&EPA
United States
Environmental Protection
Agency
EPA832-R-93-005b
September 1993
-------
SYSTEM DESCRIPTION
The community of Houghton
Lake, located in the central lower
peninsula of Michigan, has a
seasonally variable population, averag-
ing approximately 5,000. A sewage
treatment plant was built in the early
1970's to protect the large shallow
recreational lake. This treatment facility
is operated by the Houghton Lake
Sewer Authority (HLSA). Wastewater
from this residential community is
collected and transported to two 5-acre
aerated lagoons, which provide six
weeks detention. Sludge accumulates
on the bottom of these lagoons, below
the aeration pipes. Effluent is then
stored in a 29-acre pond for summer
disposal, resulting in depth variation
from 1.5 feet (fall) to 10.0 feet (spring).
Discharge can be to 85 acres of seepage
beds, or to 85 acres of flood irrigation
area, or to a 1500 acre peatland. The
seepage beds were used until 1978, at
which time the wetland system was
started up. The wetland has been used
since that tune, with only occasional
discharges to seepage or flood fields.
The average annual discharge is
approximately 120 million gallons.
Secondary wastewater is intermittently
discharged to the peatland during May
through September, at the instanta-
neous rate of 2.6 mgd.
Provisions for chlorination are
available, but have not been used,
because of low levels of fecal coliform
indicator organisms. Water from the
holding pond is passed by gravity or
pumped to a 3-acre pond which would
provide chlorine removal in the event
of the necessity of
its use. Wastewater
from this pond is
pumped through a
12-inch diameter
underground force
line to the edge of
the Porter Ranch
peatland. There the transfer line
surfaces and runs along a raised plat-
form for a distance of 2,500 feet to the
discharge area in the wetland. The
wastewater may be split between two
halves of the discharge pipe which runs
1,600 feet in each direction. The water
is distributed across the width of the
peatland through small gated openings
in the discharge pipe. Each of the
100 gates discharge approximately
16 gallons per minute, under typical
conditions, and the water spreads
slowly over the peatland. The branches
are not used equally in all years.
The peatland irrigation site originally
supported two distinct vegetation types.
One called the sedge-willow community
included predominantly sedges (Carex
spp.) and Willows (Salix spp.). The
second community was leatherleaf-bog
birch, consisting of mostly Chamae-
daphne calyculata (L.) Moench and
Betula pumila L., respectively. The
leatherleaf-bog birch community also
had sedge and willow vegetation, but
only in small proportions. The edge of
the peatland contained alder (Alnus
spp.) and willow. Standing water was
usually present in spring and fall, but
the wetland had no surface water during
dry summers. The leatherleaf-bog birch
The original leatherleaf-bog
community also had sedge
and willow vegetation in
small proportions, and very
low abundance of cattail.
-------
cover type generally had less standing
water than the sedge-willow cover type.
Soil in the sedge-willow community was
3-5 feet of highly decomposed sedge
peat; while in the leatherleaf-bog there
is 6-15 feet of medium decomposition
sphagnum peat. The entire wetland
rests on a clay "pan" several feet thick.
The wetland provides additional
treatment to the wastewater as it
progresses eventually to the Muskegon
River eight miles away. Small, natural
water inflows occur intermittently on
the north and east margins of the
wetland. These flows are partially
controlled by beaver. Interior flow in
the wetland occurs by overland flow,
proceeding from north-
east down a 0.02%
gradient to a stream
outlet (Deadhorse Dam)
and beaver dam seepage
outflow (Beaver Creek),
both located 2-3 miles
from the discharge
(Figure 1.) Wastewater
adds to the surface sheet
flow. Hydrogeological
studies have shown that
there is neither recharge
or discharge of the
shallow ground water
under the wetland.
The treated waste-
water arriving at the
peatland is a good
effluent which contains
virtually no heavy metals
or refractory chemicals.
This is due to the
absence of agriculture and industry in
the community. Phosphorus and nitro-
gen are present at 3-10 ppm, mostly as
orthophosphate and ammonium. BOD
is about 15 ppm, and solids are about
20 ppm. Typical levels of chloride are
100 ppm, pH 8, and conductivity 700
mmho/cm. The character of the water
is dramatically altered in its passage
through the wetland. After passage
through ten percent of the wetland,
water quality parameters are at back-
ground wetland levels. The system has
operated successfully in the treatment
of 1900 million gallons of secondary
wastewater over the first sixteen years.
