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 béfore reentering the lake.

12


Results of Chemical Analysis of Dredged Materials

APPENDIX A.

1/9 6

wnytssezog,

T/en bu
IN;POS,

T/uq bu
asauebueyq

t ba
unfSau6ey

‘ag Gu
st

T ou
Aeaen

MiB 85

Tflogeg but

-ssauprey

(saFun A3tPtq
-anj “uosyoer)
AYYPPqINE

wo
ASIA PUI:

(3935)
Tazem 30 Uydeq

"Do aanzereduay

Date_

0.010

426

3333.3 377
406

396
596.0
3935.8 383

34.7
23.7

2.5 8

(End)
26
Dredge
(End)
Moat

Moat

June 19, 1972
Dredge

Dredge Pipe
Moat Outlet
Dredge Pipe
Moat Outlet


62

APPENDIX A. Results of Chemical Analysis of Dredged Materials
So
o o im
2 8 « £8
s £ 3 ,f2 2 vu g
oad ~ a PSD. o a $ §
is << # 8 is SS SH KS &
: # & GH go 2 # @ GF H BE
Date & a 8 fs SF 6 8k AR 2e  8F 8k Oe
August 18, 1970
Dredge 24.5 7 35 22.4 376 80-7 0.00 0.06 40.2 0.03 34 17.6
Dredge Pipe
(End) 2176.5 380 78.4 0.01 0.02 36.4 0.70 33 18.0
Moat 37.1 410 91.5 0.00 0.02 41.9 0.31 36 26.8
Moat Outlet
26
Dredge
Dredge Pipe
(End) 1558 360 77.9 0.00 0.03 35.4 0.81 35 21.8
Moat 166 375 77.1 0.00 0.01 36.4 0.62 34 19.5
Moat Outlet 26 17.7 385 77.9 0.00 0.04 36.4 0.88 35 21.1
September 3 :
Dredge 8 27.5 385 78.9 0.01 0.03 39.2 0.02 36 18.1
Dredge Pipe
(End) 2588 360 78.9 0.01 0.03 39.2 0.02 36 18.1
Moat 3 350 36C 77.9 0.01 0.06 36.4 0.86 37 20.7
Moat Outlet 0.5 22.5 360 75.6 0.00 0.04 37.0 0.14 «37 19.4
22
Dredge 19 7 24 45 390 81. 0.00 0.10 40.8 0.04 39 18.1

2
Dredge Pipe
(End) 18 4670 375 80.2 0.00 0.12 36.4 0.78 37 18.5
Moat 20 1670 365 80.2 0.00 0.10 36.4 0.81 38 18.8
79.8

Moat Outlet 18 xi) 365 0.00 0.07 36.4 0.61 38 18.8


TECHNICAL REPORT DATA
{Please read Insdructions on the reverse before completing)

1, AE PORT NG, 2. 3. RECIPIENT'S ACCESSIONNO,
660/3-74-017 Ff

fs. TITLE AND SUBTITLE is. REPORT DATE (DATE OF
SILT REMOVAL FROM A LAKE BOTTOM JANUARY_1973__PREPARAT

|6. PERFORMING ORGANIZATION CODE

7, AUTHOR(S) |S. PERFORMING ORGANIZATION REPORT NO.

LAKE HERMAN DEVELOPMENT ASSOCIATION, INC.

9. PERFORMING ORG A\NIZATION NAME AND ADDRESS 70. PROGRAM ELEMENT NO.
LAKE HERMAN DEVELOPMENT ASSOCIATION, INC. 1BA031 |
524 SOUTHWEST FOURTH STREET _ fircontaactcnantNo.——
MADISON, SOUTH DAKOTA 57042 16010 ELF

+2. SPONSORING AGENCY NAME AND AODRESS 13. TYPE OF REPORT AND PERIOD COVERED
U.S. ENVIRONMENTAL PROTECTION AGENCY FINAL 1970-1972

PAC. NW ENVIRONMENTAL RESEARCH LAB, NERC-CORVALLIS 14. SPONSORING AGENCY CODE
200 SW 35TH STREET
CORVALLIS, OREGON 97330

15, 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
b_ “DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS |c. COSATI Ficld/Group
*EUTROPHICATION, ALGAL BLOOMS, WATER LAKE HERMAN DREDGING 05 C

POLLUTION EFFECTS, *SEDIMENTS,
*SEDIMENT CONTROL

18. VISTRIBUTION STATEMENT 19, SECURITY CLASS (Titis Report) 21. NO, OF PAGES
RELEASE UNLIMITED 20. SECURITY CLASS (This page) 22. PRICE

EPA Form 2220-1 (9-73)


nitrite, 97.4 mg NO2-N/ml. High values for orthophosphate have been
1.35 mg PO4/1; for total phosphorus, 4.33 mg PO,/ I. During the develop-
ment of very heavy algal blooms, nitrogen concentrations decline, in
some cases to 0.0 mg NO3-N/1, 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 (22-28 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 ond
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.


