EPA 660/3-74-017
FEBRUARY 1975
Ecological Research Series
Silt Removal From A Lake Bottom
Office of Research and Development
U.S. Environmental Protection Agency
Washington. D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of tho Office of Research and Development,
Environmental Protection Agency, have been grouped into five
series. These five broad categories were established to
facilitate further development an>1 application of environmental
tcchnoloqy. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface
in related fields* The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH scries.
This series describes research on the effects of pollution on humans,
plant and animal species, and materials. Problems are assessed for
their long- and short-term influences. Investigations include
formation, transport, and pathway studies to determine the fate of
pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living
organisms in the aquatic, terrestrial and atmospheric environments.
This report has been reviewed by the Office of Research and
Development. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
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EPA-660/3-74-017
February 1975
SILT REMOVAL FROM A LAKE BOTTOM
Constance L. Churchill
Clyde K. Brashler
Charles S. Johnson
Research Grant No. 16010 ELF
Program Element 1BA031
Project Officer
Charles F. Powers
Pacific Northwest Environmental Research Laboratory
National Environmental Research Center
Corvallis, Oregon 97330
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington, D.C. 20402
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PREFACE
The Lake Herman Development wishes to express appreciation to the
following for their assistance with the project.
1. City of Sioux Falls, South Dakota for leasing the dredge
for the project.
2. Kenneth Vaughn, engineer for the Sioux Falls Water Treatment
Plant, for assistance with clean-up of the dredge after its
enundation, and for remodeling the electric motors on the
dredge.
3. South Dakota National Guard, 153rd Engineering Battalion,
Company B, for the loan of their equipment such as tractors,
low-boys, bulldozers, trucks, for moving the dredge, building
dikes, and assisting on many occasions with the operation of
the dredge. A special thanks to Sgt. Stewart Bradbury who
oversaw much of the guard work and who also operated much
of the heavy machinery used in the project.
4. George Hilde who loaned and operated his crane for unloading
the dredge after its move from Sioux Falls.
5. East River Electric Power Cooperative for the loan of its
cranes on two occasions to help with the project.
6. Lake County Board of Commissioners for allocating $5,000
per year toward financing the project.
7. South Dakota Game, Fish and Parks Department for supplying
fuels and lubricants for the dredge.
8. Dakota State College scientists for assisting with the
research for the project.
9. Office of Economic Opportunity for Supplying a number of
positions to assist with the operation of the dredge.
ii
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10. Hall Equipment Company, Sioux Falls, for supplying a bulldozer
to build a loading ramp and to assist with loading the dredge
for its move to Lake Herman.
11. Dr. Clyde K. Brashier and Dr. Connie Churchill of Dakota
State College for assisting with the chemical analyses and
for supplying data from other lake research projects.
iii
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CONTENTS
Page
Preface ii
List of Figures v
List of Tables vi
Sections
I Introduction 1
II Summary 7
III Conclusions 8
IV Recommendations 9
V Dredge Design and Discharge Area 10
VI Operational and Evaluation Phase 13
VII Discussion 19
VIII Publications and Papers 21
IX Appendices 22
iv
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FIGURES
No. Page
^MM^» MW^MM*
1 Map of Lake Herman 2
2 The Lake Herman Watershed 3
3 Water and Sediment Depths in Lake Herman 4
4 Lake Herman Silt Trap for Four Interconnected Lakes 5
5 Schematic Diagram of the Dredge 11
6 Total Phosphorus Levels in Lakes Herman
and Madison During 1970 15
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TABLES
No. Page
1 Changes in Orthophosphate From Lake to Silt Deposit Area 16
2 Changes in pH From Lake to Silt Deposit Area 17
vi
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SECTION I
INTRODUCTION
Lake Herman is a recreational lake in southeastern South Dakota
(Figure 1). It is used mainly for boating, fishing, water skiing, and
swimming, and is adjacent to Lake Herman State Park, the second-most
frequently visited park in South Dakota. Visitations to the park in
1971 numbered approximately 340,000 people, an important factor in the
summer economy of the area. There are relatively few residences on
the lake, with only about 3,000 m (10,000 ft) of the approximately
13 kilometers (8 miles) of shoreline extensively developed with cabins
and resorts. Approximately 4877 m (16,000 ft) of the shoreline is
included in Lake Herman State Park, a 4-H Club Camp, and Isaac Walton
League Conservation area. The South Dakota Game, Fish and Parks
Department, in addition to maintaining the State Park, annually stocks
the lake with game fish such as Northern pike, walleye pike, bluegills
and bass.
This warm water prairie lake was formed by glacial action. It has a
surface area of 546 hectares (1350 A.), and a meandering area of
536 hectares (1325.6 A.). The watershed is approximately 145 square
kilometers (56 square miles) and is composed mainly of glacial till.
The watershed (Figure 2) contains numerous sloughs and potholes, many
of which were drained to increase available farmland. The area is
extensively farmed and grazed, but much of it lacks modern conservation
practices of terracing and contour plowing. As a result of erosion
of the watershed, an average of 2 m (6.5 ft) of silt has been deposited
in Lake Herman. Maximum depth of silt is 3 m (9.7 ft) whereas the
water in the lake has a maximum of 2.4 m (8.0 ft), and an average
depth of 1.7 m (5.5 ft) (Figure 3). The runoff from the watershed
feeds four interconnected lakes; Lake Herman, the first in the series,
acts as a silt trap for the others (Figure 4).
The nutrient components of the lake show high levels of nitrogen and
phosphorus. According to Brashier et al. (Brashier, C.K., C.L.
Churchill, and G. Leidahl, Effect of Silt and Silt Removal in a
Prairie Lake. Environmental Protection Agency, Washington, D.C.,
Publication No. EPA-R3-73-037, July 1973. 200 p.), high values for
ammonia have been 2.51 mg NHs-N/1; nitrate, 1.32 mg N03-N/1; for
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Silver Creek
^—->^
Silt Deposit Area
Figure 1. Map of Lake Herman
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-Q—
Figure 2.
The Lake Herman watershed
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M
WATER DEPTH
(In Meters)
SEDIMENT DEPTH
(In Meters) 1.9
Figure 3. Water and sediment depths in Lake Herman
(South Dakota Dept. of Game Fish 4 Parks» January 1967)
4
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I
3>
H
H>
(D
i-J
O
O
CD
O
rt
8.
