OAKWOOD LAKES BANK SHORELINE PROTECTION
PROJECT
FINAL REPORT
BY
JERRY SIEGEL
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EPA 908/>81-001
September 1982
OAKWOOD LAKES BANK SHORELINE PROTECTION PROJECT
FINAL REPORT
by
Jerry L. Siegel
East Dakota Conservancy Sub-Districu
Brookings, South Dakota 57006
EPA CLEAN LAKES GRANT NO. S804714-01
Project Officer
Ronald M. Eddy
Water Management Division
Environmental Protection Agency
Denver, Colorado 80295
WATER MANAGEMENT DIVISION
ENVIRONMENTAL PROTECTION AGENCY
DENVER, COLORADO 80295
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DISCLAIMER
This report has been reviewed by the Water Management Division,
U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute en-
dorsement or recommendation for use.
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ABSTRACT
The Oakwood Lakes are a group of shallow lakes in the Prairie
Lakes region of northeastern South Dakota. The lake area is the
site of one of South Dakota’s most highly used state parks. The
proposal to riprap the most severely eroding shoreline areas was
selected for a grant award under EPA’s Clean Lakes Program in Au-
gust, 1976. This effort followed construction of a lake tributary
sediment trap in 1976 using ASCS federal cost—sharing and local
funds. Project completion was followed by the Oakwood Lakes/Lake
Poinsett Rural Clean Water Project, a major U.S. Department of
Agriculture effort initiated in 1981 to develop water quality im-
provement measures in the lake watershed.
The shoreline protection project util-ized county, multi—
county (Sub—District) and federal funding. Areas to be riprapped
were selected by a task force of federal Soil Conservation Service,
State Department of Caine, Fish and Parks, East Dakota Conservancy
Sub—District, and Brookings Conservation District personnel. Ap-
proximately 631 m (2070 ft) of shoreline were riprapped at a total
final cost of $69,310. Most of the construction work was completed
during 1978. Two proposed areas were eliminated due to problems of
securing private easements, one was eliminated due to discovery of
archaeological artifacts during the Corps of Engineers’ Section 404
permit process, and archaeological materials were removed from one
project area prior to project construction in 1981.
Because the Oakwood Lakes are relatively undeveloped and the
surrounding area is primarily public land, unit costs for this
shoreline protection work were less than for the Lake Kainpeska
Shoreline Protection Project, a similar project on a highly devel-
oped lake.
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CONTENTS
Abstract . . . iii
Figures and Tables . v
1. Introduction . 1
The Oakwood Lakes Resource . 1
Problems Affecting the Lake . 1
2. Conclusions and Recommendations . 3
3. Development of Lake Preservation Project . . . . . . 5
Development of Project Concept and
Grant Proposal . 5
Objectives of the Demonstration Project . . 5
Multi—Entity Participation in Project
Development 5
Technical Aspects of Project Features . . . . . 6
Project Activities After Submission of Grant
Application . . . 8
4. Results and Discussion . . . 10
Selection and Design of Project Areas to
Maximize Benefit to Lake and Minimize
Benefit to Adjacent Landowners . . . 10
Economic Feasibility . . . 10
Water Quality Evaluation . . . 10
-References . . 12
Appendix
A. Water Quality Analysis 13
iv
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FIGURES AND TABLES
FIGURES
Number Page
1 Map of Oakwood Lakes showing location of
project areas 2
2 Typical cross section of project bank shoreline
works 7
TABLES
Number Page
1 Specifications for Project Bank Shoreline
Protection Works 6
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SECTION 1
INTRODUCTION
THE OAKWOOD LAKES RESOURCE
The Oakwood Lakes are a picturesque 883 hectare (2182 acre) lake
complex located about 24 kin (15 miles) northeast of the community
of Brookings in Brookings County, South Dakota.
The State Department of Game, Fish and Parks has developed a
very popular 327 hectare (808 acre) state park with camping, picnic—
ing, fishing, boating and switmuing as the main activities. The park
which encompasses a large portion of the lake shoreline has visita-
tions of about 250,000/year.