Table 1. CHANGES IN ORTHOPHOSPHATE FROM LAKE TO SILT DEPOSIT AREA
mg PO4/1

Dredge Bay Dredge Pipe Silt Deposit Deposit Area
Date of Lake Effluent Area Outlet
7/28/70 0.88 -- 0.45 --
8/11/70 1.14 0.72 0.88 0.80
8/18/70 1.16 0.72 0.85 --
8/26/70 -- 0.72 0.90 0.62
9/3/70 1,48 1.08 0.60 0.35
9/22/70 1.52 0.40 0.34 0.38
10/6/70 1.66 0.32 -- 0.51
10/13/70 1.61 0.88 “- 0.29
10/21/70 1.72 0.38 - 0.27
11/3/70 1.72 - 0.19 0.17 :
7/13/71 1.47 0.29 -- mre yp
8/18/71 1,29 0.19 0.45 --
8/25/71 1.59 0.35 0.48 0.57
9/13/71 1.25 0.54 0.30 -

16


ve

APPENDIX B.

Results of Chemical Analyses of Lake Herman *

< ®
3 2 &
z > z £
= ° 22  ¢ ~
7° > = ° ° NN NY
a Ky mE N £2. £2 2 2
3 OES #; of *3 FQ fh 2h
an SS D> Ont eo aD ex a g
ol o uo aw P—a-9 oo og H
zo 2 Bes fe ip oe Fe §
Date B22 AP S58 aE S82 SF 2e £
July 21, 1970
North 8.89 150 784 17.7 0,72 0.28 40.001
Dredg? 8.85 150 784 15.2 0.67 0.19 0.005
Center 8.57 148 794 18.2 0.71 0.21 0.066
Southeast 9.58 107 712 8.3 0.50 0.19 = 9,003
238
North 9.10 152 768 18.5 0.83 O.11 0.01
Dredge 9.07 170 778 19.4 0.88 0.27 0,02
Center 8.92 152 718 18.0 0.86 0.15 0.01
Southeast 10,41 114 747 8.4 0.10 0.34 0.00
Aug. 4
North 8.85 162 778 20.7 1.07 0.25 0.00
Dredge 8.87 «6161 788 19.8 1.11 0.20 6.02
Center 8.94 160 778 19.4 0.97 0.36 €.00
Southeast 9.47 132 747 13.5 0.75 0.26 0.03
il
North 9.33 158 753 19.5 0.93 0.26 0.000
Dredge 9.12 159 768 19.9 1.14 0.18 0.058
Center 9.17 156 768 23.9 1,09 0.29 0.010
Southeast 10.17 136 758 12.4 0.18 0.25 0.000

* See Figure 1 for sampling locations.


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


L@

Results of Chemical Analysis of Dredged Materials

APPENDIX A.
& . eo 3
8 g §
& z a &
ss 3 Se so 8, $8 S$ S$
eg 3a BS Ba aS as or of of
oso, “m~ 00 oA OD Po rN
aé oN pon ct ert foto) =a cx ce tO
oO ao ol DON IS) At) on oA, Qa H Ae
= & a al ca, a aay 2 pt 8 ee) +
Date a 22 AP BF S85 SE oF SF RE 22 SP =P
June 19, 1972
Dredge 9.15 175 13.35 82.2 802 7.6 22,3 0.50 1.67 0,024 0.018 0.0003
Dredge Pipe
(End) 8.47 177 147.0 832 6.7 21.5 0.45 5.46 0.436 6.003 0.0056
Moat 8.17 168 865.1 842 6.7 17.9 0.15 29.27 2.559 0.073 0.0069
Moat Outlet:
26
Dredge 8.66 175 7.80 27.6 854 64 21.2 0.60 0.75 0.150 0.023 0.0037
Dredge Pipe .
(End) 7.95 168 1992.2 854 7.3 16.7 0.10 30.32 2.750 0.012 0.0066
Moat

Moat Outlet


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 m> (356,000 yd) of
slurry, 47,861 > (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 m> (33 acre-feet) of silt removed. According
to recent studies by the engineering department of the Soil Conserva-
tion Service, approximately 12,335 m? (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

PO,/ 1 and the highest 109.63 mg PO4/1 (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


