Assessment of Water Quality
in Lakes by the Use of Bio-indices
front Sate/lite Imagery
A Case History in 208 Water Quality Management Planning
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EPA-440/3-77-019
January 1978
ASSESSMENT OF WATER QUALITY
IN LAKES BY THE USE OF BIO-INDICES
FROM SATELLITE IMAGERY
U.S. ENVIRONMENTAL PROTECTION AGENCY
* Environmental Research Information Center • Technology Transfer
* Office of Water Planning and Standards* Water Planning Division (WH 554)
401 "M" St. S.W., Washington, D.C. 20460
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ACKNOWLEDGEMENTS
This publication contains information prepared for the U.S. En-
vironmental Protection Agency, Environmental Research Informa-
tion Center, Office of Research and Development, and Water Planning
Division, Office of Water Planning and Standards.
The information in this publication was prepared by Alan E. Rimer,
P.E., Wiggins-Rimer and Associates, Durham, North Carolina with the
assistance of James A. Nissen, P.E., and Roger Schecter, AIP. Mr.
Richard Simms and Dr. Jack Wood of the Southcentral Michigan
Planning Council also assisted in preparing information.
NOTICE
This publication has been reviewed by the Environmental Research Information Center and the
Water Planning Division, Office of Water Planning and Standards, U.S. Environmental Protection
Agency, and is approved for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection Agency, nor does any mention
of trade names or commercial products constitute endorsement or recommendation for use.
11
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CONTENTS
Page
Introduction , iv
Background 1
The SMPC Approach to Assessment of Water Quality in Lakes 3
Refinement of Water Quality Information 7
Use of Water Quality Information in Developing Point and Nonpoint Source
Control Strategies 9
in
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INTRODUCTION
With the advent of grants to areawide water quality planning
agencies under Section 208 of Public Law 92-500, many agencies
have been designated to undertake water quality planning. While
some programs are in the early phases of planning, significant
portions of others have been completed and are being implemented.
The case history discussed in this publication is an example of the
work of one Section 208 water quality management agency which
may be applicable to the water quality planning activities of other
agencies.
IV
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ASSESSMENT OF WATER QUALITY IN LAKES
BY THE USE OF BIO-INDICES FROM SATELLITE IMAGERY
The Southcentral Michigan Planning Coun-
cil (SMPC) has identified water quality in
lakes as one of the major problems to be
addressed in its areawide planning program.
In addressing this problem, SMPC saw the
need for a water quality assessment
methodology which could be used in working
with local lake associations and governmental
units on a continuing basis. Toward this goal,
a system utilizing LANDSAT satellite imagery
has now been established to generate bio-
indices which reflect overall water quality
conditions throughout a given lake.
Rather than providing quantitative water
quality data, the remote sensing approach
identifies indicators of various water quality
conditions which are then used in conjunction
with soil, topographic, and land use informa-
tion to delineate specific problem areas and
probable causes. As part of the total lake
assessment program, remote sensing is a tool
which has helped to determine the need for
water quality strategies on a local level.
The system allows SMPC to work with local
lake associations and governmental units in
monitoring the progress of programs to im-
prove water quality. Water quality conditions
identified over an extended period of time and
assessed in conjunction with changing land use
patterns and improved agricultural practices
provide the basis for evaluations of the rela-
tive success or failure of alternative regional
water quality management strategies.
BACKGROUND
SMPC was formed in 1973 as the regional
planning agency for the counties of Barry,
Branch, Calhoun, Kalamazoo, and St. Joseph.
In June 1975, the organization was funded to
develop an areawide water quality manage-
ment plan under Section 208 of the Federal
Water Pollution Control Act Amendments of
1972. The region includes two major urban-
ized areas: the cities of Kalamazoo and
Portage with combined populations of about
130,000, and the city of Battle Creek with a
population of about 40,000. At present the
total population in the region is estimated to
be approximately 500,000. Although land use
in the region ranges from urban and industrial
to rural, agricultural, and recreational, the
region is dominated by nonurban land use
categories.
