vvEPA
United States
Environ mentaJ
Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O.Box 15027
Las Vegas, NV 89114
905R81109
Research and Development
Resource Inventory and
Septic System Survey
Moose Lake-Windemere
Sewer District, Minnesota
October-November 1980
Appendices
prepared for
EPA Regions
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905R81109
APPENDIX A
THERMAL ANALYSIS
ISLAND, STURGEON, RUSH, AND PASSENGER LAKES
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THERMAL ANALYSIS
The multispectral scanner data was collected over the study
area October 21, 1980, between 10:00 a.m. and 10:30 a.m. central
daylight time at an approximate altitude of 1,200 meters (4,000
feet) above ground level (see Figure A-l). Aircraft flight lines
were orientated such that several hundred meters of land adjacent
to lake shorelines was included in the data. The inclusion of a
significant portion of terrestrial areas provided for accurate
land-water separation during computer processing of data, and
allowed for adequate visibility of land use-land cover activities
adjacent to the lakes. The visibility and subsequent analysis of
land use activities and land cover types oftentimes provides an
indication to why some thermal variations in water bodies are
evident.
Data collected over Island Lake and the north shore of Stur-
geon Lake were partially obscured by storm clouds. The cloud
cover was not considered sufficient to degrade the final data
product. Data collected at an altitude of 1,200 meters above the
terrain provided a minimum resolution area size of 3 square
meters (10 square feet). All data was processed without a geo-
metric correction factor so slight distortions in scale and pro-
jection will be encountered when comparisons are made with a
topographic map. Relative temperatures were assigned to the
thermal data, with 0° Celsius (deep blue) assigned to the coolest
water counts and 1.5° Celsius (deep red) to the warmest. Refer
to Appendix B for a discussion of the multispectral scanner
system.
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The following is a discussion of Island, Sturgeon, Rush, and
Passenger Lakes thermal patterns.
ISLAND LAKE
Island Lake (see Figure A-2) appears to have numerous under-
ground springs located adjacent to Doeblers subdivision and east
of North Island Lake subdivision shorelines. The large mass of
red (1.5° C) and pink (1.0° C) thermal patterns concentrated in
the center of Island Lake suggest an absence of surface water
circulation. An unidentified intermittant stream source, not
visible on the image, located east of North Island Lake subdivi-
sion, appears to have no effect on lake thermal patterns. The
outflow of Island Lake, located at Sunrise Bay, is also not visi-
ble on the imagery, and apparently not affecting surface thermal
patterns. This suggests the possibility that no water was pres-
ent in either stream course at the time of data collection.
Thermal patterns in the vicinity of Doeblers subdivision reveal
two distinct areas where warm water discharges appear to be en-
tering Island Lake. The origin of these point source discharges
are not known. The discharge points have been annotated of
Figure A-2 to aid field inspection and additional water testing.
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SCALE |]250ftM)D
."-1 w L /
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FIGURE A-2
ISLAND LAKE
CLOUD
—I 1 1 1—
05 I 1.5 Cc
^.
RELATIVE TEMPERATURE
NOMINAL SCALE 1:8,500
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STURGEON LAKE
Sturgeon Lake is the most dynamic of four lakes studied.
The presence of underground springs and their thermal influences
around the entire periphery of Sturgeon Lake are evident on Fig-
ure A-3. The concentration of red (1.5° C) and pink (1.0° C)
thermal patterns in the center and southern portions of the lake,
suggests a general lack of circulation throughout the entire
water body. Concentrations of the cooler blue (0° C) thermal
pattern in the northeast corner of Sturgeon Lake indicates a
combined effect of perhaps several underground springs emitting
cool waters into the lake.
Four apparent warm water discharges, each of unknown origin,
have been annotated on Figure A-3. Two discharges in the vicini-
ty of Sturgeon Island, one, south of Sunset Shore subdivision,
and one, adjacent to Section 9, Government Lot 2, are all clearly
discernible on the imagery. Numerous similar discharge returns
are visible along the northwestern shoreline between the develop-
ments of Sunrise View and Section 17, Government Lots 1, 2, and
3. Analysis of color infrared aerial photography simultaneously
acquired with the thermal imagery, revealed that the red (1.5° C)
thermal returns do not appear to be warm water discharges but
channels or paths home owners have cleared through dense subsur-
face vegetation to provide access from lakefront property to
Sturgeon Lake. These very shallow areas are more susceptible to
the warming effect of solar heating. The lake shoreline adjacent
to the YMCA camp, south of the aforementioned area (see annota-
tion, Figure A-3), also has a very shallow beach area. The red
thermal pattern in this area is probably due to the effects of
solar heating.
RUSH LAKE
The thermal patterns of Rush Lake, located in the lower
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right portion of the Figure A-3, exhibit a general lack of water
circulation. This is evident by the even 0.5° C temperature
gradients distributed from the northern to southern end of this
shallow water body. The source of cool water (0° C) in the
northern end of the lake, appears to be eminating from under the
extensive mat of vegetation adjacent to the shoreline. This cool
water phenomenon is common to bog ecosystems. The thick floating
vegetative mat, acts as a shield and insulating blanket against
the warming effect of solar radiation.
