Complex
Cvyahoga River
Chagrin Complex
Grand River
Aahtabula-Conneaut Complex
River Basin Group 4.3 Total
Erie-Chautauqua Complex
Cattaraugus Creek
Tonawanda '.omplex
River Basin Group 4.4 Total
Total1
Load
1.100
800
2,500
620
1,200
170
5,300
11,770
1,700
48,000
5,300
7,300
3,900
66,200
16,000
4,800
1,100
2,900
1,200
26,000
2,200
1,300
3,700
7,700
Total Nitrogen
Monitored
Load
1,100
0
0
580
1,200
0
0
2,880
0
48,000
3,200
6,900
2,700
60,800
8,300
4,800
970
0
0
14,070
0
1,800
0
1,800
1975
Z3
Dif-
fuse
98
98
47
17
36
100
88
72
99
96
95
96
96
96
97
50
98
100
98
as
97
98
94
96
Unit*
Area
5.9
5.9
5.9
.57
2.0
2.0
14
6.3
27
27
19
18
14
23
67
10
14
14
14
27
13
12
12
12
Total Nitrogen 1976
2 *3 4
Total Monitored Dif- Unit
Load Load fuse Area
~~
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (rwtrlc tons/yr)
Percent of total load from diffuse sources (nonpolni
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/Vmz/yr)
-------
Table ?
I1YDROLOG1C AREA LOADS
LAKK ONTARIO
Hydro logic Area
Number
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Name
Niagara-Orleans Complex
Genesee River
Rtver Basin Croup 5.1 Total
Wayne-Cayugi Complex
Oswego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Oswagatchie River
Crass-Kaquette-SC. Regis Comp.
River Basin Croup 5.3 Total
Total1
Load
2,800
5,300
8,100
880
8,400
680
9,960
2,200
510
1,400
2.800
6,910
Total Nitrogen
Monitored
Load
0
4,800
4,800
0
8,400
0
8,400
2,200
0
1,400
2.400
6,000
1975
*3
*9
DJf-
fu.,e
66
88
80
97
23
98
35
94
100
97
94
95
Unit4
Area
6.8
6.8
6.8
6.8
1.5
2.8
2.0
4.0
4.0
3.2
3.2
3.5
Total Nitrogen
Total1
Load
3,600
7,500
11,100
1,300
12,000
1,300
14.600
3,200
760
1,900
3.700
9.560
2
Monitored
Load
0
6,900
6,9*0
0
12,000
0
12,000
3,200
0
1,900
2.300
7,400
1976
*3
Dif-
fuse
74
91
86
98
4?
99
56
98
100
98
94
96
Unit*
Area
9.9
9.9
9.9
9.9
4.4
5.2
4.9
6.1
6.1
4.2
4.3
4.9
Total lo.id from Hydrologlc Area (metric tona/yr)
Portion of total loao that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolr
£
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/knrVyr)
-------
Table ^
HYDROLOGIC AREA LOADS
LAKE SUPERIOR
Hydrologlc Area
Number
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
Name
Superior Slope Conplex
Saint Louis River
Apostle Island Conplex
Bad River
Montreal River Conplex
River Ban In Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keweenaw Peninsula Conplex
Sturgeon River
Huron Mountain Conplex
Grand Marais Conplex
Tahquanenon River
Sault Conplex
River Basin Group 1.2 Total
Nitrate (Nitrite)
1
Total
Load
820
880
210
120
84
2,114
160
140
140
98
120
220
74
52
1,004
Monitored
Load
670
880
71
120
70
1,811
81
140
0
98
64
84
74
_29
570
N 1975
%3
Dif-
fuse
100
90
100
100
80
95
62
100
99
100
81
100
90
100
91
/.
L'nlt
Area
1.4
.83
.40
.47
.86
.84
.34
.39
.39
.54
.39
.71
.30
*ZL
.45
Total
Load
600
230
210
100
64
1,204
130
140
140
64
110
220
85
-51
941
Nitrate (Nitrite)
I 7
Monitored
Load
37
230
72
100
55
494
22
140
0
64
25
0
85
_o_
33.6
N 1976
Z3
Dif-
fuse
100
61
100
100
74
91
50
100
99
100
78
100
91
1QQ
90
4
Unit
Area
1.0
.15
.41
.40
.61
.46
.24
.38
.39
.35
.39
.71
.37
^Zi
.42
Total load fror. Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load fron diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectare/yr or
10-! metric tons/kn2/yr)
-------
Table 7
HVDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydrologic Area
Number
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Maw
Neuominee Complex
Menovlnee River
Peshtigo River
Oconto River
Suamlco Complex
Fox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex *
Saint Joseph River
Black River (S. Haven) Complex
Kalamazoo River
Black River (Ottawa Co.) Comp.
Grand River
River Basin Group 2.3 Total
Muskegon River
Sable Complex
Maniatee River
Traverse Complex
Seul Choix-Groscap Complex
Mania tique River
Bay De Hoc Complex
Escanaba River
River Basin Group 2.4 Total
Nitrate
Total1
Load
71
450
320
190
170
940
1,100
3,241
2,300
4,300
310
1.80C
240
5,500
12,150
580
300
450
460
99
260
170
140
2,359
(Nitrite) N
2
Monitored
Load
31
450
320
190
59
940
580
2,570
1,100
4,300
250
1,800
0
5^500
11,850
470
0
450
110
0
260
0
140
1,430
1975
z3
Dif-
fuse
100
9i
100
99
100
29
94
76
90
79
100
73
73
76
78
94
98
96
95
100
100
100
100
97
Unit
Area
.26
.39
1.1
.72
1.3
.16
1.6
.56
3.6
2.6
3.4
2.6
2.6
2.9
2.8
.64
.64
.84
.65
.69
.69
.57
.57
.67
Total
Load
64
410
230
170
68
370
1,800
3,112
2,700
6,000
220
1,800
220
5,700
13,940
790
490
490
S8G
?5
250
130
120
2,°45
Nitrate (Nitrite)
1 2
Monitored
'Load
28
410
230
170
24
310
990
2,162
1,300
6,000
0
1,800
0
5,700
13,500
770
0
440
150
0
250
25
120
1,755
N 1976
I3
Dif-
fuse
100
90
100
99
100
0
97
86
92
85
100
71
72
78
80
96
99
97
94
ICO
100
100
100
93
Unit*
Area
.23
.35
.75
.66
.54
_
2.8
.61
4.4
4.2
2.4
2.4
2.4
3.0
3.3
1.1
1.1
.91
.83
.67
.67
.50
.50
.81
Total load from Hydrologic Area (metric tons/yr)
2
Portion of total load that was monitored (metric toaa/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; see page 87.
Percent of otal load from diffuse sources (nonpoint'
Total diffuse unit, area load (kg/hectare/yr or
iO"1 metric tons/km /yr)
-------
Table 7
HYDROLOCIC AREA LOADS
LAKE HURON
Hydrologic Area
Number Name
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.2
3.2.3
Lea Cheneaux Complex
Cheboygan River
Preaque Isle Complex
Thunder Bay River
Au Sable and Alcona Complex
Rifl«:~Au Gres Complex
River Basin Group 3.1 Total
Kawkawlin Complex
Saginaw River
Thumb Complex
River Basin Group 3.2 Total
Nitrate
Total1
Load
110
110
99
71
140
430
960
490
12,000
i.SCC;
17,290
(Nitrite) N
Monitored
Load
27
100
25
71
130
400
753
320
12.000
l.SOO
14,120
1975
Dif-
fuse
100
100
100
100
100
98
99
9&
92
100
94
Unit4
Area
.38
.26
.68
.22
.24
1.5
.46
4,7
6.3
n
7.8
Nitrate
Total1
Load
63
120
99
49
150
470
951
460
8,900
4,700
14,060
(Nitrite) N
Monitored
Load
15
120
0
49
140
27Q
594
0
8,900
660
9,560
1976
X*
Dif-
fuse
100
100
100
too
100
98
99
96
88
100
92
Unit4
Area
.21
.29
.63
.15
.27
1.6
.46
4.4
4.9
13
*:?
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectar«/yr or
10"1 metric tons/km2/yr)
-------
Table 7
HYDHOLOCIC AREA LOADS
LAKE ERIE
Hydrologic Area
Number
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Glair Complex
Clinton River
Rouge Complex
Huron River
Swan Creek Complex
Raisin River
River Baa In Group 4.1 Total
Ottawa River
Maunee River
Toussaint-Portage Complex
Sandusky River
Huron- Vermilion Complex
River Basin Group 4.2 Total
Black-Rocky Complex
Cuyahoga River
Chagrin Complex
Grand River
AahtabnlH-Conneaut Complex
River Ha Jin Group 4.3 Total
Erie- lautauqua Complex
Car" "gus Creek
Tonav/inda Complex
River Basin Group 4.4 Total
Nitrate (Nitrite) 1953
Total1
Load
710
580
1,300
290
450
J6
4,200
7,588
1,500
41, POO
4,800
6,500
2,900
56,700
12,000
2,600
570
1,500
660
17,330
1,200
1,000
2.100
4,300
Monitored
Load
710
0
0
180
450
0
0
1,340
0
41,000
2,900
6,200
1,900
52,000
6,200
2,600
510
0
0
9,310
0
1,000
0
1,000
z3
Dlf- Unit*
fuse Area
98 3.9
94 3.9
60 3.9
98 1.5
33 .68
100 .68
94 12
85 4.8
100 23
98 23
98 18
98 16
98 10
98 20
98 51
64 7.2
98 7.3
100 7.3
98 7.3
93 19
98 7.0
98 7.0
96 7.0
9? 7.0
Nitrate (Nitrite) 1976
1 2 * 4
Total Mon^ored Dlf- Unit
Load Load fuae Area
Ln
OO
Total load from Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpo
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ONTARIO
Hydrologic Area
Number
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Name
Niagara-Orleans Complex
Gene see River
River Basin Group 5.1 Total
Wayne-Cayuga Complex
Oswego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Oswagatchle River
Grasa-Raquette-St. Regis Comp.
River Basin Group 5.3 Total
Nitrate (Nitrite)
Total1
Load
1,200
2.600
3,800
440
3,500
700
4,640
2,300
550
610
1^600
5,060
Monitored
Load
0
2,400
2,400
0
3,500
0
3,500
2,300
0
610
1.400
4,310
N 1975
X3
Dif-
fuse
76
90
86
98
49
99
61
98
100
97
94
97
Unit*
Area
3.4
3.4
3.4
3.4
1.3
2.8
1.7
4.4
4.4
1.4
1.8
2.6
Nitrate (Nitrite)
Total1
Load
1,800
4,100
5,900
710
5,900
810
7,420
1,800
440
460
1.900
4,600
Monitored
Load
0
3.800
3,800
0
5,900
0
5,900
1,800
0
460
1.200
3,460
N 1976
X3
Dif-
fuse
84
94
91
99
70
99
76
98
100
96
96
97
Unit*
Area
5.6
5.6
5.6
5.6
3.2
3.3
3.4
3.5
3.5
1.0
2.2
2.4
Total load from Hydrologic Area (metric Cons/yr)
Portion of total load that was monitored (metric tons/yi)
Percent of total load froa diffuse sources (nonpoint)
Total diffuse unit area load (Rg/hectare/yr or
10"1 metric tons/kmVyr)
-------
Table 7
riYDROLOGIC AREA LOADS
LAKE SUPERIOR
Hydrologlc Are*
Number
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
Name
Superior Slope Complex
Saint Louis River
Apostle Island Complex
Bad River
Montreal River Complex
River Basin Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keweenaw Peninsula Conplex
Sturgeon River
Huron Mountain Conplex
Grind Marais Complex
Tahquamenon River
Sault Conplex
River Basin Group 1.2 Total
Ammonia T7 1375
1
Total1
Load
240
280
230
85
42
877
31
150
154
29
250
37
19
18
68?
2
Monitored
Load
190
280
78
85
38
671
24
150
0
29
140
14
19
14
390
Z3
Dif-
fuse
100
62
100
100
58
86
76
100
99
100
74
100
54
TOO
88
4
Unit
Area
.40
.19
.44
.33
.28
•.•31
.08
.43
.43
.16
.73
.12
.05
.12
.30
Ammonia N 1976
i
Total
Load
140
120
130
64
13
467
32
74
74
12
180
28
15
13
428
2
Monitored
Load
0
120
44
64
13
741
2.9
74
0
12
98
0
15
0
202
X3
Dif-
fuse
100
8
100
100
0
74
26
98
98
100
65
100
43
100
77
4
Unit
Area
.24
.01
.25
.25
-
•;i4
.03
.21
.21
.07
.36
.09
.03
.19
.16
Total load from Hydrologlc Area (metric tons/yr)
2
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt
Total diffuse unit area load (kg/hectare/yr or
10-1 metric tons/k»r/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydrologlc Area
Number
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Name
Menomlnee Complex
Menomlnee River
Peshtlgo River
Oconto River
Suamico Complex
Pox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago-Milwaukee Complex
Saint Joseph River
Black River (S. Haven) Complex
Kalamazoo River
Black River (Ottawa Co. ) Comp.
Grand River
River Basin Group 2.3 Total
Muskegon River
Sable Complex
Manlstee River
Traverse Complex
Seul Cholx-Groscap Complex
Hants tique River
Bay De Nor. Complex
Escanaba River
River Basin Group 2.4 Total
Ammonia N 1975
Total1
Load
49
240
80
1,100
95
740
280
2,584
630
390
47
250
280
980
1,947
50
96
150
130
34
90
140
110
800
Monitored
Load
22
240
80
1,100
33
740
180
2,395
260
390
37
250
0
980
1,657
49
0
150
50
0
90
0
110
449
I3
Dif-
fuse
100
81
100
100
100
0
75
66
65
0
100
0
12
0
17
42
75
98
71
100
100
100
100
88
Unit4
Area
.18
.18
.27
4.2
.76
0
.34
.39
.73
.51
0
.51
.18
.09
.03
.16
.29
.14
.24
.24
.47
.47
.21
Amnonia N 197S
Total1
Load
52
43
73
750
72
710
250
1,950
240
580
47
180
160
1,400
2,367
86
53
82
220
25
65
36
36
603
Monitored2
Load
23
43
73
750
25
710
160
1,784
43
'580
0
180
0
1,400
2.160
85
0
74
70
0
65
3.6
36
334
Dif-
fuse
100
0
100
100
100
0
71
58
9
0
100
0
21
0
3
53
55
97
82
100
100
100
100
82
Unit4
Area
.19
0
.24
2.8
.58
0
.29
.26
.04
0
.51
0
.51
0
.02
.06
.06
.27
.17
.17
.15
.15
.14
Total load fro* Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; see page 87.
Percent of total load from diffuse sources (nnnnolnt)
A
Total diffuse unit area load (kg/hectare/yr or
10'l metric tons/km /yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE HURON
Hydrologlc Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.2
3.2.3
Name
Let Cheneaux Complex
Cheboygan River
Presque lale Complex
Thunder Bay River
Au Sable and Alcona Coop lex
Rlfle-Au Gres Complex
River Basin Group 3.1 Total
Kawkawlln Complex
Saglnau River
Thurab Complex
River Basin Groujj 3.2 Total
Ammonia N 1975
Total
Load
99
32
16
39
27
48
261
32
2,000
130
2,162
Monitored
Load
23
30
4.2
39
24
45
165
21
2,000
50.
2,071
13
Dif-
fuse
100
100
100
100
100
75
95
93
19
JO.
24
Unit4
Area
.32
.08
U
.12
.05
.13
.12
.33
.23
*1L
.25
Ammonia N 1976
Total
Load
69
19
12
12
29
35
176
44
1,400
_12Q_
1,564
1 Monitored2
Load
0
18
0
12
26
U
73
0
1,400
44
1,444
X3
Dif-
fuse
100
100
100
100
100
_66
93
51
9
97
17
Unit4
Area
.23
.04
.07
.04
.05
.08
.08
.22
.08
.24
.13
Total load from Hydrologlc Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/km^/yr)
-------
TabU 7
HVDROLOGIC AREA LOADS
LAKE ERIE
Hydrologlc Area
Number
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clair Complex
Clinton River
Rouge Complex
Huron River
Swan Creek Complex
Raisin River
River Basin Group 4.1 Total
Ottawa River
Maunee River
Toussalnt-Portage Complex
Sandusky River
Huron-Vermilion Complex
River Basin Group 4.2 Total
Black-Rocky Complex
Cuyahoga River
Chagrin Complex
Grand River
Aahtabula-Conneaut Complex
River Basin Group 4.3 Total
Erle-Chautauqua Complex
Cattaraugua Creek
Tonawanda Complex
River Basin Group 4.4 Total
Ammonia 1975
1
Total1
Load
47
37
650
230
270
12
340
1,586
12
1,100
83
260
110
1,565
1,200
620
95
230
110
2,255
220
180
430
830
2
Monitored
Load
47
0
0
230
270
0
0
547
0
1,100
78
250
89
1,517
600
620
87
0
0
1,307
0
180
0
180
,3
Z
Dif-
fuse
73
75
58
0
0
100
14
10
47
13
0
52
47
22
78
0
88
99
90
60
84
87
76
80
A
Unit
Area
.19
.19
.19
_
_
.14
.14
.12
.09
.09
-
.34
.19
.13
4.0
-
1.1
1.1
1.1
1.6
1.1
1.1
1.1
1.1
Anmonia 1976
3
1 2 4
Total1 Monitored* Dlf- Unit
Load Load fuse Area
Total load from Hydrologlc Area (metric tona/yr)
2
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoint
Total diffuse unit area load (kg/hectare/yr or
ID-1 metric tons/kn^/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ONTARIO
Hydrologlr Area
Dumber
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Name
Niagara-Orleans Complex
Genosee River
River Basin Group 5.1 Total
Wayne-Cayuga Complex
Oswego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Oawagatchie River
Graas-Raquette-St. Regis Comp.
River Basin Group 5.3 Total
Ammonia N 1975
1
Total
Load
660
590
1,250
64
1,200
130
1,394
330
65
140
240
775
2
Monitored
Load
0
500
500
0
1,200
0
1,200
330
0
140
180
650
Z3
Dif-
fuse
17
49
32
83
0
95
13
83
100
88
58
77
A
Unit*
Area
.42
.42
.42
.42
_
.52
.11
.52
.52
.30
.o7
.32
Armenia N 1976
i
Total
Load
730
780
1,510
97
1,800
29
1,926
86
12
100
210
408
2
Monitored
Load
0
670
670
0
1,800
0
1,800
86
C
100
170
356
I3
Dif-
fuse
25
61
43
89
0
78
6
57
100
79
52
61
A
Unit*
Area
.68
.68
.68
.68
-
.09
.06
.09
.09
.18
.13
.13
"Total load from Hydrologie Area (metric tons/yr)
Po.-tion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpolnt)
A
Total diffuse unit area load (kg/hectare/yi or
10"1 metric tons/kmVyr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE SUPERIOR
Hydrologic Area
Number
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
*
33,000
sources
Nam:
Superior Slope Complex
Saint Louis River
Apostle Island Complex
Bad River
Montreal River Complex
River Basin Group 1.1 Total
Porcupine Mountains Complex
Ontonagon River
Keveenaw Peninsula Complex
Sturgeon River
Huron Mountain Complex
Grand Marais Complex
Tahquamenon River
Sault Complex
River Basin Croup 1.2 Total
Metric Tons/Yr fron point
on the Mineral River
Chloride 1975
Total1
Load
8,800
25,000
2,800
2,400
1,400
40', 400
36,000*
3,700
2,400
2,000
3,000
2,600
1,700
880
52,280
2
Monitored
Load
7,100
25.000
940
2,400
1,200
36,640
2,600
3,700
0
2,000
2,000
1.000
1,700
610
13,610
Z3
Dif-
fuse
100
93
100
100
72
94
9
99
98
100
56
100
88
100
34
Unit*
Area
15
25
5.4
9.1
13
16
12
10
6.7
11
6.7
8.4
6.8
8.4
9.0
Total1
Load
5,900
14,000
2,000
1,600
1 ,300
25,200
36,000*
3,400
6,200
1,300
5,700
1,700
1,600
560
56,400
Chloride
4
Monitored'
Load
360
14,000
700
1,600
1,100
17,760
820
3,400
0
1,300
1,800
0
1,600
C
8,920
1976
1 •£-
fuse
100
85
100
100
69
90
8
99
100
100
77
100
89
100
39
Unit*
Area
10
14
4.0
6.1
11
11
10
18
7.1
18
3.4
6.6
8.1
ll
Total load fro* Hydrologic Area (metric tons/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoit
*Total diffuse unit area load (kg/hectare/yr or
10"1 metric tons/k^/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE MICHIGAN
Hydrologic Area
Number
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2.1
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.4.8
Mane
Menomlnee Complex
Menomlnee River
Peahtlgo River
Oconto River
Suamico Complex
Fox River
Green Bay Complex
River Basin Group 2.1 Total
Chicago- Milwaukee Complex
Saint Joseph River
Black River (S. Haven) Coop lex
Kalanazoo River
Black River (Ottawa Co.) Comp.
Grand River
River Basin Group 2.3 Total
Muskegon River
Sable Complex
Manlscee River
Traverse Complex
Seul Cholx-Croacap Complex
Manlstlque River
Bay De Hoc Complex
Escanaba River
River Baaln Group 2.4 Total
Total1
Load
2,200
3,200
2,100
6,200
1,600
51,000
23,000
89,300
59,000
78,000
4,300
60,000
4,200
170,000
316,500
48,000
63,000
160,000
11,000
1,600
4,100
13,000
10,000
310,700
Chloride
1975
Monitored Dif-
Load
980
3,200
2,100
6,200
580
51,000
13,000
77,060
29,000
78,000
0
60,000
0
170,0.00
308,000
46,000
0
160,000
2,800
0
4,100
0
10,000
222,900
fuse
100
72
100
99
100
72
92
81
93
72
100
79
73
83
80
99
48
5
93
100
100
100
100
40
Unit*
Area
8.2
2.2
7.1
24
13
21
35
17
97
46
46
91
46
57
76
67
67
15
15
11
11
44
44
37
Chloride 1976
Total1
Load
1,700
4,000
1,900
6,300
3,800
56,000
32,000
1)5,700
72,000
87,000
5,000
57,000
4,700
: 50 j 000
(03,700
48,000
66,000
87,000
13,000
1,500
3,900
5,700
5,100
30,200
Monitored2
Load
750
4,000
1,900
6,300
1,300
56,000
18,000
88,250
36,000
87,000
0
57,000
0
ISOjOOO
294,000
46,000
0
86,000
3,300
0
3,900
1,100
5,100
145,400
Z3
Dif-
fuse
100
77
100
99
100
76
96
85
94
75
100
76
76
81
79
98
46
11
94
100
100
100
100
50
Unit*
Area
6.2
2.9
6.5
25
30
25
50
21
120
54
54
84
54
83
60
66
66
18
18
10
10
21
21
34
Total load from Hydrologic Area (metric tons/yr)
^Portion of total load that was monitored (metric tons/yr)
Point sources to the Indiana Harbor Canal and Burns Ditch
are considered direct; eee page 87.
Percent of total load from diffuse sources (nonpoint)
4
Total diffuse unir area load (kg/hectare/yr or
10"1 metric tons/km /yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE HURON
Hydrologic Area
Number
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2.1
3.2.2
3.2.3
Name
Lea Cheneaux Complex
Cheboygan River
Presque Isle Complex
Thunder Bay River
Au Sable and Alcona Complex
Rlfle-Au Ores Complex
River Baa in Group 3.1 Totsl
Kawkawlln Complex
Saglnaw River
Thumb Complex
River Basin Group 3.2 Total
Total1
Load
4,700
6,500
1,100
5,500
11,000
14.000
42,800
7,600
100,000
27,000
J 34, 600
Chloride
1975
2 Z3
Monitored Dlf-
Load
1,100
6,200
490
5,500
9,900
13.000
36,190
5,100
300,000
10,000
315,100
fuse
100
100
100
100
100
J!l
99
94
58
100
62
Unit*
Area
16
16
7.8
17
19
48_
21
72
100
M
98
Total1
Load
2,000
6,700
1,500
4,300
11,000
17rOOO
42,500
7,600
320,000
52.000
379,600
Chloride
Monitored
Load
460
6,500
670
4,300
10,000
9.800
31,730
0
320,000
7.300
327,300
1976
2 *3
2 Dif-
fua«
100
100
100
100
100
.Ji
99
94
61
100
67
Unit*
Ar«*
6.6
16
10
13
19
5i
22
72
120
140
120
Total load from Hydrologic Area (metric tons/yr)
2
Portion of total load that was monitored (metric tons/yr)
Percent of total load fror. diffuse sources (nonpolnc)
4
Total diffuse unit area load (kg/hectare/yr or
10'1 metric tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ERIE
Hydrologlc Area
Number
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4.1
4.4.2
4.4.3
Name
Black River
St. Clalr Conplex
Clinton River
Rouge Complex
Huron River
Swan Creek. Conplex
Raisin River
River Basin Group 4.1 Total
Ottawa River
Mauaee River
Toussaint-Fortage Conplex
Sandusky River
Huron- Vermilion Complex
River Basin Group 4.2 Total
Black-Rocky Complex
Cuyahoga River
Chagrin Complex
Grand River
Ashtabula-Conneaut Complex
River Basin Group 4.3 Total
Erie-Chautauqua Complex
Cattaraugu* Creek
Tonavaiida Complex
River Basin Group 4.4 Total
Chloride 1975
Total1
Load
8,100
6,600
26,000
29,000
29,000
8,300
37,000
144,000
9,600
270,000
32,000
49,000
26,000
386,600
53,000
110,000
24,000
66,000
28^000
281,000
12,000
10,000
22,000
44,000
Monitored
Load
7.80C
0
0
18,000
29,000
0
0
54,800
0
270,000
20,000
47,000
17.000
354 000
27,000
110,000
22,000
0
0
159,000
0
10,000
0
10,000
*3
Dif-
fuse
97
97
52
99
74
100
84
82
99
93
92
95
95
93
90
79
99
100
99
90
94
95
90
92
Unit*
Area
43
43
70
150
96
96
96
87
150
150
110
120
92
130
210
380
310
310
310
300
68
68
_68
68
Chloride 1976
1 2 * 6
Total* Monitored* Dif- Unit
Load Load fuse Area
Total load from Hydrologlc Area (metric tona/yr)
Portion of total load that was monitored (metric tons/yr)
Percent of total load from dlffuae sources (nonpoJ
Total diffuse unit area load (kg/hectare/yr or
10-1 neu-ic tons/km2/yr)
-------
Table 7
HYDROLOGIC AREA LOADS
LAKE ONTARIO
Hydrologlc Area
Number
5.1.1
5.1.2
5.2.1
5.2.2
5.2.3
5.3.1
5.3.2
5.3.3
5.3.4
Name
Niagara-Orleans Complex
Genesee River
River Ban In Group 5.1 Total
Wayne-Cayuga Complex
Oswego River
Salmon Complex
River Basin Group 5.2 Total
Black River
Perch Complex
Osvagatchie Threr
Grasn-Raquette-ot. Regis Comp.