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 (4-45 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 a 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
amarsh. 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


mg PO,/ 1

Total Phosphorus

3.754

3.004

2025

1.507

0.75 4

Lake Madison (average of 3 sites)
— Lake Herman (average of 3 sites)
.- Southeast Lake Herman

:

Total phosphorus levels in

Lakes Herman and Madison during 1970

Figure 6,

1s


8%

z
~~
6
z
>

Results of Chemical Analysis of Dredged Materials

(a) ty
° 3 Lo
> nl a Poco am § a oS
Pa cen BB> 88 S28 WwW SF 3S eo xf Gua
a So GS. BSH s& 8 ad ak 2 § sf as
EF 3 33 Sse B. se G2 fe $2 fe fe 2
Date 6 A ae 22a BF SF 8h AP 2? Sf af fF
July 21, 1970
Dredge 22.5 7 30 35.2 363 82.0 0.00 0.03 36.0 0.03 32 17.2
Dredge Pipe
(End) 44373959349 001024 3203013 32 18.9
Moat
Moat Outlet.
28
Dredge 26.5 7 47 31.4 368 73.4 0.01 0.02 30.4 0.01 33 17.3
Dredge Pipe
(End)
Moat 1 56.5 388 73.4 0.00 0.04 28.1 0.29 34 19.3
Moat Outlet
August 4
Dredge 23 7 20 35.9 375 73.4 0.00 0.02 28.1 0.06 32 17.9
Dredge Pipe
(End)
Moat ,
Moat Outlet
ll
Dredge 28 7 19.3 365 77.9 0.00 0.02 38.6 0.01 32 17.2
Dredge Pipe
(End) 3200 400, 77.1 0.01 0.02 38.0 0.94 34 19.4
Moat “4a —«365——s7655 0.00 0.03 «38.00.63 33—Ss«<184
Moat Outlet 18.0 360 74.7 0.00 0.08 37.6 0.79 32 20.7


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 m> (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


Silver Creek

Silt Deposit Area

Southeast

Figure 1. Map of Lake Herman

2


sz

APPENDIX A. Results of Chemical Analysis of Dredged Materials
Ss ¢ 3
2 3
we 6 8 a 3
aS 3 . “1 3 3 < ga g
ot -” a PR! Pel > = =z
os iB 2 3S 53 & & &
go 95 4 «gh Bo is gk gk Ge Es 3
date a Ze ae 682 88 62 se &e fr fe fe fe
July 13, 1971
Dredge 9.19 197 13.5 62.9 787 5.2 13.4 1.47 2.21 0.05 0.013 0.8
Dredge Pipa
(End) 8.06 190 K7 7 5.8 4.9 0.29 66.72 2.32 6.081 29.8
Moat
Moat Outlet
2
Dredge 9.23 197 15.1 46.1 776 5.1 31.4 1.23 2.15 0.00 0.027 1.4
Dredge Pipe
(End) 7.90 201 5384 806 5.3 28.6 0.33 28.50 1.10 0.048 4.5
Moat
Moat Outlet
August 18
Dredge 8.98 209 8.5 72.1 842 66 35.1 1.29 2.12 0.00 0.013 3.8
Dredge Pipe
(End) 8.13 195 848 71 24.2 0.19 75.3 0.76 0.021 5.0
Moat 8.55 209 4.5 850 Tl 28.9 0.45 2.42 0.50 0.046 4.4
25
Dredge 9,13 219 4.3 67.0 839 6.6 37.0 1.59 2.57 0.01 0.034 3.5
Dredge Pipe
(End) 8.49 207 504.6 850 6.6 28.3 0.35 41.6 1.77 0.034 2.4
Moat 8.57 9217 4.0 874.6 850 Fel 3.2 0.48 2.17 0.003 4.4
Moat Outlet 7.83 206 1.2 56.4 7.6 31.4 0.57 1.44 0.86 0.320 5.7


(x4

SECTION IX

APPENDIX A. Results of Chemical Analysis of Dredged Materials

Ss

§
E ge &
> rs

* P  .f bo og g

ee eo sg. § ég Ex oF oF GF

oe oso aN 9 > mse) Po “2

x 3 - 28 83 23 g8 gf Ge Ee xs

a) +
pate a de ae $8 8 62 fe ge 2 fs ff de
July 21, 1970
Dredge 8.85 150 8.7 784 5.08 15.2 0.67 16290-19005 3.2
Dredge Pipe
(End) 8.1 149 794 5.53 17.2 0.73 2.41 1.48 0,009 3.0
Moat 804
Moat Outlet
28
Dredge 9.07 170 1241 778 5.29 19.4 0.88 1416 0627 0,021.23
Dredge Pipe
(End)
Moat 8.26 154 5.4 8.09 5.77 17.6 0.45 0.99 2.0 0.06 18.10
Moat Outlet
August 4
Dredge 8.87 161 6.2 $5.0 788 577 19.8 lel 1.66 0.20 0,02 2.22
Dredge Pipe
(End)
Moat
Moat Outlet
rs