The lakes were ranked in the second of four priority groupings
by the State Lakes Preservation Committee (1977). Group 1 repre-
sented lakes which possess the most desirable overall characteris-
tics, group 4 the least desirable. Criteria used were lake depth
and size plus public accessiblity, public water, per capita in the
immediate area, public usage, and the public facility investment
around the lake. East Oakwood was ranked 59th and West Oakwood 58th
on a State Lake Significance Ranking List prepared by the State
Department of Environmental Protection (1978). Similar criteria
were used in this case. In early 1978, the lake was selected as a
State Water Quality Study Area under the Section “208” Area Water
Quality Management Program of PL92—500. Figure 1 is a map of the
Oakwood Lakes which shows the location of the bank shoreline pro-
tection areas financed through the Oakwood Lakes Bank Shoreline
Protection Project.
PBOLENS AFFECTING THE LAKE
Total drainage area is relatively small at about 6352 hectare
(15,696 acres) of which about 3790 hectare (9635 acres) contribute
directly to surface runoff. There is intermittent outflow from the
lake through a drainage way into the Big Sioux River.
The sediment deposited in the lake from bank erosion, surface
water runoff and other sources have caused a loss of depth and stor-
age, decreasing the value of the lakes as a fishery as well as the
overall recreational value.
1.
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Trap ——
Oakwood Lake
Figure 1. Map of Oakwood Lakes showing location of project areas .
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SECTION 2
CONCLUSIONS AND RECOMNENDATIONS
A special water quality study of the Oakwood Lakes under the
statewide 208 water quality planning effort (1978) concluded, “The
SCS (Soil Conservation Service) reports that lakeshore erosion is a
major sediment yielding source in this watershed and controlling
this would involve a thorough lakeshore bank stabilization project.
The present bank stabilization project along the lakeshore is attempt-
ing to correct this prob].ein and should be continued and expanded.”
Based on visual inspections subsequent to completion of project con-
struction, the bank shoreline protection works have restored severely
damaged shoreline erosion areas and will reduce future lake sedimen-
tation.
It is recommended for proposed publicly financed shoreline
protection projects that a reliable sediment budget for the lake be
developed in advance to determine whether shoreline erosion is a
major source of lake sediments. It is also recommended that the
selection of areas to be stabilized be made by a non—biased techni-
cal task force to minimize enhancement of private property.
Two aspects of project design should be evaluated carefully in
future projects. First, the benefit of adding a thin gravel filter
bed beneath the riprap should be considered. This is commonly done
when gabien structures are installed. Some sediment apparently
entered the lake when waves first washed over the completed riprap
and exposed sediments below the rock. Secondly, if a lake is sub-
ject to extreme high levels periodically from surface runoff and
if the fetch is long enough that strong winds could cause severe
wind action, the value of placing rock riprap one foot higher
vertically than in project design should be considered.
Considration should also be given to adding the following re-
quirements to construction specifications for lake shoreline riprap:
(1) the contractor shall use a method of sloping the lake bank that
does not allow any appreciable sediments to enter the lake, (2) rock
riprap shall be stockpiled on the lake bank beforehand so that it
can be placed as soon as the sloping work is completed, and (3) the
area above the riprap shall, be mulched and seeded as soon as the
riprap has been completed and inspected. Careless construction
methods can allow appreciable bank sediments to wash into the lake,
3
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heavy rains could cause considerable sheet erosion on recently ex-
posed slope banks, and the toe of the new slope could easily be
washed into the lake if the lake was at a high level and/or a wind—
storm occurred before the riprap was placed. All of these problems
occurred to some extent during construction of this project.
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SECTION 3
DEVELOPMENT OF LAKE RESTORATION PROJECT
DEVELOPMENT OF PROJECT CONCEPT AND GRANT PROPOSAL
In 1974, the Soil Conservation Service, assisting the Brookings
Conservation District, prepared an application for planning assis-
tance for the Oakwood Lakes Watershed under the PL566 small water-
shed program. The measures recommended in the watershed applica-
tion were as follows:
Terraces 99,500 Linear Feet
Grassed Waterways 320 Acres
Sediment Control Dams 4
Bank Shoreline Protection 3,100 Linear Feet
In 1976, the Brookings County Conservation District with finan-
cial assistance from the East Dakota Conservancy Sub—District, ASCS
federal cost—sharing, Brookings County Board of Commissioners, Oak—
wood Lakes Development Association, and the cooperation of landowner
Wallace Tangen, constructed one of the recommended sediment control
dams which was located on a drainage entering the northeast corner
of East Oakwood Lake.