Lake Madison
Round
Lake
Brandt
Lake
n
ui
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nitrite, 97.4 mg N02-N/ml. High values for orthophosphate have been
1.35 mg P04/l; for total phosphorus, 4.33 mg P04/l. During the develop-
ment of very heavy algal blooms, nitrogen concentrations decline, in
some cases to 0.0 mg NOs-N/l, while at the same time total phosphorus
and orthophosphate remain relatively high. The pH during the months
of July to September is over 9.0, reaching a high of 10.17 in the
first week of August, 1970. During the rest of the year, the pH is over
8.0 except for January and February when the pH averages 7.5.
The development of an algae bloom is a regular occurrence in Lake
Herman. The predominant organism in the bloom is a blue-green alga,
Microcystis aeruginosa. The bloom, developing by the first week in
July, occurs when water temperature rises and when wave action is almost
nil. The presence of gas vacuoles in the cells of Microcystis causes
the plants to rise to the surface forming a 13 mm (0.5 in.) surface
film which, upon exposure to sunlight, becomes bleached giving the
appearance of vinyl plastic. The consistency of the bloom at its
worst is that of latex paint.
Heavy fish kills occur approximately once every three years during the
winter months. An ice cover, occurring by November 15 and developing
to a depth of 56-71 cm C22-28 in.), is followed by an irregular snow
depth varying from 0 to 61 cm (0-24 in.) on various parts of lake ice.
Average snow cover is 15 cm (6 in.). As a result of the snow and ice
cover, photosynthesis ceases, and the dissolved oxygen content some-
times falls to nearly 0.0 ppm by December or January. Total or near-
total fish kills have been recorded by the South Dakota Game, Fish and
Parks Department on an average of every third or fourth winter. In
addition there have been summer fish kills, but not all were due to
oxygen depletion. In July, 1971, for example, heavy kills., of game
fish were caused by the fish louse, Argulus spp.
Concern by lake residence owners and other interested citizens over
the deterioration of the lake for recreational purposes led to the
establishment of the Lake Herman Development Association, Inc. The
activities of the Association included the development of fish-rearing
ponds, the promotion of thoroughfare development, and the initiation
of a feasibility study for the removal of sediments from the lake
bottom. Members of the Association assisted the East Dakota Conser-
vancy Sub-District personnel in writing the 1969 Lake Herman Report,
an extensive compilation of available data concerning the lake and
its watershed and a list of recommendations for lake improvement.
These recommendations included improved land treatment measures in
the Lake Herman watershed and the initiation of a dredging program.
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SECTION II
SUMMARY
Dredging was used as a method to remove 47,860 m3 (62,000 yd3) of
silt from Lake Herman during the summers of 1970, 1971, and 1972. The
silt was transported via a pipeline to a silt deposit area adjacent
to the northeast corner of the lake. The water removed by the dredging
process drained by gravity along a gradual slope, dropping its silt
and losing nutrients to the lush vegetation, and eventually returned
to the lake.
In the bay area where dredging occurred water depth was increased
from 1.7 m (5.5 ft) to approximately 3.4 m (11 ft). There was no
significant change in the levels of organisms or nutrients, except
for phosphorus, which increased just after the dredging began.
Whether dredging actually caused the increase is still debatable.
Vegetation in the deposit area became extremely lush. Water returning
to the lake from the deposit area was lower in nutrients than the
water in the lake.
This report was submitted in fulfillment of Research Grant Number
16010 ELF under partial sponsorship of the Office of Research and
Development, Environmental Protection Agency.
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SECTION III
CONCLUSIONS
1. Significant amounts of silt and nutrients can be removed from a lake
by dredging.
2. Removal of silt from a limited area within the lake did not
significantly change the dynamics of the lake.
3. Water mixed with the silt in the dredging operation was extremely
high in nutrients, especially phosphates.
4. Water from the silt deposit area that was allowed to gradually
return to the lake, after settling of its silt load and passage
through vegetation, was less basic and less fertile than the
lake water.
5. Recently deposited silt on the lake bottom was much more fertile
than earlier deposits.
6. Holes dredged in the accumulated silt on the lake bottom will
frequently partially refill because of wind and wave action.
7. An increase in vegetation occurred in the slurry deposit area
after deposition was begun.
8. Greenhouse chrysanthemums grown in silt exhibited larger stems,
leaves and flowers, but more poorly developed root systems than
those grown in certain commercial greenhouse preparations.
9. Flowers on the plants grown in silt did not survive as long as
those grown in the commercial preparations.
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SECTION IV
RECOMMENDATIONS
1. Dredging operations on a lake should be carried on continuously—
24 hours a day, seven days a week—during dredging seasons.
2. A project should be initiated to remove the upper 0.3 to 0.6 m
(1 to 2 ft) of silt from Lake Herman. Since the upper 0.3 m
(1 ft) of silt is much more fertile, removal of nutrients might
be more significant in removal of 0.3 m from most of the lake
bottom rather than 1.8 m (6 ft) from a small part of the lake.
3. A smaller lake should be dredged completely to determine the
effects of complete silt removal on the dynamics of a lake.
4. Efficient conservation practices—contour plowing, terracing,
grassed waterways, and no plowing within 15 to 20 m of streams or
temporary streams that empty a watershed— should be established
for the watersheds of all lakes that have significant recreational
and economic value.
5. The responsibility for dredging operations should be assumed by
a governmental entity or agency to help insure its efficiency
and its continuation.
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SECTION V
DREDGE DESIGN AND DISCHARGE AREA
A schematic design of the dredge is shown in Figure 5. The dredge*
measuring 7.3 m (24 ft) x 18.2 m (60 ft), consists of a Fremont
25 cm (10 in.) pump, a 7.3 m (24 ft) cutter ladder with a suction
intake, and a pipeline discharge system. At peak capacity it can
pump silt slurry at the rate of 76.4 m3 (100 yd3) per hour.
The suction pump is run by a G.M.C. Diesel 2-cycle, 8-cylinder motor
which has maximum of 336 H.P. at 2,300 rpm but produces 227 H.P. at
1800 rpm under normal operating procedures.