River Baaln Group 5.3 Total
-
i
Total
Load
26,000
140,000
166,000
9,400
1,000,000
3,200
1,012,600
7,500
1.400
4,800
7^600
21,300
Chloride
Monitored
Load
0
130,000
130,000
0
1,000,000
0
1,000,000
7,500
0
4,800
6,900
19,200
1975
2 *3
/ Dif-
fuse
lit
96
92
98
44
96
45
85
100
91
72
83
t
Unit
Area
72
190
160
72
350
13
280
12
11
10
6.7
9.3
i
Total
Load
26,000
140,000
166,000
9,400
1,400,000
3,600
1,413,000
8,600
1,900
7,300
11,000
28,800
Chloride
Monitored
Load
0
130,000
130,000
0
1,400,000
0
1,400,000
8,600
0
7,300
7,400
22,300
1976
2 I3
Dif-
fuse
74
96
92
98
60
96
61
87
100
94
87
90
A
Unit
Area
72
190
160
72
630
14
500
14
15
16
12
14
Total load from Hydrologic Area (metric tona/yr)
Portion of total load that vaa monitored (metric tons/yr)
Percent of total load from diffuse sources (nonpoin
Total diffuse unit area load (kg/hectare/yr or
10~ metric tons/kmVyr)
-------
DISCUSSION
ACCURACY 0? TRIBUTARY LOADING ESTIMATES
The results of the tributary loading study presented In the previous
section are based upon the best available data. The loauing estimates
probably represent the nost complete compilation of such data ever made for
the entire U.S. Great Lakes Basin. It must be remembered, however, when
utilizing this information that the loading estimates are only as good
as the available field data and that many potential sources of error exist
In the collection of data for load calculations.
Perhaps the most significant source of error during any given year
is the frequency of sampling. It is often Impossible to precisely
characterize the annual load contributed by any given river with, for
example, twelve monthly samples. The effect of hydrologic and chemical
factors (i. e., runoff events, droughts, point source spills and cbemical
exchange reactions) may be overlooked if the sampling is infrequent.
Consequently, it is possible within any given year to misrepresent the
actual load if the sampling program misses critical runoff events or other
occurrences.
During the analysis it was often noted that data points collected for
a. given tributary exhibited a high degree of variation. It was then
necessary to carefully examine these points to determine if they could be
readily explained by a high flow event or some other phenomenon. In
several cases extreme concentration data were rejected, especially if
they did not coincide with long-term historical trends or highflow
runoff events and were therefore perceived as potential sources of
reporting or data handling error.
As part of the ratio estimator method an estimated mean-square-error
(the square root of which is the estimated standard error of the mean)
is calculated along with each annual load estimate. Appendix A contains
these mean-square-eiror values calculated for individual tributaries.
While these mean-square-error terms are useful statistical information,
a low mean-square-error does not necessarily imply that the estimated load
is an accurate representation of the "true" load.
The mean-square-error is only an estimate of the error of the load
determined from a limited number of dally samples, based on the premise
that the true load can be determined by sampling flow and concentration
at the river mouth each and every day of the year. Thus, the error
estimate Implies that the true total annual load la that load given by
ptfi Mart
71
-------
the sum of 365 daily observations. This assumption, of course, implies
that sampling instrumentation and measurement errors may be neglected
and that an instantaneous flow/concentration measurement is & perfect
representation of tributary conditions on a particular day. Consequently,
while the nean-square-error terms are useful, they do not necessarily
reflect how close the estimated load is to the true load. For more
information on the statistical theory, statistical texts such as Kendall
and Stuart (1968) should be consulted.
In sunmary, the major source of error In es tuna ting river mouth
loads is likely to be the inability of the sampling program to provide a
representative temporal and spatial distribution of samples. Sampling
programs must he tailored to the unique characteristics of individual
streams if thay are to be both effective and efficient. Importantly,
all streams wi, 1 not require high sampling frequencies in order to
accurately characterize their loading contributions, e. g., monthly
instead of dally or weekly sampling may be sufficient to provide a
reasonable estimate of load. These individual tributary characteristics
which require consideration In the design of the sampling program will be
discussed in subsequent sections.
IJC Surveillance Versus U. S. Task D Total Phosphorus Loads
Total phosphorus loads have al.io been calculatei by the Surveillance
Subcommittee of the International Joint Commission. It is important to
point out the differences (and similarities) between the Surveillance
Subcommittee total phosphorus loads and the U. S. Task D (this study) loads.
Table 8 compares the li. S. total tributary loads estimated to be
delivered to Lakes Superior, Huron, and Michigan during 1976. Loads
estimated for Lakes Ontario and Erie were not directly comparable due to
the unavailability of 1976 Erie data as well as differences in drainage
demarcations.
Both estimates were based on the same computation method (ratio-
estimator method), but considerably more data were used in computing
the Task D load. Table 8 shows the total number of samples and the
number of rivers from which the loads were computed. State surveillance
data were the primary data source used by the Surveillance Subcommittee,
but for U. S. Task D, in addition to the state surveillance data, other
data were also used from university studies, the U. S. Geological Survey,
special EPA studies, and PLUARG Pilot Watershed studies. Consequently,
differences in loads as shown in Teble 8 can be accounted for in part
by the differences in sample numbers. Note that in this study (U. S.
Task D) loads were calculated for different parameters, while the
Surveillance Subcommittee calculated loads for total phosphorus only.
72
-------
TABLE 8
COMPARISON OF SURVEILLANCE SUBCOMMITTEE AND
U. S. TASK D 1976 TOTAL PHOSPHORUS TRIBUTARY LOADS
Lake
Superior
Huron
Michigan
Surveillance
Subcomaittee
U. S. Task D
(This Study)
Etric cons/year
845
1854
3894
964
1954
3596
COMPARISON OF THE TOTAL NUMBER OF SAMPLES AMD NUMBER 07 RIVERS MONITORED
WHICH WERE USED IN CALCULATING 1976 TOTAL PHOSPHORUS LOADS BY
SURVEILLANCE SUBCOMMITTEE AHD U. S. TASK D
Lake
Super ior
Huron
Michigan
Surveillance
Subcommittee
95
117
3 4
No. of Samples
U. S. Task D
Rivers Considered
157
740
Surveillance
Subcommittee
10
9
27
U. S. Task D
11
15
27
-------
EVALUATION OF U. S. GREAT LAKES TRIBUTARY LOAD ESTIMATES
Flow
In order Co evaluate the changes in load chat occur from one year to
the next, ic is helpful to first consider the variability in flow. Table 9
contains the Annual Mean Daily Tributary Flow to the Great Lakes for
water years 1975, 1976, and Che historical average. These flows are
based on USGS gaging station records. Flows from gaged rivers were
ad.-) us ted to river mouths. Also, flew from ungaged tributaries were
estiEM-.ted by extrapolating flow from gaged areas sc that the flows
estimated in Table 9 account for the total Lake watershed area.
Plow from ungaged area was estimated by multiplying t'ne unmor.itored
cre.as by the ratio of the appropriate monitored flow to monitored area.
TABLE 9
ESTIMATED TOTAL ANNUAL MEAN DAILY TRIBUTARY FLOW TO
1
THE GREAT LAKES
cfs
-------
Table 9 shows that the total annual mean daily discharge during
water years 19V5 and 1976 was generally higher than the historical
discharge. Flows were higher in 1976 coopared to 1975 for the Basin as
a whole and specifically for Ontario, Huron, and Michigan tributaries.
The 1976 tributary flow to Lake Ontario was particularly high.
Table 10 contains Basin tributary flows normalized according to the
area of drainage. Interestingly, the flow per unit area of watershed
was approximately equivalent for Lakes Superior, Michigan, Huron, and Erie.
The unit area tributary flow into Lake Ontario was significantly higher
than the flov into the other Lakes, particularly during 1976.
Table 11 provides sore detailed information on the discharge from
Individual tributaries. All tributary flows have been adjusted to the
river mouths (see methodology for discussion). Significant differences
occurred in the discharge of tributaries between water year 197S and 1976.
TABLE 10
•OTAL ANNUAL DAILY FLOW PER UNIT AREA OF WATERSHED
3.. 2 ,
m /km /year
Lake 1975 1976 Historical
Superior 330,000 290,000 320,000
Michigan 330,000 350,000 290,000
Huron 320,000 380,000 250,000
Erie 360,000 360,000 290,000
Ontario 570,000 810,000 510,000
Total Basin 370,000 420,000 320,000
75
-------
TABLE 11
INDIVIDUAL ANNUAL MEAN FLOW
FROM U.S. GREAT LAKES TRIBUTARIES
RIVER
Superior Basin
Pigeon
Baptisn
St. Louis
MA>M(k*l \ t
nenaQ j i
Bois Brule
Bad
Tahquamenon
Black
Presque Isle
Sturgeon
Carp
Ontonagon
% of Total Basin
Accounted for by
Michigan Basin
Menominee
Peshtigo
Oconto
Pensaukee
Fox
Kewaunee
East Twin
MBn4 t~ nmtfi r
nsnxcowoc
Sheboygan
Milwaukee
MencBimee
Root
St . Joseph
Black (South
Kalaaazoo
DRAINAGE
AREA, km2
1,554
363
9.440
1OQA
t £7\J
492
2,580
2,180
612
886
1,828
192
3 530
Gaged Rivers
10,610
2,983
2,551
414
17,100
354
344
1L.L. \
j***# J
1,127
1,893
344
514
12,110
Haven) 742
5,200
1975
FLOW
cfs(n3/s)
505(14.30)
155( 4.39)
2,984(84.51)
A*17 ^19 Ift^
H J / \i£- • JO J
261(13.93)
866(24.52)
1,014(28.72)
270(7.65)
342(9.69)
888(25.15)
91(2.58)
1,459(41.32)
57
3,558(100.76)
1,007(28.52)
947C26.82)
113(3.20)
4,183(118.46)
108(3.06)
81(2.29)
OQ£fO 1O\
iVD ^O* JO^
298(8.44)
547(15.49)
107(3.03)
124(3.51)
4.637M-U.32)
429(12.15)
2,492(70.57)
H76
FLOW
cf8(>3/8)
153(4.33)
1,684(47.70)
\L7 (Q fl"*\
J** f \J i O J/
262(7.42)
1,087(30.78)
984(27.87)
323(9.15)
360(10.20)
810(22.94)
100(2.83)
1,453(41.15)
53
3,382(95.78)
1,006(28.49)
966(27.36)
118(3.34)
4,386(124.21)
94(2.66)
103(2.92)
OCQ/1A AO"\
JOO \, -LU * *»
-------
TABLE 11 continued...
RIVER
Michigan Basin cone'
Black (Ottawa Co
Grand
Huskegon
White
Pere Marquette
Mania tee
Boardman
Mania tique
Escanaba
Ford
DRAINAGE
AREA, k«2
d. ..
.) 494
14,660
7,118
1,352
1,¥09
5.487
740
3,746
2,370
1,236
Z of Total Basin
Accounted for by Gaged Rivers
Lake Huron Basin
Pine
Cheboygan
Thunder Hay
Au Sable
Au Grcs
Rifle
Kawkawlin
Saginaw
Pigeon
644
4,090
4,271
5,756
727
1,013
582
16,170
322
1975
FLOW
cfs(*3/s)
208(5.89)
5,683(160.94)
2,694(76.29)
681(19.29)
839(23. ;&)
2,692(76.24)
252(7.14)
2,177(61.65)
905(25.63)
457(12.94)
83
371(10.51)
1,724(48.82)
1,030(29.17)
2,306(65,30)
132(3.74)
378(10.70)
146(4.13)
5,950(168.50)
83(2.35)
1976
FLOW
cfs(m3/8)
259(7.33)
6,491(183.83)
3,401(96.32)
876(24.81)
953(26.99)
2,476(70.12)
298(8.44)
2,257(63.92)
917(25.97)
412(11.67)
83
306(8.67)
1,748(49.50)
1,013(28.69)
2,387(67.60)
189(5.35)
428(12.12)
291(8.24)
7, 849(22?. 28)
144(4.08)
HISTORICAL AVG.
FLOW
cfs(m3/s)
173(4.90)
4,029(114.10)
2,200(62.30)
566(16.03)
671(19.00)
2,313(65.50)
246(6.97)
1,861(52.70)
968(27.41)
399(11.30)
31
1,488(42.14)
1,004(28.43)
1,996(56.53)
162(4.59)
376(10.65)
130(3.68)
4,026(114.02)
70(1.98)
Z of Total Baain
Accounted for by Gaged Rivers
81
81
80
Lake Erie Basin
Black
Belle
Clinton
Rouge
Stony Cr.
Raisin
Huron
1,800
544
2,030
1,188
306
3,206
2,200
396(11.21)
185(5.24)
931(26.37)
388(10.99)
72(2.04)
901(25.52)
653(18.49)
687(19.46)
189(5.35)
962(27.24)
495(14.02)
104(2.95)
1,136(32.17)
842(23.85)
400(11.33)
119(3.37)
546(15.46)
283(8.01)
76(2.15)
836(23.68)
521(4.75)
77
-------
TABLE 11 continued...
RIVER
DRAINAGE
AREA, ka2
Lake Zrle Basin cont'd...
Ottawa
Mauaee
Portage
Sandusky
Huron
Vermill ion
Black
Rocky
Cuyahoga
Chagrin
Ashtabula
Conneaut
Cattaraugus
Buffalo
Tonawanda
X of Total Basin
Accounted for
440
17,110
1,566
3,970
1,041
704
1,209
746
2,340
692
355
500
1,440
1,129
1,573
by Gaged Rivers
1975
FLOW
cfs(«3/s)
141(3.99)
5,545(157.03)
458(12.97)
1,418(40.16)
369(10.45)
310(8.78)
583(16.51)
424(12.01)
1,783(50.49)
507(14.36)
1,410(39.93)
218(6.17)
306(6.67)
1,055(29.88)
651(18.44)
787(22.29)
87
1976
FLOW
cf«(«3/s)
122(3.46)
5,848(165.62)
513(14.53)
1,060(30.02)
322(9.12)
252(7.14)
323(9.15)
256(7.25)
1,384(39.19)
441(12.49)
1,196(33.87)
210(5.95)
356(10.08)
1,150(32.57)
858(24.30)
84
HISTORICAL AVG.
FLOW
cfs(»3/s)
134(3.79)
4,989(141.29)
434(12.29)
1,168(33.08)
319(9.03)
249(7.05)
379(10.73)
231(7.96)
1,001(28.35)
352(9.97)
167(4.73)
280(/.93)
925(26.20)
576(16.31)
702(19.88)
83
Lake Ontario Basin
Genesee
Sterling
Oawego
Sandy
Black
Oswegatchle
Grass
Raquette
St. Regis
Z of Total Basin
Accounted for by
6,420
261
1,3160
368
5,210
4,309
1,668
3,253
2,207
Gaged Rivera
3,326(94.19)
171(4,84)
7,618(215.74)
308(8.72)
4,521(128.03)
2,654(75.16)
1,230(34.83)
2,220(62.87)
1,391(39.39)
81
3,991(113.03)
11,030(312.37)
473(13.40)
6,405(181,39)
4,431(125.49)
1,655(46.87)
3,354(94.99)
1,808(51.20)
81
2,752(77.94)
141(3.99)
6,305(178.56)
276(7.82)
3,902(110.50)
2,874(81.39)
1,150(32.57)
2,180(61.74)
1,391(39.39)
81
78
-------
Often the 1975 and/or 1976 flows were different from the historical
record flow. Even within a lake basin, both relatively high and low flows
can occur during the same year.
Important differences in flow can occur during the spring period
when for some streams a large fraction of the annual load (of some
substances) is delivered. Table 12 gives the ratio of the 1975 to
1976 spring river mouth flow for a number of tributaries. As can be
seen, many of the tributaries in Table 12 had higher spring flows in
1976 compared to 1975 (ratio less than one). Notably, two major
tributaries, the St. Louis River (draining into Lake Superior) and
the Maumee River (draining into Lake Erie) had higher spring flow in
1975 compared to 1976. Important high flow eventB also often occur in
February or other fall-winter months which are not accounted for In
Table 12. Also, short-term peak flow events may have a major -affect on
mean daily flows.
TABLE 12
RATIO OF SPRING (MARCH + APRIL + MAY) FLOWS FOR
SEVERAL GREAT LAKES TRIBUTARIES
1975/1976
St. Louis River 1.783
Nemadji River 1.085
Bad River 0.650
Ontonagan River 0.917
Grand River (Lake Michigan) 0.771
Muskegon River 0.500
Rifle River 0.694
Au Sable River 0.795
Black River (Mich., Lakp Erie) 0.641
Rouge River 0.806
Huron River 0.643
Mau-nee River ?..134
Sandusky River 0.220
Cuyahoga River 0.312
Genesee River 0.718
Oswego River 0.604
Osweftatchie River 0.552
79
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Differences in flow from year-to-year certainly account for some
of the variation in loads and will be considered in the ensuing discussion.
However, other factors, such as the time, amount and intensity of
precipitation, meteorological conditions, year-to-year differences in
land use and agricultural practices, variances In point source inputs,
and many other factors affect the load for any one year. Ideally,
a long period of record for loads, such as is available for discharge
on many tributaries, would give a better indication of year-to-year
variabilities In loads. For several streams a long-term data base is
beginning to be built up, and it is Imperative that such monitoring be
continued. Until more long-term Information is available, however, it
must be realized that tributary loads are the result of dynamic processes
and can be expected to vary widely from year-to-year.
Great Lakes Load Summary
Table 6 presented in the Results section summarizes loads to the
Great Lakes on a total Great Lakes Basin level and by individual
Lake basins. Summarized 1975 and 1976 loads are given for seven different
parameters, except for Lake Erie, where 1976 data were not available at
the time of this writing. It should be noted that discussion of the
loading data should not be taken to imply the estimated loads are
necessarily absolute. While they are believed to be the best estimates
available, an understanding of the limitations of the data is necessary for
proper use and interpretation of the estimated loads.
The largest and smallest total phosphorus tributary loads were
received by Lake Erie and Lake Huron, respectively. Lake Erie and
Lake Michigan tributaries received the largest point source input of
total phosphorus. Lake Erie received the largest annual diffuse total
phosphorus load per unit area of watershed. The monitored load
(calculated from actual flow and concentration data) comprised a large
portion of the total load to each Lake, particularly during 1975. Total
phosphorus loadings were higher in 1975 than in 1976 for Lake Superior,
while the reverse was true for the other Lakes. This is attributable
in part to fluctuations in annual discharge, but is also probably
attributable to many other factors, such as variations in the sampling
program, the accuracy of the data reported, the temporal and spatial
distribution of precipitation in different watersheds, and the intensity
of precipitation.
Suspended solids tributary loads during water year 1975 (Table 6)
were highest for Lake Erie, followed by Lake Superior and Lake Ontario.
In 1976 the Lake Ontario suspended solids load exceeded the Lake Superior
suspended solids load, which decreased significantly in water year 1976.
Other lakes (with the exception of Lake Erie, for which no 1976 loading
data were available) received larger suspended solids in water year 1976
than water year 1975.
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Further examination of Table 6 reveals that Lake Erie and Lake
Michigan received the largest loading of soluble ortho phosphorus.
Assuming 100 percent transmission from the point of entry to the river
•outh, a significant portion of the soluble ortho phosphorus input can be
accounted for by point source Inputs. It is also interesting to note
that despite the large increase in flow into Lake Ontario during 1976,
the soluble ortho phosphorus load was not substantially increased.
The summary of total nitrogen loadings to the Great Lakes (Table 6)
reveals that Lake Erie received Lhc largest tributary contribution.
Furthermore, approximately 15 percent of the total Basin tributary load
was associated with inputs from point source discharges. Table 6
indicates that Lake Erie also recieved the highest inputs of nitrate
und ammonia nitrogen. Although 80 percent or more of the nitrate
nitrogen loadings to the different Lakes was associated with diffuse
sources, point source Inputs seemed to be the primary contributor of
ammonia nitrogen loads (assuming 100 percent delivery). Nitrate nitrogen
and ammonia nitrogen exhibited similar variation patterns over the 1975
and 1976 water years.
The chloride loading summary given in Table 6 indicates that Lake
Ontario received the highest chloride load during water years 1975 and 1976.
The chloride load to all the Lakes appeard to vary between 1975 and 1976
in the same proportion as tributary flow varied. This is evidenced by
Table 6, which compares the ratio of 1975 to 1976 chloride load with
1975 to 1976 flow.
TABLE 13
RATIOS OF CHLORIDE LOAD AND ANNUAL FLOW BETWEEN WATER YEARS 1975 AND 1976
197S/1976
Basin Chloride Load Annual Flow
Lake Superior 1.14 1.15
Lake Michigan 1.09 1.04
Lake Hurcn 0.89 0.84
Lake Erie
Lake Ontario 0.74 0.70
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Table 7, presented in the Results section, summarizes loads to the Great
Lakes from individual hydrologic areas, and ia discussed below. Maps of River
Basin Groups and hydrologic areas are presented in Appendix B.
LAKE SUPERIOR
River Basin Group 1.1. The St. Louis River is the largest river in
this region. Portions of the River Basin Group 1.1 drainage area are
characterized by heavy clay soils which appear to significantly affect
tributary loads. Flow volumes varied considerably during the 1975 and
1976 water years. For example, flow from the St. Louis and Nemadji
Rivers significantly decreased from 1975 to 1976, while certain streams
in the eastern portion of the Basin (e. g., the Bad River) exhibited
increased flow. During water year 1975 the monitored load (i. e., the
load as determined from field measurements of flow and concentration)
accounted for a majority of the estimated total load from this basin group.
The number of monitored streams (and subsequent ratio of monitored load
to estimated total load) decreased for the 1976 water year as a result of
the termination of the Upper Lakes Reference Group monitoring program.
As can be seen from examination of Table 7. , the Superior Slope
Complex, the St. Louis River, and the Apostle Island Complex are the
largest contributors of total phosphorus in this river basin group.
With the exception of the St. Louis River, most of the total phosphorus
load is derived from diffuse sources. The Superior Slope Complex,
which is composed of many small tributaries, was monitored extensively
during the 1975 water year. However, monitored 1976 total phosphorus
data were unavailable for this complex.
The Apostle Island Complex also contributed a larger total phosphorus
load in 1975 than in 1976. The Apostle Island Complex contains several
tributaries, such as the Nemadji River, which drain a watershed characterized
by red clay. As shown in Table ^ , this complex represented the largest
source of total phosphorus in River Basin Group 1.1.
Total Lake loadings of total phosphorus from 1.1 decreased between
water years 1975 and 1976. This may be directly attributable to
decreased tributary flows during this time period. It should be noted
that the highest phosphorus concentrations were most often recorded on
days having high associated flow levels. This condition, in combination
with the overall increase in annual flow, may explain the high loads
contributed by the St. Louis River In 1975.
Further inspection of Table 7 reveals that soluble ortho phosphorus
generally comprised less than 50 percent of the total phosphorus load
from the tributaries included in River Basin Group 1.1. The ratio o:
soluble ortho phosphorus to total phosphorus was relatively consistent
for most streams between 1975 and 1976. Importantly, the St. Louis River
had the highest ratio of soluble ortho phosphorus to total phosphorus.
However, because monitoring of soluble ortho phosphorus was limited,
especially during 1976, the soluble ortho phosphorus load could be
underestimated.
82
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Suspended solids loads for River Basin Group 1.1 are relatively
high, reflecting the high clay content of sails in various portions of the
watershed. The Apostle Island Complex and the Bad River Complex contributed
the largest suspended solids loadings. The suspended solids loadings
from the St. Louis River were not particularly high, despite its large
basin area and significant discharges of suspended solids from point
sources within the Basin. This point source loading data is primarily
associated with extensive mining operations within the watershed.