The SMPC region forms a part of the lower
Lake Michigan drainage basin and contains
portions of three major contributing river
systems — the Thornapple, Kalamazoo, and
St. Joseph. In addition to the major river sys-
tems,'there are numerous lakes within the
region, ranging in size from several acres to
several square miles. While most of these
lakes are natural or man-made parts of river
systems, many are self-contained with no
significant tributary flow. Figure 1 illustrates
the major river systems and the predominance
of lakes throughout the five-county planning
area.
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LEGEND
RESIDENTIAL
COMMERCIAL, INDUSTRIAL,
INSTITUTIONAL, ETC,
FOREST LAND
WET LAND
AGRICULTURE & OPEN SPACE
INDIANA
Figure 1. Southcentral Michigan Planning Council 208 Area.
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Over the years, a considerable amount of
water quality information has been collected
on the various river systems as a result of
monitoring municipal and industrial waste-
water effluents. Monitoring efforts have been
intensified in recent years because the data is
necessary for ongoing 201 facilities planning
studies. In addition, various institutions and
private organizations have collected specific,
localized, water quality data (primarily biologi-
cal) from many individual lakes in the region.
However, this information has not been com-
prehensive enough for regional purposes and,
with few exceptions, has not identified pol-
lutants from nonpoint sources.
In developing an areawide planning pro-
gram for the region, SMPC saw the need to
focus on those water quality problems be-
lieved to be most important by the people
of the region. Two basic objectives were
identified and addressed. One was the in-
tegration of the various ongoing 201 planning
studies into a comprehensive plan for point
source wastewater management, and the other
was a clear-cut assessment of water quality in
the region's lakes and a formulation of plans
for improving water quality where problems
exist. Lakes have posed the biggest unre-
solved water quality problem in the region.
In this area SMPC has developed a unique
method for assessing water quality and a tool
with which the impact of best management
practices (BMPs) applied at the local level
can be determined through the monitoring of
individual lakes over a period of time.
THE SMPC APPROACH TO ASSESSMENT
OF WATER QUALITY IN LAKES
The largest collection of existing water
quality information in the region is main-
tained by the Michigan Department of
Natural Resources (DNR). The state has
set up a series of permanent monitoring
stations which have generated a wide-ranging
data base which can be used in overall water
quality planning. The monitoring stations are
located predominantly on the major river sys-
tems. While numerous studies have been un-
dertaken by DNR and other institutional and
private agencies on specific lakes in the region,
these have not generated data comprehensive
enough for areawide application. Consequently,
the development of a procedure for assessing
general water quality in lakes was necessary in
order to identify potential problem areas.
The basic causes of lake water quality
problems in the region are residential de-
delopment and surface runoff. Recently,
homes have been built on the periphery of
many of the lakes with recreational potential.
The majority of these lake developments are
not included in municipal sewerage systems
and must therefore rely on subsurface systems
for wastewater treatment and disposal. As a
result of high groundwater levels, these dis-
posal systems have not always been adequate
and many have significantly increased nutrient
loadings to some lakes. In addition, runoff
from nearby agricultural lands and fertilized
residential lawns has increased nutrient levels
in many lakes, and stormwater runoff from
newly developed and agricultural areas around
the lakes has led to increasing sediment loads.
Given the large number of lakes in the
region and the time and financial constraints
of the SMPC water quality management pro-
gram, it would have been impossible to sam-
ple and generate laboratory data for each lake.
It was also felt that water quality sampling
data per se would not be of substantial bene-
fit in identifying problems and developing
potential solutions. While sampling and labora-
tory analysis would generate specific con-
stituent levels at the sampling point, it would
not necessarily depict the overall condition of
water quality in various sections of the lakes
unless each section was sampled. In addition,
the sampling approach would be cost prohibi-
tive on a continuing basis and, therefore, could
not be used as an an ongoing method for devel-
oping and evaluating the success or failure of
local BMPs utilized to upgrade water quality.