It became apparent during that period that a PL566 watershed
project would not be implemented for some time, so local officials
began looking for another approach to implement the second phase of
lake preservation measures. A Clean Lakes proposal was submitted to
EPA for a $26,500, 50% cost—sharing grant to implement part of the
bank shoreline protection proposed in the watershed project.
OBJECTIVES OF THE DEMONSTRATION PROJECT
The objectives of the proposed project were to prolong the life
of the lake through reduction of lake sedimentation by control of
bank shoreline erosion and to improve the aesthetics of the area by
utilizing local rock piles as a source of riprap material.
MULTI-ENTITY PARTICIPATION IN PROJECT DEVELOPMENT
The Brookings Conservation District through the Brookings County
Commissioners provided $5,000 project match and located sources of
local rock. The East Dakota Conservancy Sub—District contributed
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$10,000 project match, submitted and administered the EPA Clean
Lakes grant, and provided overall project coordination. The State
Department of Game, Fish and Parks provided a $10,000 grant which
included $4,000 toward project design and construction supervision.
At the federal level, the Environmental Protection Agency provided
$34,655 cost—sharing funds for project construction. In—kind ef-
forts of the non—federal entities were used to match a supplemental
EPA grant.
Prior to project construction, the non—federal entities de-
veloped and signed a Memorandum of Agreement covering the responsi-
bilities of each agency to eliminate any misunderstanding.
TECHNICAL ASPECTS OF PROJECT FEATURES
The project involved shaping existing slough banks to a flatter,
stable slope by cut and/or fill, placing riprap on the new slope,
and establishing grass on the exposed soil areas above the riprap.
Where possible for stability, the bank was sloped shoreward from
the toe of the existing slope. In cases where this would have dis-
turbed important land features, fill was used to bring the bank to
the flatter slope.
General specifications for the project bank shoreline protec-
tion works are contained in Table 1. Figure 2 illustrates a typ-
ical cross section of project bank shoreline protection.
TABLE 1. SPECIFICATIONS FOR PROJECT BANK SHORELINE PROTECTION WORKS
(1) Maximum Project Slope — 3:1 or as shown in the plans to
blend into existing shoreline
contours.
(2) Riprap Type — Fieldstone of the type that will not dis-
integrate upon contact with the elements.
(3) Material Size — 60% in the 150 lb class (15” diameter)
20% larger than 150 lb.
20% smaller than 150 lb.
(4) Depth of Rock — A Minimum of 18”.
(5) Placement of Rock — The rock to be placed by dumping or other
mechancial means to keep the surface
fairly level and to allow the rock to
interlock. Riprap was placed three foot
vertically both aboe and below normal
pool elevation. On a 3:1 slope, the
rock would thus be placed on about 18’
of slope.
(6) Protection of Exposed Bank Areas Above Riprap — Six inches
of black dirt placed, grass planted
and guaranteed for one year.
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Normal Lake
Elevation 1720 ft. msl.
Existing Grade
of
Bank
Cut Area
6 ft. of
to Grass
3:1 Minimum Slope
(Slope may be greater to
blend with natural contours)
Riprap
18” Deep Dirt Fill
Area
Figure 2. Typical cross section of bank shoreline protection work
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The plans and specifications were checked by the EPA Project
Officer with assistance from other federal technical experts in
Denver and approved prior to bid letting.
PROJECT ACTIVITIES AFTER SUBMISSION OF GRANT APPLICATION
Shortly after the EPA grant application was submitted on
April 15, 1976, the Brookings Conservation District held an in-
formational meeting and tour of the entire watershed project in-
cluding proposed sediment traps, shoreline riprap areas and feed—
lot runoff problem areas. The District, with technical assistance
from the Soil Conservation Service, planned to design project works,
call for bids, and handle construction contracts. In late July,
representatives of the participating agencies met and established
priorities for twelve shoreline erosion areas which had been iden-
tified as the most severe around the lake.