Dredge 9.12 189 15.0 62.6 768 577 19.9 1614 1.45 0.18 0,058 4.09
Dredge, Pipe
fad) °° 8.08171 376 819.605.1569 0.72 :13.36 2.47 0,012 6.31
Moat 7.69 168 38.1 829 5.77 22.0 0.88 1.15 5.14 0.004
Moat Outlet 7.20 163 57.7 829 6.01 21.9 0.80 1.10 3.36 0.005 8.36


FIGURES

Page
Map of Lake Herman 2
The Lake Herman Watershed 3
Water and Sediment Depths in Lake Herman 4

Lake Herman Silt Trap for Four Interconnected Lakes 5
Schematic Diagram of the Dredge 11

Total Phosphorus Levels in Lakes Herman
and Madison During 1970 15


CONTENTS

Preface

List of Figures

List of Tables

Sections

I Introduction

II Summary

III Conclusions

Iv Recommendations

Vv Dredge Design and Discharge Area
VI Operational and Evaluation Phase
VII Discussion

VIII Publications and Papers

IX Appendices

iv

10
13
19
21
22


OQ OQ

[7 ENGINE PUMP

SUCTION
INTAKE 7

D
a

L_ pontoons Ne

ANCHOR SPUD

PLAN

DISCHARGE PIPE [

aL.

r
a
—

‘RULE SUCTION
INTAKE
SPUD
PROFILE
E.0CS0.
Nar. 1969

Figure 5. Schematic diagram of the dredge

ll


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 NH3-N/1; nitrate, 1.32 mg NO3z-N/1; for


Table 2. CHANGES IN pH FROM LAKE TO SILT DEPOSIT AREA

Dredge Bay Dredge Pipe Sil t Deposit Deposit Area

Date of Lake Effluent Area Outlet
7/28/70 9.07 - 8.26 -
8/11/70 9.12 8.08 7.69 7.20
8/18/70 9.19 7.30 7.80 --
8/26/70 -- 7.60 7.28 7.27
9/3/70 9.32 8.39 8.35 7.98
9/22/70 9.16 8.50 8.44 8.28
10/6/70 9.07 8.34 -- 8.16
10/13/70 8.93 8.27 8.53 7.89
10/21/70 8.97 8.32 = 8.14
11/3/70 8.85 -- 7.98 7.97
7/13/71 9.19 8.06 -- --
8/18/71 8.98 8.13 8.55 -
8/25/71 9.13 8.49 8.57 7.83
9/13/71 8.80 8.15 7.95 --

17


EPA 660/3-74-017
FEBRUARY 1975

Ecological Research Series



WATER DEPTH
(In Meters) —~1,.9~—~

SEDIMENT DEPTH
(In Meters) 1.9

Figure 3. Water and sediment depths in Lake Herman
(South Dakota Dept. of Game Fish & Parks, January 1967)

4


— 3
Tt ow r s

o 8

7 -_ 8

5 ited

imi 7

o = H
<> 7 EE
© oy ® fo} a ® = g
mo) & _1 _ 4
oS 2
ot o lo & BE



9f

APPENDIX C. Analyses of Interstitial Water From Lake Herman Sediments*

Silica Ca Total Total

Date Sol. Hardness Hardness Na___K Ci___ S04 Carbon
March 11, 1969
A-Core Hi (3" top missing

from lst foot) 36.3 370 517 40 238 245
A-Dredge A 30.9 340 700 87 36 30 740 209
B-Dredge 3 36.0 340 700 30 = ©6700 187
B-Core #3 (Top Foot) 32.4 420 567 30 525 184
B-Core #4 (Bottom 10" of

32" core) 46.8
C-Core #2 (Top Foot) 31.8 340, 400 91 35 635 )= «6800 187
July 31
South Silt 19 260 36 #19 46 350 2.4 48
Fast Silt 23 293 340 «6170 (39s 270 8.4 56
North Dredge 23 25 34° #16 =«6©70 = «6310 7.4 48

*All 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 mg/l.

Samples from August were delayed during shipment so that results on interstitial water may not be

accurate.


74

APPENDIX A.