It became apparent that a system was needed
to assess general water quality in a lake, not
necessarily through the use of parametric data,
but through the use of bio-indices which could
lead to the identification of particular problem
zones throughout a lake and, ultimately, to
potential causes of the problems.
Toward this objective, the SMPC staff and
their consultants worked with the Bendix
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Company, Aerospace Systems Division, in de-
veloping a methodology for identifying differ-
ent aquatic-biological community types by
means of LAND SAT satellite imagery. Multi-
spectral scanners in the satellite detect re-
flected light from the earth's surface at an
altitude of 570 miles. Land and water fea-
tures exhibit differing light reflectance charac-
teristics and a particular feature will exhibit a
particular reflective index. Shallow water, for
example, has a reflective index different from
deep water or water with emergent vegeta-
tion. Some features may have similar reflec-
tive indexes and consequently, computer
analysis of the satellite imagery is required to
separate or categorize the particular features
into the desired classifications.
Using multi-spectral analysis techniques, it
was possible to interpret the satellite imagery
to delineate bodies of water and then separate
various aquatic classifications within them.
These classifications were categorized (or
calibrated) according to known biological com-
munities and available water quality informa-
tion on specific lakes. Six biotic communities
were established as indicators of general water
quality in lakes throughout the region. The
six bio-indices chosen were interpreted to be
indicative of the water quality conditions
listed in table 1.
Table 1, —Bio-indices identified using LANDSA T imagery
Water quality category
Shallow clear water
Blue-green algae
Green algae
Emergent vegetation
Silt and sediment
Deep clear water
Explanation
Water generally considered to have a low algal, silt and sediment content. The
water may be shallow or appear so because of submerged vegetation or some
other factor limiting light penetration.
Water considered to have blue-green algae concentrations in excess of levels
normally found in cold water plankton populations. It generally is an indicator
of high nitrate and phosphorus levels and warm water temperature, resulting in
eutrophication.
Water considered to have green algae concentrations in excess of those normally
found in cold water plankton populations. It is an indicator of nutrient rich
water containing high phosphorus levels as well as high levels of nitrates. These
waters may be somewhat cooler but are, nonetheless, subject to eutrophication.
Water generally dominated by plant life covering much of the surface. It may
also indicate organic bottoms or very shallow waters exhibiting such charac-
teristics as algal blooms.
Water dominated by high levels of soil particles or organic matter in suspension.
Included in this category are suspended benthic materials, heavy detritus,
zooplankton having a large percentage of debris and possibly heavy concentra-
tions of bacteria and other non-algal organics. It may be indicative of heavy
organic or nutrient loads where conditions are not favorable to algal or plant
growth.
Water not nutrient enriched beyond normal levels for a cold water lake. The
waters may be naturally eutrophic, but do not contain heavy concentrations
of phytoplankton or zooplankton. This category is an indicator of generally
good water quality as based on records and opinions of the Michigan Depart-
ment of Natural Resources (DNR).
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The categories noted in table 1 are the pre-
dominant bio-indices in the lakes as deter-
mined by computer interpretation of LAND-
SAT data. Each 1.1-acre area is indicated on
the computer output. A water quality profile
of the lake is obtained by analyzing the pat-
tern of these features.
In order that the public become involved in
the lake assessment program and become
aware of the program's value as a continuing
planning tool, the assistance of the SMPC
Water Quality Commission's Citizens Advisory
Committee was solicited. Twenty lakes of
specific interest to members of the committee
or of known water quality were used for test-
ing the validity and benefit of the procedure.
Color photographs of the computer video
display unit, indicating the nature of water
quality in these lakes, were prepared and dis-
tributed to the local lake associations involved.