A $26,500 EPA grant was awarded to the East Dakota Conservancy
Sub—District August 10 with the Sub—District Manager Jerry Siegel
named project manager. That same month the Soil Conservation Ser-
vice provided notice that due to loss of personnel they could not
provide futher engineering assistance. After a series of meetings,
the Department of Game, Fish and Parks agreed to take over engineer-
ing responsiblities. The change of engineers altered the design
concept. The District originally planned to dump rock over the
eroding bank without formal engineering design or detailed speci-
fications and, thus, without shaping the bank. Department of Game,
Fish and Parks engineers imposed the requirement for bank shaping
and placement of the rock according to more detailed specifications.
Because of this, the Department was required to take over responsi-
bility for bid letting, handling construction contracts, and super-
vision during construction.
John Brink, EPA—Denver Clean Lakes Coordinator, examined and
approved the selected project sites on September 21. The require-
ments for a Corps of Engineers’ Section 404 permit for placement of
lake shoreline riprap became effective October 1. This regulatory
burden, plus the loss of the Department’s chief design assistant,
caused a year’s delay in preparation of final plans for project con-
struction. New EPA—Denver Clean Lakes Coordinator Bruce Perry
toured the lakes in May, 1977 and concurred in the priorities set
for installation of erosion protection measures.
On January 31, 1978, final plans and specifications were trans-
mitted to EPA—Denver for review, At the same time, a 404 permit
application was submitted to the Corps of Engineers. Bids were
opened on March 9 for areas 1—5, all of which were located on Depart-
ment public lands. Because the bids were much lower than engineer-
ing estimates, areas 6—9 which were located on private lands, were
added to the construction contract. Debbie Patterson, who became
EPA Clean Lakes Program Coordinator during this period, concurred
in the awarding of the contracts.
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During the 404 permit review by the State Historical Preserva-
tion Office, Indian artifacts were discovered at areas 1, 7 and 9.
After looking over these areas with State Historical Preservaiton
Office archaeologist Steve Ruple and the local project manager on
April 26, Ms. Patterson determined that EPA would need to make an
archaeological survey of these three sites. An EPA stop—work order
was issued July 25, 1978. Areas 7 and 9 were eliminated from the
project by the Project Administrator and Project Engineer due to
difficulties in securing easements and working on private lands, so
the archaeological survey was required only for area 1. Construc-
tion on areas 2, 3, 4, 5, 6 and 8 commenced on June 5 and was es-
sentially completed by September 1, 1978.
EPA contracted for an archaeological survey of area 1 in early
October, 1978. From the survey it was concluded that there were
three options for handling area 1. (1) The area could be eliminated,
(2) the area could be stabilized without sloping the bank, or
(3) archaeological resources could be removed and the area stabil-
ized as originally designed. In September, 1979, new EPA Project
Officer Ron Eddy secured EPA funds for archaeological evaluation of
area 1. The work was done in October-November, 1979. The EPA
stop—work order was cancelled on March 28, 1980.
Due to inflationary construction cost increases caused by the
extended work stopage, remaining funds were not sufficient to con-
struct area 1. A supplemental EPA 50% cost—sharing grant of $8,155
was received on April 1, 1980 to allow completion of the project.
Due to unavailability of project engineer’s staff to revise the
detailed plans and call for bids, construction of erosion protection
measures on area 1 was delayed until the spring of 1981. Project
construction was completed in May, 1981.
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SECTION 4
RESULTS AND DISCUSSION
SELECTION AND DESIGN OF PROJECT AREAS TO MAXIMIZE BENEFIT TO LAKE
AND MINIMIZE BENEFIT TO ADJACENT LANDOWNERS
The Oakwood Lakes are relatively undeveloped with much of the
shoreline held in public ownership. Development of shoreline pro-
tection can increase the value of the adjacent property since
slough banks are an eyesore and can threaten the existence of por-
tions of the property. Thus, areas to be stabilized were selected
by a technically oriented multi—agency task force. Selected areas
were the most severe sloughing banks and the riprap was placed only
high enough on the banks to protect them from erosive wave action.