The amount of suspended solids from these point sources which actually
reach Lake Superior la not known, but significant transport loss is
possible. Since the annual diffuse unit area load of suspended solids
is so low for the St. Louis basin, assuming 100 percent delivery of
these point sources, it is in fact likely that a large fraction of the
estimated point source load does not find its way to >->.•> Lake. The
lake-like widenings of the St. Louis near its mouth, in combination with
the large wetland area contained in the drainage basin, prrbably accounts
for the relatively low quantity of suspended solids discharged to
Lake Superior.
The variation in the suspended solids loading frow River Basin Group 1.1
during the 19/5 and 1976 water years was similar to that of total
phosphorus (see Table 7 ). The Bad River represents one exception.
Here the suspended solids load was higher in 1976 than in 1975, although
the anmial fotal phosphorus load decreased over the sane period.
However, this increased suspended solids load is consistent with the
increase in flow which occurred In the Bad River between 1975 and 1976.
Furthermore, the high total phosphorus load calculated for 1975 may be
overestimated due to some unusually high concentrations reported during
the 1975 water year and thus the calculated load for 1975 may not be
representative of actual conditions.
Table 7 indicates that the highest total nitrogen loads from
T\iver Basin Group 1.1 were from the Superior Slope Complex and the St.
Louis River basin. This may reflect the larger quantity or organic
matter present in the watersheds of these basins. The Apostle Island
Complex, which had the largest suspended solids and total phosphorus
input, did not contribute the largest total nitrogen input. Generally,
total nitrogen loads decreased between 1975 and 1976, which reflects the
overall decrease in flow for the tributaries in this river basin group.
Nitrate nitrogen loads most often exceeded the inputs of ammonia nitrogen
for River Basin Group 1.1. Diffuse sources accounted for a majority of
the nitrate nitrogen loads, while point source inputs accounted for a
large fraction of the amnonla nitrogen load.
Chloride loadings for River Basin Group 1.1 (see Table 7 ) reflect
the relatively undeveloped nature of the watershed. Only the St. Louis
River basin and the Montreal River Complex contain extensive urban areas
within their watersheds, and both receive significant point source inputs
of chloride. Chloride loads generally decreased between 1975 and 1976;
this again coincides with decreased flows in 1976 (see Table 11). The
Bad River represents one exception. Here the chloride load decreased in
spite of Increased flow between 1975 and 1976. Upon review of the Bad
83
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River Loading data, it was noted that an unusually high chloride concentration
was reported in 1975. This high concentration may have biased the loading
estimate, resulting in an unrepresentative estimate of the 1975 chloride
load from the Bad River.
River Basin Group 1.2. Several small rivers which drain relatively
undeveloped land characterize this region. Measured flow from this river
basin group did not change significantly between 1975 and 1976. In fact,
pleasured flows during 1975 and 1976 were very close to the long-term
average historical flows. The flows during the spring months of water
years 1975 and 1976 were alao relatively constant. Roughly two-thirds of
all estimated loads for River Basin Group 1.2 were based on monitored data.
Table 7 indicates that calculated total phosphorus loadings varied
little between 1975 and 1976. The Ontonagon River was the largest
phosphorus contributor in this hydrologic area, and also had the highest
annual diffuse unic area uadlng rate for total phosphorus. The
calculated total phosphorus did decrease between 1975 and 1976, although
tht Jiesn annual flow from the Ontonagon River did not.
Soluble ortho phosphorus loads were comparatively low from River Basic
Group 1.2 during the 1975 and 1976 water years (see Table 11). The
calculated load from the Ontonagon River increased over this period, while
other hydrologic areas exhibited little variation in their calculated
soluble ortho phosphorus output. Municipal point source discharges
accounted for a Itrge fraction of the soluble ortho phosphorus load.
Examination of the ratio of soluble ortho phosphorus to total phosphorus
loads revealed a wide variation over this two-year period of study.
The lowest ratio of soluble ortho phosphorus to total phosphorus for this
river basin group was associated with the Ontonagon River In 1975.
Monitored loads of suspended solids to Lake Superior comprised 70
percent or more of the total suspended solids loadings from River Basin
Group 1.2. The Ontonagon River represented the largest contributor.
Aa will be discussed later, the Ontonagon River drains a watershed
containing extensive clay soil areas. It is interesting to note that a
large decrease in suspended solids loadings occurred between 1975 and 1976
fron the Ontonagon River. This decrease coincides with the decrease
observed for total phosphorus. Diffuse source inputs accounted for
all the suspended solids loadings from River Basin Group 1.2, except In
Hydrologic Area 1.2.1 - the Porcupine Mountains Complex. Discharges
from mining operations In the Mineral and Iron River watersheds accounted
for much of the load from this complex.
Monitored loads of total nitrogen accounted for approximately 50
percent of the total load In 1975. In 1976 this percentage was somewhat
less. The Ontonagon River was the largest contributor of total nitrogen
in water year 1975 (see Table 7 ), while the Keweensw Peninsula Complex
contributed the largest load in 1976. However, because the tributaries
within the Keweenaw Peninsula Comply were not Monitored, the Keweenaw
load is only a rough approximation. The Huron Mountain Complex and the
84
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Porcupine Mountains Complex both received significant point source inputs
of total nitrogen.
Nitrate nitrogen loads remained relatively constant between 1975 and
1976. Anaemia nitrogen loads were small during both water years.
Point source contributions were substantial in the Porcupine Mount ain-j Complex,
the Huron Mountain Complex, and the Tahquamenon River hydrologic area.
The major source of chloride loads from River Basin Group 1.2 is
the Porcupine Mountains Complex. Discharges of brine from mining
operations into the Mineral River appear to account for this high
chloride lo.id. In fact, point source loads from these operations of 33,000
metric tons per year have been estimated which accounts for 35 to 40
percent of the total U. S. tributary load of chloride to Lake Superior.
Municipal discharges comprise the other point source inputs of chloride
to the Iron Mountain Complex and to the Tahquamenon River. The Carp
River received all the municipal discharges to the Huron. Mountain Complex.
Lake Michigan
River Baain Group 2.1. This river basin group is comprised of
undeveloped watersheds in the north and more developed agriculturalized
watersheds in the south. The area was extensively monitored and
approximately 70 percent of the loads estimated for this group were based
on field data. The 1975 and 1976 monitored flows in River Basin Group 2.1
were similar. Additionally, the 1975 and 1976 mean a.k,. annual flow.
Table 7 shows the Fox River to be the largest contributor of total
phosphorus in this river basin group. The Green Ba • Complex, which
includes the Manitowoc and Sheboygar. Rivers as well at a number of smaller
tributaries, also contributed a significant amount of phosphorus to L,ake
Michigan. The Fox River had a large point source component (assuming
100 percent delivery of point source loads). Similarly, the Green Bay
Complex contained significant point source inputs, par-.icularly for 1975
as shown in Table 7. Significant portions of the Fox River and the
Green Bay Complex are located in the more agriculturalized *nd urbanized
southern portion of the river basin group.
Despite the fact that the Fox River contributed the largest total
phosphorus load, its annual diffuse unit area load was quite small.
This is a result of at least two factors—the large sire of the Fox River
watershed and the fact that the majority of this area drains into Lake
Wlnnebago, where many constituents settle out. Therefore, diffuse drainage
to the Fox River is less than would normally be expected for a watershed
of this size.
Few significant differences were observed in total phosphorus loads
between 1975 and 1976 for the major hydrologic areas. Areas having small
associated loads understandably exhibited a greater percent variation from
85
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year-to-year, but the magnitude of the total load remained small in
comparison to the input from or.ht r watersheds. The generally small
variation in total phosphorus loads reflects the relatively constant
flow conditions between 1975 and 1976 for these tributaries.
As was the case for total phosphorus, the largest contributors of
soluble ortho phosphorus to Lake Michigan in River Basin Group 2.1 were
the Fox River and the Green Bay Complex (see Table 7 ). Point source
inputs of soluble ortho phosphorus ware significant in the Green Bay
Complex, the Fox River, and the Menominee River. Although so1able ortho
phosphorus loads comprised roughly 50 percent of the total phosphorus loads
to the Menominee River during 1975, there was significant reliction in the
soluble ortho phosphorus to total phosphorus ratio in 1976. The Green Bay
Complex maintained a relatively high soluble ortho phosphorus to total
phosphorus load ratio in both water years 1975 and 1976.
The Fox River and the Green Bay Complex also were the largest sources
of suspended solids to Lake Michigan from River Basin Grot.p 2.1. Point
source contributions were significant for the Fox River, as well as for
the Oconto and Menominee Rivers during both 1975 and 1976. Suspended
solids increased between 1975 and 1976 with the exception of the Green Bay
Complex. The large reduction in suspended solids loadings for the Greer
Bay Complex was primarily due to a large decrease in loadings from the
Manitowoc River. The reason for this decrease is not obvious, although
it may be related to the fact that some high flow and field concentration
measurements were ccincidently collected during 1975 but not in 1976.
The Fox River and the Green Bay Complex again contributed the largest
quantities of total nitrogen from River Basin Croup 2.1. The Fox River
also received the largest contribution trom point sourc.-5 i.r. terms of the
percentage of the total nitrogen load. Generally, there was little
difference between the 1975 and the 1976 total nitrogen load.
Ammonia nitrogen and nitrate nitrogen loadings were unlike s ae of
the other parameters in that the Fox River was not the largest conttibutor.
The Oconto River contributed the largest ammonia nitrogen input from
River Basin Group 2.1. The Green Bay Comple-t was the largest contributor
of nitrate nitrogen. Assuming 100 percent delivery, point sources of
ammonia accounted for all the ammonia nitrogen discharged from the Fox River.
Point sources also accounted for all the nitrate nitrogen loads from the
Fox River in 1976 and approximately 70 percent in 1975. In most cases
both nitrate nitrogen and ammonia nitrogen loadings were higher in 1975
than in 1976.
With respect to chloride, the Fox River was again the largest
contributor from River Basin Group 2.1. Identified point sources
accounted for portions of the load delivered by the Menominee River, the
Fox River, and the Green Bay Complex (see Table 7 ). The Suamoco Complex
showed the greatest variation in chloride loading between 1075 and 1976.
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River Baa In Group 2.2. This rivet basin group consists of tfc
Chicago-Milwaukee Complex, which includes the Milwaukee River, Nenomonee
River, Root River, Waukeegan River, Burns Ditch, Indiana Harbor Canal,
and Galien River. Table 11 indicates that the flow for some of these
tributaries is highly variable. The flow for the Milwaukee River In 19/5
was higher than in 1976, and both exceeded the long-term historical average.
On the other hand, the Root River had a higher flow in 1976 than in 1975,
and the total flow was belrw the long-term historical average. Loads
were only calculated for Uie Milwaukee River, the Menomonee River, and the
Root River. Several tributaries, including the Indiana Harbor Canal,
Burns Ditch, and the Galien River, while potentially important due to their
highly urban drlinage, lacked sufficient flow and concentration data to
estimate their associated loads. Point sources associated with the
Indiana Harbor Canal, while significant, were assumed for the purposes
of this report to be direct sources and will be included in Subactivity 3-4
of U S. Task D, PLUARG. Evaluating loads for these tributaries is
further complicated by diversions of water to the Mississippi drainage
and the fact that flows tend to be intermittent.
Overall total phos;horus leads in 1976 exceeded those in 1975
in River Basin Group 2.2. Additionally, soluble ortho phosphorus
loadings increased from water year 1975 to water year 1976. The soluble
ortho phosphorus loads were about 20 percent of the total phosphorus
loads during both years.
Unlike phosphorus loads, suspended solids loads decreased between
1975 and 1976 from both the Menomonee and Milwaukee Rivers. These
changes account for the overall drop in the River Basin Croup 2.2
suspended solids loadings over the fwo-year period- Flov for both
rivers also decreased between water years 1973 and 1976.
Loadings of total nitrogen from River Basin Group 2.2 were fairly
constant Between water years 1975 and 1975. Nitrate nitrogen loadings also
exhibited little variation over the two water years, while ammonia
nitrogen loadings decreased. Assuming 100 percent delivery, point sources
accounted for about 10 percent of the nitrate nitrogen load. Chloride
loads increased between water year 1975 and 1976. Most of the chloride
load was apparently derived from diffuse sources.
River Basin Grr ip 2.3. This basin group is comprised of relatively
large rivers (e. g., the St. Joseph River, the Kalamazoo liver, and the
Crard River). Gaging stations in the region indicated relatively little
change in flow between water years 1975 and 1976 for the Kalamazoo Riv^r,
while the St. Joseph and the Grand River exhibited a marked increase in
annual mean daily flow during 1976. In all cases, flowa monitored during
water years 1975 ai.u 1976 were greater than the long-term average annual
aean daily flow.
37
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Monitored loads for all parameters accounted for nearly all the
total load in River Basin Group 2.3. Thus, only a small percentage of this
basin group's total loading was based on extrapolated Information.
As shown in Table 7 the Grand River contributes the largest quantity
of total phosphorus of any tributary draining into Lake Michigan. Other
rivers which deliver major inputs from River Basin Group 2.3 are the
Kalamazoo, St. Joseph, and the Black River (in Ottawa County). Differences
in total phosphorus loads between 1975 and 1976 were generally consistent
with differences in the flow between these two water years. Point source
inputs accounted for a large part of the total phosphorus load fron this
rivet basin group.
Soluble ortho phosphorus loads from River Basin Group 2.3 varied in
roughly the same fashion as total phosphorus loads between water years
1975 and 1976. The St. Joseph River was one exception. Here the soluble
ortho phosphorus load increased significantly between 1975 and 1976. The
relative importance of point sources varied widely within the river basin
group, and in some cases, point source inputs accounted for all the total
soluble ortho phosphorus load.
The St. Joseph River contributed the largest quantity of suspended
solids of any tributary in River Basin Group 2.3 and, in fact, of any
Lake Michigan tributary during water year 1975 (see Table 7 ). During
1976, the Grand River was found to be the largest contributor of suspended
solids to Lake Michigan. Suspended solids loads were generally higher
in 1975 than 1976. A particularly large increase in suspended solids load
was observed for the Grand River between water year 1975 and 1976
(primarily due to an increase in flow). The Kalamazoo River had some
significant point source loads from both municipal and industrial inputs.
Total nitrogen loads varied little between water years 1975 and 1976.
The Grand River was not only the largest contributor of total nitrogen in
River Basin Group 2.3, but also the largest contributor to Lake Michigan
(see Table 7 ). Assuming 100 percent delivery, point sources of total
nitrogen account for up to 50 percent of the tributary load from River
Basin Group 2.3. Nitrate nitrogen behaved similarly tc total nitrogen
during 1975 and 1976. Point sources accounted for as much as 70 percent of
the nitrate load. The ammonia nitrogen load fron rivers within River Basin
Group 2.3 was variable between 1975 and 1976. Estimated point source inputs
of ammonia accounted for all the total load from the St. Joseph River, the
Kalamazoo River, and the Grand River (assuming 100 percent delivery).
The Grand River was the largest contributor of chlorides to Lake
Michigan for both water years. Despite the fact that the flow of the Grand
River was significantly higher in 1976, the chloride load decreased from
the 1975 value. Assuming 100 percent delivery, point source Inputs of
chloride accounted for up to 30 percent of the chloride loads in River Basin
Group 2.3, as shown in Table 7.
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River Basin Group 2.4. The Huskegon, Pere Marquette, Betsie,
Boardman, Manlstique, and Escanaba Rivers are Che major rivers Included in
River Basin Group 2.4. About 60 percent of all the total loads associated
with this river basin group are based on field data. Generally, loads
were higher during 1976 than 1975. The Muskegon River, one of the largest
rivers in this river basin group, had a significantly higher mean annual
flow in 1976 than in 1975. Also, flow levels during March, April, and May
were significantly higher in 1976 than in 1975. With the exception of the
Escanaba River in Michigan's Upper Peninsula, measured mean annual flows
during both 1975 and 1976 were above the historical average.
The Muskegon River and the Sable Complex, which includes the Pere
Marquette, the Big Sable, and the WMte Rivers, were the largest contributors
of total phosphorus in River Basin Group 2.4. With the exception of the
Escanaba River, total phosphorus loads were the same or higher in wat?r
year 1976 than in water year 197j Point sources accounted for the
greatest percentage of the total load in the Manlstee River.
Soluble oreho phosphorus loads generally increased between water years
1975 and 1976 with the exception of the several Upper Peninsula (Michigan)
hydrologic areas. Point source inputs accounted for most of the soluble
ortho phosphorus load from the Manistee River. The ratio of soluble
ortho phosphorus to total phosphorus, although slightly less in 197 ,, was
fairly consistent over both water years.
The Muskegon River was the largest contributor of suspended solids to
Lake Michigan from River Basin Group 2.4 during both 1975 and 1976. It
also exhibited a sharp increase in suspended solids load between 1975 and
1976. As usual, point sources accounted for only a small percent of the
total suspended solids load.
As indicated in Table 7, the Muskegon River was the largest
contributor of total nitrogen from River Basin Group 2.4. Total nitrogen
loadings from River Basin Group 2.4 were generally higher in water year
1976 with the exception of the Bay De Hoc Complex and the Escanaba River.
Total nitrogen loads in these two complexes were low for both years,
however. The Muskegon River was also the largest contributor of nitrate
nitrogen. On the other hand, contributions of ammonia nitrogen were
higher from other hydrologic areas in both 1975 and 1976. Point sources
accounted for a large fraction of the total ammonia nitrogen loads from
tributaries draining into Lake Michigan from the Lower Peninsula to the
State of Michigan.
Chloride loads either remained relatively constant or decreased over
the 1975 and 1976 water years. The Manistee River contributed the largest
chloride load. Almost all these loads during 1975 and 1976 could be
attributed to point source inputs. Industrial salt operations in the
Manistee watershed apparently contributed to the high chloride load
associated with the river. In addition, point sources also accounted for
a large portion of the chloride loading from the Sable Complex.
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Lake Huron
River Basin Group 3.1. River Basin Group 3.1 is relatively undeveloped
and its tributaries are all comparatively small. Discharges of tributaries
in 1975 and 1976 were generally higher than the long-term historical record.
Tributaries located in the southern part of this river basin group exhibited
significantly higher flows in 1976 compared to 1975. The monitored load
accounted for less than SO percent of the total load for some parameters
during both 1975 and 1976, indicating the relative scarcity of field
monitoring data near the river mouths of these tributaries.
Contributions of phosphorus from the hydrologic areas in River Basin
Group 3.1 were generally low (see Table 7 )• The largest contributing
hydrologic area was the Les Cheneaux area. Only in the Rifle-Au Gres
Complex did point source inputs account for a significant portion of the
total phosphorus load. Soluble ortho phosphorus loads were also relatively
low, usually less than 50 percent of the total phosphorus loads. In the
case of Presque Isle Complex, the estimated soluble ortho phosphorus
load in 1975 exceeded the total phosphorus load. This, of course, is an
impossibility and is an anomaly resulting in part from the fact that two
different data sets were used in calculating the load. Further, both
soluble ortho phosphorus and total phosphorus concentrations were bordered
on the analytical detection limit, so that a small difference in concentration
could result in a relatively large change In the load.
The suspended solids loads from River Basin Group 3.1 were dominated
by the Les Cheneaux Complex (see Table 7 ). This complex produced a
significantly higher load during water year 1975 and 1976. The only
monitored river in this complex was the Fine River and the high load for
1975 was apprently the result, in part, of a high concentration measured
during the high flow conditions in 1975. Because of this excessive
suspended solids load from the Pine River in water year 1975, the overall
suspended solids load from River Basin Group 3.1 was approximately twice
as high in water year 1975 than in 1976.
As shown in Table 7 , diffuse sources accounted for the majority of
the total nitrogen loads from River Basin Group 3.1. Diffuse sources alao
appear to be responsible for most of the nitrate nitrogen loading (see
Table 7 ). Point source inputs of ammonia nitrogen accounted for a
significant portion of the ammonia nitrogen load in the Rifle-Au Gres
Complex. The Rifle-Au Gres Complex was a major source of all forms of
nitrogen in River Basin Group 3.1.
The Rifle-Au Gres Conplex and the Au Sable-Alcona Complex were the
largest contributors of chloride to Lake Huron during the 1975 and 1976
water years from River Basin Group 3.1 (see Table 7 ). The contributions
of chloride from identified point sources in this river basin group were
quite small.
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Rjygr Basin Group 3.2. This particular river basin groui> consists of
only three byerologic areas. The dominate of these is the Saginaw River
basin, which ;ncludes major industrialized areas. The Thumb Complex is
an agriculturiilized watershed characterized by extensive man-made drains
located In tiuch of the complex. As shown In Table 11, rivers within these
complexes had a greater discharge in water year 1976 than In water year 1975.
In addition, discharges during both years were greater than the long-term
historical average. The monitored load accounted for the majority of the
loads reported in River Basin Group 3.2 (see Table 7 ).
The Se.ginaw River represented the major source of total phosphorus
loads from River Basin Group 3.2 and from the entire U. S. Lake Huron
baain. About 70 per ent of the total phosphorus load from U. S. tributaries
comes from the Saginaw River. This large percentage is also found for
other parameters. Point source inputs accounted for a significant portion
of the '.otal phosphorus load for both the Saginaw River and Kawkawlin Complex.
The ra'.io of soluble ortho phosphorus to total phosphorus was equal to or
less than 0.5 for all three complexes.
The suspended solids loads from River Basin Group 3.2 were also
dominated by the Saginaw River. Although a significant portion of the
tocal suspended solids load from the Thumb Complex was nased on projected
estimates rather than monitored data, the results indicate that this
complex also contributes a large portion of the suspended solids load
from this river basin group. A sharp increase in the suspended solids
loading was observed between 1975 and 1976 in the Saginau River and the
Thumb Complex.
The Saginaw River was also the largest contributor of total nitrogen
from River Basin Group 3.2. Nitrate nitrogen loads were relatively high
in this complex compared to the toial nitrogen loads. Approximately
12 percent of the Saginaw River load could be atributed to point source
inputs of nitrate. The Saginaw River also represented the most significant
source of ammonia nitrogen loads. Ammonia point sources accounted for the
majority of the load contributed to Lake Huron from the Saginaw River.
As might be expected, the Saginaw River contributed the highest
chloride loads from River Basin Group 3.2. Chloride loads from the
Saginaw River and Thumb Complex Increased between water year 197.• and
1976 (see Table 7 ). Approximately 40 percent of the chloride load from
the Saginaw River could be attributed to point source discharges.
Lake Erie
As discussed in the methodology, the Lake Erie loads are basically
the same loads reported by the U. S. Army Corps of Engineers in their
Lake Erie Waatewater Management Study. Because Lake Erie tributaries
have been extensively discussed and analyzed (Corps of Engineers, 1975),
only a brief evaluation of inputs from Lake Erie tributaries will be given
here. Furthermore, 1976 loading data were not available from the Corps
of Engineers at the time of thla writing. For additional information on
91
-------
Lake Erie tributaries, one may consult the reports of the Lake Erie
Waatewater Management Study.
River Baain Croup 4.1. This river basin group Includes a number of
tributaries draining into the St. Clair River, Lake St. Glair, and the
Detroit River. Total phosphorus loadings bete highest from the Rouge
Complex and the Raisin River. Point source Inputs of phosphorus vere
significant except in the Swan Creek Complex. Soluble oitho phosphorus
to total phosphorus ratios exhibited large variations wlthi;i this river
basin group. Analysis of the data indicated that the Raisin River was a
large contributor of suspended solids. Less than 25 percent of the 1975
suspended solids load for River iasin Group 4.1 was based on monitored data.
As shown in Table 7 , the Rouge Complex, which drains some heavily
industrialized land in the Detroit area, received a large point source input
of suspended solids.
Total nitrogen loads in River Basin Group 4.1 were largely estimated
from unit area load factors rather than monitored data. The Raisin River
was the largest: contributor of both total nitrogen and nitrate nitrogen
during water year 1975. The monitored load of ammonia nitrogen also
comprised less than half of the total estimated load. Point source inputs
ol" ammonia were significant, accounting for the total load from the Rouge
complex and the Huron River hydrologic area. The Raisin RJver contributed
the largest amount of chloride from tributaries in River Basin Group 4.1.
Examination of the data indicated that chloride point sources were again
significant in some of the hvdrologic areas.
River Basin Group 4.2. This river basin group consists of tributaries
which drain into the western basin of Lake Erie. The Maumee River is the
dominant member of this river basin in terns of loading contributions.
As can be seen from Table 7 , the total phosphorus and suspended solids
loads from the Maimee River exceeded those of any other tributary in this
river basin group. Soluble ortho phosphorus inputs accounted for about
20 percent of the total phosphorus load.
Total nitrogen loads were again highest from the Maumee River, as were
nitrate and ammonia loads. Point source contributions nf ammonia were
significant and, in the case of the Maumee River and the Toussaint-Portage
Complex, accounted for a majority of the total ammonia load. The Maumee
River was the primary source of chloride from River Basin Group 4.2,
and identified point sources accounted for only a small percentage of the total.
River Basin Group 4.3. River Basin Group 4.3 contains a number of
similar-sized rivers and includes the drainage of the Cleveland metropolitan
area. Inspection of Table 7 reveals that Cuyahoga River was the largest
contributor of total phosphorus from this group. The largest contributor
of soluble ortho phosphui.au, however, was the Black-Rocky Complex.