These lake associations are made up of local
residents who have a specific interest in main-
taining the integrity of lakes in their area and
detailed knowledge of water quality condi-
tions in the lakes. The lake associations were
informed of what the photographs depicted
and for what use they were intended. They
were asked to verify the information shown,
based on their knowledge and visual inspection
of the lake systems. Replies were received
from the lake associations and, for the most
part, the water quality information depicted
on the color photographs was verified as ac-
curate. Furthermore, acceptance of the pro-
gram was widespread and its usefulness in
identifying potential problem areas was
established.
Figure 2 is an example of a LAND SAT-
generated color photograph taken from the
computer video display unit. Shown in this
particular figure are Austin and West Lakes,
both of which are located in the SMPC region
and serve as contrasting illustrations of the
information which can be derived from the
water quality assessment program. The colors
in the figure indicate bodies of water, with
the black background constituting land. Each
colored block, as indicated previously, re-
presents an area of approximately 1.1 acres.
Austin Lake appears to be a shallow lake
with areas of green and blue-green algae prob-
lems, particularly in the northwest, east, and
southeast portions. These areas may be as-
sociated with inadequate subsurface disposal
systems adjacent to the lake. Scattered areas
of silt and sediment indicate some potential
problem with stormwater drainage discharg-
ing into the lake. West Lake contrasts with
Austin Lake in +hat its major water quality
problem appears to be silt and sediment.
Nutrient loadings to West Lake do not appear
to be nearly as high as to Austin Lake, but
stormwater runoff from adjacent residential
development and nearby agricultural lands is
causing significant amounts of sediment to be
washed into the lake.
As illustrated in figure 2, the information
developed from the program has been directed
toward a qualitative comparison of lake water
quality throughout the region. The program
has not attempted to provide a quantitative
analysis of the biological or chemical con-
stituents of a specific lake water. However,
the bio-indices identified can be compared on
the basis of percent of area classified in each
category. The conceptual approach of the
program has the limitation of being unable
to consider the intensity of localized problems
(e.g., relative density of algal populations or
relative concentration of silt and sediment).
It is able to examine broad problems, how-
ever, and is suitable for correlation with
existing land use data to aid in the identifica-
tion of potential causes of those problems.
The information can then be used in working
with local lake associations and governmental
units, such as municipalities and townships, to
develop alternative strategies for solving
specific water quality problems.
The key to the development of this assess-
ment program was public participation, both
for political and financial reasons. Obviously,
it took a great deal of work on the part of the
SMPC staff and consultants to synthesize ex-
isting water quality data for use in calibrating
and categorizing computer interpretations of
the LANDSAT imagery. However, the role of
the public sector (i.e., in verifying results and
accepting the program as a beneficial tool)
was critical in making the approach effective.
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Legend
Color
Light blue
Medium blue
Dark blue
Green
Rust
Yellow
Water quality category
Blue-green algae
Shallow, clear water
Deep, clear water
Green algae
Emergent vegetation
Silt and sediment
Figure 2. Example of LANDSAT-generated color photograph for Austin and West Lakes.
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REFINEMENT OF WATER QUALITY
INFORMATION
The initial remote sensing work was per-
formed to evaluate the use of satellite im-
agery for assessing general water quality con-
ditions in lake systems. The categorized
imagery also provided a means of obtaining
field verification of the information and
promoting public participation in the pro-
gram. However, in order to make use of
the information for technical purposes in
identifying and solving problems, it became
apparent that refinement of the satellite
imagery interpretations would be needed.
This refinement, which could not be achieved
by further use of color photographs, thus
introduced a research element into the work
effort.
Discussions with the Laboratory for Ap-
plications of Remote Sensing (LARS) at
Purdue University indicated that potential
refinement of the water quality information
was a possibility. The LARS system, known
as LARSYS, utilizes the same satellite tech-
nology and a similar computer interpretation
system to that of the system at Bendix. The
main difference in the two systems is that
LARSYS generates the water quality in-
formation in standard computer output form
instead of the color photographs produced
by the formerly-used Bendix interpretation
system. A LARSYS printout provides a
line-column designation for each grid in a
body of water, thereby allowing surface
cross-sectional analyses to be performed and
the accuracy of information to be better de-
termined.