ECONOMIC FEASIBILITY
For the Oakwood Lakes, 631 m. (2070 ft.) of shoreline were
stabilized at a total project cost of $69,310 for a unit cost of
$110 per m. ($38.5 per ft.) of shoreline. The cost per unit length
was somewhat higher for a similar project on Lake Kampeska, a more
highly developed lake located about thirty miles northwest: 1152 m.
(3780 ft.) were stabilized at a total project cost of $147,208.80
for a unit cost of $128 per m. ($39 per ft.)
Assuming (1) a dredging cost of 1.95 per cubic meter (1.50 per
cubic yard), (2) that the bank material would swell 20% when it was
deposited in the lake, and (3) an average bank height of 3.6 m.
(12 ft.), the installed riprap would need to eliminate erosion
of at least .37 m. (1.2 ft.) of bank into the lake before the shore-
line protection would be more cost effective than removing the
material by dredging once it had entered the lake.
WATER QUALITY EVALUATION
Although there were no project funds allocated for water qual-
ity monitoring, some samples were collected and analyzed through a
cooperative East Dakota Conservancy Sub—District/South Dakota De-
partment of Environmental Protection lake monitoring program during
1975—1978. A composite of three grab samples collected at 0.5 in
depth was analyzed for each sampling occasion at the State Health Lab
in Pierre. Although none of the main water quality labs in the state
were equipped to analyze chlorophll a, the Sub—District financed
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the collection and analysis of some chlorophyll a samples by Randall
Brich, a Department of Biology graduate student at South Dakota
State University.
An evaluation by the Department of Water & Natural Resources —
Division of Water Quality of the water quality data collected
through this project and other sources since 1975 is contained in
the appendix.
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RE FE RENCE S
1. State Lakes Preservation Committee. 1977. A plan for the
classification—preservation—restoration of the lakes in north-
eastern South Dakota. State of South Dakota and the Old West
Regional Commission.
2. South Dakota Department of Environmental Protection. 1978.
Unpublished lake significance ranking list.
3. The South Dakota Statewide 208 Water Quality Management Plan.
Department of Environmental Protection, Office of Water Qual-
ity, November 1978, pp. 75—78.
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APPENDIX A. WATER QUALITY ANALYSIS
Sampling was initiated in the fall of 1975 and continued through
spring of 1978 to determine the effects of shoreline riprapping on
in—lake water quality. Samples were collected in West Oakwood, at
the boat landing in the southeast quadrant, near the boat launch in
the northeast quadrant, and near the gravel road in the northwest
quadrant. East Oakwood samples were collected near shore at the north
end of the lake along the gravel road, near the center of the west
side in the state park, and on the extreme south end along the black-
top road. Three grab samples were collected and composited for analy-
sis. Samples were collected with a Van Darn bottle at approximately
0.5 m depth. Since samples were composited no valid statistical an-
alysis could be performed on the results so the following analysis is
based on observation of general trends within the data.
Seasonal trends as influenced by natural factors within the Oak—
wood Lakes ecosystem were evident (Table 2) but trends or water qual-
ity changes affected by the project work were limited at best (Tables
3—10). Total solids, total suspended solids, total dissolved solids,
and conductivity showed no definite trends through the sampling period.
Frequency and intentsity of sampling were probably inadequate to assess
the subtle changes that would be expected from riprapping only a por-
tion of a large windswept lake. Visual assessment of the benefits to
a particular zone of the lake adjacent to, or in the prevailing wind
pattern of the riprapped area would probably more accurately describe
water quality improvements than the sampling regime that was conducted.
During 1978 there were decreases in TS and conductivity in West Oakwood
indicating possible improvements due to the project works. Samples
collected during suimner 1979 in conjunction with compilation of the
South Dakota Lakes Classification Survey also show reductions in TS
and conductivity in East Oakwood. West Oakwood samples collected dur-
ing the same project show decreases in TS. Samples collected during
suimner 1979 in conjunction with compilation of the South Dakota Lakes
Classification Survey also show a reduction in TS values. These water
quality changes could be expected as a result of shoreline erosion
control but since construction activities did not end until 1978 the
changes observed may only reflect the cessation of heavy equipment
operating on the project areas. Water quality parameters from East
Oakwood Lake are basically only baseline measurements since construc-
tion on sites 1 and 9 were not completed until 1981 due to funding
problems. Determinations of the impact of riprapping activities on
water quality of Oakwood Lakes are also limited by sheer size of the
riprapped area in comparison to the entire shoreline. Only a small
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percentage of the shoreline was treated for erosion control so even if
total control was achieved on those areas, windblow sediments from un-
treated areas would easily interfere with water quality monitoring of
project areas (Figure 1).
