5.2. SR 09-22-1997ITEM 5.2.
~ty of
Memorandum
iver
FROM:
MAYOR AND CITY COUNCIL
STEPHEN ROHLF, BUILDING
AND ZONING ADMINISTRATOR
DATE:
SEPTEMBER 22, 1997
SUBJECT: DRAFT STUDY ON LAKE ORONO
Attached for your review is a copy of the draft Lake Orono Sedimentation and
Water Quality Study. To save money, the consultant for this study, Andrew
Syverson of Wenck Associates, Inc., will not be at Monday night's meeting.
He will, however, be at the council meeting when the final study is presented.
Hopefully, staff will be able to address questions you have on the draft study.
As of the end of August, 1997, a little more than $17,000 has been spent on
the study. There are additional issues, such as fecal coliform levels in the
lake, that staff would like to further study prior to finalizing the report.
These items that need further research will raise the cost of the study, but
will also give a more complete picture that better prepares the city for the
permitting process, when a project proceeds. Even with these additional
items the total cost for the study will be far below the $29,000 originally
estimated.
When the final study is presented to the City Council, staff and the Lake
Orono Improvement Association will also present our recommendations on
what a lake improvement project should include. Our preliminary thoughts
are to deepen certain designated areas of the lake to accommodate high speed
watercraft, while other areas would be designated, with signage, for only
slow speed boating. In addition, some sort of basin where the Elk River runs
into the lake to slow future sedimentation has been discussed.
Financing a future project is going to be a difficult issue. We hope to have
cost estimates to go along with our recommendation on a lake improvement
project. To that end we are requesting permission from the City
Council to lower the lake as much as four feet. Lowering the lake will
allow us to have potential lake improvement contractors estimate the
quantity of material proposed be removed so we can come up with at least
rough cost estimates. Lowering the lake will also allow the contractors to
determine what equipment is best for a project.
f:\shrdoc\b&z\stever\lowlake.doc
13065 Orono Parkway · P.O. Box 490 · Elk River, MN 55330 · TDD & Phone: (612) 441-7420 · Fax: (612) 441-7425
If an adequate estimate of material to be removed can not be obtained from
contractors or no contractors are interested, staff is requesting permission
to have the City Engineer's survey crew take enough shots to
estimate volumes.
We are requesting the lake be lowered by the following schedule:
October 15, 1997 - two feet
October 16 - three feet
October 17, 18, & 19 - four feet
October 20 - lake back to normal elevation
We are proposing that the lake remain four feet below normal on Saturday
and Sunday, October 18 & 19, so lake owners will have a chance to clean
their shoreline, if desired.
City staff has also been in contact with the DNR regarding our proposal to
temporarily lower the lake. If the City Council and DNR grant permission to
lower the lake, the Lake Orono Improvement Association will do a direct
mailing to notify lake owners and city staff will run a notice in the Elk River
Star News.
f:\shrdoc\b&z\stever\lowlake.doc
Lake Orono
Sedimentation
and
Water Quality
Study
Wenck File #0598-01
Prepared for:
CITY OF ELK RIVER
Prepared by:
WENCK ASSOCIATES, INC.
1800 Pioneer Creek Center
P.O. Box 428
Maple Plain, Minnesota 55359-0428
(612) 479-4200
DRAFT
Lake Orono
Sedimentation and
Water Quality
Study
Draft
September 1997
~Wenck
DRAFT
Table of Contents
go
INTRODUCTION ............................................................................................................. 1
A. BACKGROUND INFORMATION ............................................................................. 1
B. SCOPE OF INVESTIGATION .................................................................................... 1
II.
DESCRIPTION OF INVESTIGATION AND RESULTS ............................................ 3
A. LAKE SEDIMENT SAMPLING ................................................................................. 3
1. Sediment Sampling Procedures ........................................................................ 3
2. Chemical Analyses ............................................................................................ 4
3. Physical Analyses ............................................................................................. 5
B. WATER QUALITY MONITORING ........................................................................... 5
1. Suspended Solids and Phosphorus Monitoring ................................................ 5
2. Suspended Solids and Phosphorus Loading ........................... . .......................... 6
3. Fecal Coliform and Fecal Streptococci Monitoring .......................................... 7
C. COMPARISON OF 1970 AND 1996 DNR LAKE SURVEYS .................................. 8
III.