The wetland treatment site
is located southwest of the
lake. The land belongs to the
State of Michigan and is
dedicated to public and
research uses. Dots indicate
water monitoring stations*
-------
HISTORY
The Porter Ranch peatland has
been under study from 1970 to
the present. Studies of the
background status of the wetland were
conducted during the period 1970-74,
under the sponsorship of the Rocke-
feller Foundation and the National
Science Foundation (NSF). The natural
peatland, and 6m x 6m plots irrigated
with simulated effluent, were studied
by an interdisciplinary team from The
University of Michigan. This work gave
strong indications that water quality
improvements would result from
wetland processes.
Subsequently, pilot scale (100,000
gal/day) wastewater irrigation was
conducted for the three years 1975-77.
This system was designed, built and
operated by the Wetland Ecosystem
Research Group at The University of
Michigan. NSF sponsored this effort,
including construction costs and
research costs. The pilot study results
provided the basis for agency
approval of the fullscale wetland
discharge system.
The full scale system was designed
jointly by Williams and Works, Inc.
and the Wetland Ecosystem Research
Group at The University of Michigan.
Construction occurred during winter
and spring, 1978, and the first water
discharge was made in July, 1978.
Compliance monitoring has been
supplemented by full scale ecosystem
studies, spanning 1978 to present, which
have focussed on all aspects of water
quality improvement and wetland
response. Those studies have been
sponsored by NSF, and in major part by
the Houghton Lake Sewer Authority.
This wetland treatment system has
functioned extremely well for nutrient
removal over its sixteen year history.
Table 1. Economics
Capital
(1978 dollars)
Holding Pond Modification $38,600
Dechlorination Pond .153,200
Pond-Wetland Water Transfer 83,600
Irrigation System 112,800
Monitoring Equipment................r.... 7............ 9,700
,: :":.. . .'r!T:V ..:'.:' ": $397,906
Annual Operating Costs
(1991 dollars)
Pumping $2,000
Monitoring 800
Maintenance ...................... .500
Research - 12,000
'" -' -- ; ."- $15,300
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HYDROLOGY
On average, most of the
water added to the
wetland finds its way to
the stream outflows. But in
drought years, most of the water
evaporates; and in wet years,
rainfall creates additions to flow.
During most of the drought
summers of 1987 and 1988, all
the pumped water evaporated in
the wetland.
Water flow is strongly depth
dependent, because litter arid
vegetation resistance is the hydrologic
control. Doubling the depth causes a
ten-fold increase in volume flow. There-
fore, when the pump is turned on, water
depths rise only an inch or two. For
similar reasons, a large rainstorm does
not flood the peatland to great depths.
There are no man-made outlet control
structures, but both man and beaver
have relocated the points of outflow, via
culvert and dam placements. Inflows at
El and E2 have ceased (see Figure 1).
The point of principal stream outflow
has changed from E8 to E9; and E9 has
been relocated three times, twice by
beaver and once by man.
The soil elevations in the discharge
area were originally extremely flat, with
a gentle slope (one foot per mile)
toward the outlet. There has developed
a significant accumulation of sediment
and litter in the irrigation area, which
has the effect of an increased soil eleva-
tion. This acts as a four-inch-high dam.
As a consequence, the addition of
wastewater along the gated irrigation
pipe gives rise to a mound of water with
the high zone near and upstream of the
Table 2. Summary of Water Budgets.
Thousands of m3, 1 .0 km2 zone. Inventory change not shown.
The interval is the pumping season, typically May 1 September 14.
-Year
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
Precipitation ,
minus
Evapotranspiration
80
-4
-137
99
-38
-110
-24
44
-11 :
-273
-311
-153
-43
-100
-250 (est)
. Averages -82
Wastewater
Addition
240
384
407
455
404
485
546
379
465
347
425
672
622
724
,719
485
Watershed
Runoff
0
18
0
30
20
132
73
0
0
0
0
0
0
0
0
18
Outflow
135
333
304
558
386
487
602
347
412
74
114
522
628
624
469
400
Outflow
Percent
56
87
75
123
96
100
110
92
89
21
27
78
101
86
65
80
discharge pipe; in other words, there is
a backgradient "pond". Depth at the
discharge is not greater, but depths are
greater at adjacent up and downstream
locations. There is a water flow back
into the backgradient pond, which
compensates for evaporative losses
there. But most water moves down-
gradient, in a gradually thinning sheet
flow, (see Figure 2)
The hydroperiod of the natural
wetland has been altered in the zone of
discharge: dryout no longer occurs
there, even under drought conditions.