An example of a LARSYS printout, fea-
turing ten water quality categories, is shown
in figure 3. The lakes are again Austin and
West Lakes and are based on the same satellite
imagery used in the Bendix interpretation (see
figure 2). However, the LARSYS interpreta-
tion provides ten water quality categories
(within acceptable confidence limits) whereas
LANDSAT color analyses had provided only
six.
Based on the LARSYS interpretation,
Austin Lake shows large areas of submerged
vegetation throughout the west, central, and
south portions and appears to be severely
eutrophic. However, the pockets of blue-
green algae are isolated from the submerged
vegetation. It appears that the submerged
plants may be serving to tie up nutrients,
thus limiting algal growth. Isolated areas of
organic sediments predominantly due to local
drainage can also be seen in Austin Lake.
West Lake appears to have heavy organic sedi-
ment loads as well as a large number of sub-
merged plants. The problems with this lake
appear to be associated with drainage from
surrounding bog-type lands which are easily
disturbed by development and other human
activities.
While the analyses derived from the
LARSYS interpretations of the June 1973
satellite imagery are no more significantly
detailed than those derived from the Bendix
interpretations, LARSYS has the additional
capability of being used in conjunction with
a mobile, truck-mounted spectrophotometer
to increase resolution to an area as small as
an 8-inch diameter circle. If the truck-
mounted unit is used when the satellite is
passing, more detailed information can be
obtained within the standard 1,1-acre grid.
This information, combined with selective
sampling and laboratory analysis, can result
in more detailed knowledge of what each
category represents and a greater number of
water quality categories in future efforts.
Of major concern to the SMPC staff was
the cost of providing water quality infor-
mation on the many lakes throughout the
region. A comprehensive sampling and
laboratory analysis program would have
been cost prohibitive. On the other hand,
the initial work at Bendix to evaluate the
use of satellite imagery cost approximately
$2,000 for an analysis of about 40 lakes.
The work at LARS to refine computer in-
terpretations and provide more detailed in-
formation regarding relative compositions
and concentrations will amount to about
$22,000 for the analysis of approximately
300 lakes. It should be emphasized that
much of this cost is related to development
of a system to provide the specific informa-
tion desired by SMPC. Once the system is
set up, the major costs will be for new tapes
of LANDSAT data and for computer time,
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which amounts to about $250 per hour. Rep-
resentative runs indicate that a LARSYS
printout of five lakes can be accomplished in
less than ten seconds of computer time. This
corresponds to a computer cost of less than
one dollar per lake. While the cost of op-
erating the truck-mounted unit must also be
included in some cases, it can be seen that the
overall approach of using satellite imagery to
analyze lake water quality in the SMPC plan-
ning area is cost-effective on a continuing
basis and was a positive factor in its develop-
ment.
USE OF WATER QUALITY INFORMATION
IN DEVELOPING POINT AND NONPOINT
SOURCE CONTROL STRATEGIES
As an areawide planning tool, the remote
sensing of lake water quality has been used,
in conjunction with storm runoff and stream
modeling, to determine the need for BMPs
on a sub-basin level. In a sense, areawide
BMPs are being defined on a broad con-
ceptual basis, with actual point and non-
point source control measures being devel-
oped and implemented on a local basis.
This type of analysis was made possible
by the nature of the water quality informa-
tion generated by LARSYS. Since the
drainage areas of many of the lakes con-
stitute major portions of sub-basins, the
information generated on water quality
can be used in assessing the overall impact
of stormwater runoff from those sub-basins.
The most important use of the remote-
sensing water quality information as a plan-
ning tool is in assessing the impact of chang-
ing land use around the lakes. These changes
in land use are most prevalent where residen-
tial development around the periphery of
lakes has accelerated in recent years. In
making this assessment, SMPC had planned
to compare the original satellite imagery
from June 1973 with more recent informa-
tion to be generated by LARSYS. This more
recent information was to be based on satel-
lite imagery taken in June 1976. However,
because of weather conditions, it was not
possible to obtain suitable LANDSAT data
from June 1976 and therefore imagery from
July 1976 was utilized. Although SMPC ex-
pected that changes in land use during that
3-year period would produce changes in lake
quality (based on satellite imagery as well as
other ongoing studies in water quality), it is
difficult to draw conclusions about actual
changes in lake ecosystems on the basis of
data taken in two different calendar months.