SEDIMENTATION AND WATER QUALITY ANALYSES .................................... 11
A. SEDIMENTATION RATES ...................................................................................... 11
1. Volumetric Comparison of 1970 and 1996 DNR Lake Surveys .................... 11
2. Sediment Loading Analysis ............................................................................ 12
B. WATER QUALITY ASSESSMENT ......................................................................... 14
1. Suspended Solids and Phosphorus .................................................................. 14
2. Fecal Coliform and Fecal Streptococci ........................................................... 15
IV. CONCLUSIONS ............................................................................................................. 17
V. RECOMMENDATIONS ................................................................................................ 18
TABLES
1
2
3
Water Quality Data
Storm Event Monitoring Data
Fecal Coliform and Fecal Streptococci Data
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DRAFT
Table of Contents (Cont.)
FIGURES
1 Site Location Map
2 Elk River Watershed
3 Monitoring Station Location Map
APPENDICES
A
B
C
D
E
F
Lake Sediment Chemical Data
Lake Sediment Physical Data
Water Quality Monitoring Data
Loading and Sedimentation Rate Worksheets and Figures
Streamflow Gauging Data
DNR Lake Surveys
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DRAFT
Introduction
A. BACKGROUND INFORMATION
Lake Orono is a 254 acre lake with a mean depth of approximately 5 feet. Lake Orono is also
identified as Minnesota Department of Natural Resources (DNR) Protected Water 71-13P. The
lake was created when the Elk River Dam was constructed in 1915. The Elk River Dam is
located approximately 1.1 miles above the confluence of the Elk River with the Mississippi
River, in the City of Elk River, Sherbume County, Minnesota (Figure 1). Drainage from the
388,000-acre Elk River watershed flows through Lake Orono, dominating the lakes water quality
(Figure 2).
B. SCOPE OF INVESTIGATION
The City of Elk River hired Wenck Associates, Inc. in June 1996 to perform a sedimentation
study for Lake Orono. The study is a cooperative effort with Sherburne County and the Lake
Orono Improvement Association. The scope of the project included review of the watershed and
development and implementation of a monitoring plan. Major inflows and the outflow from
Lake Orono were monitored 18 times over a one year period, and sediment and phosphorus loads
were calculated for these. Minor inflows to Lake Orono were monitored during three storm
events. Lake sediment was sampled and chemical and physical analyses performed. Lake Orono
was remapped by the DNR in 1996 and lake volume comparisons were made with a map
prepared by the DNR in 1970. Additional lake and river monitoring was also conducted for fecal
coliform and fecal streptococci contamination. The monitoring, analysis and findings of the
N:\0598\01 LELKRIVE1LRPT-rlb 1
investigation are documented in this report.
also provided.
DRAFT
Recommendations for managing Lake Orono are
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DRAFT
II.
Description of Investigation and Results
A. LAKE SEDIMENT SAMPLING
1. Sediment Sampling Procedures
Four sediment sampling locations were identified in cooperation with the Minnesota Pollution
Control Agency (MPCA) to characterize sediment within Lake Orono in preparation for
anticipated future dredging activities. Sampling locations are indicated on Figure 3. Per the
MPCA's suggestion, samples from the upper 6-inches of sediment were obtained with a Ponar
dredge at each of the four sampling locations. Sediment cores were also collected to a depth of
4 feet by two methods described below.
Sediment coring was completed using a modified Wildco K-B stainless steel core sampler. This
core sampler collected sediment samples that were 2 inches in diameter and 20 inches in length.
The K-B sampler utilized clear cellulose acetate butyrate (CAB) core liners and eggshell-type
core catchers. The sampler was manually lowered into the water and penetrated the sediments by
either the force of its own weight or by being pushed or driven as dictated by sediment
consistency. After the sampler reached maximum penetration, it was carefully retrieved and
disassembled. The filled liner was then removed from the core tube, capped and labeled. The
core sampler was then cleaned using a non-phosphate detergent solution and deionized water
rinses and reassembled with new liner tube.