Figure 2
Water moves at about
30-100 m/d with a depth
of about 20 cm.
-------
WATER QUALITY
The phenomena ulterior to the
irrigation zone lead to gradients
in the concentrations of dissolved
constituents in the direction of water
flow. As the water passes through the
ecosystem, both biotic and abiotic
interactions occur which reduce the
concentration for many species, includ-
ing nitrogen, phosphorus and sulfur.
Surface water samples from the waste-
water irrigation area are collected and
analyzed throughout the year. The
changes in water chemistry as a function
of distance from the discharge point
are monitored by sampling along lines
perpendicular to the discharge pipe,
extending to distances up to 1000
meters. Such transects are made in
the former sedge-willow area, along
the central axis of the wetland.
The transect concentration profiles
are all similar. Water flow carries
materials a greater distance in the
downgradient (positive) direction than
in the upgradient direction. Through
the early years of operation, the zone
of concentration reduction increased
in size; background concentrations are
now reached at distances of about
500 meters downstream of the discharge.
The advance of nutrient concentration
fronts during the application of waste-
water is illustrated by tracking the
location of phosphorus drop-off.
Concentrations in excess of 1.0 mg/liter
were confined to within 440 meters
Treatment Area and Nutrient Reductions
DIN = Dissolved Inorganic Nitrogen = Nitrate plus Ammonium Nitrogen TP
Area, ha
Year
78
79
80
81
82
83
84
85
86
87
88
89
90
91
AVERAGES:
10
13
17
24
30
55
50
48
46
46
61
54
67
76
In
0.56
3.68
3.22
2.83
5.85
3.76
10.04
7.64
9.63
4.26
6.26
8.13
8.14
7.80
5.69
DIN, mg/l
Out
0.10
0.10
0.10
0.094
0.093
0.148
0.078
0.194
0.176
0.244
0.080
0.156
0.119
0.112
0.129
Reduction
82
97
97
97
98
96
99
98
98
94
99
98
99
99
96
In
2.85
2.87
4.41
2.83
3.27
2.74
4.52
4.11
5.26
2.90
2.66
1.66
2.93
2.59
3.31
= Total Phosphorus.
TP, mg/i
Out
0.063
0.047
0.068
0.088
0.064
0.066
0.079
0.099
0.063
0.074
0.086
0.047
0.112
0.147
0.074
Reduction
97
98
97
96
98
97
97
97
99
97
97
97
96
94
97
-------
of the discharge point in 1990. It
appears that nutrient removal processes
are stabilizing.
Nitrogen species include organic,
ammonium and nitrate/nitrite nitrogen.
The wetland micro-organisms convert
nitrate to nitrogen gas. Other bacteria
convert atmospheric nitrogen to ammo-
nium, which is in short supply; both for
the natural wetland and for the fertilized
zone. Large amounts are incorporated
in new soils and in extra biomass.
Because the irrigation zone is
imbedded in a natural wetland of
larger extent, care must be taken in the
definition of the size of the treatment
portion of this larger wetland. A zone
extending 300 meters upstream and 700
meters downstream, spanning the entire
1000 meter width of the wetland,
encompasses the treatment zone with
room to spare. Nutrient removal is
essentially complete within this zone;
some background concentrations will
always be present in outflows.
The reductions in dissolved nutrient
concentrations are not due to dilution,
as may be seen from' the water budgets.
There are summers in which rainfall
exceeds evapotranspiration, but on
average there are evaporative losses,
which would lead to concentration
increases in the absence of wetland
interactions..
It is possible to elucidate the mech-
anisms by which water-borne substances
are removed in this freshwater wetland
ecosystem. There are three major cate-
gories of removal processes: biomass
increases, burial, and gasification. The
\
V)
1
o
a
(0
o
o
I
-200 -100 0 100 200 300 400 500 600 700 800
Distance From Discharge, meters
-200 -100 0 100 200 300 400 500 600 700 800
Distance From Discharge, meters
production of increased biomass due to
nutrient stimulation is a long-term
temporary sink for assimilable
substances. Accretion of new organic
soils represents a more permanent
-------
sink for structural and sorbed compo-
nents. A few species, notably nitrogen,
carbon and sulfur compounds, may be
released to the atmosphere, and thus
are lost from the water and the wetland.