A. U.S. Motor Diesel generator, 30 K.W., 3-phase, 220 volts with a
6-cylinder Hercules engine is the power plant, and can produce 37.5
KVA at 1800 rpm. This generator provides power for electrical equip-
ment, such as the electric welding machine. The generator provides
power for ten electric motors; two operate the leg winches, two the
port and starboard bow winches, one the cutter head, three are used to
prime the pump and two others are available for operating bilge pumps
when necessary. The pump motor and the generator were both purchased
new prior to the commencement of dredging.
At the bow of the dredge is located the cutter ladder and cutter head.
The cutter head is a spiral closed-nose basket type with three rotary
blades which turn at 20 rpm.
A slurry discharge pipeline system was constructed using 6 m (20 ft)
length spiral weld 25 cm (10 in.) pipe with 4.8 mm (3/16 in.) wall
thickness joined together by 0.9 m (3 ft) rubber connectors. The
connectors were of the wedge-lock type that allowed 12° flexibility.
The internal spiral of the pipe allows for a more rapid movement of
water through the discharge line than does straight line pipe. The
pipeline system was held afloat by using floatation units each
consisting of five 0.2 m3 (55 gal.) drums with wooden harnesses.
Pierce (1970) stated that "procurement of adequate disposal areas for
the dredged material is a major problem in lake dredging." Although
this may usually be true, easements to a low-lying area immediately
10
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o
ENGINE
DISCMAHGE
-F'ir'E
PONTOONS
O
•-ANCHOR SPUD
o
1
- LL
-PUMP
3
O
:>
SUCTION
INTAKE-,
I I
PLAN
DI?Ci!AH-3E PIPS
r
ENGINE
r-PUMP
PROFILE
E.O.C.S.D.
Mar. 1969
Figure 5. Schematic diagram of the dredge
11
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across the lakeshore road were readily obtained. This area approxi-
mately 122 m (400 ft) x 305 m (1000 ft), was a low, wet grassland with
a slight easterly slope. One and one-half meter (5 ft) dikes were
constructed along the perimeter of the deposit area (moat). At the
west end of the moat a pipe was placed beneath the lake road, connected
to the terminal end of the discharge system. Thus the slurry entered
the moat at this location, moved slowly down the easterly gradient
and dropped its silt load. At the east end, the water, free of silt,
returned to the lake through the moat outlet, a pipe beneath the road-
bed. The elevation of the return pipe was such that the water would
stand for several hours before reentering the lake.
12
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SECTION VI
OPERATIONAL AND EVALUATION PHASE
Dredging began in early July, 1970, and continued through mid-November.
Dredging was carried on in 1971 for five months, and in 1972 for three
months, closing down in early August at the end of the three-year
period.
Over the three dredging seasons a total of 272,183 m3 (356,000 yd3) of
slurry, 47,861 m3 (62,600 yd3) of which were solids, were removed from
the dredge area (Figure 1). A 4.2 hectares (10.5 A.) area of lake
bottom was dredged free of silt during the three-year program and a
total of about 40,700 m3 (33 acre-feet) of silt removed. According
to recent studies by the engineering department of the Soil Conserva-
tion Service, approximately 12,335 m3 (ten acre-feet) of silt per
year is now entering Lake Herman from its watershed. Thus with a
partial dredging operation such as this, more silt was being removed
from the lake than was entering. With a full dredging operation, the
siltation trend in Lake Herman could be reversed.
The silt was removed from the bottom as a slurry averaging approxi-
mately 18 percent solids and 82 percent water. The slurry initially
consisted of about ten percent solids and 90 percent water. By the
end of the operation improved efficiency resulted in a composition
of 23 percent solids and 77 percent water.
The slurry was transported from the dredge through a pipeline to the
deposit area (Figure 1), an abandoned farm that had become a dumping
area for local lake residents. Bulldozers were used to construct a
dike around the area.
Chemical analyses of the dredged materials were performed by Dr.
Constance Churchill and her staff at the Division of Science and
Mathematics, Dakota State College, Madison. The water in the slurry
as it came out of the pipeline was rich in nutrients, especially in
total phosphates. The lowest concentration observed was 2.41 mg
P04/l and the highest 109.63 mg P04/l (See Appendix A). Ortho-
phosphates, however, were uniformly lower in the slurry, in the deposit
area, and in the return pipe than they were in the lake water at the
13
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point of dredging (See Table 1). As the slurry drained by gravity from
the pipeline toward the east, the silt dropped out. The vegetation
in the silt deposit area through which the water moved was lush,
suggesting nutrient removal by the vegetation. At the east end of
the deposit area the water returned to the lake through the pipe
under the road.
The silt deposit area was approximately 3.4 hectares (8.4 A.). The
silt that was dropped from the slurry filled the deposit area to an
average of 1.4 m (4.6 ft). At the end of the three-year project we
found that drying reduced the bulk of the silt until it occupied
approximately 50-60 percent of the original volume.
The vegetation in the deposit area was quite luxuriant and according
to Brashier et al. there were over twice as many plant species
growing in the area after the silt deposition than before.
A local wholesale greenhouse used samples of dredged silt in
chrysanthemum growth experiments. In pure silt the chrysanthemums
grew larger flowers, larger and greener leaves and stouter stems.
However, the root system was more poorly developed, probably because
of the compactness of the silt. The blooms did not last as long as
did those on the chrysanthemums grown in commercial greenhouse
preparation, probably an indirect effect of a poorly developed root
system. Mixtures of silt and commercial preparation showed inter-
mediate results.
Shortly after dredging commenced the phosphate concentration in the
lake water increased from 0.5 mg Ptfy/l to 1.5 mg P04/l (Figure 6).
Hardness, silica and turbidity also increased. Agreement was not
reached as to whether this was a result of resuspension of silt by
the dredging operation. Dredging did not result in extensive muddying
of the lake water, which some observers believed would be necessary
if the increase were to be related to dredging. Further, no phosphate
gradient was observed from the dredge to the surrounding lake, which
would probably be expected if the dredging did indeed cause the 1 >C
phosphate increase (See Appendix B). Not only was there no gradient
from the dredge area to the surrounding lake, but occasionally other
parts of the lake exhibited even higher phosphate concentrations
than did the dredge area. Also, high winds, which occur frequently
in South Dakota, may stir the bottom to a greater extent than the
dredge. However, it must be pointed out that there were no other
noticeable environmental changes that could readily account for this
dramatic increase in phosphates. For example, there was no heavy
runoff at that time that could have brought phosphate fertilizers
into the lake, and no extensive algal die-off which could have released
large quantities of phosphates to the water.
