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
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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

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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

-------
 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)

-------