Sediment samples were also collected utilizing a modified 3-inch stainless steel AMS bucket
auger. A 4-inch diameter PVC casing was first driven into the sediment. The bucket auger was
then utilized to manually bore into and collect the sediment from within the PVC casing. The
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DRAFT
sediment collected in the auger was placed in a covered stainless steel bowl and thoroughly
composited. The bucket auger, extension rods and PVC casing were all cleaned between sample
locations using non-phosphate solution and clelonlzecl water, gecllment samples were placecl on
ice in a cooler and transported to the analytical laboratory within 24 hours of sampling. Samples
were also transported to the soils engineering testing laboratory.
2. Chemical Analyses
Samples collected from the upper 6-inches of sediment were analyzed for the following "Tier I"
parameters: moisture content, ammonia nitrogen, kjeldahl nitrogen, total phosphorus, and total
organic carbon (TOC). Total organic carbon and kjeldahl nitrogen were analyzed within
48 hours and the results evaluated by the MPCA to determine at which sampling sites "Tier II"
analysis was required. "Tier II" parameters include metals, cyanide, phenol, pesticides,
herbicides, polychlorinated bi-phenyls (PCBs), and polyaromatic hydrocarbons (PAHs). A
complete list of MPCA selected "Tier II" parameters is included in Appendix A along with the
lake sediment chemical data.
Upon review of the "Tier I" data, the MPCA selected sampling locations #2 and #3 for additional
"Tier II" analysis. Sediment from sampling locations #2 and #3 had the highest TOC
concentrations of the four sampling locations and therefore the highest potential for containing
contaminants of concern.
Samples collected for "Tier II" analysis were composited from sediment collected at depths
between 0-4 feet. No organic parameters were detected at either sampling location #2 or #3. A
number of inorganic "Tier II" parameters were detected at both sampling locations, within the
normal background range for sediment. The MPCA has indicated that they have no concerns
with the quality of the sediment sampled.
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DRAFT
3. Physical Analyses
Sediment samples were also classified by a soil engineering testing firm and grain size
distribution performed on sediment from the four sampling locations. In-place cores of the top
20-inches of sediment as well as composites of sediment collected at depths between 0-4 feet
were analyzed. The above analyses are contained in Appendix B. The surface cores are denoted
as T-l, T-2, T-3, and T-4 as samples contained in tubes. The composite samples are denoted as
B-l, B-2, B-3, and B-4 as samples contained in bags. The sediment samples varied in
composition from approximately 30 to 90 percent sand and gravel and approximately 10 to 70
percent silt and clay.
B. WATER QUALITY MONITORING
1. Suspended Solids and Phosphorus Monitoring
Water quality monitoring was conducted on the major inflows and the outflow from Lake Orono.
Grab samples were collected a minimum of 18 times over a one year period from the Elk River at
County Road 15 (ERCR 15), Tibbits Brook at County Road 35 (TBCR 35), and the outflow of
Lake Orono at the dam. See Figure 3 for the location of the monitoring stations. The sum of the
drainage areas upstream of the two major inflow monitoring stations constitutes approximately
98 percent of the total Lake Orono drainage area of 388,000 acres (Figure 2). Total suspended
solids (TSS), total phosphorus, and ortho phosphorus were analyzed for each sampling event.
Volatile suspended solids (VSS) were analyzed for the last eleven sampling events. Monitoring
at the Elk River and Tibbits Brook stations was conducted by the Sherburne Soil and Water
Conservation District. Monitoring at the Lake Orono Dam was conducted by the Lake Orono
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Improvement Association. See Table 1 for a summary of the water quality data.
monitoring data are contained in Appendix C.
DRAFT
Water quality
In addition, minor inflows to Lake Orono were monitored during three storm events. See Table 2
for a summary of the monitoring data. Water quality monitoring data are contained in Appendix
C. Grab samples were collected at five locations in total. These locations are culverts under
Islandview Drive and Highway 10, and stormsewer outfalls located near 189th and Concord,
Orono Road and Mississippi Road, and Orono Road at City Hall. Samples were collected at
each location during selected sampling events. Stream flow measurements were made and
stream flows estimated at these locations at the time of sample collection. Storm event
monitoring was conducted by Wenck Associates, Inc. After sample collection, samples were
immediately placed on ice in a cooler and were transported to the laboratory within 24 hours of
collection.