Future projects of this type should perhaps have a somewhat mod-
ified monitoring and evaluation program. Monitoring of water quality
in proposed riprap areas should commence at least one seasonal cycle
before construction begins and continue through one seasonal cycle
following completion of construction so to include the “control”
seasonal time period in post construction monitoring. If this approach
is followed a small sample of basline data can be compared to post
treatment data that has been collected in a similar manner from iden-
tical sites. Emphasis should be placed on physical parameter measure-
ments such as secchi depth, wind direction, speed, and prior duration
(i.e. several days from the same direction prior to sampling), pre-
cipitation, TSS, TDS, TS, and conductivity. These parameters should
more directly reflect the effects of sediment reduction structures or
procedures. Further information regarding Oakwood Lakes can be found
in the South Dakota Lakes Classification Survey 1981.
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Table 1. West Oakwood Lake 1975—1978 — Seasonal Means of Selected
Parameters.
1975 1976 1977 1978
NH 3 —N Spring 1.01 3.16 3.1
Summer — .02 .1 —
Fall NA .03 .66
Winter 4.9 4.32 6.76
NO 3 Spring .1 .10 .15
Sunnuer l 410 —
Fall Li <.1 .10
Winter Al (1 .07
NO 2 Spring - NA .02 .02
Summer — NA .01 —
Fall NA NA .01
Winter NA NA .01
T—PO 4 Spring .185 .136 .199
Summer .370 .223 —
Fall .262 .275 .198
Winter .188 .149 .158
O—P0 4 Spring .047 .035 .094
Summer — .240 .049 —
Fail NA .225 .014
Winter .011 .002 .006
TSS Spring 47 27 99.5
Summer 159 58 —
Fail 86 51 63 —
Winter 52 28 37
TDS Spring 634 1050 791
Summer 953 1158
Fall 852 1265 949
Winter 1081 1413 1426
TS Spring 680 1077 791
Summer — 1112 1249
Fail 938 1316 1012
Winter 1133 1441 1463
FECAL COL. Spring - .(3 5 <3
Summer — (3 dC3 —
Fail 3 27 60
Winter 3 43 8
COND MHO Spring — 765/23°
Summer — 1090/23° —
Fall 930/23° 1240/22° 1090/23°
Winter 1340/23° — —
15
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Table 2. East Oakwood Lake 1975—1978 — Seasonal Means of Selected
Parameters.
1975 1976 1977 1978
NH 3 —N Spring — 1.09 .92 6.5
Summer — (.02 .69 .165
Fall 2.40 3.48 .34 —
Winter — — 4.34
NO 3 Spring l l0
Summer (1 < .l0 (.10
Fall 41 (.10 —
Winter — .l0
NO 2 Spring NA NA .015
Summer — NA .01 .01
Fall NA NA .01 —
Winter — — .01
T-PO 4 Spring .204 .161 .098
Summer .410 .205 .052
Fall .419 .250 .182 —
Winter — — .110
O—PO 4 Spring .072 .031 .018
Suxmner .300 .057 .013
Fall .042 .002 .014 —
Winter — — .004
TSS Spring 47 48 79
Summer 100 155 98
Fall 59 87 138 —
Winter 17
TDS Spring 856 1531 1575
Summer 1490 1464 2032
Fall 1093 1979 1520
Winter 1821
Spring 918 1579 1479
Summer 1590 1631 2130
Fall 1157 2066 1658
Winter 1838
FECAL COL. Spring Z3 3 4.8
Summer 3 23 20
Fall 48 NA
Winter 3
COND. MHO Spring 1005/23° 1610/24° —
Summer — 1610/23° — 2045/23°
Fall 1230/23° 1960/22° 1670/23° —
Winter — — 2000/24°
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I - .