Mass balance models have been
constructed that adequately character-
ize these processes on both short and
long term bases.
Some substances hi the wastewater
do not interact as strongly with the
wetland as do nutrients. Chloride,
calcium, magnesium, sodium and
potassium all display elevated values
in the discharge affected zone. Chlo-
ride, especially, moves freely through
the wetland to the outlet streams.
Oxygen levels in the pumped water
are good, approximately a 6 mg/1 aver-
age. In the irrigation zone, levels are
typically 1-2 mg/1 in surface waters. The
surrounding, unaffected wetland usually
has high DO, representing conditions
near saturation. The zone of depressed
oxygen increased in size as the affected
area increased, as indicated by the
advance of an oxygen front both
upgradient and downgradient. In
addition, the diurnal cycle appeared to
be suppressed in the irrigation zone.
Redox potentials indicate that
the sediments are anaerobic in the
irrigation area, even at quite shallow
depths. Steep gradients occur, leading
to sulfate and nitrate reduction zones,
and even to a methanogenesis zone,
only a few centimeters deep into the
sediments and litter.
Phosphorous Pools in the Discharge Zone
8 9 10 11 12
Fourteen Year Phosphorous Budget, Kilograms
Wastewater = 22,200
Precipitation = 80
Gaseous = 0
Run-in = 20
Burial = 15.200
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SOILS AND SEDIMENTS
Wastewater solids are relatively
small in amount and deposit
near the discharge. Incoming
suspended solids average about 25 mg/1,
and the wetland functions at levels of
about 5-10 mg/1. But internal processes
in both natural and fertilized wetlands
produce large amounts of detrital
material, thus complicating the concept
of "suspended solids removal".
Some fraction of each year's plant
litter does not decompose, but becomes
new organic soil. It is joined by detritus
from algal and microbial populations.
Such organic sediments contain sig-
nificant amounts of structural compo-
nents, but in addition are good sorbents
for a number of dissolved constituents.
The accretion of soils and sediments
thus contributes to the effectiveness of
the wetland for water purification. The
natural wetland accreted organic soils at
the rate of a two to three millimeters
per year, as determined from carbon-14
and cesium-137 radiotracer techniques.
The wastewater has stimulated this
process to produce a net of ten millime-
ters per year of new organics in the
discharge area. The maximum
accumulation rate is located a short
distance downflow from the discharge.
Sediment fall in the discharge area
totals several millimeters per year, and
this combines with wetland leaf litterfall
to produce a large amount of large and
small detritus. The majority of this
detritus decomposes each year, but
there is an undecomposable fraction.
The result of continued generation and
deposition of sediments, combined with
Soil/Sediment Density
O <'
CO e/5
2
~3
ID
.01-
.00
10 15 20
Depth Below Water, cm
r
25
o
«
ui
-400 -300
-100 0 100 200 300
Distance from Discharge, meters
400
500 600
-------
the accumulation of the mineralized
fraction of leaf and stem k'tter, is the
accretion of new organic soil.
Part of the sediments are suspend-
ible, and are transported by the flowing
water. The rate of travel caused by
sequential suspension and sedimenta-
tion is much slower than the rate of
water flow; solids move only some tens
of meters per year.
Estimated mass balances for particu-
late, transportable solids indicate the
large internal cycle superimposed on
net removal for the wetland.
Wetland Suspendible Solids
Annual Budget, 1.0 km Discharge Zone
Wastewater
9 metric tons
Run-in
4 metric tons
160 Resuspended 230 | Settling
After more than a decade, sediment and litter
accumulation total about 15 cm.
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VEGETATION
I any changes have occurred in
the composition, abundance
I and standing crops of the
wetland plants in the zone of nutrient
removal. There are two observable
manifestations of the wastewater addi-
tion: elevated nutrient concentrations
in the surface waters, and alterations of
the size, type and relative abundance of
the aboveground vegetation. Vegetative
changes occur in response to changes
in hydraulic regime (depth and duration
of inundation) and to changes in water
nutrient status. The treatment area is
taken to be the greater of these two
measurable areas for each year.
When a wetland becomes the
recipient of waters with higher nutrient
content than those it has been experien-
cing, there is a response of the vegeta-
tion, both in species composition and in
total biomass. The increased availability
of nutrients produces more vegetation
during the growing season, which in
turn means more litter during the
non-growing season. This litter requires
several years to decay, and hence the
total pool of living and dead material
grows slowly over several years to a new
and higher value. A significant quantity
of nitrogen and phosphorus and other
chemical constituents are thus retained,
as part of the living and dead tissues, in
the wetland. This response at the point
of discharge in the Houghton Lake
wetland has been slow and large. Below
ground biomass responded differently
from above ground biomass, however.