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STURGEON AND RUSH LAKES
FIGURE A-3
RELATIVE TEMPERATURE
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PASSENGER LAKE
Passenger Lake (see Figure A-4) appears to be similar to
Island, Sturgeon, and Rush Lakes in that an apparent lack of
water circulation is very pronounced. This is evident by the
uniform temperature gradients that range from 1.5° C along the
north shore to 0° C at the lakes outlet. Passenger Lake drains
into Big Slough Lake via a narrow stream that is not completely
visible on the image. The cool water (0° C) moving out of
Passenger Lake has noticeably increased in relative temperature
to 1.5° C, at the point of discharge into Big Slough Lake (see
outlet annotation, Figure A-4). The discharge appears as a
significant warm water entry point due to the overall lower
general temperature of Big Slough Lake.
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FIGURE A-4
PASSENGER LAKE
.5
RELATIVE TEMPERATURE
NOMINAL SCALE 1:18,300
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APPENDIX B
THE EMSL-LV MULTISPECTRAL SCANNER SYSTEM
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AIRBORNE MULTISPECTRAL SCANNER
The airborne multispectral scanner (MSS) acquires data at
altitudes ranging from 370 to 6,100 meters (1,200 to 20,000
feet) above ground level. This is an 11-band system designed
to collect and record radiant energy data in the near-
ultraviolet through the thermal infrared portions of the elec-
tromagnetic spectrum (see Table on MSS Wavelength Bands). The
scanner has a rotating mirror that scans across the ground
scene, perpendicular to the line of flight. Radiant energy
from the ground surface is reflected through focusing optics to
a beam splitter which diverts the visible radiation (Channels
1-10) to a 10 channel spectrometer and the thermal infrared
radiation (Channel 11) to a solid state detector. Electronic
signals from the 11 detectors are digitized and recorded on
magnetic tape in a high density format. During operation, the
MSS scan rate is controlled and synchronized to the aircraft
ground speed and altitude, resulting in scan line contiguity at
nadir (see Figure on MSS Imaging Characteristics). The scanner
is equipped with internal visible and thermal reference
sources, which provide information for calibration of the data.
The aircraft sensor tape is processed on a ground based Data
Analysis System (DAS) to display, analyze, and create images of
the surveyed scene.
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MSS WAVELENGTH BANDS
Channel
1
2
3
4
5
6
7
8
9
10
11
Wavelength
Band
0.38-0.42ym
0.42-0.45ym
0.45-0.50ym
0.50-0.55ym
0.55-0.60ym
0.60-0.65ym
0.65-0.70ym
0.70-0.79ym
0.80-0.89ym
0.92-1.10ym
8.00-14.00ym
Color/Spectrum
Near Ultraviolet
Blue
Blue
Green
Green
Red
Red
Near Infrared
Near Infrared
Near Infrared
Thermal Infrared
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MULTISPECTRAL SCANNER
IMAGING CHARACTERISTICS (SIMPLIFIED)
SCAN LINE
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THERMAL DATA PROCESSING
For thermal mapping applications, the scanner's internal,
temperature calibration reference sources (blackbodies) are used
along with surface temperature measurements to develop an accu-
rate surface temperature map. Data processing is accompished
with the Data Analysis System (DAS) (see attached figure) con-
sisting of a sensor tape playback unit, a high speed digital com-
puter, an interactive color display system, and an off-line color
film recorder.
The Thermal Data Computer Processing diagram illustrates the
steps involved in processing the scanner data. The sensor tape
is reformatted to a 9-track computer compatible tape. Computa-
tions are then performed to calibrate the thermal image. Land
and water areas in the imagery are separated. The water surface
data are sliced into temperature levels and displayed in color.
Land surfaces are displayed in shades of gray. A geometric cor-
rection is applied to the data to rectify scan line distortions.
The data are output to magnetic tape and the desired film product
is recorded on color film. Finally, an annotation print is gen-
erated on a printer/plotter. A color film print of the thermal
image is then combined with a duplicate of the annotation print
to complete the finished product.
The thermal image is essentially a temperature map. The
temperature of the water surface is represented by distinct
colors. The color bars establish relative temperatures in 1° C
or 0.5° C increments. The ground truth reference, when provid-
ed, establishes absolute calibration. This defines the tempera-
ture within ±0.5° C tolerance for all points on the water. When
ground truth is not provided, the thermal image indicates rela-
tive temperatures, with the coldest water surface in the image as
0° C.
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DATA ANALYSIS SYSTEM
OPERATOR'S TERMINAL
AND CARD READER
9 TRACK MAGNETIC
TAPE DRIVES
COLOR FILM RECORDER
PCM PLAYBACK SYSTEM AND
VARIAN V-75 COMPUTER
COMTAL 8100 COLOR DISPLAY
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THERMAL DATA COMPUTER PROCESSING
RAW DATA (SENSOR TAPE)
DECOM/REFORMAT
TEMPERATURE CALIBRATION
LAND/WATER SEPARATION
IL
GEOMETRIC CORRECTION
COLOR-CODE
ANNOTATION BACKGROUND
PAGE GENERATION
FILM IMAGE GENERATION
6
THERMAL/TURBIDITY REPORT
a
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