Point sources accounted for a large portion of phosphorus loads from the
Cuyahoga River. The Cuyahoga River was also the largest contributor of
suspended solids. Essentially all the suspended solid load for the river
basin group were derived from diffuse sources.
-------
The Black-Rocky Complex dominated the total nitrogen loads from River
Basin Group 4.3 and also contributed the highest quantity of ammonia
nitrate nitrogen. Identified point sources accounted for a large percent
of the total nitrogen and nitrate nitrogen load from the Cuyahoga, as
well as 100 percent of the amnonia nitrogen load during water year 1975.
The Cuyahoga River contributed the largest chloride load to Lake Erie
from River Basin Group 4. 3.
River Basin Group 4.4. River Basin Group 4.4 drains into the eastern
basin of Lake Erie. Its watershed Includes portions of Pennsylvania and
New York. Of the three hydrologic areas in River Basin Group 4.4,
only the loads estimated for Cattaraugus Creek were based on field data.
The Tonawanda Complex, which drains the Buffalo area was estimated to
contribute the largest amount of total phosphorus from River Basin Group 4.4
(see Table 7 )• A large fraction of this load oould be attributed to
point source inputs. The ratio of soluble ortho phosphorus loads to total
phosphorus loads was consistently low, and point source inputs accounted
for a large portion of the soluble ortho phosphorus load. Cattaraugus
Creek contributed the largest amount of suspended solids from River Basin
Group 4.4.
Table 7 Indicates that the Tonawanda Complex was estimated to be the
largest contributor of total nitrogen, nitrate nitrogen, and ammonia
nitrogen from River Basin Group 4.4. Point source discharges of ammonia
accounted for up to 25 percent of the total load from the hyrologic
areas in River Basla Group 4.4. Additionally, the Tonavanda Complex was
estimated to contribute the largeet chloride load from River Basin Group 4.4.
Lake Ontario
Rivar Basin Group S.I. River Basin Group 5.1 consists of two complexes,
from which only the Gerusee River was monitored. The Genesee River
significantly increased in discharge between 1975 and 1976, as shown in
Table 11. Also, the discharge during both years was greater than the
historical average.
Total phosphorus loads from the Genesee River increased between 1975
and 1976. Point source Inputs of total phosphorus accounted for 20 to
30 percent of the total load. Soluble ortho phosphorus loads comprised
roughly 15 percent of the Genesee River total phosphorus load during both
1975 and 1976. Point source Inputs could account for a large fraction
of soluble ortho phosphorus load in River Basin Group 5.1.
Suspended solidsi loadings from the Genesee River nearly doubled
between 1975 and 1976. All the suspended loads from the Genesee River
were apparently attributable to diffuse source inputs.
As shown la Table 7 , total nitrogen loads also increased between
1975 and 1976 in River Basin Group 5.1. Point source inputs account for
about 10 to 30 percent of the total nitrogen load. Similarly, nitrate
nitrogen loads increased between 1975 and 1976, as did ammonia nitrogen
93
-------
loads. Point source inputs accounted for a large percentage of the total
load of ammonia nitrogen in River Basin Group 5.1.
Interestingly, chloride loads were the same for 1975 and 1976 for
River Basin Group 5.1, despite the fact that the tributaries experienced
a significant increase in flow. Point source inputs of chloride to the
Niagara-Orleans Complex were relatively large.
River Basin Group 5.2. This river basin group includes three
hydrologic areas. As was the case for River Basin Group 5.1, only one
of these areas, the Oswego River, was monitored. The Oswego River is by
far the largest river in this river basin group, however. Discharge from
the Oswego was significantly higher in !,976 than in 1975. In fact, the
1976 discharge from the Oswego was about twice the long-term average.
Inspection of Table 7 reveals a significant increase in total
phosphorus loads from 1975 to 1976. The Oswego River total phosphorus
load was entirely attributable to point sources during 1975 (assuming
100 percent delivery). In 1976, point source inputs could account for
60 percent of the total phosphorus load from the Oswego. The soluble
ortho phosphorus load behaved similarly to the total phosphorus load in
all areas except the Salmon Complex during water year 1975. Here a
relatively high (compared to the total load) soluble ortho phosphorus
load was recorded. During both 1975 and 1976 point sources accounted for
all the soluble ortho phosphorus load from the Oswego River (see Table 7 )•
Suspended solids loads increased between 19/5 and 1976 from both the
Oswego River and the Salmon Complex. There was a decrease, however, of
suspended solids loads from the Wayne-Cayuga Complex. About 25 percent of
the Oswego River suspended solids loads could be attributed to point
source Inputs.
Nitrogen loads from River Basin Group 5.2 were also dominated by the
Oswego River. All the hydrologic areas in 5.2 had higher total nitrogen
and nitrate nitrogen loads in 1976 than in 1975. Ammonia nitrogen loads
were higher in 1976 except in the Salmon Complex, which had a very low
amnonia nitrogen load. Point source inputs accounted for a significant
portion of the total nitrogen load, as well as all the amnonia nitrogen
load from the Oswego River.
The Oswego River contributed large chloride loads to Lake Ontario,
and these loads Increased between 1975 and 1976. In fact, the Oswego
River is responsible for about 85 percent of the U. S. tributary load of
chloride to Lake Ontario. Identified point sources accounted for about
50 percent of the chloride load from the Oswego River. These discharges
were apparently largely the result of industrial operations in the watershed.
An additional discussion on the Oswego River chloride load may be found
in a later section.
94
-------
River Baain Croup 5.3. This river basin group drains into eastern
Lake Ontario. The largest river In the group is the Black River. As
Table 11 nhows, flow was significantly higher in water year 1976 than in
1975, and in both years the flow was higher than the average over the
historical period of record. A relatively high percentage of the total
loads reported for these tributaries was baaed on field monitoring data.
Phosphorus loads increased markedly fron 1975 and 1976 (see Table 7 ).
Point sources total phosphorus contributions were significant in the Grass-
Raquette-St. Regis Complex and the Black River hydrologlc area. The
soluble ortho phosphorus to total phosphorus ratios were considerably
lower in water year 1976. The estimated soluble ortho phosphorus load
from the Black River in water year 1975 was comparatively high. Point
source inputs of soluble ortho phosphorus were significant for the Black
River, Oswagatchie River, and the Grass-Raquette-St. Regis Complex.
Unlike total phosphorus, little or no increase in soluble ortho phosphorus
loads was no;ed between 1975 and 1976.
Suspended solids loads from the Black River were highest in water
year 1975. Despite the large increases in flow, none of the hydrologic
areas, except for the Black River, had higher suspended solids loadings
in 1976 than 1975. The reason for this is not clear, but it may be a
result of sampling during periods of high flow in 1975 but not in 1976.
Total nitrogen loads generally increased between 1975 and 1976. On the
other hand, three out of four hydrologic areas from River Basin Group 5.3
had decreased nitrate nitrogen loads in 1976 than In 1975. Of the three
nitrogen forms measured, ammonia nitrogen point source inputs were the
largest.
The Grass-Raquette-St. Regis Complex was the largest contributor of
chloride during water year 1975 and 1976. Less than 30 percent of the
total loads were attributable to point source inputs. In all cases total
loads of chloride from River Basin Group 5.3 were higher in water year
1976 than in 1975. In comparison to the load of shloride delivered
by the Oswego River in River Basin Group 5.2, the chloride loads from
River Basin Group 5.3 were small.
DIFFUSE LOADS
An effective pollution management strategy must recognise the
relative importance of point and diffuse sources. As discussed earlier,
diffused sources account for a large fraction of the total tributary load.
If the actual delivery of point source inputs is less than 100 percent
(which is likely often the case), the diffuse loads would represent an
even larger percentage of the total.
95
-------
Transmission of Point Sources
Table 14 shows the diffuse tributary load for several tributaries
assuming either 50 percent or 100 percent delivery of upstream, point sources.
The definition of upstream and downstream was discussed In an earlier section.
Tributaries included in Table 14 generally had at least 24 or nore samples
available aver the 1975 water year.
As shown in Table 14, the estimated diffuse load from the Oswego
River presents an interesting situation. It can be seen that if all
point sources* are considered to be delivered to the river mouth (100 percent
diffuse load column), the point source load accounts for the total load
from the basin. The Oswego River has many very large lakes within the
basin which likely impede the transport of point sources to the river mouth.
For example, In the case of phosphorus, it is well known that lake
bottom sediments serve as a phosphorus sink. Thus, phosphorus derived
from point sources may be lost permanently to sediments of an impoundment
or lake-like widening of the river before reaching the Great Lakes.
Consequently, assuming 50 percent delivery of upstream point sources
may be more realistic for many parameters. However, although tha actual
transport of point sources is not known over the long-term, at least for
tributaries that do not have major impoundments Impeding transport, the percent
transported may be close to 100 over the long term (1- e., several years).
TABLE 14
TOTAL PHOSPHORUS DIFFUSE LOADS ASSUMING 50 AND 100 PERCENT
DELIVERY OF UPSTREAM POINT SOURCES
1975 (MT/YR)
1 2
Diffuse Load Diffuse Load
Total River (50 Z Delivery of (100% Delivery of
River Mouth Load Upstream Point Sources) Upstream Point Sources)
St. Louis 260 210 170
Kalamazoo 230 150 78
Grand (MI) 760 550 350
Saginaw 1200 890 640
Maumee 2600 2400 2200
Cuyahoga 790 620 510
Oswego 510 210 0
Fox 500 190 120
Diffuse Load - Total river mouth load minus (100% of downstream plus 50%
of upstream point sources).
Diffuse Load * Total river mouth load minus (100% of downstream plus 100%
of upstream point sources).
-------
Because of the uncertainty of the transmission of point sources,
point source data have been grouped at >rdlng to upstream and downstream
sources. This information has been cc ..futerized (see Table 15) and to
permit easy computations of the effect of different assumptions on
deliveries of point source loads. This work will be further explored as
part of subactivity 3-4 of U. S. Task D, PLUARG.
Diffuse Unit Area Loads
The results (Table 7 ) presented in an earlier section indicate
a wide varier> of annual diffuse unit area loads were found for different
watersheds in the Great Lakes Basin. Further, a diffuse unit area load
can vary greatly from one year to the next, depending on factors such as
variation in flow, types and frequency of storms, frequency at which
samples were taken, and whether runoff f'ents were sampled or not. All
these factors must be considered when trying to interpret the meaning
of a diffuse unit area load. The diffuse unit area loads are also an
integration of the overall characteristics of the watershed. Individual
portions of watersheds may have quite different unit area loading rates
than the overall unit area load at the river mouth.
Keeping the limitations of the diffuse unit area load data in mind,
large differences in diffuse unit area loads can be used to differentiate
between watersheds. Maps contained in Append'X B illustrate differences
in diffuse unit area loads for total phosphorus and suspended solids.
Appendix B figures are arranged according to river basin groups. Diffuse
unit area loads in the figures are the average diffuse loads over 1975
and 1976 (with the exception of Lake Erie watersheds, for which only 1975
data were available). Unit area loads have been divided into three
different ranges to Illustrate major differences between watersheds.
The first set of figures in Appendix B show diffuse unit area loads for
total phosphorus. Inspection of these figures indicates that unit area
loads are highest in the Lake Erie basin, the thumb area of the Lake
Huron basin, and parts of the Lake Ontario basin. Some relatively high
diffuse unit area loads are also found in parts of the Lake Superior
basin and Lake Michigan basin. A fairly large part of the Lake Michigan
basin has low diffuse total phosphorus unit area loading rates.
Suspended solids diffuse unit area loads generally follow the same
pattern as total phosphorus. Highest unit area loads of suspended solids
were found for the Lake Erie basin, the thumb area of the Lake Huron basin,
and parts of Lake Ontario. Interestingly, the Pine River and Carp River
draining from Michigan's Upper Peninsula also had high unit area load
rates for suspended solids. Differences in unit area load rates appear
to reflect different characteristics of watersheds. For example, those
watersheds that are rich in clay soils, such as found in the Lake Erie
basin, have high unit area load rates. A further discussion of the ef
of the watersheds on the diffuse contributions will be discussed in a
later section.
97
-------
Table 15
EXAMPLE COMPUTER PRINTOUT OF UPSTREAM AND DOWNSTREAM
POINT SOURCE LOADS - TOTAL PHOSPHORUS 1975 (mt/yr)
RIVER LOAll Al UlflNUAKLi
NUMBER
21501
21601
21701
21711
21712
21713
21718
22102
22103
22106
23101
23203
23301
23501
24102
24202
24206
24301
24302
24402
24406
24601
24801
NAME
PENSALJKEE
FOX
KEUAUNEE
EAST TWIN
WEST TWIN
MANITOWOC
SHEBQYGAN
MILWAUKEE
MENOMONEE
ROOT
ST JOSEPH
BLACK SHAYE
KALAMAZOQ
GRAND
MUSKEGQN
WHITE
PERE MARQUET
LITTLE MANIR
MANISTEE
BETSIE
BOARDMAN
ftMANISTIQJE
ESCANABA
MOUTH
15
499
19
8
15
42
60
109
35
20
446
109
227
758
78
25
39
1
51
6
5
45
36
.5
.6
.7
,9
.2
.6
.1
.2
.6
.1
,1
.5
.3
,0
.6
.0
* 4.
.6
,6
.5
.2
.6
.9
ERROR
6
61
1
0
1
7
10
31
4
r>
56
33
13
96
10
5
6
0
5
2
0
8
10
.0
.5
.7
.6
.3
.0
.7
.9
.6
.1
.0
.5
.7
,0
.6
.7
.8
.3
*6
.4
.8
, 1
.7
* ui-
SAMP
12
12
12
12
12
13
12
6
48
ft
8
3
22
9
22
11
9
3
21
3
6
22
22
I-UINI aUUrl'C LUMl'S
MUN-DN
0.0
44.0
1.1
0.0
2.5
1.8
15.9
12.2
20.6
0.7
56.2
0.0
0.0
5.8
1.8
0.0
0.0
0.0
0.0
0.0
2.3
0,0
0,0
MUN-UF-
0
112
0
0
0
10
1
4
0
10
193
0
134
401
5
0
0
0
0
0
0
0
0
.0
.0
.0
.0
.0
.4
.0
.8
.0
.4
.6
.0
.5
.7
.8
.6
.0
.0
,0
.0
.0
.0
.0
IND-DN
0.0
58.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0,0
0.0
0.0
0.0
0.0
0.0
0.0
0,0
0.0
0.0
7.0
57.2
IND-UP
0,0
26.1
0.0
0.0
0,0
0.0
0.0
0,0
0,0
0.0
1,4
0.0
16.7
2.4
0.0
0.0
0.4
0.0
20.8
0.0
0.0
0.0
0.0
HUN - Municipal
IND - Industrial
UP - Upstrean of a point 50 river kilometers (or major Impoundments) from the river mouth
DN - Downstream of a point 50 river kilometers (or major impoundments) fron the river mouth
-------
Types of Diffuse Sources
The diffuse load consists of inputs such as rural runoff, urban runoff,
combined sewer overflows, and base flow. In other words, the diffuse
load consists of the load not attributable to identified point sources.
Unfortunately, at this time it Is not possible to accurately evaluate the
relative magnitudes of these various diffuse load components. However,
despite liuiited availability of information, some perspective can be
given to the importance of the diffuse load components at this time. This
will be dibcussed below.
Although urban runoff generally has been found to contribute
slightly more total phosphorus than agricultural runoff on a unit
area basis (the actual values of the unit area loading rates from
agricultural and urban land varies widely between watersheds), the larger
amount of rural land causes the rural or agricultural load to many
watersheds to be dominant. In a study done by the Ontario Ministry of
the Environment on the Canadian Grand River basin (Lake E»-ie) and the
Saugeen River basin (Lake Huron) (Van Fleet, 1977), preliminary results
indicate that urban runoff accounts for only one percent or less of the
annual total phosphorus loads. Agriculture, on the other hand, was
estimated to account for 70 percent or more of the total phosphorus
loads. In a study of many watersheds and subwatersheau ir. Er^r nd Niagara
Counties in the U. C. portion of the Lake Erie/Niagara River basin
(Wendel Engineers, 1977), urban runoff contributions of suspended solids
averaged about six percent of the total, while rural runoff averaged
approximately 90 percent. Combined sewer overflows averaged less than
cne percent. Since total phosphorus loads would likely be correlated
with suspended solids loads, rural rvnoff would likely represent a more
significant source of total phosphorus for this area than would urban runoff.
The City of Rochester, New York, which is located near the mouth of
the Genesee River, represents one of the major urban areas influencing
water quality in Lake Ontario. In order to gain some perspective -> i the
potential suspended solids load associated with the area, a version of
U. S. EPA's Needs Estimation Model tor Urban Runoff (NEMUR) (U. S. SPA,
1977), was used in conjunction with input from U. S. EPA Needs Sur\ev data
to generate an urban load associated with a 90th percentile storm
(the magnitude of which is approximately 2 percent of the average annual
rainfall). This load, which includes contributions from both urban runoff
and combined sewer overflow, was estimated to be 567 metric tons of
suspended solids. Assuming a ratio of 3 mg of total phosphorus per gram
of suspended solids (a national average for urban runoff, U. S. EPA, 1974),
a load of about 1.7 metric tons of total phosphorus is associated with
the storm. This load is less than one percent of the 1975 diffuse r?tal
phosphorus load from the Genesee River. Consequently, although the above
calculations are extremely crude, and it is difficult to extrapolate tl e
effect of Individual storms over an annual basis, It would appear that the
urban runoff load from the Rochester area may be less than the annual load
from other sources (e. g., rural runoff) in the Genesee P.iver basin.
99
-------
As previously mentioned, base flow and combined sewer overflow arc
also components of the overall diffuse load. Bane flow, which is derived
fron ground water Inputs, can represent a very lurge portion of the
diffuse tributary load. This la particularly true for undeveloped
regions with good drainage characteristics and minimal runoff, e. g. ,
sandy soils. Combined stormvater overflew* can be significant in certain
densely populated areas such as Cleveland or Detroit, Although highly
variable, combined sewer overflows often increase the total phoartorus
load from large treatment plants by about 10 percent.
In summary, although current information is very limited, it would
appear that rural runoff generally is the largest contributor to the tof.al
phosphorus diffuse load in many areas.
Control of Diffuse Sources
It appears that diffuse sources represent a large fraction of the
total tributary load. Effective control of these sources will not be
easily accomplished. However, for many tributaries it seems likely that
approximately 30 to 50 percent of the diffuse load may be controlled
through existing technology, 1. e., improved conservation practices,
specialized plowing techniques, and control of street litter. Furthermore,
a large fraction of the total diffuse load may be attributable to a few
specific "problem" areas. Treatment of these problem areas, as opposed
to the whole basin, may lead to substantial reductions in the diffuse
load at A relatively small cost.
In conclusion, control of diffuse sources will not likely be achieved
rapidly. Socio-economic factors will undoubtedly have a major Impact on
the implement atioa of diffuse control procedures over the next 20 years.
More information on diffuse source remedial measures is expected to be
available in the near future as a result of ongoing Pl.UARG activities.
POINT SOURCE LOADS
A considerable effort was expended in determining point source loads
delivered to tributaries draining Into the Great Lakes. However,
it must be remembered these estimates are >till rather rough estimates,
particularly the industrial point source estimates, due to the limited
data available. In some cases, point source loads were estimated based
on only a few concentration measurements a year (which may not necessarily
have been representative measurements).
Municipal Versus Industrial Sources
Municipal loads were estimated based on actual, or in some cases,
estimated concentration data (see Table 5 ). However, because actual
flow data were available for almost all municipal point sources, it Is
felt that the municipal point source loads are reasonable estimates of
true conditions. In term* of industrial sources, however, no attempt
was made to estimate an effluent concentration when no field measurements
were available. Consequently, the industrial load represents only the
load from those sources identified as contributors of the parameter of
-------
concern, and thus may underestimate the true load. In particular,
Industrial inputs of nitrogen and chloride, which were given less emphasis
in this study compared to phosphorus and suspended solids, *ay be an
underestimate of the true industrial load. Mo Industrial loads were given for
Lake Erie In the Lake Erie Wastewater Management Study (U.S. Army Corps of
engineers, 197S).
Table 16 compares the summarized municipal and industrial contributions
to U. S. Great Lakes tributaries. Based on these data, municipal sources
contribute far more phosphorus than industrial sources. This is not
unexpected, however, since only certain industrial operations are likely
to discharge phosphorus in significant quantities. Municipal sources
also appear to contribute more suspended solids than identified industrial
sources. High industrial suspended solids inputs, such as found for
parts of the Lake Superior drainage, are generally associated with
mining operations. While suspended solid discharges can be high, the
amount which reaches the Great Lakes may be low. Also, suspended solids
discharged from municipal treatment plants may consist of a large percentage
of volatile solids, which may be degraded before reaching the river mouth.
Thus, the suspended solids measured in point source discharges may be
physically different than that measured In tributaries. In future work
It might be useful to distinguish between suspended sediment and suspended
solids. Suspended sediments would be defined as that portion of the
suspended solids consisting of soil particles. Consequently, although
suspended solids point source discharge to tributaries may be high, the
suspended sediment component may be low. The effect of these discharges
on the Great Lakes is uncertain, especially relative to the suspended
solids (or suspended sediment) derived from land runoff.
Table 16 also sunjiarizes point source loads for nitrogen and soluble
ortho phosphorus. Again, municipal inputs appear to be large compared
to Identified Industrial point source inputs. As discussed previously,
while it is believed that essentially all municipal plants with flow
greater than 0.1 mgd (2.62 x 10 ~3 m-Vs) have been identified in the
Great Lakes Basin, some industrial plants could have been neglected due
to lack of available Information. Nevertheless, It appears that for the
parameters considered, identified indust ial sources are of no major
Importance, with the possible exception of ammonia nitrogen. When
considering other parameters, "uch as heavy metals or other toxic substances.
industrial discharges could have a much more significant role.
Point source loads of chloride, including industrial inputs (Table 16 ),
do appear to be a significant fraction of the total tributary chloride load.
Large chloride inputs were Identified for the Oswego River draining into
Lake Ontario, the Mineral River draining into Lake Superior, and the
Manlstee River draining into Lake Michigan. Importantly, the Mineral
River and Manlstee River Industrial inputs were not based on discharge
monitoring data, but were determined by subtracting an estimated diffuse
load (determined from appropriate annual diffuse unit area load rates)
from the total load. As discussed earlier, the Mineral River chloride load
is the result of discharge of brine from mining operations. The Manlstee
River receives Inputs from industrial salt operations. The Oswego River
101
-------
TABLE 16
1975 TOTAL TRIBUTARY POINT SOURCE LOADS (mt/yr) FROM MUNICIPAL (M) AND INDUSTRIAL (I) PLANTS
TOTAL
Total
Phosphorus
(TP)
Qrtho
Phosphorus
(OP)
Suspended
Solids
(SS)
Total
Nitrogen
-------
TABLE 16 (continued)
1976 TOTAL TRIBUTARY POINT SOURCE LOADS (mt/yr) FROM MUNICIPAL (M) AND INDUSTRIAL (I) PLANTS
Lake Superior
Total
Phosphorus
(TP)
Ortho
Phosphorus
(OP)
Suspended
Solids
(SS)
Total
Nitrogen
(TH)
Nitrate
+ Nitrite
(N02-N03)
Aononia
(NH3)
Chloride
(CO
M
I
M
I
M
I
M
I
M
I
M
I
M
I
107.
24
33.1
58.
0
939.
48,358.
451.
30.
177.
0
211.
30.
4,331.
32,788.
46
1
0
1
0
2
9
0
3
8
Lake Michigan
998
192
491
17
25,253
12,182
8,871
1,049
3,692
22
4,173
650
87,052
114,829
.1
.7
.4
.5
.3
.0
.9
.0
.3
.1
.1
.2
.4
.3
Lake Huron Lake Erie
269.
80.
143.
0
4,051.
7,313.
2,761.
879.
1,082.
0
1,296.
0
25,101.
97,729.
4
9
02
-
6
3
3
1
8
-
2
—
4
9
Lake
28,
23,
5,
2,
2,
2,
2,
57,
510,
Ontario
874.
51.
420.
0
473.
904.
700.
150.
351.
0
785.
150.
231.
779.
4
8
15
6
8
0
4
7
7
4
7
2
St. Lawrence
90. 0
0
27.11
0
432.33
0
266.3
1.4
104.5
0
125.05
1.4
2,532.2
0
-------
chloride load is heavily Influenced by a Solvay process plant located on
Onodaga Lake. Onodaga Lake, which drains into the Oswego, has extremely
high chloride concentrations, presumably the result of the industrial
operations on or near the lake. The estimated point source chloride
input to the Oswego River accounts for about one-third to one-half the
total point source chloride load to the Great Lakes. Despite this high
point source load, the total tributary load is higher than would be expected,
indicating the point source chloride load may be underestimated. Natural
ground water from areas rich in salt draining into tributaries may also
contribute to the chloride load, but the contribution is likely small
relative to point sources (Kramer, J., 1977).
Effect ofSmall Point Sources
It should also be mentioned that any municipal or industrial plants
discharging leas than C.l mgd (2.83 x 10~' m-Vs) were not considered in
the point source load estimate. Also, plants that had intermittent
discharges to a river, such as many lagoon system?, were not Included
as part of the contributing point sources.