Results of Chemical Analysis of Dredged Materials

< o
o ov a
a » x]
> a Q
x > Pod s
o Pe ou a
BS 9 Bo « § 8 $s $s
ge ks BS ed FS FQ gt te aha
goo ow BR OBS OER Ook gk EE Be ts
SD fo 83 ee de de de Se fe fe 2
Date SB 2P 82 8 S8s GP BF SF Ae 2 ef 22
October 6, 1970
Dredge 9.07 187 9.5 46.7 873 6.20 24.5 1.66 2.80 0.24 0.020 2.02
Dredge Pipe
(End) 8.34 182 2117 883 6.97 0.32 25.63
Moat
Moat Outlet 8.16 177 6.1 44.7 893 6.97 0.51 1.05
13
Dredge 8.93 185 10.4 51.5 874 6.72 24.8 1.61 3.01 0.15 0.125 1.50
Dredge Pipe
(End) 8.27 244 53.3 895 6.46 24.0 0.88 109.63 0.007 0.01
Moat 8.53 208 54.3 885 7.23 19.2 14.07 3.17 0.020 0.01
Moat Outlet 7.89 176 204 39.0 866 6.46 19.2 0.29 0.76 2.64 0.167 59.4
21
Dredge 8.97 188 10.8 38.4 873 6.20 16.8 1.72 2.02 0.12 0.025 4.64
Dredge Pipe
(End) 8.32 215 2613 862 6.20 19.0 0.38 27.60 2,90 0.027 4.18
Moat
Moat Outlet 814 181 3.6 42.6 852 6.20 12.5 0.27 1.04 1.50 80.6
November 3
Dredge 6.85 190 12.3 39.7 873 6.20 14.6 1.72 2.46 0.02 0.051 1.11
Dredge Pipe
(End)
Moat 7.98 159 34.0 834 6.20 8.25 0.19 1.10 0.18 1.01 31.5
Moat Outlet 7.97 156 37.0 785 9.17 5.50 0.17 1.11 0.30 1.88 51.4


£2

APPENDIX A. Results of Chemical Analysis of Dredged Materials
5 9
z 3 2
Ke > 2 2
3 2 a. ‘a.
x 3 z ~ g 8 gg ¢g
Sg Ba Bs 8. UR EQ FQ Be oF gi
a3 ° Soke ee be Pye) 40 xf ss as
go go aw BN BO nO BR GR OBE EEG
bate a gp ag 88 &: Se se be 82 $2 Sr ge
August 18, 1970
Dredge 9.19 163 9.0 56.9 778 4.8 27.0 1.16 1.89 0.07 0.013 3.16
Dredge Pipe
(End) 7.30 148 36.4 788 5.0 25.3 0.72 16.73 1.07 0.020 1.22
Moat 7.80 153 3.1 90.1 942 6.5 14.5 0.85 2.02 2.03 0.022 1.92
Moat Outlet
26
Dredge
Dredge Pipe
(End) 7.6 163 263 835 5.7 20.5 0.72 7.95 4.16 0.008 5.21
Moat 7.28 160 7.95 65.5 835 6.2 42.5 0.90 21.34 1.18 0.017 2.09
Moat Outlet 7.27 160 2.75 57.1 835 6.7 19.8 0.62 1.39 0.59 0.006 4,53
September 3
Dredge 9.32 * 176 59.8 797 6.7 26.3 1.48 1.96 0.06 0.036 4.19
Dredge Pipe
(End) * 8.39 200 900 817 5.4 25.1 1.08 35.90 2.14 0.015 15.5
Moat 8.35 186 ~~ 139 627 6.2 24.0 0.60 3.41 2.35 0.013 16.7
Moat Outlet 7.98 153 46.6 817 10.8 22,0 0.35 1.24 0.42 0.013 15.5
22
Dredge $.16 179 10.9 54.5 800 8.78 23.9 1.52 2.15 0.04 0.010 2,16
Dredge Pipe
(End) 250 179 681 806 8.01 19.2 0.40 28.41 1.13 0.045 3.07
Moat 8.44 176 6.8 68.1 816 6.72 18.9 0.34 2.18 2.13 0.0615 5.32
Moat Outlet 8.26 168 4.6 50.7 826 6.72 13.5 0.38 1.17 1.90 0.016 4.13


TABLES

Page
Changes in Orthophosphate From Lake to Silt Deposit Area 16

Changes in pH From Lake to Silt Deposit Area 17

vi


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 PO4/1 to 1.5 mg PO4/1 (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 >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