14
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3.75 +
3.00+
2
2.25 +
Lake Madiaon (average of 3 sites)
Lake Barman (average of 3 sites)
Southeast Lake Herman
0.00
Pi
I
Pi
•
CO
•4* c
-*g<
o
•
o
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Table 1. CHANGES IN ORTHOPHOSPHATE FROM LAKE TO SILT DEPOSIT AREA
ng P04/1
Date
7/28/70
8/11/70
8/18/70
8/26/70
9/3/70
9/22/70
10/6/70
10/13/70
10/21/70
11/3/70
7/13/71
8/18/71
8/25/71
9/13/71
Dredge Bay
of Lake
0.88
1.14
1.16
—
1.48
1.52
1.66
1.61
1.72
1.72
1.47
1.29
1.59
1.25
Dredge Pipe
Effluent
—
0.72
0.72
0.72
1.08
0.40
0.32
0.88
0.38
0.29
0.19
0.35
0.54
Silt Deposit
Area
0.45
0.88
0.85
0.90
0.60
0.34
—
—
—
0.19
0.45
0.48
0.30
Deposit Area
Outlet
—
0.80
—
0.62
0.35
0.38
0,51
0.29
0.27
0.17
., ... \
—
0.57
—
16
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Table 2. CHANGES IN pH FROM LAKE TO SILT DEPOSIT AREA
Date
7/28/70
8/11/70
8/18/70
8/26/70
9/3/70
9/22/70
10/6/70
10/13/70
10/21/70
11/3/70
7/13/71
8/18/71
8/25/71
9/13/71
Dredge Bay
of Lake
9.07
9.12
9.19
—
9.32
9.16
9.07
8.93
8.97
8.85
9.19
8.98
9.13
8.80
Dredge Pipe
Effluent
—
8.08
7.30
7.60
8.39
8.50
8.34
8.27
8.32
—
8.06
8.13
8.49
8.15
Silt Deposit
Area
8.26
7.69
7.80
7.28
8.35
8.44
8.53
—
7.98
—
8.55
8.57
7.95
Deposit Area
Outlet
—
7.20
—
7.27
7.98
8.28
8.16
7.89
8.14
7.97
—
—
7.83
—
17
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One interesting aspect of the dredging that was not anticipated was
the fact that dredged holes partially refilled when strong winds
roiled the bottom. The silt from the surrounding lake bottom that
refilled the holes was relatively soft and was easily removed by
subsequent dredging. However, this did require dredging to continue
in a given location longer than was originally expected.
Core samples taken from the bottom of the lake were analyzed by
Mr. Arnold R. Gahler, Pacific Northwest Environmental Research
Laboratory, E.P.A., Corvallis, Oregon, at about the time that dredging
began. It was almost impossible to obtain cores greater than three
feet in length. The top 0.3 m (1 ft) of the silt was relatively
soft but compactness increased rapidly with sediment depth. By the
time the 0.9 m (3 ft) depth was reached any attempts to proceed
beyond that resulted in breaking the lining of the core sampler.
Gahler summarized the results as follows:
1. "Relatively high concentrations of soluble orthophosphate,
total phosphorus, ammonia, and total Kjeldahl nitrogen
occur in the interstitial water of the sediment."
2. "The C/N ratios in the sediment are relatively high, i.e.,
11/1 to 12/1 which indicates pollutional effects."
3. "The carbon and nitrogen decrease greatly with depth in
the area where dredging will occur. On the single core,
the carbon decreased from 6.7 to 2.5% and the nitrogen
from 0.7 to 0.19%."
The complete analysis of the interstitial water of the Lake Herman
sediments are given in Appendix C. Locations of core sampling sites
are shown on Figure 1.
18
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SECTION VIII
DISCUSSION
Dredging has been suggested by many as a method of removing nutrients
from a lake and as a method of prolonging the life of lakes. Several
dredging operations such as those at Worthington, Minnesota, and
Owatona, Minnesota, have been used to prolong the life of lakes. The
operation at Worthington, Minnesota, has also used the dredged silt
to fill in nearby low areas, which have subsequently been used for
residential developments, public building areas, and recreational
areas.
This study has contributed further evidence that dredging can prolong
the life of a lake. Silt removal from the lake exceeded input rates
from nearby farmland erosion. However, silt loads to the lake are
more or less evenly distributed over the lake bottom, whereas
removal of silt by dredging is localized. Therefore, the dredging
has benefited only a restricted portion of Lake Herman. Water through-
out most of the lake averages about 1.7 m (5% ft) in depth. When that
drops to 1.2-1.4 m (4-4% ft) in late summer, especially in dry years,
the bays become clogged with Potamogeton spp. A heavy rain of one-in-
fifty-years frequency or perhaps even a rain of one-in-twenty-five-
years frequency might bring enough silt into the lake to decrease the
water depth to the critical level where the lake assumes the character-
istics of a marsh. Even if such a heavy rain does not occur, biologists
from the South Dakota Game, Fish and Parks Department and from Dakota
State College believe that enough silt will probably enter the lake
over the next 25 years to 50 years to decrease the water depth to
the critical level where the lake will begin its transformation to
a marsh. This suggests that if Lake Herman is to be prolonged a much
more extensive dredging program will be necessary. One possibility
is to remove by dredging only 0.3 to 0.6 m (1 to 2 ft) of silt, and
try to do this in all of the bays and shallow areas, rather than
dredging to the original bottom in one relatively small part of the
lake. Based on the data from this study, this type of dredging might
well have very beneficial side effects. As earlier discussed, the
surficial sediment is the most fertile. This is undoubtedly because
of the use of increased amounts of fertilizers in crop production in
the watershed in recent years. If this were the part removed by
19
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dredging, significant amounts of nutrients would be removed from many
areas of the lake. It was also shown by this project that silt could
be used to grow flowers. However, root systems were not able to
develop properly under greenhouse conditions. By taking only the top
foot of silt a much greater uniformity in the fertility of the silt
would prevail, and the entire amount removed would be much more fertile
than that removed in this project. A much smaller silt to garden
soil ratio or silt to commercial greenhouse preparation might be
necessary to produce stout stems, luxuriant leaf growth and larger
blooms. The relative small amount of silt in this combination would
probably eliminate the excessive compactness which caused poor root
development.