Original vegetation required greatly
reduced root biomass in the presence of
3000-
CM
2000H
TO
O
m
o
1
C5
I
.Q
1000-
Live and Dead Aboveground Biomass
Discharge Zone
76
"I I I I I 1 1 1 1 1 1 1 1 1 1 1 T
78
80
82
84 86
Year
88
90
92
94
-------
added nutrients; 1500 gm/m2 versus
4000. However, the sedges initially
present were replaced by cattail, which
has a root biomass of 4000 gm/m2.
Approximately 65 hectares of the
wetland have been affected in terms of
visual vegetative change. Some plant
species - leatherleaf and sedgehave
been nearly all lost in the discharge
area, presumably due to shading by
other species and the altered water
regime. Sedges in the discharge zone
went through a large increase followed
by a crash to extinction. Species compo-
sition within the discharge area is no
longer determined by earlier vegetative
patterns; cattail and duckweed have
totally taken over. Cattail has extended
its range out to about 600 meters along
the central water track.
The cattail cover type did not exist in
enough abundance (1.76% of the peat-
land area) to warrant study in pre-irriga-
tion years, but was present in many loca-
tions (17% of all test plots). The early
years of wastewater addition produced a
variable but increasing annual peak
standing crop of cattail. This change has
been completed in the irrigation area,
and there is no space for more plants,
nor can they grow any larger.
The willows and bog birch are
decreasing in numbers in the irrigation
area. The fraction standing dead is
low because the dead shrubs are
pulled down by the falling cattail.
Nonetheless, a high fraction of the
standing stems are now dead. Further,
the number of surviving clumps of
stems is decreasing.
The aspen community near the
pipeline completely succumbed in 1983.
A second aspen island, located 500
meters downgradient, had also totally
succumbed by 1984. The aspen on the
edges of the peatland have died in back-
gradient and side locations where the
shore slopes gradually. The alteration of
the water regime has caused tree death
along much of the wetland perimeter, in
a band up to 50 meters wide at a few
locations. Long-dead timber at these
locations indicates that similar events
may have occurred naturally in the past.
-------
PUBLIC USE
The project was not designed for
purposes of public use, but a set
of regular users has evolved. The
site serves several organizations as a
field classroom. Each year, the sixth
grade science classes from the
Houghton Lake School pay visitsand
ask the best questions. Ducks Unlimited
and the Michigan United Conservation
Clubs also schedule trips to the wetland.
The Michigan Department of Natural
Resources includes field trips to the
system as part of their annual training
course. And, Central Michigan Univer-
sity conducts a portion of its wetlands
course at the site.
Many visitors, some from as far as
New Zealand, come to inspect the treat-
ment facility to learn of its performance.
The authorized operating period is
set to allow deer hunting: the discharge
is stopped in September to permit the
wetland to "relax" from the influence of
pumping. The bow-and-arrow season in
October, and the rifle season in Novem-
ber, both find numerous hunters on and
near the wetlands. Those hunters
receive a questionnaire, which has
demonstrated nearly unanimous accep-
tance of the project. The only complaint
is that the boardwalk allows too easy
access to the wetlands.
Duck hunting and muskrat trapping
have occurred on an intermittent basis.
These activities are new to this wetland,
which was formerly too dry to support
waterfowl and muskrats.
-------
ANIMALS
In addition to game species, coyotes,
bobcats and raccoons frequent the
wetland. Small mammals include a
variety of mice, voles and shrews. The
relative numbers have shifted with time
in the discharge area; generally there
are now fewer and different small
mammals. The number of muskrats has
increased greatly in the irrigation zone.
Bird populations have also changed.
The undisturbed wetland (1973)
contained 17 species, dominated by
swamp sparrows, marsh wrens and
yellowthroats. In 1991, the irrigation
zone had 19 species, dominated by tree
swallows, red wing blackbirds and
swamp sparrows.
Insect species and numbers fluctuate
from year to year, with no discernible
pattern. In some years there are fewer
mosquitoes near the discharge; in other
years they are more numerous there.
There are typically more midges in the
discharge zone, and fewer mayflies,
caddisflies and dragonflies.