The relative effect of small point source operations (less than
0.1 mgd), particularly when situated in a developed area, would be small.
However, it is possible that in certain undeveloped areas, point sources
from many small industrial operations or municipal plants could collectively
have a measurable impact. For example, the Door Peninsula of Wisconsin
and the thumb area of Michigan both have many small packaging and dairy
operations. These dischargers were not included in the point source loads,
but which collectively could have a measurable, although probably minor,
impact.
In order to get some idea of the effect of not including small
discharges, the estimate of the Lake Erie tributary point source load
calculated for this study considering only those point sources with a
flow greater than 0.1 mgd (2.83 x 10-1 m^/s) (and excluding intermittent
point sources such as lagoons) were compared with point source loads
calculated by the Lake Erie Wastewater Management Study (Corps of Engineers,
1975). In the Lake Eric Wastewater Management Study, an intensive survey
was made of municipal point sources, which included many small municipal
point sources, such as motels, service stations, supermarkets, shopping
centers, camp grounds, small villages, mobile homes, schools, lagoons,
and other extremely small point sources. Table 17 compares the point
sources calculated for Lake Erie tributaries by the Lake Erie Wastewater
Management Study with the results of this study. As can be seen, there is
very little difference between the two estimates, indicating that exclusion
of small point sources likely does not significantly affect the point
source load. The fact that all point source loads calculated in this
study were slightly higher than the Corps of Engineers estimate, despite
the fact that some of the smaller point sources were excluded, Is due
primarily to differences in the gaged drainage areas considered as well
as some differenced in the point source data used.
104
-------
TABLE 17
COMPARISON OF POINT SOURCE PHOSPHORUS INPUTS TO LAKE ERIE TRIBUTARIES
COMPILED BY THE LAKE ERIE VASTEWATEK MANAGEMENT STUDY1 AND GLBC (THIS STUDY)
1975
Point Source Load
(metric tons/vr)
Huron River
Raisin River
Maumee River
Portage River
Sandusky River
Huron River
Vermilion River
Black River
Rocky River
Cuyahoga River
Chagrin River
Grand River
Cattaraugus Creek
TOTAL
COS
193
69
318
40
38
44
4
78
81
385
17
13
32
1312
U. S. Task D
185
86
445
36
117
44
1
36
145
279
7
1
12
1394
Corps of Engineers (1975)
Effect at Reducing Municipal Loads
Table 18 summarizes the reductions In phosphorus loadings to be
expected from various limitations of the phosphorus concentration in
municipal plant effluents. This table assumes 100 percent delivery
of point sources co the river mouth. Total tributary loads are 1976
load estimates, with the exception of the 1975 Lake Erie data. The
reductions in total loads are based on current flow from municipal plants.
However, It effluent flow increases due to population growth, the percent
reduction over current conditions obtained by the effluent limitations
could be less. Note that the effect of direct municipal Inputs, which
include some of the large coastal Municipal plants (e. g., Detroit) are
not included In Table 18.
105
-------
It ia cleat from Table 18 Chat, given current flows from treatment
plants, the percent reduction In the tributary total phosphorus loads
to the Great Lakes that would be achieved by limiting phosphorus concen-
trations in municipal effluents to one milligram per liter is not
particularly great (the load reduction could be significant to local
stream segments, however). Further, reducing concentrations beyond one
milligram per liter will not have a major effect on total loads. This
is particularly true for Lake Superior and Lake Huron. More detailed
information on costs projected for various phosphorus removal programs,
as well as detergent control programs, may be found in McClarren (1977).
TABLE 18
U.S. TRIBUTARY TOTAL PHOSPHORUS LOADS ASSUMING
DIFFERENT MUNICIPAL EFFLUENT PHOSPHORUS CONCENTRATIONS
LAKE
Superior
Michigan
Huron
Erie (1975)
Ontario (not
including St.
Lawrence River)
St. Lawrence
1976 TOTAL
TRIBUTARY
mt/yr.
964
3,59»
1,954
8,639
2,874
639
TOTAL
POINT LOAD
mt/yr.
107
1,191
350
1,756
926
90
TOTAL TRIBUTARY LOAD (mt/yr) UNDER DIFFERSN'T
HUNICIPAL
EFFLUENT P
TION IN TOTAL LOAD)
1.0 mg/£
884(8)
3,130(13)
1,849(5)
7,519(13)
2,351(18)
0.5 mg/r.
870(10)
2,864(20)
1,767(10)
7,237(16)
2,175(24)
565(12)
557(13)
O.j
860(11)
2,651(26)
1,701(13)
7,011(19)
2,035(29)
551(14)
1. Assumes 100* delivery of point sources to the mouth.
106
-------
FLOW/CONCEKTRATION RELATIONSETfS
The variability of men's Influences as well as unpredictable changes In
natural systems make it very difficult to characterize the Impact that an
individual river has on the Great Lakes for any given year. Host sanpllng
progtai.. are set up on a once or twice per Month basis which In many cases
is inadequate to characterize the trends for a particular water year. A
number of the major variables that Influence the load during any one year
are discussed below.
Variability of Flow
Many rivers undergo dramatic changes in flow over a period of hours
during a storm runoff event. Changes also occur from month-to-month
and year-to-year within a given basin depending upon precipitation and snow melt.
Since the Great Lakes Basin extends over a large geographical area,
the climate nay vary considerably within the basin during the same year.
For example, within a given year one portion of Che Great Lakes Basin can
suffer from a drought while another can experience unusually heavy
precipitation. Figure 1 compares the mean annual flows of two different
rivers for water years 1967 through 1976. The mean annual flows have been
divided by the mean historical flow for each river so that a direct
comparison can be made of each flow ratio. As can be readily seen from
Figure 1 , the Bad River and Grand River (draining into Lake Superior and
Lake Michigan) respectively, can have similar or vastly different flow
trends. Both of these rivers show a substantial rise in discharge
between the years 1970 and 1974. During this period the flows are in
general above the mean historic flow which is indicated by a flow ratio
of 1.0. However, between 1973 and 1974 the Bad River decreased in flow,
while the Grand River experienced a dramatic increase in mean annual flow.
In order to compare a load from a tributary from any given year with
that from another year, the mean annual flow must be considered. Annual
decreases In load can occur as a result of decreased flow, while no
appreciable changes in water quality occur, for many rivers flow was
greater during water year 1976 than In water year 1975, and in a number
of instances there was an increase in load for the same period (see Table 7).
Perhaps a more important factor to consider In evaluating loads
are the more short tent fluctuations In flow. For example, a large
portion of the total annual discharge can occur during a runoff event.
Figure 2 presents the mean monthly variations in flow of the Grand River
and the Nemadji River (draining Into Lake Superior near the Bad River)
during water year 1976. Discharge Is higher for both rivers during the
spring period of February through May. However, the pattern that evolves
is much different for these two rivers. The Nemadji, judging by the
monthly figures, may exhibit a relatively high flashy flow over a short
period, while the Grand River has a more gradual flow change over a
longer period. Characteristics of the watershed may greatly affect
the flow patterns of Individual rivers.
107
-------
u
a:
tn
o
»—o
O-J
ZDU.
cc
cc
UJ
ie
2 00
CC
CE
- OC
5 UJ
ouyy Moid
108
-------
FLOUVCOMCEMTRATIOH RELATIONSHIPS
The variability of nan's influences as veil as unpredictable changes in
natural systems ma'-* it very difficult to characterize the Impact that an
individual river has on the Great Lakes for any given year. Mast sampling
programs are set up on a once or twice per month hauls which in many cases
is inadequate to characterize the trends for a particular water year. A
lumber of the major variables that influence the load during any one year
are discussed below.
Variability of Flow
Many rivers undergo dramatic changes In flow over a period of hours
during a storm runoff event. Changes alsi occur from month-to-month
and year-to-year within a given basin depending upon precipitation and snow melt.
Since the Great Lakes Basin extends over a large geographical area,
the climate nay vary considerably within the basin during the same year.
For example, within a given year one portion of the Great Lakes Basin can
suffer from a drought while another can experience unusually heavy
precipitation. Figure 1 compares the mean annual flows of two different
rivers for water years 1967 through 1976. The mean annual flows have been
divided by the mean historical flow for each river so that a direct
comparison can be made of each flow ratio. As can be readily seen from
Figure 1 , the Bad River and Grand River (draining into Lake Superior and
Lake Michigan) respectively, car. have similar or vastly different flow
trends. Both of these rivers show a substantial rise in discharge
between the years 1970 and 1974. uring this period the flows are in
general above the mean historic flow which is indicated by a flow ratio
of 1.0. However, between 1973 and 1974 the Bad River decreased in flow,
while the Grand River experienced a dramatic increase in mean annual flow.
In order to compare a load from a tributary from any given year with
that from another year, the mean annual flow must be considered- Annual
decreases in load can occur as a result of decreased flow, while no
appreciable changes in water quality occur. For many rivers flow was
greater during water year 1976 than in water year 1975, and In a number
of instances there was an increase In load for the same period (see Table 7).
Perhaps a more important factor to consider in evaluating loads
are the more short term fluctuations In flow. For example, a large
portion of the total annual discharge can occur during a runoff event.
Figure 2 presents the mean monthly variations In flow of the Grand River
and the Nemadji River (draining into Lake Superior near the Bad River)
during water year 1976. Discharge is higher for both rivers during the
spring period of February through May. However, the pattern that evolves
is much different for these two rivers. The Nemadji. judging by the
monthly figures, may exhibit a relatively high flashy flow over a short
period, while the Grand River has a more gradual flow change over a
longer period. Characteristics of the watershed may greatly affect
the flow patterns of individual rivers.
107
-------
FIGURE 1
YEflRLY FLUCTUflTIONS
IN FLOW
o
oo
o
a:
oc
o
u_
1967 1968 1969 1970 1971 1972 1973 1974 1975 197*
WflTER YEflRS
Floy lUllo:
LEGEND
CMM> R (HJ)
BROR MI)
-------
FIGURE 2
6.
0.
MONTHLY FLUCTUflTIONS
IN FLOW
OCX MOV DEC JAM Ttt MAR APR HAV JUN JUL MIC SEP
WflTER YEflR 1976
»nnthl> Q
annual Q
LEGEND
QWNO It (HI)
NEHMXJI II WI1
-------
Aside from Monthly fluctuations, dally or even hourly fluctuations
can be very important in many streams. A river that rises quickly ct.n
potentially transport more sediment than one that rises gradually, ad
velocities are often higher and overland runoff rates are usually greater.
Individualities of stream discharge patterns must be remembered when
comparing loading results.
Variability of Concentration
It is well known that concentrations of chemical constituents may
vary with flow. The variance depends on the chemical constituent as
well as on the particular hydrologic characteristics of the tributary.
For example, total phosphorus concentrations may increase with flow,
while total dissolved solids concentrations may decrease with flow.
Similarly, the extent with which these constituents vary with flow are
different for the Maumee River compared to the Grand River. Further,
within a given tributary, the nature of the flow event may greatly affect
the relationship between flow and concentration.
Based on the field data used in this study, it was obvious that for
some tributaries throughout the Great Lakes Basin the concentration of
certain parameters was flow dependent. Unfortunately, due to the relative
lack of concentration data during periods of high flow (except for Lake
Erie tributaries), information gained on flow-concentration relationships
was limited.
Despite the scarcity of field data during periods of high flow,
some significant observations can be made. Figure 3 compares the
total phosphorus concentration measured in Wisconsin's Manitowoc River
(which drains into Lake Michigan) and Michigan's Muskegon River (which also
drains into Lake Michigan) during water year 1975. As can be readily
seen from Figure 3 , there are significant differences between the rivers
not only in concentration values, but also in the change in concentration
that occurs between any two data points. Total phosphorus concentrations
in the Muskegon River were very stable, never exceeding 0.05 mg/l P
and never varying more than 0.02 mg/£ F between any two data points.
Total phosphorus concentrations in the Manitowoc River, on the other
hand, varied froa 0.05 to 0.39 mg/£ P over the sampling period. Further,
between August Id and September 10 the total phosphorus concentration
changed by over 0.3 mg/l P.
There are many fact its in addition to flow that may Influence the
variability in concentration observed in Figure 3 . Point sources
in a basin can discharge at various rates and at various times of the year.
Canning and food processing plants, for example, may only discharge
seasonally and some municipal operations, such as lagoons and spray
Irrigation facilities, may discharge slugs of treated waste periodically.
Farming operations and the application of fertilizers and pesticides can
also cause seasonal fluctuations in concentration. Street litter may
also vary seasonally with seed and leave fall, which in turn affects
the concentration of contaminants in urban runoff.
110
-------
in
r-
2
cc
CE
UJ
111
-------
Perhaps one of the most significant factors, however, is the soil
texture and credibility of that soil within a given basin. Overland
runoff is more prevelant on clay soils than sandy soils, since sandy
soils tend to have higher water Infiltration rates. Referring back to
the rivers in Figure 3 , the Muskegon River drains a predominately
sandy basin while the soils of the Manitowac tend to b>: more clayey.
Consequently, the soil texture of the watersheds may explain, at least in
part, the variability in total phosphorus concentration as noted in Figure 3.
The soil conditions not only affect what is transported but the volume
of water that actually moves over the basin on a unit area basis. The
effect that soil texture has on a given basin will be discussed in more
detail in a following section.
Variability of Loads
When you combine flow and concentration to get a load, you are
combining the variable nature of those flows and concentrations. Because
of the variability, the calculated mean dally loads can vary by orders of
magnitude from one sampling day to another. For example, refer to
Table 19, which Hats dally suspended solids loading data for the
Hanitovoc River. While the mean annual flow for 1975 was substantially
less than for 1976, the load for 1975 was over four times greater than
for 1976. The primary reason for this difference is that in 1975 two
samples were taken during very high flows. Suspended solids concentrations
were also very high at these times. These two days accounted for 94 percent
of the sum of the daily loads calculated for the 19 days sampled. In
1976 the highest flow encountered on a sampling dry was only about half
as great as the high flows encountered in 1975. Also, the corresponding
suspended solids concentrations were relatively lower for the high flows
in 1976 than they were for 1975. This example provides a good illustration
of the difficulty that can be encountered in accurately characterizing the
loads in streams from one year to the next, using a United data base.
It should be noted, however, that not all streams encountered in this
study appear to be this difficult to characterize. Many rivers examined
show a remarkable stability In concentration, as was indicated by the
Musekgon River In Figure 3. Generally, those rivers draining sandy
watersheds were more stable both in terms of flow and concentrations. It
is Important tc realize that while the data In Table 19 indicates the
importance of sampling the Manitowac River during high flows, it may not
be necessary to sample all tributaries in the U. 5. Great Lakes Basin
in this fashion.
Tributary Response Variations
In an effort to determine any correlations of concentration with flow,
linear regressions were run using total phosphorus and suspended solids data
from several tributaries for which there was considerable data. Slopes
and regression coefficients from these calculations are given in Table 20.
112
-------
TABLE 19
LOAD
kg/ day
9,343
250
8,592
916.U4
485,253
5,683
1,468
506
5,152
3,083
1,057
778
15,575
3,205
5,064
1,431
440
8,769
23,634
« 79,000
Mean Flow
Estimated
19/5
FLOW
cfste^/s)
67(1.90)
34(0-96)
439(12.43)
2,370(67.12)
2,110(59.76)
101(2.86)
40(1.13)
69(1.95)
162(4.59)
90(2.55)
36(1.02)
53(1.50)
1,061(30.05)
131(3.71)
207(5.85)
65(1.84)
18(0.51)
28(0.79)
345(9.77)
390(11.04)
for Year 296 cfs
Load for Year 23
MAN1TOWOC RIVER
SUSPENDED SOLIDS
CONCENTRATION
mg/1
57
3
8
158
94
23
15
3
13
14
12
6
6
10
10
9
10
128
28
32
(8.38)
,000 metric tons
(WISCONSIN)
LOADING DATA
LOAD
kg/day
1,859
1,167
4,167
1,177
18,496
50,615
38,460
19,215
528
396
14,000
Mean Flow
Estimated
1976
FLOW
cfT<>?/8)
40(1-13)
53(1.50)
131(3.71)
37(1.05)
315(8.92)
1,293(36.62)
1,048(29.68)
561(15.89)
36(1.02)
18(0.51)
350(9.91)
for Year 368
CONCENTRATTOH
mg/t
19
9
13
13
24
16
15
14
6
9
14
cfs (10.42)
Load for Year 5,200 metric t<
113
-------
TABLE 20
LINEAR REGRESSION OF FLOW (cfa) v« CONCENTRATION (mg/1)
RIVER
TOTAL PHOSPHORUS
SUSPENDED SOLIDS
St. Louis
Nemadji
Carp (L. Superior)
Fox
Black (L. Michigan)
Grand
Sagiraw
Genesee
Oswego
Black (L. Ontario)
Maumee1-
Portage1-
Sandusky1-
Huron1'
Vermilion1'
Black (L. Erie)1'
Cuyahoga1'
Chagrin1-
Cattaraugus1-
SLOPE rZ
(multiply by 1CT3)
-0.001 0.01
0.052 0.48
1.107 0.05
-0.005 0.05
-0.157 0.16
-0.003 0.10
-0.002 0.07
-0.001 0.01
-0.003 0.10
0.000 0.00
0.029
0.175
0.038
0.106
0.040
-0.028
-0.011
0.100
0.043
SLOPE
(multiply by 10~3)
2.2
188.1
331.8
1.3
10.6
0.5
4.0
56.6
o.y
0.9
11.1
62.8
32.2
89.2
108.2
46.0
145,2
13.3
444.0
^r-
0.79
0.68
0.30
0.07
0.08
0.06
0.70
0.48
0.10
0.19
1.
Slopes estimated fron Lake Erie Wastewater Management Study (Corps, of
Engineers. 1975) p3ots
114
-------
The linear regression results presented in this table were conputed
with flow in cfs as the x variable and total phosphorus or suspended
solids as the y variable. The slope of the line generated gives a general
relationship between flow and concentration with the large positive slope
showing a rise in concentration with a rise in flow, anJ the small or
negative slope showing no change in concentration with an Increase in flow
or an actual decrease in concentration with larger flows.
The coefficient of linear correlation (r ) between flow and concentration
la a measure of the strength of the linear relationship between flew and
concentration. The proportion of the variance of concentration explained
by a linear regression on flow Is indicated by r^. If r* - +1, there is
a perfect linear relationship between flow and concentration; if r2 - 0,
there is no linear relationship. In Table 20 there is generally little
linear relationship between flow and total phosphorus concentration,
while there are some strong linear relationships between flow and suspended
solids concentration.
Data used in this analysis were taken primarily from 1975 and 1976
water years. All regressions were run on at least 40 samples with some
on as
-------
P
T
2.:
1 .50
1.00
_l
cr
>—
CD 0. 7o
t—
0.50
0.25
0.00 -MM
FIGURE 4
MPUMEE RIVER flT HflTERVILLE. OHIO
(U. S. Army Corpa of Engineers, 1975)
+•
-<-M I > ! M )
MM
5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 55000
DISCHRRGE IN CFS
-------
Black (Ohio), Saginaw, and Carp Rivers, alao shows an upward trend in
concentration as flows increase, although the slope of the increase is
less than the first group. The third group contains streams that show a
very alight to non-existent increase in concentration with increase in flow.
These include the Fox, St. Louis, Oavego, Grand (Michigan), and two Black
Rivevs (one draining into Ontario, and the other into Lake Michigan
at South Haven, Michigan).
Assuming the data are representative, it can be concluded that not all
tributaries respond to runoff events in the same fashion. The loads from
some tributaries, termed "stable response" tributaries, are not dominated
by runoff events because the concentrations of many parameters such as
total phosphorus and suspended solids, do not vary greatly with flow
and the flow Itself tends to be relatively stable (less flashy). The
loads of other tributaries, termed "event response" tributaries, are
greatly influenced by runoff events. Obviously, these are only two
general classifications, and many individual variations do exist.
Example of Stable Response Tributary - Grand River. The Grand River,
which was one of the tributaries where total phosphorus generally decreased
with flow and suspended solids increased only slightly (Table 20),
is of particular interest since it was sampled on a daily basis for over
a year as part of Subactivity 2-2 of U. S. Task D. Consequently, the data
available for the Grand is probably representative of actual conditions
and interpretations of these data are not confused by data gaps.
Because of the fact that total phosphorus and suspended solids
concentrations near the mouth of the Grand River va.ied relatively
slightly with the flow, the (1976) loads calculated based on daily
sampling would likely differ little from the load calculated using only
monthly tiamples given adequate flow data. In order to verify this
assertion, 1976 suspended solids and total phosphorus loads were calculated
assuming Lhe only data available were monthly samples taken on the first
of the inonth (when the Grand River was usually sampled over the years).
The load was then compared to the load based on daily sampling over a
large part of the water year. Table 21 presents the results of the loads
calculated based on these data sets. As can be seen the differences in
the loads based on 10 samples and 212 samples was not large, especially
with regard to total phosphorus. Consequently, for many purposes the load
estimated from only a few samples per year may be satisfactory for a
river such as the Grand, especially given the cost of dally versus monthly
sampling.
There has also been very little change in suspended solids and total
phosphorus concentrations over the years. Table 22 shows the average
yearly concentrations measured for the Grand River beginning as early as
1963. This Indicates the stability of this river in terms of concentration
over the years. Significantly, average concentrations for 1976, whether
based on monthly observations or a large data set, are also similar to the
historical averages, again Indicating the stability of the Grand River.
117
-------
Example of Event Response Tributary - Bemadji River. Importantly,
the Grand River la an example of a group of rivers that are not greatly
affected by runoff events. An example of a river that undergoes more
dramatic concentration/flow changes is the Henadji River, which drains
into western Lake Superior. A daily sediment station wvs established near
the mouth of the Nemadjl in 1973, so that a good suspended solids data
base is obtainable for the last few years.
Table 23 contains a set of dally sediment data collected near the
mouth of the Nemadji. The data show that during a 15-day period in June
of ^975, concentrations and flows were extremely variable. Also, the
concentration of suspended solids generally increa- .d with flow. The
computed daily sediment load also shown in Table 23 Indicates the need
to sample for chemical constituents at various representative flows if
the annual loads are to be estimated for this tributary. The probability
of not collecting representative samples if the sampling program
consisted of one sample per month on the first of the moneh would be
relatively high. Consequently, such limited data would lead to inaccurate
estimate of the load.
Interestingly, the Grand River is one of the largest tributaries
to the Great Lakes, while the Nemadjl River is relatively small. In fact,
the watershed of the Nemadjl is less than 10 percent of the watershed
area of the Grand River. Nevertheless, the estimated 1976 suspended
solids load from the Nemadji, 71,000 metric tons, is almost SO percent
of the load estimated for the Grand River. On a unit area basis, the
Nemadji watershed contributed 550 kg/ha-year, while the Grand River
contributed only 98 kg/ha-year.
TABLE 21
GRAND RIVER TOTAL PHOSPHORUS AND SUSPENDED SOLIDS LOADS
CALCULATED BASED ON DAILY SAMPLING AND A MONTHLY SUBSET
OF THFSE SAMPLES (DURING WATER YEAR 1976)
Metric Tons/Yr
Total Phosphorus Suspended Solids
All Sanples (212) 840 150,000
Samples from First 710 102,000
of Month Only (10)
118
-------
TABLE 22
AVERAGE ANNUAL TOTAL PHOSPHO US AND SUSPENDED SOLIDS
CONCENTRATIONS MEASVktD NEAR THE MOUTH
07 THE GRAND RIVER SINCE 1963
WATER YEAR
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
AVERAGE SUSPENDED
SOLIDS
26.3
22.1
31.1
18.4
18.3
15.0
18.5
16. 2
14.5
17.6
21.1
17.2
16.4
NO. OF
SAMPLES
12
15
8
18
7
17
13
12
10
12
7
8
7
AVERAGE TOTAL
PHOSPHORUS
mg/1 P
.204
.247
.263
.175
.186
.170
.180
.167
NO. OF
SAMPLES
7
13
12
10
12
7
8
9
Weighted Average 19.2 0.204
-------
TABLE 23
RIVER (WISCONSIN)
SUSPENDED SOLIDS DATA
DATE
6/11/75
6/12/75
6/13/75
6/14/75
6/15/75
6/16/75
6/17/75
6/18/75
6/19/75
6/20/75
6/21/75
6/22/75
6/23/75
6/24/75
6/25/75
MEAN
DISCHARGE
rfst^/s)
112( 3.17)
772(21.86)
2,560(72.50)
1,330(37.67)
1, 100(31.15)
1,520(43.05)
895(25.35)
650(18.41
536(15.18)
440(12.46)
617(17.47)
1,310(37.10)
803(22.74)
533(15.09)
407(11.53)
MEAN
CONCENTRATION
mg/1
15
610
1,070
302
722
646
145
94
72
63
646
801
146
101
77
SEDIMENT
LOAD
Metric Ton/Day
4.1
2,585
7,220
980
2,304
2,594
329
151
95
67
1,179
2,703
291
133
77
1975 Mean Daily Flow » 437 cfs (12.38 m3/s)
Suspended Solids Load for 1975 - 154,000 Metric Tons (based on 365 samples)
120
-------
Watershed Characteristics Versus Tributary Response
The reason for the difference in loading rates of the Grand River and
the Nemadji is probably the result of many factors. However, as mentioned
previously, one factor that stands ou' in importance is the soil texture
of their basins. Figures 5 and 6 present the soil textures of
River Basin Group 1.1 and 2.3 which contain the Grand River basin and the
Nemadji basin, respectively. These figures show that the Grand River
watershed Is composed of sandy to loamy surface soils, while the Nemadji
River watershed surface soils ire predominately clay. The Nemadji
River basin is part of the well known red clay area located in the western
basin of Lake Superior.