An overall lake improvement program is needed. Dredging can be only
a partial answer to the problems of prairie lakes such as Lake Herman.
Extensive land management programs in lake watersheds should be
promulgated. If the lakes are to persist, silt loading must be
curtailed as much as possible. Where necessary, contour plowing and
terracing should be encouraged. Grassed waterways with gradual slopes
should be used to drain the land. Dugouts and stock dams should be
promoted in tributary streams, slowing water and allowing silt to
settle out. Silted-in dugouts can be easily and inexpensively cleaned
with nitrate explosives. All streams in the watershed should have
adjacent grassland, to slow movement of water into the stream and
retard transport of silt.
Sanitary districts for each lake, such as Lake Herman, should be
established and regulations regarding lake activities drawn up,
including distance between residences, distance from residences to
lake, and types of acceptable sewage disposal programs. Lake shores
should be zoned for residential, business, and recreational uses.
Permanent surveillance programs in conjunction with colleges or
universities, where possible, should be established to monitor for
changes in pollution levels, winter oxygen deficiencies, and changes
in dynamics. This type of program should be especially important in
heavily populated areas and where lakes are sparce. If lake recreation
is important, and a significant part of the people believe that it is,
then the lakes that are heavily used for recreation should be given
priority for programs that will insure their maintenance. Some sort
of standardization should be worked out for programs for the various
types of lakes, and these programs set up with federal, state and local
government support and control. If the initiative is left up to the
local citizenry, a select few lakes will receive the benefits of
available programs, but the vast majority will be left to deteriorate.
20
-------
PUBLICATIONS AND PAPERS
The following publications and papers are related to this project.
1. Brashier, C. K. and R. G. Anderson, 1972, Lake Dredging—
A Biological Viewpoint, presented to Phycological Society
of America at the annual AIBS meetings at the University
of Minnesota, Minneapolis.
2. Anderson, R. G., C. K. Brashier, and G. Leidahl, 1971,
Viable Algae in Chironomid Larvae, presented to Phycological
Society of America at joint meeting of AIBS and Canada
Botanical Society in Edmonton.
3. Churchill, C. L., 1971, A Preliminary Report on Some Effects
of Dredging a Lake, presented at the annual meeting of
South Dakota Academy of Science.
4. Churchill, C. L., 1971, Lake Restoration, presented at
the annual Gooch-Stephens Seminar at Baylor University.
21
-------
SECTION IX
APPENDIX A. Results of Chemical Analysis of Dredged Materials
Date
July 21, 1970
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet-
28
Dredge
10 Dredge Pipe
(End)
Moat
Moat Outlet
August 4
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
11
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
fc
8.85
8.1
9.07
8.26
8.87
9.12
6.08
7.69
7.20
iTt^
C^O
•HO
J3
<§*
150
149
170
154
161
159
171
168
163
o
"L
>•-<
^^x^
« 0^
Si1 8$
8.7
12.1
5.4
6.2 55.0
15.0 62.6
376
38.1
57.7
$
«-i
•HO
Ov{>
•DOCM
(ffe
784
794
804
778
8.09
788
768
819
829
829
o
•a *H
«H^*^
0 O
6 S1
5.05
5.53
5.29
5.77
5.77
5.77
5.05
5.77
6.01
0)
ID
•§.
\ J3.H
^^ CL "^^
>
R) 1 0) 1
•rl CO •*-> C*)
eg n»O
§ g> -H C>
0.19 0.005
1.48 0.009
0.27 0.02
2.0 0.06
0.20 0.02
0.18 0.053
2.47 0.012
5. 14 0.004
3.36 0.005
*^.
0/1
"hs
SS1
3.2
3.0
1.23
18.10
2.22
4.09
6.31
8.36
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
c
o>
o>
Date
58
.-4 n)
JOO
o
•o
«
"sf^
in
•H g>
08
§1
i
'•pod
•oooi
Jfe
o>
•a-*
Vlr-4
00
rH
-------
APPEiNDIX A. Results of Chemical Analysis of Dredged Materials
Date
o.
•H c«5
.58
r— t flj
« o
5 i
c
01
X
O
•o
O --i
Si §1?
•HBO
-t-'O
•OOCN
Si+>
Oaro
CO
(0 O
t-t 2
•P
S i1
1—4
Q) 1
-P OJ
•HO
Si
October 6, 1970
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
13
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
21
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
November 3
Dredge
Dredgs Pipe
(End)
Moat
Moat Outlet
9.07
8.34
8.16
8.93
8.27
8.53
7.89
8.97
8.32
8.14
S.85
7.98
7.97
187
182
177
185
244
208
176
188
215
181
190
159
156
9.5 46.7
2117
6.1 44.7
10.4 51.5
53.3
54.3
2.4 39.0
10.8 38.4
2613
3.6 42.6
12.3 39.7
34.0
37.0
873
883
893
874
895
885
866
873
862
852
873
834
785
6.20
6.97
6.97
6.72
6.46
7.23
6.46
6.20
6.20
6.20
6.20
6.20
5.17
24.5
24.8
24.0
19.2
19.2
16.8
19.0
12.5
14.6
8.25
5.50
1.66
0.32
0.51
1.61
0.88
0.29
1.72
0.38
0.27
1.72
0.19
0.17
2.80
25.63
1.05
3.01
109.63
14.07
0.76
2.02
27.60
1.04
2.46
1.10
1.11
0.24
0.15
3.17
2.64
0.12
2,90
1.50
0.02
0.18
0.30
0.020
0.125
0.007
0.020
0.167
0.025
O.C27
0.051
1.01
1.80
2.02
1.50
0.01
0.01
59.4
4.64
4.18
80.6
1.11
31.5
51.4
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
in
Date
=§.