Tg

APPENDIX A. Results of Chemical Analysis of Dredged Materials
§ 4 i
@ & ey 83
3 = a as 3 s e g
» bd a » o 6 5 o 3
os ° bal § 38 go Cal a) ort Ort al A
& fod od TMD o aS Ss i Ey el
s so 6 Benz 35 @8 86 cf 2 2 32 se
= as of HSS & a a 66 5 2 3 3
Date & [= [er Pa oF 82 AF 2F Sf &8P &P
July 13, 1971
Dredge 24 10 43 27.5 359 80.2 0.000 0.011 43.3 0.51 33.3 18.0
Dredge Pipe
(End) 4590 365 73.7 0.004 6.082 34.9 2.67 34.5 18.7
Moat
Moat Outlet
20
Dredge 28 7 46 27.2 379 83.7 0.008 0.022 42.0 0.04 34.0 17.2
Dredge Pipe
(End) 22 3900 359 84.1 0.004 0.176 37.8 2.72 32.5 19.3
Moat
Moat Outlet
August 18
Dredge 2 ° 6 32 44.0 412 94.5 0.007 0.018 40.7 0.02 33.4 19.3
Dredge Pipe
(End) 24.5 7600 392 88.7 0.003 0.106 33.3 1.94 32.8 21.0
Moat 25.5 4200 399 88.7 0.005 0.023 36.5 1.38 33.9 20.3
Moat Outlet
25
Dredge 24 6 22 40.0 426 92.9 0.003 0.013 39.2 0.41 36.4 19.6
Dredge Pipe
(End) 6100 412 85.3 0.004 0.063 35.5 1.93 35.3 21.1
Moat 3 4570 is 85.7 0.002 0.040 36.0 1.43 34.7 21.7
Moat Outlet + 39.0 439 93.7 0.003 0.019 35.8 1.74 35.3 22.2


ze

APPENDIX A.

Results of Chemical Analysis of Dredged Materials

ag 8 _
® & “ 53
8 = “ af € S s ‘o €
Fs} on a PeS o § & 5
Pa ce od 33> ae BS oat 2 aa el et Ga
o oe Pod wt £ Ae o o eo oO 2 0 a
Po Us DO $5 00 a6 cw c a oe es
§ $e ge 383 5. ap fe Ee $2 de 32 3
Date e — oe evs se S2 88 AP Pf 2f SP 2eP
September 1, 1971
Dredge 23 6 33 405 86.6 0.003 0.022 37.0 0.20 32.9 191
Dredge Pipe
(End)
Moat 23 i 250 5066 0.007 0.108 23.1 0.70 21-1 17-1
Moat Outlet
13 .
Dredge 19 6 30 37 446 92.0 0.003 0.040 37.8 0.04 33.5 19.1
Dredge Pipe
(End) 19 2600 422 88.3 0.005 0.105 35.2 1.19 33.5 20.0
Moat 3800 431. «Ss 8843. -0.011 0.102 34,8 = 1655 34.3 22.3
Moat Outlet
30
Dredge u ° 33 33.2 422 92.0 0.000 0.010 37.5 0.02 35.1 18.7
Dredge Pipe
(End) 15 1317. 419 «B7.8 += :0.005 0,006 «38.5 = 04343547 18.9
Moat 2
Moat Outlet 17 449 419 87.0 0.007 0.008 36.0 1.58 34.9 19.7
June 12, 1972
Dredge 24 6 55 23.1 393 . 0.013
Dredge Pipe
(End) 644 412 0.037
Moat 3147410 0.337

Moat Outlet


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


PREFACE

The Lake Herman Development wishes to express appreciation to the
following for their assistance with the project.

1.

2.

4.

5.

7.

8.

9.

City of Sioux Falls, South Dakota for leasing the dredge
for the project.

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.

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.

George Hilde who loaned and operated his crane for unloading
the dredge after its move from Sioux Falls.

East River Electric Power Cooperative for the loan of its
cranes on two occasions to help with the project.

Lake County Board of Commissioners for allocating $5,000
per year toward financing the project.

South Dakota Game, Fish and Parks Department for supplying
fuels and lubricants for the dredge.

Dakota State College scientists for assisting with the
research for the project.