Investigation of the soil texture characteristics reveal that,
in general, those watersheds with surface soils that contain considerable
amounts of clay-sized pa.'tides tend to contribute significantly higher
loads per unit area of suit;ended solids and phosphorus than watersheds
tha': have more coarse grained (sandy) solAa. Also, water quality of the
livers draining sandy t-'pe ac Is is often much better than those rivers
draining clay. Further, as discussed previously, streams draining
clay soils appear to be more flashy in teros of the variability of
concenr.i sLiono rfith flow. Streams draining sandy soils are often less
variable in terms of their chemical constituents and have flows which
are more stable.
Lake Erie streams, at least western basin streams, are good examples
of streams draining predominately clayey surface soils. Parts of the
Lake Michigan basin (predominately the Wisconsin side) and parts of the
Lake Superior basin also have high clay content and the rivers appear to
act accordingly. Interestingly, the Superior basin has patches of clay
soil Interspersed with more sandy soils. This accounts for the fact,
at least in part, that certain streams in this basin, despite the
undeveloped status of the region, are often turbid in appearance and
contribute relatively high suspended solids loads. Parts of the Lake
Huron (thumb area) and Lake Ontario watersheds also have soils tending
toward the clay side.
Sandy soils are prevelant in the Lake Michigan basin, particularly
on the Michigan portion of the basin. Streams from these areas generally
have good water quality.
Intuitively, it is not surprising that clayey soils produce higher
loads of suspended solids and certain chemicals than sandy soils. As
was discussed in detail in Montelth and Sonzogni (1977), clay soils generally
have more pollutants associated with them due to the chemical and physical
characteristics of clay particles. Also, once clay-sized particles get
>uapended, they are much less prone to settle out compared to larger-
sized particles. Therefore, the likelihood of clay-sized particles being
transported over the land to the river mouth is comparatively high. Also,
in clay soils water la less likely to infiltrate compared to sandy soils,
thus, there is a greater possibility for runoff to occur following a
121
-------
SOIL TEXTURE
Rivtr Basin Group 1.1
Nemadjl River
Basin
VtCWMTVMA*
Soil Texture
1.22
-------
Figure 6
SOIL TEXTURE
River Basin Group 23
Grand River Basin
LAKE MICHIGAN
vtcmnv IMP
Predominant
Soil Texture
i ?•»
-------
precipitation event In clay soils. Land cover or use, while certainly
important and lelated to soil texture, Is certainly not exclusively
responsible for non-point source problems as may be Implied by some
investigators. For example, the Nemadjl River watershed is hc.rvily
forested, yet produces relatively large unit area loads of suspended solids.
Soil naps showing the predominate texture of surface soils have been
prepared for all U. S. river basin groups. These naps will be presented
in the report on Subactivity 3-4 of the U. S. Task D, PLUARC. In addition,
information as to the percent of the different soil textures in individual
watersheds has been digitized, and the information has been computerized.
An example of this type of information stored Is given In Table 24 .
Note that in addition to soil texture, Information Is available on other
factors such as watershed area, flow (both current and the historical
mean) ard erodibility (K factor). It la intended that this data, along
with loading information, also computerized, will be analyzed for
statistical Correlations and other relationships. The results of this
analysis will a.uo be reported as part of Subactivity 3-4 of U. S. Task D,
PLUARG.
Recommended Sampling Strategy tor Stable Response Versus Event Response Streams
It is clear that rivers behave In very different ways and that
precipitation events can have substantially different Impacts on the total
river mouth loads. As a result of flow, concentration and load trends
observed in this study, it is felt that for the purpose of calculating
loads not every stream needs to be sampled routinely during runoff events.
By examining watershed characteristics, Including (but not limited to)
surface soil textures, it Is believed possible to predict whether an
event response or stable response can be expected. Where possible,
however, limited sampling during one or more runoff events, particularly
during spring, would provide further and more definitive information on
whether routine event sampling is necessary to characterize tne annual
load. The cost of event sampling is obviously prohibitive in many cases,
but fairly precise sampling strategies can still be established at a
minimal cost by interpreting existing data. For example, in the western
half of the lower peninsula of Michigan, almost every stream examined
behaves in a manner similar to that of the Grand River. Th's would
indicate that these tributaries can be sampled on a monthly basis (as
is currently the case) to obtain an adequate e«timate of tributary loadings.
In northwestern Ohio streams draining into Lake Eric are clearly event
response streams and require extensive sampling to accurately characterize
their loads, as the Lake Erie Wastewater Management Study (Corps of
Engineers, 1975) has demonstrated.
On many streams In which concentration remains fairly stable,
sampling over several years on a monthly basis may produce representative
data which can be used to calculate loads for future years. In order to
verify this point, the 1976 load of suspended solids was computed using
the ratio estimator method (the mean annual flow based on continuous
gaging was used to adjust the load) from 212 measurements of suspended
solids and flow collected at daily intervals between March 1, 1976, and
124
-------
Table 24
L«ht HURON
HYIiRUIOBIC. AREA SIIKh.W
SII1I liATA
*
31 1OO
31203
31300
31401
31500
31*00
32100
32201
32300
TOTAL
NAME AREA
KM 2
LES CHENEAUX 3440.
CHEB VOAN 4090.
PRES'.IUf ISLE 1450.
THUNDCR BAY 3270.
AU SASLE-ALC 57 AO.
RIFLE- AUGRES 2670.
KAUKAUI IN CO 10OO.
SAQTNAU 16170.
IHUHP COM 3 A 70.
9 41920.
SAND
HA
10920O.
306 7SO.
65250.
245250.
535680.
143SOO.
33000 .
727ASO.
0.
21AB2BO.
X
30.
75.
45,
75.
93.
SO.
35.
45.
0.
32.
COARSE
HA
109200.
12270,
9B1O.
O.
0.
0.
0.
0.
1747HO.
LOAN rtFUItlH 1 OAM HHF
X
30.
3.
3.
0.
O.
0.
O,
O.
4.
HA
3A400.
4O900.
1/B~*SO
4?or;o.
20000 .
IOO4-.O.
?5000.
64AOOO.
9I7HO.
1055400.
%
10.
10.
ftr-
15.
5.
35.
25».
4O.
25.
25.
Hrt
3A400.
0.
0.
2.J890.
I tWCl.
4JO50.
40000.
247S5O.
275:'30.
A7)AAO.
LOAM
Z
10.
O.
0 .
7.
IT..
40.
15.
75.
14.
CLAY
HA
72BOO.
B1BO.
0.
O.
0,
0.
0.
0.
0.
B09BO.
X
20.
2.
o,
0.
0.
0.
0.
0.
0.
2.
ETDflriTEiTl CTtWCTUTT Al r*f\kl_
E.t^UI.1 i «JiL I U Tl_n 1 » F^L I^VTIT
HUCK ITY K TRIfUTINO t>f?>
HA
0.
40900.
0.
0.
0
Ut
0.
O.
0.
40700.
X
0.
10.
0.
0.
o.
0.
0.
0.
0.
1.
MFP
LOU
MF D
LOU
LOU
MED
HIGH
HIGH
HIGH
HA
145AOO.
4090.
1450.
3270.
S7AO.
43OSO.
CiPf .
4U-IK-V.
347000.
11053^0.
X
40.
1 .
1.
1 .
1.
15.
SO.
30.
too.
2*.
-------
September 30, 1976, front the Grand River. This load was then compared
to the load calculated using 143 monthly measurements of flow and
concentration taken between 1963 and 1975, which were adjusted to the 1976
mea.i annual flow using rhe ratio estimator method. The load generated
using the flow adjusted historical samples was 120,000 metric tons per
year, or about 80 percent of the suspended solids load calculated using
the 1976 data. This would indicate that for rivers such as the Grand,
it might even be possible Co estimate a load by adjusting historical
concentration and fi.^w data with the observed mean annual flow. In other
words, for certain rivers a knowledge of the flow for a yiven year would
be all that is necessar-; to calculate a reasonable estimate of the load,
assuming no major changes occur in the characteristics of the watershed
(e. g., land use) or point source inputs.
l:\ conclusion, many streams require detailed and expensive sampling to
characterize loads dt certain parameters. However, it appears that all
rivers need not necessarily be sampled in such a manner. Applying
knowledge of watershed characteristics and careful interpretation of
existing data could lead to a more limited and economical sampling
program for many streams.
Critical Erosion Period
Generally greatest amounts of sediment and associated materials are
eroded from the laad when the surface is unvegetated, such as after plowing.
The longer the soil remains unvegetated, the greater the possibility for
extensive erosion. Fall plowing, then, would appear to provide a greater
opportunity for erosion than plowing in the spring. However, erosion
can occur even without plowing.
As discussed earlier, the NemadH River, despite the fact its watershed
is mostly forested, still contributes significant amounts of sediment.
Apparently, in watersheds like the Nemadji with clayey soils, erosion can
occur despite a vegetative cover. Some of this erosion may be attributable
to streambank erosion as well as sheet and gully or overland erosion.
Once clay soils are eroded and dispersed in water, thjy, in general,
settle out very slowly. Consequently, when clay-sizi d sediment is
suspended, it has a relatively high probability of being transported for
considerable distances. Certainly, however, land use may affect the amount
of material contributed from a clayey watershed, but it does not appear
to be the dominant factor based on the admittedly limited data available.
Burwell et al. (1975) in a study of erosion of loam soils, considered
three seasonal periods: (1) a critical runoff period during snowmelt,
(2) a critical erosion period between the spring melt and two months
after a crop cover was established, and (3) a noncritical erosion period.
They concluded that much of the annual sediment and total nutrient losses
occurred during the critical erosion period (2). Snowmelt, however,
accounted for much of the water loss as well as the soluble nutrient losses.
This pattern likely holds for much of the Great Lakes Basin's agricultural
126
-------
land. Should fall plowing occur, the critical erosion period probably
extends to the fall between the time It Is plowed and when the ground
becomes snow covered or frozen.
In a study of phosphorus and nitrogen losses from disposal of dairy
manure during winter (Klausner et. _al., 1976), it was found that manure
applied to the land during active thaw periods can result in increased
nutrient losses. B> applying manure over the winter so it was covered
by snow which melted at a later date, nutrient losses were minimized.
The above examples indicate that critical periods exist which can
affect the erosion and loss of materials from the watershed. Tributaries,
at least at the river mouth, are the integrated effect of many different
factors and activities in the watershed. More research and Information
is needed on these factors and activities to effectively and economically
manage watersheds to minimize loads of pollutants to the Great Lakes.
127
-------
REFERENCES
Burwell, R.E., Timmons, D.R. and R. F. Holt (1975). "Nutrient Transport In
Surface Runoff as Influenced by Soil Cover and Seasonal Periods," Soil
Sci. Soc. Amer. Proc., 39, pp. 523-528.
Chester Engineers (1977). "Baseline Facilities, Waste Load, and Residual
Projections," Preliminary Draft, Prepared for East Central Michigan
Planning and Development Region.
Clark, J. (1976), personal communication, International Joint Commission,
Great Lakes Regional Office, Windsor, Ontario.
Great Laki 5 r -fr '^.mission (1974) Great Lakes Basin Framework Study,
Appendix i3, GLBC, Ann Arbor, Michigan, p. 7.
Hall, J.R., Jarecki, E.A., Monteith, T.J., Skimin, W.E., and W.C. Sonzogni
(1976). "Existing River Mouth Loading Data in U.S. Great Lakes Basin,"
Prepared by the Great Lakes Basin Commission Staff for the International
Joint Commission, Windsor, Ontario, 713 pp.
Internatioral Joint Commission (1976). Great Lakes Water Quality Board,
Appendix B, Surveillance Subcommittee Report, Great Lakes Regional Office,
Windsor, Ontario.
Kendall, M.G. and Stuart, A. (1968). The Advanced Theory of Statistics, Vol. 3,
2nd Edition, Hafner Pub. Co., N.Y., pp. 217f. and p. 238 (exercise 40.14).
Klausner, S.D., Swerman, P.J. and D.F. Ellis (1976). "Nitrogen and Phosphorus
Losses from Winter Disposal of Dairy Manure," J. Environ. Quality
5, 1, p.47-49.
Kramer, J. (1977). Personal communication, Department of Geology, McMaster
University, Hamilton, Ontario.
McClarren Limited (1977). "Strategies to Control Phosphorus Inputs to the
Lower (>reat Lakes from Municipal Wastewater Treatment Plants," Report to
the Great Lakes Research Advisory Board, International Joint Commission,
Windsor, Ontario.
129
«•
-------
Menomonee River Pilot Watershed Study (1977). "Summary Pilot Watershed Report,"
Pollution from Land Use Activities Reference Group, International Joint
Commission, Windsor, Ontario, in press.
Monteith, T.J. and W.C. Sonzognl (1976). "U.S. Great Lakes Shoreline Erosion
Loadings," prepared by the Great Lakes Basin Commission Staff for the
Pollution from Land Use Activities Reference Group, International Joint
Commission, Windsor, Ontario, 211 pp.
New York Department of Environmental Conservation (1971) "St. Lawrence River
Basin Plan for Pollution Abatement," Albany, N.Y., 37 pp.
New York Department of Environmental Conservation (1975) "Water Quality
Management Plan for the St. Lawrence Basin (09-00)," Albany, N.Y. 386 pp.
Patterson, D.J., Epstein, E. and J. McEvoy (1975) "Water Pollution
Investigation: Lower Green Bay and Fox River" EPA-905/9-74-017, 371 pp.
Sargent, D.H. (1975) "Water Pollution Investigation: Buffalo River"
EPA-905/9-74-010, 144 pp.
U.S. Army Corps of Engineers (1975), "Lake Erie Wastewater Management Study
Preliminary Feasbility Report," Buffalo District Army C'orps of Engineers,
Buflalo, N.Y.
U.S. Environmental Protection Agency (1977). "1976 Needs Survey - Summary of
Technical Data for Combined Sewer Overflows and Stormwater Discharges,"
EPA Repoit No. 430/9-76-012, Office of Water Programs Operations,
Municipal Construction Division Report Number 48C.
U.S. Environmental Protection Agency (1974). "Water Quality Management
Planning for Urban Runoff" EPA Report No. 40/9-75-004.
Upper Lakes Reference Group (1976). "The Waters of Lakes Huron and Superior;
Volume I," Report to the International Joint Commission, Windsor,
Ontario, 236 pp.
VanFleet, G.L. (1977), personal communication, Ontario Ministry of the
Environment, Toronto, Ontario.
Wendel Engineers (1977). "Urban Storm Runoff Program," Interim Report,
Task 9, Areawide Waste Treatment Management and Water Quality Improvement
Program, Erie and Niagara Counties Regional Planning Board.
130
-------
Wisconsin Department of Natural Resources (1977). "Manitovac River Basin
Report," Appendix B, Point Source Information, Madison, Wisconsin, 46 pp.
Wisconsin Department of Natural Resources (1976) "Southeastern Wisconsin River
Basins - A Drainage Basin Report," Madison, Wisconsin, 135 pp.
Wisconsin Department of Natural Rtsources (1975). "Water Quality Management
Basin Plan for the Rivers of ihe Northwest Shore of Lake Michigan,"
Madison, Wisconsin, 113 pp.
131
-------
APPENDIX A
INDIVIDUAL TRIBUTARY
RIVER MOUTH LOADING DATA
PracMhfWMaik
133
-------
TOTAL PHOSPHORUS 1975
I 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
33
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY
NAME
OSUEGATCHIE
GRASS
RAQUETTE
ST REGIS
GENESEE
OSUEGO
BLACK NY
MAUMEE
PORTAGE
SANDUSKY
HURON
VERMILION
BLfiCK
CUYAHOGA
CHAGRIN
CATTARAGUS
HURON
RAISIN
ROCKY
GRAND
ASHTABULA
CONNEAUT
PLACK MICH
ROUGE
BELLE
CLINTON
ST LOUIS
BAD
MONTREAL
BOIS BRULE
NEMADJI
BAPTISM
PIGEON
BRULE
CASCADE
TEMPERANCE
CROSS
MANIfOU
BEAVER
SPLIT ROCK
KNIFE
LESTER
FRENCH
GOOSEBERRY
POPLAR
SUCKER
TAHC1UAMENON
ONTONAGON
LAKE
BASIN
ONTA
ONTA
ONTA
ONTA
QNTA
ONTA
ONTA
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
RIVER
GROUP
3
3
1
3
1
2
3
2
2
2
2
o
3
3
3
4
1
1
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
LOAD
MT\YR
125.5
47.3
35.9
20.2
529.8
510.3
153.8
2628.0
154.0
595.0
136.0
34.0
351.0
788.0
144*0
185.0
253.0
279.0
313.0
332.0
69.0
104.0
46.4
199.8
22.6
256.0
257.6
156.0
27.2
17.1
124.3
10.4
65.0
10.0
5.0
6.0
4.0
4.0
7.0
4.0
6.0
5.0
1.0
5.0
8.0
3.0
12.5
158.1
SQUARE
iYR>**2
685.0
35.6
36.9
3.3
4281.8
1006.9
561.8
5329.0
9.0
361.0
25.0
169.0
256.0
3249.0
100.0
225.0
3249.0
25.0
8281.0
64.0
1.0
4.0
59.9
591. &
5.0
796.7
1135.2
7230.9
8.1
25.4
3175.3
278.7
289.0
4.0
4.0
1.0
1.0
1.0
4,0
4.0
4,0
4.0
1.0
4.0
4.0
1.0
6.7
7573.7
NUM OF
SAMPLES
9
8
9
12
30
17
20
262
281
277
399
43
42
45
41
41
12
12
12
12
12
12
a
5
10
8
15
13
14
13
12
12
31
31
31
31
30
31
31
31
31
31
31
31
31
31
27
27
134
-------
TOTAL PHOSPHORUS 1975
49
50
51
52
53
54
55
56
57
58
59
60
£1
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
TRIBUTARY LAKE
NAME BASIN
CARP SUPE
BLACK G SUPE
PRESQUE ISLESUPE
STURGEON SUFE
IRON SUPE
MINERAL SUPE
FALLS SUPE
SILVER SUPE
DEAD SUPE
CHDCOLAY SUPE
TWO-HEARTED SU^iE
BETSY SUPE
UAISKA SUPE
AU GRES HURO
RIFLE HURO
MPINE HURO
THUNDER BAY HURO
AU SABLE HURO
TAWrtS HURO
WHITNEY DRN HURO
APINE HURO
CHEBOYGAN HURO
GREENE CR HURO
TROUT HURO
MULLIGAN HURO
OCQUEOC HURO
SCHMIDTS CR HURO
CARP CR HURO
PINCONNJNG HURO
SAGINAU HURO
KAWKAWLIN HURO
PIGEON HURO
PINNEBOG HURO
SEBEWAING HURO
WILLOW HURO
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
EAST TWIN MICH
WEST TWIN MICH
MANITOWOi: MICH
SHEBOYBAN MICH
MILWAUKEE MICH
MENOMONEE MICH
RIVER
GROUP
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
I
j
1
1
1
•1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
2
2
LOAD
MTVYR
34.3
6.7
4.7
18.5
5.0
4.0
1.0
1.0
2.0
9,0
2.0
1.0
10.0
9.0
19.0
18.2
32.7
29.8
7.0
9.0
10.0
29.2
0.1
0.3
0,1
1.8
0.1
0.1
3.0
1189.9
17.6
33.0
15.0
36.0
4.0
4.7
86.5
59.4
50.6
15.5
499.6
19.7
8.9
15.2
42.6
60.1
109.2
35.6
SQUARE
.YR)**2
75.2
2.6
1.3
25.7
4.0
1.0
1.0
1.0
1.0
4.0
1.0
1 .0
9.0
14.4
13.6
17.4
134.6
10.9
1.0
25.0
9.0
38.0
0.0
0.0
0.0
0.0
0.0
0.0
1,0
4275.0
12.6
576.0
25.0
900.0
1,0
0.1
56.3
107.6
101.3
36.0
3784.9
3.0
0.4
1.6
48.7
113.6
1016.0
21.0
HUM OF
SAMPLES
15
12
15
15
30
26
30
30
30
30
28
29
52
12
15
15
15
14
29
28
30
19
11
11
11
11
11
11
30
50
45
29
30
30
27
18
12
12
12
12
12
12
12
12
13
12
6
48
135
-------
TOTAL PHOSPHORUS 1975
97
98
99
100
101
102
103
104
105
106
107
108
109
110
TRIBUTARY
NAME
ROOT
ST JOSEPH
KALAMAZOO
GRAND
LAKE RIVER
BASIN GROUP
MICH
HIGH
MICH
MICH
BLACK SHAVE MICH
UHITE MICH
PERE MARDUETMICH
BOARDMAN MICH
MANISTEE MICH
*MANISTIQUE MICH
LITTLE MANISMICH
BETSIE MICH
MUSKEGON MICH
ESCANABA MICH
2
3
3
3
3
4
4
4
4
4
4
4
4
4
LOAD
MT\YR
20.1
446.1
227.3
758.0
109.5
25.0
39.2
5.2
51.6
45.6
1.6
6.5
78.6
36.9
MEAN SQUARE
ERRtMT\YR>**2
4.4
3135.8
187,3
9220,3
1125.5
33.0
45.6
0.6
30.9
65.9
0.1
5.6
112.6
114.6
NUM OF
SAMPLES
6
8
22
9
3
11
9
6
21
22
3
3
22
22
136
-------
TOTAL PHOSPHORUS 1976
I 1
2
3
4
5
&
7
B
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
23
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME BASIN
OSWEGATCHtE ONTA
CRASS ONTA
RAOUETTE ONTA
GENE SEE ONTA
OSUEGO ONTA
BLACK NY INTft
ONTONAGQN SUPE
TACHJAMENON SUPE
ST LOUIS SUPE
BDIS BRULE SUPE
BAPTISM SUPE
MONTREAL SUPE
CARP SUPE
PRESQUE ISLESUPE
STURGEON SUPE
BAD SUPE
NEMADJI SUPE
CHEBOYGAN HURO
RIFLE; HLIRO
THUNDER BAY HURO
AU SABLE HURO
VAN ETTEN CRHURO
AU LiRES HJRD
PINE HURO
PINNEBOG HURO
SAGINAW HURO
GREENE CR HURO
TROUT HURO
CARP HURO
MULLIGAN CR HURO
OCGUEOC KURD
SCHMIDTS CR HURO
FORE MICH
MENOMINEE MICH
EAST TWIN MICH
KEUAUNEE MICH
FOX MICH
PENSAUKEE fICH
PESHTIGO MICH
DCONTO MICH
SHEBOYGAN MICH
MAHITOHOC MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT MICH
BURNS DITCH MICH
TRAIL CREEK MICH
ST JOSEPH RIMICH
RIVER
GROUP
3
3
3
1
2
3
2
2
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
•2.