Sediment
Sample Site*
Riprapping
Blacktop Rd.
Gravel Rd.
West Oakwood Lakes*
1 mile
EAST OAKWOOD
LAKE
Figure 1.
Map of Oakwood Lakes showing locations of project areas
and water quality monitoring sample sites.
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Table 3. West Oakwood Lake 1975 — Selected Parameters.
Date 9—5—75 11—19—75 12—30—75
No. Samples 3 3 3
NH 3 —N NA 3.20 6.6
NO 3 1 l <1
NO 2 NA NA NA
T—P0 4 .262 .216 .159
O—P0 4 ND ND .011
TSS 86 62 41
TDS 852 922 1240
TS 938 984 1281
FECAL COL. 3 (3 <3
COND. MHO 930/23° 1140/23° 1540/23°
18
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Table 4. West Oakwood Lake 1976 — Selected Parameters.
Date 3—25—76 5—26—76 8— 4—76 9—14—76 11—16—76
No. Samples 3 3 3 3 3
N11 3 —N 2.00 .O2 .02 .03 4.32
NO 3 (l <1 <1 <1 <1
NO 2 NA NA NA NA NA
T—P0 4 .195 .175 .370 .275 .149
0—P0 4 .084 .009 .240 .225 .OO2
TSS 57 36 159 51 28
TDS 435 832 953 1265 1413
TS 492 868 1112 1316 1441
FEC AL.C0L. <3 < <3 27 C3
C0ND.k HO 590/23° 940/23° 1090/23° 1240/22°
19
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Table 5. West Oakwood Lake 1977 — Selected Parameters.
Date 1—18—77 3—8—77 53-’77 8—5—77
No. Samples 3 3 2 1
NH 3 —N 8.1 5.80 .51 .12
NO 3 .03 lO (.lO 1O
NO 2 .00 .01 .03 .01
T—P0 4 .181 .126 .146 .232
O—P0 4 .002 .040 .029 .037
TSS 12 21 33 58
TDS 1776 1001 1098 1014
TS 1788 1002 1131 1072
FECAL COL. 13 (3 7 <3
CONDU. MHO 1890/23° 1180/24° 1140/25° NA
Date 8—10—77 9—27—77 12—13—77
No. Samples 3 3 3
NH 3 N .08 .66 5.42
NO 3 /,.10 ç.1O <.10
NO 2 <.01 .01 .01
T—P0 4 .214 .198 .135
O—P0 4 .060 .014 .009
TSS 63 61
TDS 1301 949 1076
TS 1426 1012 1137
FECAL COL. iC3 60 43
QJND. MHO 1350/23° 1090/23° 1320/24°
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Table 6. West Oakwood Lake 1978 — Selected Parameters
Date 3—8—78 4—25—78 5—10—78 5—23—78
No. Samples 3 3 3 3
NH 3 —N 8.25 1.00 .03
NO 3 <.l0 .2 .2 <.1
NO 2 .01 .03 .01
T—P0 4 .330 .223 .102 .141
o—P0 4 .241 .015 .027
TSS 79 55 43 22
TDS 1356 582 605 621
TS 1435 637 448 643
FECAL COL. ‘ 3 <3
COND.4 1 NH0 1650/24° 760/22° 730/22° 750/24°
21
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Table 7. East Oakwood Lake 1975 — Selected Parameters.
Date 9—5—75 11—19—75 12—30—75
No. Samples 3 3
N}i 3 —N NA 2.40 .49
NO 3 -l -.. ..1 (1
NO 2 NA NA NA
T—P0 4 .144 .153 .198
O—P0 4 ND .042 .028
TSS 93 25 70
TDS 1051 1135 1570
TS 1154 1160 1640
FECAL COL. 3 Z .3
C0ND. ,i MHO 110/23° 1350/23° 1850/23°
22
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Table 8. East Oakwood Lake 1976 — Selected Parameters.