Alkalinity
mg CaOOa/l
o>
•D
§k
I1&
Jfe
o>
•O-*
ou
6S
*>
fun
T-4
•f*4 Qt
01 6
o
4*
I
in
3
H
O
•a
in
o
JG "4
«2
.2 £
mi
SV,
«oo
S£
1
July 13, 1971
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
20
Dredge
Dredge Pipe
(End)
Koat
Moat Outlet
August 18
Dredge
Dredge Pipe
(End)
Moat
25
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
9.19
8.06
9.23
7.90
8.98
8.13
8.55
9.13
8.49
8.57
7.83
197
190
197
201
209
195
209
219
207
217
206
13.5 62.9
907
15.1 46.1
584
8.5 72. i
4.5
4.3 67.0
504.6
4.0 874.6
1.2 56.4
757
777
776
806
842
848
850
839
850
850
5.2
5.8
5.1
5.3
6.6
7.1
7.1
6.6
6.6
7.1
7.6
13.4
4.9
31.4
28.6
35.1
24.2
28.9
37.0
28.3
30.2
31.4
1.47
0.29
1.23
0.33
1.29
0.19
0.45
1.59
0.35
0.48
0.57
2.21
66.72
2.15
28.50
2.12
75.3
2.42
2.57
41.6
1.44
0.05
2.32
0.00
1.10
0.00
0.76
0.50
0.01
1.77
2.17
0.86
0.013
0.081
0.027
0.048
0.013
0.021
0.046
0.034
0.034
0.003
0.320
0.8
29.8
1.4
4.5
3.8
5.0
4.4
3.5
2.4
4.4
5.7
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
Date
X
a.
Alkalinity
mg CaC03/l
0)
•o "> u
<-t -»-»O
O)O •— i TJOCN
U) Q\ c,C
•<~* 0^ O Q> O C •!-*
Q 6 O E O.3.
h
o
1
u>
o
a,~x
•— t O
too.
~H CO
li1
i— i
4> 1
•»-> ro
2S
•H D^
Z 6
—t
z~
'£z
z e
September 1, 197.1
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
13
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
30
Dredge
Dredge Pipe
(End)
Moat
Moat Outlat
June 12, 1972
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
8.
7.
8.
8.
7.
8.
8.
8.
9.
80
40
80
15
95
79
56
47
,00
8.34
7.
,93
211
150
219
216
217
223
254
227
176
242
411
7.7 60.5 844
3.6 48.5 575
8.8 88.0
796
910
8.9 51.9 942
429 1002
52.8 1102
14.45 50.2 817
209.4 838
448.3 858
5.8
5.1
6.0
5.8
7.3
6.1
6.6
7.6
6.2
6.2
5.9
37.9
20.2
39.4
34.2
24,8
36.2
35.4
31.6
21.8
20.4
16.2
1.52
0.89
1.25
0.54
0.30
1.07
0.91
0.37
0.53
0.46
0.15
2.52
2.13
1.67
8.59
5.46
1.39
5.33
27.63
0.03
1.07
0.10
0.69
2.18
0.01
0.23
0.93
0.031
0.287
1.808
0.016
0.040
0.018
0.041
0.063
0.131
0.013
0.069
0.0
0.019
0.0
3.1
85.1
2.4
5.5
11.4
0.0013
0.0013
0.0086
0.0
0.0003
0.0121
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
Is)
41
in
Date
Q.
Alkalinity
mg CaC03/l
X
o
0>
*0 CJ
(A O — 1
u> Q\
S i1 Si1
•H
>
•4-> O
•OOCN1
CO
•— H
01 1
-H CM
•H O
-p
S e
June 19, 1972
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
26
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
9.15
8.47
8.17
8.66
7.95
175
177
168
175
168
13.35 82.2
147.0
865.1
7.80 27.6
1992.2
802
832
842
854
854
7.6
6.7
6.7
6.4
7.3
22.3
21.5
17.9
21.2
16.7
0.50
0.45
0.15
0.60
0.10
1.67
5.46
29.27
0.75
30.32
0.024
0.436
2.559
0.150
2.750
0.018
0.003
0.073
0.023
0.012
0.0003
0.0056
0.0069
0.0037
0.0066
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
o
Date
July 21, 1970
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet.
28
Dredge
w Dredge Pipe
(End)
Moat
Moat Outlet
o o>
O (Q
h S
3
(0 O
^ *~*
o> «c+»
O* ^«* fl>
6 O,xif
4* 0)*4^
!•* fr •*
22.5 7
26.5 7
1
h
CO I-* -H
•n ;x C
Q -H C 3
T< O
i-l TJ tfl >,
-5-2, S"o ii
0 S h^CO T3
CO^^ H« — ' J3
30 35.2
4437
47 31.4
56.5
i
« c*>
WO
Q)O
C 0)
TOO
H
n o>
x e
363
395
368
388
Q ••-(
'oo
»-l
5?
82.0
93.9
73.4
73.4
§
_| _| i-l r-l
V >~t ^
c\ e*v.
tO C 3 <0
OZ -rtZ
C T3
(0 O> O O*
2 E (OS
0.03 32
0.13 32
0.01 33
0.29 34
6
•rt
£ff
17.2
18.9
17.3
19.3
August 4
Dredge 23
Dredge Pipe
(End)
Moat ,
Moat Outlet
20
35.9
375
73.4 0.00 0.02 28.1 0.06 32
17.9
11
Dredge 28 7
Dredge Pipe
(End)
Moat
Moat Outlet
19.3
3200
44
18.0
365
400,
365
360
77.9
77.1
76.5
74.7
0.00
0.01
0.00
0.00
0.02
0.02
0.03
0.08
33.6
38.0
38.0
37.6
0.01
0.94
0.63
0.79
32
34
33
32
17.2
19.4
18.4
20.7
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
ro
O 01
0> (0
I *
eg o
t .
ft r -«
Q> r; gj
Q ^> flj
6 Q.O)
o> o>t-i
Date f- Q-^
August 18, 1970
Dredge 24.5 7
Dredge Pipe
(End)
Moat
Moat Outlet
26
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet 26
September 3
Dredge * 8
Dredge Pipe
(End)
Moat 3
Moat Outlet 0.5
22
Dredge 19 7
Dredge Pipe
(End) 18
Moat 20
Moat Outlet 18
U> t~l.r*
-1 >• C
«-< O
•rt TJ "> >-
fO O)
40.2
36.4
41.9
35.4
36.4
36.4
39.2
39.2
36.4
37.0
40.8
36.4
36.4
36.4
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
Date
o w
0> flJ
to o
O ^M ^^
O. +» «
ET Q.4)
i --»
M S^-<
Hardness
rng CaCOj/1
OO
•— 1
SP"
s3
(Si4
cu<
o
€
o»
o>
u
c
<— i
P
li1
e
October 6, 1970
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
13
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
21
Dredge
Dredge Pipe
(End)
Moac
Moat Outlet
November 3
Dredge
Dredge Pipe
(End)
Most
Moat Outlet
16 7
18
7 7
7.5 3
8.5
10 7.