The LARS water quality information gen-
erated to date has been used by sewage treat-
ment facility planning agencies and shows
that water quality in the region's lakes has
changed in some areas served by septic sys-
tems. Although replacement of subsurface
disposal systems by sewerage systems may
be effective in some cases, SMPC has shown,
using the same water quality information,
that sewers may not be the answer in all cases
and that there are other nonpoint sources of
pollution which could result ^alternative so-
lutions. The satellite imagery program has
been useful in locating areas of the lakes
showing the greatest impact.
Several specific, nonpoint source pollution
problems have been identified in lakes as a
result of the total water quality assessment
program. For example, Goquac Lake has
been severely impacted by stormwater run-
off from surrounding residential development.
Gull Lake has been impacted by septic tank
discharges and fertilizers from residential
lawns. Barton Lake has been impacted by
the discharge of treated municipal waste-
water. Several other lake systems have been
shown to be degraded due to agricultural
contributions of silt and nutrients.
By using the lake assessment program to
identify current and past water quality con-
ditions and by correlating this information
with existing and past land use data, SMPC is
able to verify problems caused by inadequate
control of land use activities. With this in-
formation, it will be possible to suggest
controls which might, for example, guide
development or impose subdivision regula-
tions in the vicinity of lakes.
The initial areawide plan lists sediment
control procedures and other forms of con-
trol strategies which can be adopted and im-
plemented locally. Work on model ordin-
ances is now proceeding. SMPC will monitor
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land use activities and it hopes to reassess the
lakes periodically to provide information
either confirming the need for controls or
proving that the controls are not effective and
other methods need to be considered. The
importance of such a continuing program is
emphasized by the fact that the majority of
townships surrounding lake areas do not now
control land use and/or development acti-
vities as they relate to water quality. In some
areas, SMPC will monitor specific lake sys-
tems to determine the impact of proposed
sewer facilities which are currently being
planned. If it is found that lake water
quality is continuing to be degraded after
these systems have been constructed, the
annual updates will serve as evidence that
other control measures, in addition to
wastewater collection, are needed.
From the time of initial public partici-
pation in verifying water quality informa-
tion, support of the program has grown
significantly. Two lake boards were
formed by the Michigan legislature and
have the authority to regulate development
and assess charges for programs. They are
actively involved in planning studies and
are investigating the possibility of obtaining
federal lake restoration grants using SMPC
information to document problems. At
least seven other local lake associations,
which do not have the authority to regulate
or levy assessment, are investigating the
possibilities of similar grants through their
elected officials. In addition, many other
lake associations are actively investigating
measures, one of which might be the crea-
tion of a lake board, in order to better control
related water quality activities.
To date, no specific control strategies have
been implemented as a direct result of the wa-
ter quality assessment program. However, the
program has identified general water quality
problems, and local water quality priorities
have been established. Each sub-basin has
been evaluated in detail regarding land use,
surface runoff and water quality, and the re-
sulting priorities will be used in establishing
specific local control programs. The public
has been kept informed about the water
quality assessment study, verified its ac-
curacy and have become aware of its benefit
to them on the local level. SMPC is now
laying the political groundwork for estab-
lishing some of the controls that they and
local goverments will ultimately need in
order to implement the areawide waste-
water management plan.
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U.S. ENVIRONMENTAL PROTECTION AGENCY
* ENVIRONMENTAL RESEARCH INFORMATION CENTER • TECHNOLOGY TRANSFER
* OFFICE OF WATER PLANNING AND STANDARDS • WATER PLANNING DIVISION
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