Date 3—25—76 5—26—76 8—4—76 9—14—76 11—16—76
No. Samples 3 3 3 3 3
NH 3 —N 2.15 .02 <.02 .25 6.70
NO 3 <1 <1 <1 <1
NO 2 NA NA NA NA NA
T—P0 4 .249 .158 .410 .355 .145
0—P0 4 .139 .004 .300 ND 4 .OO2
TSS 50 43 100 127 47
TDS 544 1168 1490 1964 1994
TS 594 1241 1590 2091 2041
FECAL COL. < 3 Z3 &3 93 <.3
C0ND. 4HO 710/23° 1300/23° 1610/23° 1960/22° NA
23
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Table 9. East Oakwood Lake 1977 — Selected Parameters.
Date 5—3—77 8—10—77 8—31—77 9—27—77 12—3—77
No. Samples 3 3 3 3
NH 3 —N .92 .21 .95 .34 4.34
NO 3 .lO <10 .l0 (.10 (.10
NO 2 NA .01 .01 .01 .01
T—P0 4 .161 .248 .162 .182 .110
0—po 4 .031 .077 .037 .014 .004
TSS 48 NA 155 138 17
TDS 1531 1271 1656 1520 1821
TS 1579 1451 1811 1658 1838
FECAL COL. 3 23 NA NA 3
COND.((MHO 1610/24° 1390/23° 1670/22° 1670/23° 2000/24°
24
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Table 10. East Oakwood Lake 1978 — Selected Parameters.
Date 3—8—78 4—25—78 5—10—78
No. Samples 3 3 3
N}1 3 —N 16.8 2.67
NO 3 (.10 4.10 Z.lO
NO 2 .01 .03 .01
T—P0 4 .104 .100 .091
O—P0 4 .029 .011 .015
TSS 190 60 58
TDS 2905 886
TS 3095 946 934
FECAL COL. Z. 10 3
COND)qMHO 3100/24° 1060/22° 1004/2°
Date 5—23—78 8—2—78 831—78
No. Samples 3 2 3
NH 3 —N .04 .31 .02
NO 3 410 .10 .1
NO 2 .01 .01 <.01
T—P0 4 .095 .074 .029
O—P0 4 .016 .021 .005
TSS 9 49 147
TDS 933 992 3072
TS 942 1041 3219
FECAL COL. < 3 17 23
C0ND. s MHO 1140/23° 2590/23°
25
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Table 11.
East Oakwood Lake Chlorophyll a Data secured by East
Dakota Conservancy Sub—District for EPA Lake Restora-
tion Project.
Station 1—S — South side near Highway 30
Station 2—S — West side in State Park
*caicu] tjong based on acidified samples; phaeo—pigments are
inactive forms of cholorphyil
Date
Station
a
(mg/iT
Clii.
(mg/iT
7/25/77
1—S
i—S
2—S
2—S
340.3
198.5
255.0
228.4
223.6
142.4
197.6
117.5
8/30/77
1—S
1—S
2—S
2—S
284.7
311.9
151.3
257.4
238.6
220.8
52.2
104.5
9/26/77
1—S
i—S
2—S
2—S
272.5
325.6
265.7
284.6
251.1
277.8
234.5
260.5
10/27/77
i—S
1—S
2—S
2—S
63.0
52.4
43.4
32.8
24.2
16.0
26
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*calculations based on acidified samples; phaoe—pigments are
inactive forms of chlorophyll
Chi.
( mg/i )
1—S
i—S
2—S
2—S
223.0
237.5
208.1
288.2
7/25/77
8/30/7 7
9/26/77
10/27/77
179.8
174.4
153.1
275.9
1—S
1—S
2—S
2—S
121.6
137.1
46.1
126.4
Table 12. West Oakwood Lake Chlorophyll a Data secured by East
Dakota Conservancy Sub—District for EPA Lake Restora-
tion Project.
Chi. a
Date Station ______ ( mg/fY
Station 1—S — Resort (8outh quadrant)
Station 2—S — Boat landing (northeast quadrant)
80 . 7
97.3
26.1
78.3
1—S
1—S
2—S
2—S
142.2
194.9
187.3
181.4
132.6
180.0
172.9
172.9
1—S
1—S
2—S
2—S
29.5
35.6
17.8
30.4
16.0
21.4
12.5
27
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