10
12 1
3 6
2 2"
2 1
41 20.5
3891
41.1
26.3
6625
5250
40.0
50 21.0
1540
56.5
50 21.3
r"1
40.9
49.8
405
395
390
375
365
400
377
385
408
368
375
85.9
81.7
77.9
8.12
79.8
83.5
82.1
81.2
82.1
76.5
72.0
0.00
0.01
0.00
0.00
0.00
0.01
0.00
0.00
0.00
0.01
0.01
0.02
0.04
0.08
0.18
0.06
0.04
0.31
0.18
0.03
0.08
0.22
44.1
42.4
41.3
40.8
39.2
47.8
43.4
43.4
46.5
37.3
36.4
0.03
0.04
1.06
0.63
0.69
0.02
1.12
0.76
0.04
0.27
0.59
39
38
39
39
39
38
40
40
39
36
34
18.9
18.2
18.4
19.4
18.5
18.2
18.3
18.6
18.1
17.5
16.5
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
o
Date
July 13, 1971
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
20
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
August 18
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
25
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
o o
O 0 .X
h S u>
3 sf
% -s °
* JS? £
§• "aS o's
a> am* ai u
24 10 43
28 7 46
22
25 ' 6 32
24.5
25.5
24 6 22
3
i
£gi
•o 8 >.
27.5
4590
27.2
5900
44.0
7600
4200
40.0
6100
4570
39.0
i-H
«» O
0) O
I6
(0 CJ*
a: e
359
365
379
359
412
392
399
426
412
405
439
10 O)
O 6
80.2
73.7
83.7
84.1
94.5
88.7
88.7
92.9
85.3
85.7
93.7
a
o o>
0 2L
0.000
0.004
0.008
0.004
0.007
0.003
0.005
0.003
0.004
0.002
0.003
r-t
C (JU
O
0.011
0.082
0.022
0.176
0.018
0.106
0.023
0.013
0.063
0.040
0.019
6
•HI— t
O* !£
C
0.51
2.67
0.04
2.72
0.02
1.94
1.38
0.41
1.93
1.43
1.74
-i
•HZ
O Q)
33.3
34.5
34.0
32.5
33.4
32.8
33.9
36.4
35.3
34.7
35.3
Potassium
mg K/1
18.0
18.7
17.2
19.3
19.3
21.0
20.3
19.6
21.1
21.7
22.2
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
u
o
f-t
«
K>
Date
September 1,
Dredgs
Dredge Pipe
(End)
Moat
Moat Outlet
13
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
30
Dredge
Dredge Pipe
(End)
Moat •>
Moat Outlet
June 12, 1972
Dredge
Dredge Pipe
(End)
Moat
4) 10
H 3:
3
10 O
S .c-?
Q. -P 0)
(— c Q^~*
1971
23 6
23 1
19 6
19
15 '
15
17
24 6
^ D +•>
0> H -rl
.rl >» C
Q H-> C =>
•»H O
«H TJ U) >s
o e h n -o
a> o 3<-> ^-i
33
30 37
2600
3800
33 33.2
1317
449
55 23. 1
^44
3147
o> rt
<°O
0)O
li1
405
250
446
422
431
422
419
419
393
412
410
0 O Q.U C U-,
f-> a. o
to O) O O^ ti Ot
86.6 0.003 0.022
50.6 0.007 0.108
92.0 0.003 0.040
88.3 0.005 0.105
88.3 0.011 0.102
92.0 0.000 0.010
87.8 0.005 0.006
87.0 0.007 0.008
m
£
Ol
37.0
23.1
37.8
35.1
34.8
37.5
38.5
36.0
a>
-------
APPENDIX A. Results of Chemical Analysis of Dredged Materials
w
O* (-<
O 01
Date
June 19, 1972
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
26
Dredge
Dredge Pipe
(End)
Moat
Moat Outlet
£n> A(
X «i>
2 °^-» .ri
0 JC*4? JC
Q. +> 4) U-^.
e 0.0* o E
01 9<* OU
21 8 40
20.5 8 80
^ iJ
5^ ^j C
**"^ O
•a * >.
J3 0 *4
h « tj
HI— • J3
34.7
596.0
3333.3
23.7
3935.8
^
:**^
0>O
4>Q
C (u
t»c5
M
2?
396
426
3T/
406
383
E a> E
S-i 1-1 »-« ^ w "3
3i> J"? 5i* 58* *SP ^S1 off
OS O M. ME ggg -g g OTg Q. g
0.010
-------
APPENDIX B. Results of Chemical Analyses of Lake Herman *
Date
July 21, 1970
North
Dredg-j
Center
Southeast
28
North
Dredge
Center
Southeast
Aug. 4
North
Dredge
Center
Southeast
11
North
Dredge
Center
Southeast
:E
8.39
8.85
8.57
9.58
9.10
9.07
8.92
10.11
8.89
8.87
8.94
9.47
9.33
9.12
9.17
10.17
:*— •
is
«O
_x
SSP
150
150
148
107
152
170
152
114
162
161
160
132
158
159
156
136
c
en
X
O
•o
at
*0 CM
o
tft
a i1
8.9
8.7
6.8
11.0
11.5
12.1
8.9
14.8
5.8
6.2
6.9
7.4
19.0
15.0
15.2
15.8
Q^x..
sr
51.6
s-55.0
>55.0
54.5
71.7
62.6
53.2
86.4
-»->4->
•rf 1C
TJ O
C.CO
O aCN
784
784
794
712
768
778
778
747
778
788
778
747
753
768
768
758
a> —4
••-t ••-«
f-H •
6 2
5.77
5.05
5.53
5.33
5.53
5.29
6.25
5.77
5.53
5.77
5.29
5.29
5.53
5.77
5.29
5.53
ID O
0 -*
i— 1
•r-i Fft
10 £
17.7
15.2
18.2
8.3
IS. 5
19.4
18.0
8.4
20.7
19.8
19.4
13.5
19.5
19.9
23.9
12.4
•P
0 ?