Office of Economic Opportunity for Supplying a number of
positions to assist with the operation of the dredge.

li


ce

APPENDIX C, Analyses of Interstitial Water From Lake Herman Sediments

P N
P Total N Total N N Total

Date Ortho Sol. NHK NOx NOD Al d.
March 11, 1969
A-Core #1 (3” top missin:

from Ist foot. 1.0 11 9.9 21300 £.01 1183 8.3
A-Dredge A 1.5 1.5 3.0 5.2 08 <.01 378 1446 8.3
B-Dredge 5 2.2 3.0 5.4 08 ¢€.01 1446 8.3
S-Core #3 (Top Foot) 84 1.0 5.8 05 = €. OL 1407 7.9
B-Core #4 (Bottom 10" of

32” core) 2.4 2.6 14.0 8.2
C-Core #2 (Top Foot) 56 8.0 08 01 334 999 8.4
July 31
South Siit 208 216 222 2.9 202 <.01 196 927 7.5
East Silt 236 250 1.9 4.6 +02 2.01 228 986 7.4
North Dredge 19 2B 1.4 4.0 204 OL 219 933 75
March 2, 1970
Core A' (Top 5 in.) 72 292 6.0 204 +02 888
Core A' (Middle 6+”) 1.12 1.6 946 206 102 897
Core A’ (Bottom 74") 0 Ar-) Bai 205 <.01 703

All concentrations are in mg/l.

Samples from August were delayed during shipment so that results on interstitial water may not be
accurate.


SECTION II
SUMMARY

Dredging was used as a method to remove 47,860 m3 (62,000 yd>) 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.


1.

2.

SECTION IV
RECOMMENDATIONS

Dredging operations on a lake should be carried on continuously—
24 hours a day, seven days a week— during dredging seasons.

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.

A smaller lake should be dredged completely to determine the
effects of complete silt removal on the dynamics of a lake.

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.

The responsibility for dredging operations should be assumed by
a governmental entity or agency to help insure its efficiency
and its continuation.


EPA-660/3-74-017
February 1975

SILT REMOVAL FROM A LAKE BOTTOM

by

Constance L. Churchill
Clyde K. Brashier
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.8. Government Printing Office, Washington, D.C. 20402


APPENDIX A, Results of Chemical Analysis of Dredged Materials

& 3 1a

2 £ 3 Ae g

Bg . 8 Bes g s. 38 5

i fo z= te BES S$ HBS &

@ £8 § des Bo 2o @ gece gf ge Be
Date & 8© of ees sf SF 8h AP 3f $3? SF ecF
October 6, 1970
Dredge 16 7 4. 20.5 405 85.9 0.00 0.02 44.1 0.03 39 18.9
Dredge Pipe
(End) 3891
Moat
Moat Outlet 18 41.1

13
Dredge 7 7 26.3 395 81.7 0.01 0.04 42.4 0.04 38 18.2
Dredge Pipe
(End) 6625 390 77.9 0.00 0.08 41.3 1.06 39 18.4
Moat 7.5 3 5250 375 8.12 0.00 0.18 40.8 0.63 39 19.4
Moat Outlet 8.5 40.0 365 79.8 0.00 0.06 39.2 0.69 39 18.5
2

Dredge 10 7 50 21.0 400 83.5 0.01 0.04 47.8 0.02 38 18.2
Dredge Pipe
(End) 10 1540 377 82.1 0.00 0,31 43.4 1.12 40 18.3
Moat -
Moat Outlet 12 1 56.5 385 81.2 0.00 0.18 43.4 0.76 40 18.6
November 3
Dredge 3 6 50 21.3 408 82.1 0.00 0.03 46.5 0.04 39 18.1
Dredge Pipe : .
(End) . °
Moat 2 2" 40.9 368 76.5 0.01 0.08 37.3 0.27 36 17.5
Moat Outlet 2 1 49.8 375 72.0 0.01 0.22 36.4 0.59 34 16.5


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


RESEARCH REPORTING SURIES

Research reports of the Office of Research and Development,
Environmental Protection Aqency, have been grouped into five
series, These five broad categories were established to
facilitate further development an’ application of environmental
technology. 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 lonq- 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 heen 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.