-------
PERMITS
The project operates under two
permits: an NPDES permit for
the surface water discharge, and
a special use permit for the wetlands.
The Michigan Water Resources
Commission issues the NPDES permit
in compliance with the Federal Water
Pollution Control Act. Both the irriga-
tion fields and the wetlands are permit-
ted. The wetlands part of the permit
establishes three classes of sampling
locations: the effluent from the storage
or dechlorination ponds, a row of
sampling stations approximately 800
meters downgradient from the discharge
pipeline in the wetland (Figure 1), and
steamflows exiting the wetland. Lagoon
discharges are monitored weekly;
interior points and stream outflows are
measured monthly. Each location has
its own parameter list (Table 3). The
interior wetland stations are the early
warning line. Background water quality
was established in pre-project research.
Target values are set which are the basis
for assessing the water quality impacts
at the interior stations.
The special use permit is issued by
the Wildlife Division of the Michigan
Department of Natural Resources.
Under this permit, the Roscommon
County Department of Public Works is
granted permission to maintain a water
transporting pipe across State-owned
lands, maintain a wooden walkway on
the peatlands to support a water distri-
bution pipe, and to distribute secondar-
ily treated effluent onto the peatlands.
Under the terms of this permit, if
circumstances arise that are detrimental
to plant and animal life, the project
Table 3. Permit Monitoring Points and Target Values
L = Lagoon Discharge
Parameter
Chloride
pH
Ammonium Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Total Phosphorus
Total Dissolved
Phosphorus
BODS
Suspended Solids
Fecal Coliforms
1 = Wetland Interior O = Stream Outflow
Location
L,l,0
1,0
U,0
u,o
L,I,0
L,0
L,l,0
L,0
L
L
Background Value
28 mg/l
7.0 SU
0.7 mg/l
0.04 mg/l
0.008 mg/l
0.05 mg/l
Target Value
8.0 SU
3 mg/l
0.12 mg/l
0.1 mg/l
0.5 mg/l
comes under immediate review. Detri-
mental circumstances include detection
of toxic materials, excessive levels of
pathogenic organisms and excessive
water depths. There has not been such
an occurrence. This permit also requires
monitoring of plant and animal popula-
tions, hydrology and water quality.
Water samples were collected for
analysis at the points of input and
output from the wetland for purposes
of compliance
monitoring.
Water chemis-
try data for
these inflows
and outflows
shows no
significant
increases in the
nitrogen or
phosphorus in
the wetland
waters at these
exit locations.
12
i,11"
>
g"
9-
8-
7-
6
5-
4
3-
2-
1
0
Stream Outflow #1
Stream Outflow #2
Input NH4-N
76
78
80
82
84
I
86
90
92
6-
*
I2:
Stream Outflow #2
Stream Outflow #1
Lagoon
76
78
80
82
84
Year
l
86
I
83
90
-------
Operator Opinions
Mr. Brett Yardley, operator of the facility,
believes "It is a great system. It has low
maintenance, and is good for the community".
Importantly, he feels that the regulators
(Michigan DNR) are "on my side". The
comments he receives are all positive.
Awards
Clean Waters Award 1974,1985
Michigan Outdoor Writers Association
Award of Merit 1977
Michigan Consulting Engineers Council
Award for Engineering Excellence 1977
American Consulting Engineers Council
State of Michigan
Sesquicentennial Award
Michigan Society of Professional
Engineers
.1987
People
The treatment facility is operated by:
Mr. Brett Yardley
Houghton Lake Sewer Authority
P. O. Box 8
1250 S. Harrison Road
Houghton Lake, MI 48629
Wildlife and land use considerations are coordinated by:
Mr. RichEarle
Research/Surveys Section Head
Houghton Lake Wildlife Research Station
Box 158
Houghton Lake Heights, MI 48630
Research is conducted and archived by: Dr. Robert H. Kadlec
Wetland Ecosystem Research Group
Department of Chemical Engineering
Dow Building
The University of Michigan
Ann Arbor, MI 48109-2136
Literature
Several thousand pages of documentation exist for this
project. The principal categories of documents are:
Annual reports. Each operating year: compliance monitoring
results; research results for vegetation, hydrology, internal
water chemistry; and research results for all types of animals,
insects, and invertebrates.
Research reports. Background studies and pilot system
performance are contained in several reports and
monographs.
Technical papers. Forty published papers appear in a wide
variety of literature sources, and involve many authors.
Dissertations. Fourteen MS and PhD theses have originated
from the project.
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