0.72
0.67
0.71
0.50
0.83
0.88
0.88
0.10
1.07
1.11
0.97
0.75
0.93
1.14
1.09
0.18
U)
f-4
0
a.
in
O
£. *-•
-• O
O!
z a>
2.5
3.2
2.6
3.6
1.36
1.23
2.36
1.00
3.34
2.22
2.78
3.34
3.05
4.09
2.84
6.75
See Figure 1 for sampling locations<
-------
APPENDIX B. Results of Chemical Analyses of Lake Herman
en
Date
=§.
•rt <^
*rl O
.X
Dissolved Oxygen
mg 02/1
t-H
Conductivity
umhos/cm at
25» C.
4>
f-l —4
Si1
re O
0 -r4
•rt tn
«
+*
«j
fc
w>
o
.C -t
^
s?
u>
2
o
£
(A
O
JZ—i
ma.
r-4
0) 1
ii
Iff
*-«
0) 1
-(-' ro
-------
APPENDIX C. Analyses of Interstitial Water From Lake Herman Sediments*
o»
Date
March 11, 1969
A-Core tti (3" top missing
from 1st foot)
A- Dredge A
B-Dredge 3
B-Core #3 (Top Foot)
B-Core 04 (Bottom 10" of
32" core)
C-Core #2 (Top Foot)
July 31
South Silt
East Silt
North Dredge
Silica Ca
Sol. Hardness
36.3
30.9
36.0
32.4
46.8
31.8
19
25
23
370
340
340
420
340
260
293
255
Total
Hardness
517
700
700
567
400
Na
87
91
36
34
34
K
36
35
19
17
16
Cl
40
30
30
30
35
46
39
70
SOi Fe Mn Md
238
740
700
525
800
350 .20 2.4 48
270 .30 8.4 56
310 .30 7.4 48
Total
Carbon
245
209
187
184
187
*A11 data in this table has been provided by Arnold Gahler of the Pacific Northwest Water Laboratory,
200 South 35th Street, Corvallis, Oregon.
All concentrations are in rng/1*
Samples from August were delayed during shipment so that results on interstitial water may not be
accurate.
-------
APPENDIX C. Analyses of Interstitial Water From Lake Herman Sediments
Date
P
Ortho
P
Total
Sol.
N
Total
.1C.11.
N
NQg
Total
Alk.
Cond.
pH
March 11, 1969
A-Core Hi (3" top missing
from 1st foot)
A-Dredge A
B-Dredge E
3-Core #3 (Top Foot)
B-Core #4 (Bottom 10" of
32" core)
C-Core #2 (Top Foot)
July 31
South Siit
East Silt
North Dredge
March 2, 1970
Core A1 (Top 5 in.)
Core A1 (Middle 6£")
Core A' (Bottom ?t")
1.0
1.5
2.2
.84
2.4
.56
1.1
1.5
1.0
2.6
9.9
3.0
3.0
5.8
14.0
8.0
5.2
5.4
.13
.08
.08
.05
.08
.08
.36
.19
.72
1.12
.40
.16
.50
.28
.92
1.6
.60
.22
1.9
1.4
6.0
9.6
8.1
2.9
4.6
4,0
/.Ol
378
334
02
02
04
04
06
05
Ooi
4.01
.01
.02
.01
<«01
196
228
219
1183
1446
1446
1407
999
927
986
933
888
897
703
8.3
8.3
8.3
7.9
8.2
8.4
7.5
7.4
7.5
All concentrations are in tag/1.
Samples from August were delayed during shipment so that results on interstitial water may not be
accurate.
-------
TECHNICAL REPORT DATA
(I'li-asc read /»Ufticlii>nx tin the reverse bcjore rtMn/rf«7i»ij?/
ru I'oiu NO. 2.
_660/3-74-017_ , _
"lITLb ANUSUOII1LE
SILT REMOVAL FROM A LAKE BOTTOM
3. RECIPIENT'S ACCESSION"NO.
6. PERFORMING ORGANIZATION CODE
REPORT DATE
JANUARY 1973
(DATE OF
PREPARATION)
.AUTHORIS)
LAKE HERMAN DEVELOPMENT ASSOCIATION, INC.
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORG \NIZATION NAME AND ADDRESS
LAKE HERMAN DEVELOPMENT ASSOCIATION,
524 SOUTHWEST FOURTH STREET
MADISON, SOUTH DAKOTA 57042
10. PROGRAM ELEMENT NO.
INC.
1BA031
11. CONTRACT/GRANT NO.
16010 ELF
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. ENVIRONMENTAL PROTECTION AGENCY
PAC. NW ENVIRONMENTAL RESEARCH LAB, NERC-CORVALLIS
200 SW 35TH STREET
CQRVALLIS, OREGON 97330
13. TYPE OF REPORT AND PERIOD COVERED
FINAL 1970-1972
14. SPONSORING AGENCY CODE
18. SUPPLEMENTARY NOTES
16. ABSTRACT
Dredging was used as a method to remove 62,600 cubic yards of silt from Lake
Herman during the summers of 1970, 1971, and 1972. The silt was transported via a
pipeline to a silt deposit area adjacent to the northeast corner of the lake. The
water removed by the dredging process drained by gravity along a gradual slope,
dropping its silt and losing nutrients to the lush vegetation, and eventually returned
to the lake.
In the bay area where dredging occurred water depth was increased from 5.5 feet to
approximately 11 feet. There was no significant change in the levels of biological
organisms or nutrients, except for phosphorus, which increased just after the dredging
began. Whether dredging actually caused the increase is still debatable. Vegetation
in the deposit area became extremely lush. Water returning to the lake from the
deposit area was lower in nutrients than the water in the lake.
This report was submitted in fulfillment of Contract Number 16010 ELF under
partial sponsorship of the Water Quality Office, Environmental Protection Agency.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
*EUTROPHICATION, ALGAL BLOOMS, WATER
POLLUTION EFFECTS, *SEDIMENTS,
*SEDJMENT CONTROL
b.lDENTIFIERS/OPEN ENDED TERMS
LAKE HERMAN DREDGING
COSATI Field/Group
05 C
STATL-MENT
RELEASE UNLIMITED
19. SECURITY CLASS (Tint Report)
21. NO. OF PAGES
20. SECURITY CLASS (This paft)
22. PRICE
EPA Form 2220-1 (V-73)
------- |