9%

APPENDIX A,

Results of Chemical Analysis of Dredged Materials

& a $
F > z
xm 2 eG $ 4§ -“ « «
£3 3 2 g 4 £ 2 § |
58 oat brawny a od a = a oF or oa
a3 oA SM Br S82 0 Pts) a2 sg aS
oO ano a TON eo ort WD ca oO, Zz hed He
x w as eg a a eS e 2 2 ee]
Date B 22 af 8F 8h GF ae SF SF EP SE BE
September 1, 1971
Dredge 8.80 211 7.7 60.5 844 5.8 37.9 1.52 2.52 0.03 0.016 3.1
Dredge Pipe
(End)
Moat 7.40 150 3.6 48.5 575 Sel 20.2 0.89 2.13 1.07 0.040 85.1
Moat Outlet:
13
Dredge 8.80 219 8.8 88.0 6.0 39.4 1.25 0.10 0.018 2.4
Dredge Pipe
(End) 8.15 216 796 5.8 34.2 0.54 0.69 0.041 5.5
Moat 7.95 217 910 7.3 24.8 0.30 2.18 0.063 11.4
Moat Outlet
30 .
Dredge 8.79 223 8.9 51.9 942 6.1 36.2 1.07 1.67 0.02 0.131 0.0013
Dredge Fipe
(End) 8.56 254 429 1062 6.6 35.4 0.91 8.59 0.23 0.013 0.0013
Moat
Moat Outlet 8.47 227 52.8 1102 7.6 31.6 0.37 5.46 0.93 0.069 0,0086
June 12, 1972
Dredge 9.00 176 14.45 50.2 817 6.2 21.8 0.53 1.39 0.031 0.0 0.0
Dredge Pipe
(End) 8.34 242 209.4 838 6.2 20.4 0.46 5.33 0.287 0.019 0.0003
Moat 7.93 411 448.3 858 5.9 16.2 0.15 27.63 1.808 0.0 0.0121

Moat Outlet


s¢

APPENDIX B, Results of Chemical Analyses of Lake Herman

c o
& 2 z
x > £ 2
roy Pe a a
SS 3 Be - 8. 3. & $$ §
Eg 2s B35 sh FS RS sh th th
as o Ssw7O ket on ° 2 “ad ex oo ot fo]
g° 3° < Bg. 22 28 § se 92 $2 &
Date BSF SF 8F S888 6P af S&F SF FP Sf se
Aug. 18, 1970
North 9.04 163 9.2 62.0 788 4.8 27.8 1.28 1.98 0.10 0.017 4.30
Dredge 9019 163 9.0 56.9 778 4.3 27.0 1.16 1.89 0.07 0.013 3.16
Center 8.97 163 9.1 55.5 788 4.8 26.3 1.13 1.92 0.07 0.014 3.26
Southeast 9.63 135 11.4 61.3 730 5.8 14.3 0.61 1.51 0.10 0.009 4,20
Sept. 3
North 9.23 173 54.9 777 5.4 26.2 1.44 2.13 0.07 0.170 1.56
Dredge 9.32 176 59.8 797 6.7 26.3 1.48 1.96 0.06 0.036 4.19
Center 9.23 176 54.6 787 5.7 26.5 1.61 1.91 0.09 0.027 2.09
Southeast 9.99 138 71.3 747 5.4 20.7 0.53 1.39 0.10 0.020 3.13
22
North 9.16 177 9.8 46.7 806 5.94 21.9 1.50 2.11 0.01 0.013 1.25
Dredge 9.16 179 10.9 54.5 800 8.78 23.9 41.52 2.15 0.04 0.010 2.18
Center 9.15 176 10,2 50.2 800 6.20 23.9 1.56 2.68 0.06 0.021 2.07
Southeast 9614 168 10.0 58.1 786 7.23 22.5 1.26 2.36 0.03 0.005 1.62
Oct. 6
North 9.03 186 9.6 48.0 873 5.68 23.3 1.74 2.81 0.03 0.011 1.46
Dredge 9.07 187 9.5 46.7 873 6.20 24.5 1.66 2.80 0.24 0.020 2.02
Center 9.07 186 9.5, 42.7 873 5.68 24.5 1.71 2.34 G.01 0.018 1.40
Southeast 8.80 189 Ged 61.3 883 6.72 27.6 1.48 3.05 0.04 0.002 1.00
13
Dredge 8.93 185 10.4 51.5 874 672 248 1.61 301 0.15 0,125 1.50


PUBLICATIONS AND PAPERS

The following publications and papers are related to this project.

1,

2.

3.

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.

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.

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.

Churchill, C. L., 1971, Lake Restoration, presented at
the annual Gooch-Stephens Seminar at Baylor University.

21


Brandt
Lake

Round
Lake

Lake Madison

Figure 4. Lake Herman— Silt trap for four interconnected lakes


2.

3.

4.

SECTION III

CONCLUSIONS

Significant amounts of silt and nutrients can be removed from a lake
by dredging.

Removal of silt from a limited area within the lake did not
significantly change the dynamics of the lake.

Water mixed with the silt in the dredging operation was extremely
high in nutrients, especially phosphates.

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.

Recently deposited silt on the lake bottom was much more fertile
than earlier deposits.

Holes dredged in the accumulated silt on the lake bottom will
frequently partially refill because of wind and wave action.

An increase in vegetation occurred in the slurry deposit area
after deposition was begun.

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.

Flowers on the plants grown in silt did not survive as long as
those grown in the commercial preparations.