2
2
3
LOAD
'1TXYR
294.5
122.9
112.4
719.2
919.0
410.9
100.0
19.9
123.0
9.2
5.0
18.6
49.1
8.0
39.0
52.2
85.8
23.0
15.7
15.4
36.2
6.6
8.2
21.9
35.8
1428.9
0.2
0.9
0.4
0.3
4.6
O.2
15.4
73.1
11.9
9.7
520.6
32.2
39.4
57.0
47.9
46.6
69.1
29.6
35.6
151.2
15.1
488.9
MEAN SQUARE
EftR**2
2050.9
450.3
1486.7
13814.4
46354.8
5164.3
210.8
1,3
129,4
2,7
0.7
15.5
143.0
22.6
462,5
68.2
1204.6
10.0
2.9
1.0
14.6
3, 4
3.4
101.6
21Z.3
23168.8
0.0
0.0
0.0
0.0
2.3
0.0
23.7
20.6
0.4
0.3
7894.2
64.0
85.6
148.6
42.6
58.1
67.9
1.0
41.3
3588.7
27.2
4159,9
NLJH OF
SAMPLES
9
9
9
25
13
10
24
24
20
3
5
15
12
12
12
15
15
24
24
12
12
12
11
11
12
33
43
42
41
43
42
40
23
24
12
12
12
9
12
12
12
11
12
163
6
11
8
11
137
-------
TOTAL PHOSPHORUS 1976
TRIBUTARY
NAME
LAKE RIVER
BASIN GROUP
LOAD
MT\YR
MEAN SQUARE
ERR(MT\YR)**2
NUH OF
SAMPLES
49 KALAHAZOO MICH 3
SC MUSKEGON MICH 4
51 MANISTEE MICH 4
52 *MANISTIQUE MICH 4
53 ESCANABA MICH 4
54 GRAND MICH 3
55 WHITE MICH 4
56 PERE MARQUETMICH 4
57 BETSIE MICH 4
58 BOARDMAN MICH 4
S9 UHITEFISH MICH 4
226.1
100.4
56.3
50.8
32.2
841.0
23.7
67,5
5.5
6.4
3.6
289.7
34,3
26.1
14.6
58.7
625.0
8.6
172.2
0.8
3.6
0.2
23
23
24
24
24
212
12
12
12
12
12
138
-------
SUSPENDED SOLIUS 1975
1
2
3
4
5
f,
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
r>f'
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBU™F:Y LAKE
NAME BASIN
OSUEGO ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
ST REGIS ONTA
GENESEE ONTA
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
E TWIN MICH
MANITOUOC MICH
SHEBQYGAN MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT HIOH
ST JOSEPH MICH
BLACK SHAWENMICH
KALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
LITTLE MANISMICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
ftMANISTIQUE MICH
ESCANABA MICH
AU GRES HURO
AU SABLE HURO
VAN ETTEN CRHURO
CHEBOYGAN HURO
OCQUEOC HURO
MPINE HURO
RIFLE HURO
TAUAS HURO
THUNDER BAY HURO
WHITNEY DRN HURO
APINE HURO
PINCONNING HURO
KAUKAULIN HURO
SAGINAU HURO
PIGEON HURO
PINNEBOG HURO
SEBEWAING HURO
RIVER
GROUP
2
3
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
3
4
4
4
4
4
4
4
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
LOAD
MT\YR
105612.4
73393.7
43962.6
8583.4
6824.5
6102.0
544823.0
2501.9
12684.4
3911.6
7324.8
9287.1
60078.6
5033.8
6418.1
2332S.6
6422.6
22046.4
15516.0
12698.9
82440.7
2846.4
27303.9
76557.3
39655.9
1530.5
18766.1
3128.5
1583.9
12511.8
4086.8
6624.4
11249.1
1197.0
6868.7
2216.0
42831.3
11818.2
912.0
6017.3
6680.0
1292,0
226.0
2016.3
121022.8
14746.0
2135.0
20476.0
MEAN SQUARE
ERR**2
81792368.0
532197632.0
396244480.0
3447278.0
2524028.0
2354574.0
30*0279040.0
226213.8
4501624.0
285778.4
2171340.0
65144496.0
79819280.0
1176637.0
3551395.0
118421824.0
1^27074.0
40959440.0
1.0
71V83088.0
38656256O.O
207947.6
10947752.0
98265696.0
55361616.0
113357,9
4841969.0
4152027.0
339008.8
1265363.0
226662.2
21814480.0
4514902.0
48841.0
1986628.0
833569.0
357356288.0
20546704.0
32041.0
920254.7
16112196.0
508369.0
10201.0
818777.7
138531056.0
153859216.0
537289.0
353139200,0
NUM OF
SAMPLES
16
23
7
8
9
12
183
22
9
12
11
24
23
23
22
19
12
24
273
19
8
3
22
7
22
3
20
3
6
23
23
12
14
26
25
30
15
15
29
15
28
30
30
29
37
29
30
30
139
-------
SUSPENDED SOLIDS 1975
J /?
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
77
78
79
80
81
82
83
84
85
86
87
38
, 9
90
91
92
93
94
95
96
TRIBUTARY
NAME
WILLOW
ONTONAGON
TAHQUAMENON
CARP
LAKE
BASIN
HURO
SUPE
SUPE
SUPE
PRESQUE ISLESUPE
STURGEON
IRON
MINERAL
BLACK G
FALLS
SILVER
DEAD
CHOCOLAY
TWO-HEARTED
BETSY
WAISKA
MONTREAL
ST LOUIS
BAD
BOIS BRULE
NEMADJI
PIGEON
BRULE
CASCADE
TEMPERANCE
CROSS
MANITOU
BAPTISM
BEAUER
SPLIT ROCK
KNIFE
LESTER
FRENCH
GOOSEBERRY
POPLAR
SUCKER
MAUMEE
PORTAGE
SANDUSKY
HURON
VERMILION
BLACK
CUYAHOGA
CHAGRIN
CATTARAGUS
BLACK MICH
ROUGE
HURON
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPt
ERIE
ERIE
ERIE
ERIL
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
RIVER
GROUP
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
3
3
3
4
1
1
1
LOAD
MT\YR
821.0
578559.4
7425,0
3188.1
3293.1
204SS.9
9746.0
12264.0
3879.6
438.0
602.0
898.0
1285.0
1763.0
726.0
8220.0
4708.0
69564.9
101145.5
4684.4
154323.0
19126.0
1194.0
1237.0
1208,0
518,0
610.0
906,7
1329.0
573,0
1657.0
2238.0
254.0
1836.0
1599.0
478.0
1435696.0
66000.0
321840.0
78707.0
102592.0
239904.0
631281.0
246132.0
684180.0
1561«i.7
16650.0
23255.6
MEAN SQUARE
ERR(MT\YR>**2
101761.0
107476353024.0
5516052.0
5488907.0
3621554.0
41498192.0
25654224.0
80066704.0
3140850.0
18225.0
72361.0
72361.0
98596. O
276676.0
24649.0
11758041.0
3196944.0
125412176.0
258014192.0
1447500.0
1.0
72624480.0
285156.0
266256.0
229441.0
24336.0
46225.0
30697.8
291600.0
54289.0
986049.0
1669264.0
14641.0
1155625.0
339889.0
55696.0
1680999936.0
28090000.0
249640000,0
26010000.0
510759936.0
118310000,0
11024998400.0
4147360000,0
8537759744.0
36342144.0
26339264.0
31??6336.0
NUM OF
SAMPLES
27
4
25
15
15
6
30
26
12
30
30
30
30
28
29
52
24
22
10
76
365
31
31
31
31
30
31
21
31
31
31
31
21
31
31
31
262
281
277
399
43
42
45
41
41
8
5
7
140
-------
SUSPENDED SOLIDS 1976
: i
2
3
4
5
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
36
37
38
39
40
41
42
43
44
45
46
47
48
49
TRIBUTARY LAKE
NAME BASIN
OSKEGO ONTA
BLACK NY ONTA
ObJEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
GENE SEE ONTA
FORD MICH
MENOMINEE MICH
e-TSHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
E TUIN MICH
MANITOWOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENQNONEE MICH
ROOT MICH
ST JOSEPH MICH
KALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MANISTIQUE MICH
WHITE FISH MICH
ESCANABA MICH
THUMPER BAY HURO
RIFLt HURO
AI.I GRES HURO
SAGINAU HURO
CHEBOYGAN HURO
PINNEBOG HURD
AU SABLE HURO
VAN ETTEN CRHURO
MPIWE. HURO
TftHOUAMENON SUPE
MONTREAL SUPE
PRESQUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
ST LOUIS SUPE
BO IS BRULE SUPE
NEMADJI SUPE
BAD SUPE
BAPTISM SUPE
RIVER
GROUP
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
4
4
4
4
4
4
4
1
1
1
2
1
2
1
1
1
2
1
2
2
2
2
i
1
1
1
1
LJ4D
h.T\YR
140524.0
41085.8
19624.7
5407.7
8631.0
1056506.0
7526.1
16210.2
5989.4
10394.4
18320.0
103360.0
1413.2
1721.6
5169.8
4796.4
11116.7
12238.4
9239.4
113285.4
37091.7
148666.9
61280.4
15963.6
3205.3
1024.0
15515.0
1370.5
4052.9
6900.1
8403.2
4406.7
362747.6
8*28.0
8d21.3
10216.1
1367.8
13271.2
7898.9
2730.8
4659 . 8
26260.6
925.5
146083.9
26947.7
2756.1
71080.0
152578.0
3767.2
MEAN SQUARE
ERR**2
240267680.0
41882928.0
13576520.0
389327.8
1571103.0
1.0
2911374.0
4457253.0
533105.7
12265794.0
337B2416.0
551121984,0
36330.1
16534.2
92249.1
1414157.0
7357446.0
1.0
6739663.0
211897824.0
34153840.0
43B63600.0
203384240.0
4368610.0
522006.4
30514.1
4101016.0
68135.4
1198793,0
2-20240.0
444538.0
1712668.0
10631012352.0
991941.1
26449664.0
6142244.0
405419.9
96028880.0
5293305.0
1049827.0
15797813.0
377924608.0
85029.0
3576136960.0
19252624.0
314556.9
1.0
7214981120.0
30726.7
NUM OF
SAMPLES
13
10
9
9
9
366
18
12
10
12
8
19
11
12
10
12
11
163
6
11
23
212
24
24
12
12
23
12
22
12
24
11
J3
25
12
12
12
11
IB
12
12
12
12
18
19
12
253
7
7
141
-------
SOLUBLE ORTHO PHOSPHCRUS 1975
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
OT
23
24
25
26
•;j -i
28
29
30
31
32
33
34
35
36
J7
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME BASIN
GENE3SEE ONTA
OSUEGO ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
ST JOSEPH MICH
BLACK SHAVE MICH
NALAMAZOO MICH
GRANH MICH
MUSKEGON MICH
LITTLE MAN ISM I CH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MANISTIQUE MICH
ESCANABA MICH
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
E TWIN MICH
MANITOUOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT MICH
TAHGUMENON SUPE
BLACK G SUPE
PREBQUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
BOIS BRULE SUPE
BAD SUPE
BETSY SUPE
CHOCOLAY SUPE
DEAD SUPE
FALLS SUPE
IRON SUPE
MINERAL SUPE
SILVER SUPE
TWO-HEARTED SUPE
UAISKA SUPE
MONTREAL SUPE
RIVER
GROUP
1
2
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
1
1
2
2
2
2
2
2
2
2
2
I
LOAD
MT\YR
67.6
119.4
113.2
31.3
16.4
28.2
96.2
32.3
95.2
320.9
28.6
1.6
17,5
2.5
2.2
26.3
23.8
2.8
37.4
33.7
15,3
7.5
219.8
9.2
3.5
30.7
36.5
27.4
10.3
7.0
7,9
2.0
2.1
4.7
16.3
18.6
8.2
32.2
0.7
5.4
1.7
0.5
2.3
2.1
0.6
1.8
4,4
5.6
idUARE
,YR>**2
28.0
1238.2
2892. A
80.3
66.5
11.3
159.2
34.4
55.1
1345.3
37.9
0.1
4.8
0.7
0.2
16.3
24.5
0.1
48.3
147.1
11.2
3.2
4432,4
1.2
0.2
96.8
108.0
31.3
7,1
6.0
0.6
0.9
0.3
0.2
18.6
15.2
10.1
862,9
0.0
1.9
0.2
0.0
1.0
0.2
0.0
0.0
1.0
1.2
NUM OF
SAMPLES
14
8
12
9
8
7
8
3
10
7
10
3
9
3
6
13
12
12
9
9
8
9
9
9
9
10
9
4
3
9
15
12
16
15
15
15
13
13
29
30
30
30
30
26
30
28
26
11
142
-------
SOLUBLE ORTHO PHOSPHORUS
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
6B
69
70
7\
72
73
74
75
76
77
78
79
TRIBUTARY
NAME
MEMADJI
OCQUEOC
PIGEON
SAGANAW
KAUKAULIN
PINCONNING
APINE
PINNEBOG
SEBEUAING
TAUAS
THUNDER BAY
RIFLE
AU GRES
CHEBOYGAN
AU SABLE
MPINE
VAN ETTEN
UHITNEY CRN
UILLOU
MAUMEE
-•LJRTAGE
SANDUSKY
HURON
VERMILION
BLACK
CUYAHOGA
CHAGRIN
CATTARAGUS
BLAf.K MICH
ROUGE
HURON
LAKE
BASIN
SUPE
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
RIVER
GROUP
1
1
2
2
2
2
1
2
2
1
1
1
1
1
1
1
1
1
o
2
2
2
2
2
3
3
3
4
1
1
1
LOAD
MTNYR
40.1
2.2
8.5
259.4
5.1
2.0
4.8
9.6
6.7
2.8
10.1
6.2
4.3
12.2
19.6
8.5
2.6
2.3
1.7
612.0
52.2
83.4
33.4
10.1
141.1
183.0
21.7
12.7
25.9
106.8
39.8
rtJARE
'R)**2
45.1
1.8
10.9
595. 0
1.9
0.2
2.2
10.3
12.5
0.2
4.3
0.8
10.4
4.1
0.9
2.1
0.4
0.8
0.4
355.1
1.5
1.5
18.1
1.5
62.5
310.8
3.3
1.5
34.8
301.6
26.2
NUM OF
SAMPLES
17
30
29
50
45
30
30
30
30
29
15
15
12
15
14
15
26
28
27
262
281
277
399
43
42
45
41
41
8
5
7
143
-------
SOLUBLE ORTHO PHOSPHORUS 1976
1
2
3
4
5
A
7
8
9
10
11
12
13
14
15
16
17
18
IV
20
21
22
23
24
25
26
27
2ft
29
30
31
3<;
33
34
35
36
37
38
39
40
41
42
43
TRIBUTARY LAKE
NAME BASIN
6ENESEE ONTA
OSUEGG ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
BRASS ONTA
RAQUETTE ONTA
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TWIN MICH
MANITOUOC MICH
SHEBOYGAN MICH
MENOMONEE MICH
ROOT MICH
ST JOSEPH MICH
KALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MANISTIQUE MICH
WHITE FISH MICH
ESCANABA MICH
TAHOUMENON SUPE
MONTREAL SUPE
PRESQUE ISLESIIPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
SAGINAU HURO
CHEBOYGAN HURO
THUNDER BAY HURO
RIFLE HURO
AU GRES HURO
PINNEBOG HURO
AU SABLE HURO
VAN FATTEN CRHURO
MPINE HURO
RIVER
GROUP
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
3
3
3
4
A
4
4
4
4
4
2
1
2
2
2
2
2
1
1
1
1
2
1
1
1
LOAD
MTXYR
89.3
200.7
49.9
33.1
16.2
27.9
3.2
22.9
10.4
9.4
7.0
113.4
4.6
4.7
27.0
27.9
8.4
15.8
158,8
86.7
343.6
36.9
18.1
1.5
3.9
19.8
0.7
14.3
4. 1
9.4
1.4
8,2
24.5
38.6
615.0
5,7
2.7
4.0
2.8
20,5
12.3
1.8
6.5
SQUARE
,YR>**2
283.4
1388.2
150.7
58.2
6.2
73.3
13.0
6,9
1.1
0,5
0.8
1908.0
0.2
0.2
39.3
18.0
1.0
22.2
2458,7
87,0
142.2
31.5
4.6
0.0
4.1
13.2
0.0
59.6
0.4
3.9
0,3
10,6
20.6
19.1
4747.7
1,3
0.4
0.3
0.6
66.8
2.8
0.5
7.5
NUM OF
SAMPLES
17
9
10
9
8
9
12
12
12
12
9
12
12
12
11
12
163
6
11
12
211
12
12
12
12
12
12
12
12
12
12
12
12
12
23
12
12
12
11
12
12
12
11
144
-------
CHLORIDE 1975
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Id
17
IB
19
2O
21
^';>
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
TRIBUTARY
NAME
GENE SEE
OSUEGO
BLACK NY
OSUEGATCHIE
CRASS
RAQUETTE
ST REGIS
FORD
MENDMINEE
PESHTIGO
OCONTO
PENSAUKEE
FOX
KEUAUNEE
E TWIN
MANITOUOC
SHEBOYGAN
MILWAUKEE
MENOMONEE
ROOT
ST JOSEPH
KALAMAZOO
GRAND
MUSKEGON
MANISTEE
BETSIE
BOARDMAN
*MANISTIGUE
ESCANABA
GREENE CR
MULLIGAN CR
SCHMIDTS CR
CARP CR
OCQUEOC
TROUT
PIGEON
PINCONNING
APINE
PINNEBOG
SEBEWAING
TAUAS
LAKE
BASIN
ONTA
ONTA
ONTA
ONTA
ONTA
ONTA
ONTA
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
MICH
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
VAN ETTEN CRHURO
WHITNEY DRN
WILLOW
SAGINAW
KAKAULIN
THUNDER BAY
RIFLE
AU GRES
CHEBOYBAN
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
RIVER
GROUP
1
2
3
3
3
3
3
i
I
1
1
1
1
1
1
1
1
2
2
2
3
3
3
A
4
4
4
4
4
1
1
1
1
1
1
2
2
1
2
2
1
1
1
2
2
2
1
1
1
1
LOAD
MTXYR
129819.1
1057788.0
7548.4
4834.5
2798.0
2481.3
1599.6
978.3
3214.7
2130.3
6229.0
579.5
51168.1
1373.9
857.9
3779.2
7066.7
14558.7
10336.1
3923.0
78264.8
60226.6
171490.2
46548.0
163375.4
937.5
1848.2
4071.3
10511.5
5.8
8.1
27.2
17.9
316.0
116.4
2784.9
668.0
2514.9
3215.7
3084.3
675.3
1277.5
1259.3
1051.2
295139.8
4434.8
5529.0
5475.4
2973.9
6216.1
MEr*N SQUARE
ERR(MT\YR)**2
74638992.0
11548844032.0
3239712.0
289190.5
2527699.0
93326.8
22801.8
3334.8
299902.2
410943.3
677186.8
75777.6
8983847.0
2192.1
2758.0
181695.5
420774,9
243160&4.0
3409737.0
10212406.0
10816331.0
5254486.0
41900128.0
5107921.0
157896192.0
23635,2
4459.1
29090.3
4736482.0
2.2
5.6
38.3
11.5
803.6
476.8
457560.8
14388.0
166328.7
462024.3
527856.5
5259.6
26171.5
65843.6
43232.0
1798453504.0
484439.4
107080.9
92691.4
795724.1
115453.9
NUM OF
SAMPLES
33
16
16
9
8
9
12
22
8
11
12
11
24
12
12
12
11
16
48
24
8
22
7
22
21
3
6
23
23
11
11
1.1
11
11
11
29
30
30
30
30
29
26
28
27
48
41
15
15
12
25
145
-------
CHLORIDE 197S
1 51
52
53
5A
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
TRIBUTARY
MANE
AU SABLE
MPINE
ST LOUIS
BOIS BRULE
NEMADJI
BAD
BAPTISM
BEAVER
BRULE
CASCADE
CROSS
FRENCH
GOOSEBERRY
KNIFE
LESTER
MANITOU
PIGEON
POPLAR
SPLIT ROCK
SUCKER
TEMPERANCE
MONTREAL
TAHHUAMENON
LAKE
BASIN
HURO
HURO
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
PRESQUE ISLESUPE
STURGEON
CARP
ONTONAGON
BETSY
BLACK
CHOCOL4Y
DEAD
FALLS
IRON
MINERAL
SILVER
TWO-HEARTED
UAISKA
MAUMEE
PORTAGE
SAN DUSKY
HJRDN
VERMILION
BLACK
CUYAHOGA
CHAGRIN
CATTARAGUS
BLACK MICH
ROUGE
HURON
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
RIYER
GROUP
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
4
1
1
1
LOAD
MTNYR
9925.6
1100.4
25467.9
131.9
811.8
2357.4
55i.&
500.0
638.8
331.8
267.5
89.1
208.4
358. *
336.5
376.0
2069.6
605.9
223.4
165.0
427.0
1208.2
1670.4
723.8
2036.9
1361.7
3697.3
67.9
846.8
781.1
463.6
125.2
981.8
21243.0
50.7
152.9
606.2
273017. 6
19525.0
-46845.6
12711.0
4715.2
27342.0
110964.3
21672.0
1O224.7
8075.0
17724.5
28599.9
MEAN SQUARE
ERR**2
98168.8
12220.0
1658515.0
1999.3
8876.2
6252352.0
488053.0
18772.3
20432.8
9798.9
4920.3
718.9
3717.0
7041.2
14228.9
11418.2
155229.0
25796.2
4828.8
4384.0
7737.0
618017.0
51360.1
64400.7
131977.3
20632.3
236698.9
129.5
31895.8
4178.4
7620.9
234.9
26438.9
5279860.0
123.8
490.3
4431.8
44715040.0
59127.3
175^4064.0
59127.3
2218198.0
1629696.0
49726080.0
5912732.0
175940.7
3652481.0
4749344.0
1027752.9
NUM OF
SAMPLES
14
15
12
16
11
10
12
31
31
31
31
31
31
31
30
31
31
31
31
31
30
23
27
15
15
14
27
28
30
30
30
30
30
26
30
28
26
262
281
277
399
43
42
45
41
41
8
5
7
146
-------
CHLORIDE 197.4
1
2
3
A
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
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
xS*
TRIBUTARY LAKE
NAME BASIN
ST LOUIS SUPE
BOJS BRULE SUPE
NEMADJI SUPE
BAD SUPE
BAPTISM SUPE
TAHQUAMENON SUPE
MONTREAL SUPE
PRESQUE ISLESUPF
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
DENESEE ONTA
OSUEGO ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
GRASS ONTA
RAOUETTE ONTA
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
E TWIN MICH
MAMTOUOC MICH
SHEBOYGAN MICH
MILWAUKEE rtlCH
MENOMONEE MICH
ROOT MICH
ST JOSEPH MICH
KALAMAZOO MICH
GRAND MICH
MUSKEOON MICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
tMANISTIQUE MICH
UHITE FISH Mir:H
ESCANABA MICH
THUNDER BAY HURO
RIFLE HURO
AU GRES HURO
SAGINAU HURO
CHEBOYGAN HURO
PINNEBOG HURO
AU SABLE HURO
VAN ETTEN CRHURO
MPINE HURO
GREENE CR HURO
MULLIGAN CR HURO
SCHMIDTS CR HURO
CARP CR HURO
OCQUEOC HURO
TROUT HURO
RIVER
GROUP
1
1
1
1
1
2
1
2
2
2
2
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
4
4
4
4
4
4
4
1
1
1
2
1
2
1
1
1
1
1
1
1
1 147
1
LOAD
MT\YR
14350,9
211.5
486.0
1566.1
364.1
1622.2
1120.1
817.5
1293.4
1763.9
3380.8
129358.6
1386606.0
8605.5
7348.1
4108.0
3308.1
748.0
3966.0
1948.2
6345.9
1337.1
55742.3
1731.6
1574.0
7270,4
7231.4
18297.1
10834.2
6665.6
86846.1
57017.1
149924.3
46235.1
85695.9
1092.9
2176.9
3929 . 0
1118.6
5090.1
4300.9
6033.5
3797.3
320889.6
6473.7
7326.7
10046.7
1068.8
46S.7
16.5
21.5
29.8
26.1
356.8
218.5
MEAN SQUARE
ERft(MT\YR)**2
7773813.0
174.6
12652.6
104954.3
4348.9
29081.8
74107.9
71386.5
68409.9
14717.6
183502.2
230125696.0
11063869440.0
281966.7
375263.0
131971.8
49047.7
9409.5
642851.9
322458.4
108V513.0
3441.4
16032160.0
43073.9
4663.5
1044872.3
208205.7
10915365.0
1897349.0
1496772.0
8585668.0
15914057,0
17938864.0
8313055,0
110266640.0
12537.1
9440.9
75174.5
78232.4
2801563.0
87940.0
48825.0
1049305.0
1941606144.0
80014.5
8461026.0
96088,6
42235.8
14694.0
20.3
20.0
26.4
16.6
1575.0
1433.1
NUM OF
SAMPLES
19
11
23
24
7
24
12
12
12
12
24
25
13
10
9
9
9
24
4
12
12
9
24
12
12
11
12
12
72
6
11
23
212
24
23
12
12
24
12
24
12
24
11
33
25
12
12
12
11
43
43
43
43
43
43
-------
TOTAL NITROGEN1975
t 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
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME BASIN
GENESEE ONTA
OSUEGO ONTA
BLACK NY ONTA
OSWEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
ST REGIS ONTA
FORD MICH
MENOHINEE MICH
PESHTIGO HICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TUIN MICH
MANITOUOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT MICH
ST JOSEPH MICH
BLACK SHAYE MICH
KALAMAiZOO MICH
GRAND MICH
MUSKEGON MICH
LITTLE MANXSMICH
MANISTEE MICH
BETSIE MICH
BOARBMAN MICH
*M4NISTIdUE MICH
ESCANABA MICH
TAHQUAMENON SUPE
BLACK G SUPE
PRESOUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
ST LOUI5 SUPE
BOIS BRULE SUPE
NEMADJI SUPE
BAD SUPE
BAPTISM SUPE
BEAVER SUPE
BRULE SUPE
CASCADE SUPE
CROSS SUPE
FRENCH SUPE
GOOSEBERRY SUPE
RIVER
GROUP
1
2
3
T
3
3
3
1
2
2
2
3
3
3
3
4
4
4
4
4
4
4
2
2
2
2
2
2
1
1
1
1
LOAD MEAN SQUARE
MT\YR ERR**2
4838.6
8375.2
2228.6
1435.0
802.1
1023.9
591.0
196.5
1645.5
595.2
1403.8
157.1
4698.2
211. 6
117.9
408.8
599.4
1235.8
212.2
533.2
7749.4
746.3
3828.8
11052.8
1550. A
56.2
1198.1
128.3
152.4
1104.1
549.5
489.8
178.6
179.4
486.0
292.8
1087.8
2468.3
119.1
374.8
642.7
196.1
153.7
229.6
127.0
109,1
24.2
75.9
26953.3
45198.8
990196.9
15631.1
7992.4
19807.3
475.2
29.3
23043.9
1368. 9
18779.2
152.9
156860.1
241.6
456.0
814.0
9194.0
23221.7
506.6
1837.8
484385.4
23094.2
18619.8
1554260.0
11212.7
373,2
3832.2
1018.9
254.1
8063.8
1881.1
852.6
786.2
2536.9
3804.6
1367.2
33722.8
26245.9
321.7
5423.8
39505.8
1550.8
1519.8
1952.0
689.4
540.5
49.9
534.7
NUM OF
SAMPLES
31
17
12
9
8
9
12
22
12
9
9
9
19
9
9
10
9
18
3
5
8
3
22
7
22
3
21
3
6
23
23
27
12
15
15
15
27
4
14
13
12
12
30
30
30
29
30
30
143
-------
TOTAL. NITROGEN 1975
49
SO
51
52
53
54
55
56
57
SB
59
40
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
TRIBUTARY LAKE
NAME BASIN
KNIFF. SURE
LESTER SURE
MANITOU SUPE
PISEON SUPE
POPLAR SUPE
SPLIT ROCK SUPE
SUCKER SUPE
TEMPERANCE SUPE
MONTREAL SUPE
BETSY SUPE
CHOCOLAY SUPE
HEAD SUPE
FALLS SUPE
IRON SUPE
MINERAL SUPE
SILVER SUPE
TWO HEARTED SUPE
WAI SKA SUPE
THUNDER BAY HURO
RIFLE HURO
AU ORES HURO
CHEBOYUAN HURO
AU SABLE HURO
MPINE HURO
KAWKAWLIN HURO
OCQUEOC HURO
PIGEON HURO
PINCDNNING HURO
APINE HURO
PINNEBOG HURO
SAGINAU HURO
SEBEUAING HURO
TAUAS HURO
VAN ETTEN CRHURO
UHITNEY BRN HURO
WILLOW HURO
MAUMEE ERIE
PORTAGE ERIE
SANDUSKY ERIE
HURON ERIE
VERMILION ERIE
BLACK ERIE
CUYAHOCA ERIE
CHAGRIN ERIE
CATTARAGUS ERIE
BLACK MICH ERIE
ROUGE ERIE
HURON ERIE
RIVER
GROUP
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
2
1
2
2
1
2
2
2
1
1
1
2
2
2
2
2
2
3
3
3
4
1
1
1
LOAD
MTNYR
77.4
73.0
152.9
755.6
211.0
73.7
46.7
197.8
325.2
45.6
117,5
79.6
20.2
66.8
112.4
28.5
105.8
177.0
527.9
336.6
233.2
564.2
688.5
250.9
580.4
92.3
636.2
74.1
147.8
491.8
18542.0
846.9
102.6
129.6
154.4
172.6
47707.5
3245.0
6886.1
1730.5
868.0
8299.6
4835.9
972.2
1763.7
1089.8
579.0
1213.6
MEAN SQUARE
ERR**2
531.6
848.1
2182,2
18120.4
4195.6
631.2
194.0
1870.5
9210.0
49,7
150.3
132.9
5.7
268,7
511.7
58.7
236.6
1037.6
7387,6
4832.3
7377.2
3077.1
10377.9
1151.2
32373.7
407.7
54997.1
742.9
1853.2
23492.0
11676595,0
117325.0
210.4
531.3
2239,1
2215.0
310070. C
4231.0
6488.0
1490.0
1138.0
594633.0
5774.0
3549.0
2395.0
24349.7
1259.3
7850.0
NUM OF
SAMPLES
30
30
30
30
30
30
30
30
13
29
30
30
29
30
26
30
28
26
15
15
12
25
14
15
30
30
29
30
30
30
44
30
29
26
28
27
262
281
277
399
43
42
45
41
41
8
5
7
149
-------
TOTAL NITROGEN 1976
1 1
2
3
4
5
6
7
9
9
10
11
12
13
14
15
16
17
113
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME: BASIN
ST LOUIS SUPE
BOIS BRULE SUPE
NEMADJI SUPE
BAD SUPE
ONTONOGON SUPE
THAQUAMENON SUPE
MONTREAL SUPE
PRESQUE ISLESUPE
STURGEON SUPE
CARP SUPE
GENESEE ONTA
OSWEGC ONTA
BLACK NY ONTA
OSWEGATCHIE ONTA
GRASS ONTA
RAOUETTE ONTA
FORt MICH
MENOMINEE MICH
PESHTIBO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TUIN MICH
MANITOWOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMCNEE MICH
ROOT MICH
ST JOSEPH MICH
KALAMAZGO MICH
GRAND MICH
MUGKEGON MICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MAMISTIQUE MICH
UHITE FISH MICH
ESCANABA MICH
THUNDER BAY HUKO
RIFLb! HURO
AU GRES HURO
SAGINAU HURO
CHEBOYCAN HURO
PINNEBOG HURO
AU SABLE HURO
VAN ETTEN CRHURO
MPINE: HURO
RIVER
GROUP
1
1
1
1
2
2
1
2
2
2
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
4
4
4
4
4
4
4
1
1
1
2
1
2
1
1
1
LOAD
MT\YR
1201,5
87.9
339.9
649.3
743.4
467.4
230.7
154.9
355.7
214.7
6871.1
12139.0
3236.6
1881.3
797.8
1514.0
248.2
1578.8
842.1
1713.7
142.9
4614.4
205.6
198.5
643.5
792,6
1009,6
259.3
811.2
10040.0
3612.0
12652.7
2122.8
1131.5
135.3
221.6
1139.6
107.7
529.7
381.6
262.5
323.4
16730.9
497.7
867.4
705.8
114.3
103.5
MEAN SQUARE
ERR(MT\YR)**2
16039.4
418.2
6884.7
1456.9
1104.4
1990.4
4620.9
4242.6
8930.3
2025.8
262288.3
664046.7
114514.6
15143.1
3204.8
27805.2
1144.2
3266.8
11970.3
86093.4
110.7
108251.3
70.5
207.3
13143.2
9889.9
14172.7
398.3
39152.5
226126.9
16848.2
632.3
15263.5
3378.3
410.3
89.0
8593.6
95.8
708.1
610.1
603.6
6010.0
1234414.0
674.5
125746,3
1761.7
1261.1
1534.7
NUM OF
SAMPLES
3
3
15
14
24
24
12
12
12
12
25
13
10
9
9
9
24
12
12
12
8
24
12
12
11
12
12
40
6
11
23
321
23
24
12
12
24
12
24
12
24
11
33
25
12
12
12
11
150
-------
AMMONIA N 1975
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
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME BASIN
GENESEE ONTA
OSWEGO ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
MENOMINEE HIGH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TWIN MICH
MANITOWOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT MICH
ST JOSEPH MICH
BLACK SHAYE MICH
NALArfAZOO MICH
GRAND MICH
MUSKEGON MICH
LITTLE MANISMICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MANISTICJUE MICH
ESCANABA MICH
FORD MICH
TAHOUAMENON SUPE
BLACK G SUPE
PRESQUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
ST LOUIS SUPE
BOIS BRULE SUPE
NEMADJI SUPE
BAD SUPE
BAPTISM SUPE
BEAVER SUPE
BRULE SUPE
CASCADE SUPE
CROSS SUPE
FRENCH SUPE
GOOSEBERRY SUPE
KNIFE SUPE
RIVER
GROUP
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
3
4
4
4
4
4
4
4
1
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
LOAD
MTNYR
498.9
1193.2
326.6
145.0
87.6
97.2
240.7
79.9
1081.3
33.4
739.3
14.3
10.7
111.5
41.6
240.1
31.8
21.3
389.6
37.3
250.6
985.3
49.3
3.9
147.6
6.4
43.5
89.9
110.6
21.7
18.7
4.2
2.7
28.6
132.8
154.7
285.0
16.5
61.3
85.1
12.8
10.2
29.1
8.9
7.2
2.5
5.5
5.6
MEAN SQUARE
ERR**2
9845.1
58580.4
10359.3
1847.2
2221.4
1899.5
1290.9
238.3
67839.9
89.6
15723.1
1.1
0,5
892.6
11.6
2642.2
15.9
27,0
20120.4
3.6
3478.0
34630.3
84.4
0.0
712.7
16.0
9.9
129.5
216.3
14.6
49.3
12.3
1.1
116.2
767.0
3015.1
718.8
31.9
1737.1
7644.5
107.1
7.3
170.6
5.5
3.4
0.8
3.3
2.5
NUM OF
SAMPLES
14
8
12
9
8
9
12
12
12
12
12
12
12
13
12
6
47
18
8
3
10
7
10
3
9
3
6
13
13
12
15
12
15
15
15
15
5
14
12
13
12
30
30
30
29
30
30
30
151
-------
AMMONIA N 1775
A9
50
51
52
53
54
55
56
57
58
59
60
61
62
63
&4
65
66
67
68
67
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
TRIBUTARY LAKE
NAME BASIN
LESTER SURE
MANITOU SUPE
PIGEON SUPE
POPLAR SUPE
SPLIT ROCK SUPE
SUCKER SUPE
TEMPERANCE SUPE
MONTREAL SUPE
BETSY SUPE
CHOCOLAY SUPE
DEAD SUPE
FALLS SUPE
IRON SUPE
MINERAL SUPE
SILVER SUPE
TWO-HEARTED SUPE
UAISKA SUFE
THUNI'ER BAY HURG
RIFLE HURO
AU GRES HURO
CHEBOYQAN HURO
AU SABLE HURO
MPINE HURO
OCOUEOC HURO
PIGEON HURO
PINCONNING HURO
APINE HURO
PINNEBOC HURO
SEBEWAING HURO
TAWAS HURO
VAN E.TTEN CRHURO
WHITNEY CRN HURO
WILLOW HURO
SAGINAU HURO
KAUKAWLIN HURO
MAUMEE ERIE
PORTAGE ERIE
SANDUSKY ERIE
HURON ERIE
VERMILION ERIE
BLACK ERIE
CUYAHOGA ERIE
CHAGRIN ERIE
CATTARAGUS ERIE
BLACK MICH ERIE
ROUGE ERIE
HURON ERIE
RIVER
GROUP
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
2
2
1
2
2
1
1
1
2
2
2
o
2
2
2
•z
3
3
3
4
1
1
1
LOAD
HT\YR
5.8
10.2
58.0
14.7
A. 7
3.9
11.8
37.6
3.6
6.0
6.6
0.8
3.3
14.2
1.1
4.5
14.0
38.7
12.2
9.6
30.3
24.5
23.0
4,2
20.7
2.1
7.4
11.4
13.9
9.7
11.6
6.4
4.0
1976.4
18.5
1136.8
78.4
253.9
51.3
38.1
596.2
622.1
86.7
185.0
47.3
234.2
267.5
MEAN SQUARE
ERR**2
5.5
16.8
234.9
9.0
12.9
1.2
5.2
92.0
0.4
1.2
5.1
0.0
0.7
33.9
0.1
0.8
12.3
145.0
17.2
12.5
25.0
3.4
28.6
1.4
222.3
0.2
3.9
12.7
88.3
1.2
14.3
4.3
1.1
40479.4
20.3
4887.2
9.2
269.4
5.9
5.9
33481.2
8204.3
163.0
249.8
24.6
233.7
3350.3
NUM OF
SAMPLES
30
30
30
30
30
30
30
23
29
30
30
30
30
26
30
28
26
15
16
12
15
14
15
30
29
30
30
30
30
29
26
28
27
50
45
262
281
277
399
43
42
45
41
41
a
5
7
152
-------
AMMONIA N 1976
: i
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
36
37
38
39
40
41
42
43
44
45
46
47
TRIBUTARY LAKE
NAME BASIN
GENESEE ONTA
OSWEBO ONTA
BLACK NY ONTA
OSWEGATCHIE ONTA
GRASS ONTA
RAOUETTE ONTA
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEUAUNEE MICH
E TWIN MICH
MANITOWOU MICH
SHEBOYGAN HICH
MENOMONEE MICH
ROOT MICH
ST JOSEPH MICH
NALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
*MANISTIC1U£ MICH
WHITE FISH MICH
ESCANABA MICH
THUNDER BAY HURO
RIFLE HURO
AU GRES HURO
SAGINAW HURO
CHEBOYGAN HURO
F'INNEBOG HURO
AU SABLE HURO
VAN ETTEN CRHURO
MPINE HURO
TAHQUAMENON SUPE
MONTREAL SUPE
PRESQUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
ST LOUIS SUPE
BOIS BRULE SUPE
NEMADJI SUPE
BAD SUPE
RIVER
GROUP
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
3
3
3
4
4
4
4
4
4
4
1
1
1
2
1
2
1
1
1
2
1
2
2
2
2
1
1
1
1
LOAD
MT\YR
673.8
1838.1
85.7
101.8
92.9
74.1
22.7
43.3
73.1
752.2
25.4
711.0
13.1
16.7
78.3
52.7
25.2
18.2
583.9
183.4
1404.1
84.7
73.6
5.9
A3. 9
64.7
3.6
35.8
11.9
9.7
7.0
1389.8
17.9
44.0
26.1
3.8
5.9
15.1
13.3
2.9
12.1
VS. 4
74.4
115.8
13.5
30.6
64.0
MEAN SQUARE
ERR(MT\YR)**2
4917.0
42073.8
120.7
246.0
144.9
198.7
482.4
62.2
48.6
33074 . 2
19.1
26025.3
2.6
4.2
699.4
73.9
7.4
25.7
20607.9
1956.8
12704.3
405.5
122.4
2.8
76.3
279.8
0.2
226.9
10.0
6.5
4.8
42579.4
4.7
704.6
27.4
2.2
3.7
7.2
18.6
0.9
12.8
375.5
488.2
348.2
10.9
4.6
913.5
NUM OF
SAMPLES
25
13
10
9
9
9
12
12
12
12
9
12
12
12
11
12
74
6
11
12
212
12
12
12
12
12
12
12
12
12
11
23
12
12
12
12
11
12
12
12
12
12
12
3
3
3
3
153
-------
NITRATE 1975
S 1
2
3
4
5
6
7
8
9
10
11
12
13
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
TRIBUTARY LAKE
NAME BASIN
GENESEE ONTA
OSWEGO ONTA
BLACK NY ONTA
OSUEGATCHIE ONTA
GRASS ONTA
RAQUETTE ONTA
ST REGIS ONTA
FORD MICH
MENOMINEE MICH
PESHTIGO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TWIN MICH
MANITOUOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMONEE MICH
ROOT MICH
ST JOSEi H MICH
BLACK SHAVE MICH
KALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
LITTLE MANISMICH
MANISTEE MICH
BETSIE MICH
BOARDMAN MICH
KCMANJSTIQUE MICH
ESCANABA MICH
TAHOUAMENON SUPE
BLACK G SUPE
PRE3QUE ISLESUPE
STURGEON SUPE
CARP SUPE
ONTONAGON SUPE
ST LOUIS SUPE
BO IS BRULE SUPE
NEHADJI SUPE
BAD SUPE
BAPTISM SUPE
BEAVER SUPE
BRULE SUPE
CASCADE SUPE
CROSS SUPE
FRENCH SUPE
GOOSEBERRY SUPE
RIVER
GROUP
1
2
3
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
3
4
4
4
4
4
4
4
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
LOAD
MT\YR
2383.7
3497,1
2326,5
609.6
379.3
701.1
312.1
31.4
451.6
315.4
185.3
59.2
943.2
128.2
61.5
79.2
311.6
585.4
143.2
417.9
4344.7
248.6
1812.1
5495.7
467.2
14.9
436.5
44.9
65.1
259.0
135.6
73.8
31.9
38.6
98.2
22.3
138.1
876.2
20.2
51.0
121.2
90.1
34.7
49.6
37.6
31.7
4.5
13.0
MEAN SQUARE
ERR
-------
NITRATE 1V7S
t 49
: so
51
52
53
5-4
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
TRIBUTARY
NAME
KNIFE
LESTER
HANITOU
PIGEON
POPLAR
SPLIT ROCK
SUCKER
TEMPERANCE
MONTREAL
BETSY
CHOCOLAY
ICAD
^ ALLS
IRON
MINERAL
SILVER
TWO-HEARTED
WAI SKA
THUNDER BAY
RIFLE
AU GRES
CHEBOYGAN
AU SABLE
MPINE
OCQUEOC
PIGEON
PINCONNING
APINE
PINNEBOG
SEBEWAING
TAUAS
LAKE
BASIN
SUPE
SUPE
SUPS
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
SUPE
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
HURO
VAN E7TEN CRHURO
WHITNEY
WILLOW
SAGINAW
KAUKAWLIN
MAUMEE
PORTAGE
SANtiUSKY
HURON
VERMILION
BLACK
CUYAHOGA
CHAGRIN
CATTARAGUS
BLACK MICH
ROUGE
HURON
HURO
HURO
HURO
HURO
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
ERIE
RIVER
GROUP
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
2
2
1
2
2
1
1
1
2
2
2
2
2
2
2
2
3
3
3
4
1
1
1
LOAD
Mt\YR
15.3
15.3
47.1
150.0
83.2
20.3
10.4
70.1
70.4
6.3
51.8
30.4
5.7
10.7
54.0
5.3
26.4
29.1
71.0
104.7
128.0
103.4
127.1
26.6
25.2
518.3
60.2
85.8
394.2
711.8
21.4
41.?
56. V
130.3
11954.6
261.3
40835.0
2856.0
6162.6
1315.7
572.3
6209.3
2640 . 1
512.4
1030.1
712.7
130.2
454.7
MEAN SQUARE
ERR**2
32.2
93.4
309.5
1252.1
1002.0
78.6
14.8
348.2
292.7
1.8
18.2
58.7
0.7
10.8
179.2
1.3
5.4
54.3
318.5
1604.5
6175.2
127.6
424.0
6.6
34.9
27575.3
566.0
651.4
16370.7
668.5
28.9
120.0
439.7
1465.6
29138608.0
5284.0
369546.0
923.8
14781.8
923.8
2424.6
1921046.0
9460.1
3695.4
1420.5
15058.5
208.3
7719.7
NUM OF
SAMPLES
30
30
30
30
30
30
30
30
13
29
30
30
30
30
26
30
28
26
15
15
12
25
14
15
30
29
30
30
30
30
29
26
28
27
50
45
262
340
277
399
43
42
45
41
41
8
5
7
155
-------
NITRATE (NITRITE) 1976
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
24
27
28
29
30
31
34
35
36
37
38
39
40
41
42
43
44
45
44
47
48
49
TRIBUTARY LAKE
NAME BASIN
GENESEE ONTA
OSWEGO ONTA
BLACK NY ONTH
OSWEGATCHIE ONTA
GRASS flNTA
RAQUETTE ONTA
FORD MICH
MENOMINEE MICH
PESHTICO MICH
OCONTO MICH
PENSAUKEE MICH
FOX MICH
KEWAUNEE MICH
E TWIN MICH
MANITQUOC MICH
SHEBOYGAN MICH
MILWAUKEE MICH
MENOMGNEE MICH
ROOT MICH
ST JOSEPH MICH
KALAMAZOO MICH
GRAND MICH
MUSKEGON MICH
MAMISTEE MICH
BETSIE MICH
BOARDMAN MICH
#MAN1STIQUE MICH
WHITE FISH MICH
ESCANAEA MICH
'HUNDER BAY HURO
RIFLE HURO
AU ORES HUr,-0
SAGINAU HURO
CHEBOYGAN HURO
PINNEBDG HURO
AU SABLE HURO
VAN ETTEN CRHURO
MPINE HURO
TAHOUAMENON SUPE
MONTREAL SUPE
PRfJSQUE ISLESUPE
STURGEON SUPE
CAf;P SUPE
ONTONAGON SUPE
SI LOUIS SUPE
BOIS BRULE SUPE
NEMABJI SUPE
BAD SUPE
BAPTISM SUPE
*I<
tiRi
1
2
3
3
3
3
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
4
4
4
4
4
4
4
1
1
1
2
1
2
1
1
1
2
1
2
2
2
2
1
1
1
1
1
LOAD
MT\YR
3779. 8
5929.0
1839,5
461.7
237,3
946.1
-'8.1
408.8
22S.O
169.6
23.8
312.2
138.9
106.0
255.5
487.2
614.9
116-6
6..5.0
5973 . 2
17)30.0
56 72. 5
76' .3
433.3
51.0
95,2
249.7
24.5
118.4
40.1
75.5
195.1
8928 . A
115,3
658.9
140.3
22.0
14.6
84.5
54.7
22. A
63.7
24.9
135.3
227. 8
13.0
59.4
103.5
37.1
MEAN SQUARE
ERR
-------
APPEND I X B
MAPS SHOWING REGIONAL DIFFERENCES
IN THE TOTAL PHOSPHORUS AND
SUSPENDED SOLIDS DIFFUSE
UNIT AREA LOADS
157
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
RMT tain Group 1.1
158
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Group 1.2
LAKF SUPERIOR
159
sou.! m «"tis
0 5 10 IS JO
-------
Riwr Basin Group 2.1
suu.1 m »ni.8
o s 10 i> an as
2.1
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Rhrarl
o •> 10 li ro
-------
DIFFUSE UNIT AREA LOADS
Rtor Batin Group 2.3
kg/ht/yr
0.0-0.2
OJ1-0.7
0.71-2.5
162
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Rim Basin Group 2.4
kg/lM/yr
Q 0.0-0.2
0.21-0.7
0.71-2.5
I^.^X I
^MUSKCOON I
SCALEINMK.CS
0 5 10 It 20 25
-------
DIFFUSE UNIT AREA LOADS
• Bwin Group 3.1
kg/lu/yr
0.0-0.2
0.21-0.7
0.71-2.6
SCALt IN MILES
164
-------
I VJ I «u rnwwr i
DIFFUSE UNIT AREA LOADS
River Basin Group 3.2
LAKE HURON
Harbor B*«cfi
165
SCAU IN HUES
10 15
3.2
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Riv«r Basin Group 4.1
166
SCALt IN MILES
0 5 1O
4.1
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Rivtr Basin Group 4.2
kg/ha/yr
0.0-0.2
0.21-0.7
0.71-2.S
167
SCALE IN MILIS
i-=a;*_3ai!i i
D ft 10 IS ?P
42
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Rivw Baiir Group 4.3
kg/ha/yr
0.0-0.2
0.21-0.7
0.71-2.S
SCAtC INMILIS
0 S 10
168
4.3
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Riw Basin Group 4.4
LAKE ONTARIO
L.--jT\
t, .
..''.^ r£?=^y-\
Yfi 'A\\
VlClNITM M»J-
,^:^T^^"
kg/ha/yr
0.0-0.2
0.21-0.7
0.71-2.5
169
SCALE IN MliES
Q 5 10 15
4.4
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Riw Batin Group 5.1
I A K E
ONTARIO
170
SCALE 'N MILE
0 5 10
* 1
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Riv«r B**in Group 5.2
I •';''
i '~ ^—
kj/hi/yr
0.0-0.2
0.71-2.5
SCALE IN MILES
171
0 5 10 15 ?0
-------
TOTAL PHOSPHORUS
DIFFUSE UNIT AREA LOADS
Rivtr BMin Group 5.3
- •
172
SCALt W MILLS
0 5 10 IS
5?
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
Rwec Batin Group 1.1
173
3C*U IN MILES
scrj=!i:-t*-i
o > ig i» K n
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
RHmr B«ln Group'
LAKE SUPERIOR
174
SCALE IM MILCS
0 ft 10 "
-------
DIFFUSE UNIT AREA LOADS
RhMr Bjfin Group 2.1
175
SQU.C m mitts
0 S 10 tt 10 K
2,1
-------
DIFFUSE UNIT AREA LOADS
SCALE IN Milts
-------
DIFFUSE UNIT AREA LOADS
River Basin Group 2.3
kgAu/yr
D
41-200
201-4800
177
SCAIE IN MILES
0 5 10 19 M
Z.3
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
Rtar tain Group 2.4
u
178
SCALl IN HUES
t»a-f -*~-3- >«!-(
O » 10 15 10 !*
2.4
-------
DIFFUSE UNIT AREA LOADS
River Bcsln Group 3.1
0-40
41-200
201-4800
179
-------
Rtar Basin Group 3.2
HURON
IC INI 11 MAP
130
SCALI IH Mil fcS
0 S 10
3.2
-------
SUSPENDED dULIUO
DIFFUSE UNIT AREA LOADS
River Basin Group 4.1
181
SCAU IN MILES
0 1 10 f,
41
-------
SUSPENDED SOLIDS
DIFFUSE UNIT /PEA LOADS
River BMin Group 4.2
LAKE ERIE
D
kg/ha/yr
41-JOO
201-4800
182
SOUF IN k'liro
4.2
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
River Basin Group 4.3
kg/b»/yr
D
41 - ?00
201-4800
SCALC IN MlltS
183
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
River B«in Group 4.3
kg/ha/yr
D °^°
Q 41-200
• 201-4800
SCALE IN MILtS
0 5 1O IS
183
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
Rtor BHin Group 4.4
LAKE ONTARIO
CH«UT»UOUA NEW YORK CATTARAUCUS
D
41-200
201-4800
184
SCALE IN MILES
I I—1 &ii
0 S 10 IS
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
Rivtr (tain Group 6.1
L A K £
O N T A « / O
185
SCALE IN MtlCS
0 5 10 II
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
River Basin Group 5.2
Lj1' ^ ..^
^
kg/ha/yr
D 0-«
Cl 41-200
• 201-4800
186
SCALE m MILCS
0 5 10 15
-------
SUSPENDED SOLIDS
DIFFUSE UNIT AREA LOADS
River Bwin Group 6.3
187
SCALE IN MILES
------- |