2. Suspended Solids and Phosphorus Loading
The water quality and flow data were used to calculate sediment and phosphorus loading rates.
The calculations were done for TSS, VSS, TSS-VSS, (i.e., non-volatile suspended solids), total
phosphorus, and ortho phosphorus.
Samples for total phosphorus, ortho phosphorus, and TSS were collected between August 27,
1996 and August 5, 1997. Samples for VSS were collected only during the time interval April 9,
1997 through August 5, 1997. The VSS data for the remaining period were estimated from
known values of TSS using a curve fitted through the observed data (see Appendix D).
The stream inflow data were obtained for two locations: ERCR 15 and TBCR 35. The stream
outflow data were obtained at the Lake Orono Dam.
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DRAFT
The flowrates at ERCR 15 were obtained from the U.S. Geological Survey (USGS), Minnesota
District (see Appendix E). The USGS considers flow data to be "provisional" until eventual
official publication.
The flowrates at TBCR 35 were monitored by the Sherbume Soil and W~iter Conservation
District. Flowrates for 11 of the flow measurements were based on stream gauging data collected
in the field. Flow rates for the other seven monitoring events were calculated through
interpolation on a rating curve developed for the station (see Appendix E).
The flowrate at the dam was assumed to be the sum of the flowrates at ERCR 15 and TBCR 35.
Concentration data (mass/volume) were multiplied by the average flowrate (volume/day) for the
dates samples were collected to obtain the mass inflow rates at ERCR 15 and TBCR 35
(mass/day) and the mass outflow rates (mass/day) at the dam (see Appendix D).
3. Fecal Coliform and Fecal Streptococci Monitoring
Grab samples were collected from four locations on the Elk River and two locations in Lake
Orono (see Figure 3). The samples were collected to verify reported elevated bacterial counts at
the municipal swimming beach on Lake Orono as well as to identify potential bacterial source
locations. The samples were collected using sterile Whirl-Pack sample containers. The Whirl-
Packs were attached to a 15-foot pole to allow the samples to be collected away from the river
bank. The containers were filled approximately 6-inches below the water surface. Upon filing,
the Whirl-Packs were carefully sealed leaving approximately 25 percent of the container capacity
as an airspace. The samples were immediately placed on ice in a cooler and were transported to
the laboratory within four hours of collection. See Table 3 for a summary of the fecal coliform
and fecal streptococci data. Water quality monitoring data are contained in Appendix C.
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Ce
COMPARISON OF 1970 AND 1996 DNR LAKE SURVEYS
DRAFT
Based on fieldwork completed on May 5, 1970, the Minnesota Department of Conservation (now
the DNR), mapped the depth to sediment and produced a lake map for Lake Orono. At the
request of the City of Elk River, Lake Orono was remapped on August 28, 1996, for the purpose
of comparing the two surveys such that any changes in lake depth could be observed for the 26-
year time period between surveys (see Appendix F).
The 1970 survey was scanned into a computer and, using the computer-aided design package
Intergraph, the 1970 survey was compared to the 1996 survey electronically and the volume
differential computed. To compare the two surveys in the above manner, the following
adjustments were made to the survey data:
The lake outlines on the two surveys were drawn from two different aerial
photographs taken 28 years apart. The later survey omitted the very shallow
upper portion of the lake; as a result the areas were approximately 10 percent
different, and the lake outlines between the two surveys varied and could not be
directly compared. During the analysis, the volumetric comparison was based on
only the lake area included in both surveys and does not include lake area
upstream of the limits of the 1996 survey. To normalize the lake outline
differences, the 1996 lake outline was utilized due to its higher level of detail.
The two lake surveys do not reference the same benchmarks. The survey
benchmarks were investigated and the surveys adjusted to account for the varying
lake elevations on the two survey dates. Benchmarks referenced in both surveys
were surveyed together and it was confirmed that their relative elevations are
correct. The 1970 survey references two benchmarks. Benchmark #2 is a brass
monument on top of the concrete wingwall on the south side of the Lake Orono
Dam west of Main Street. The benchmark was established in 1970 by the
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DRAFT
National Geodetic Survey, formerly the U.S. Coast and Geodetic Survey, as
benchmark S-257. The elevation for benchmark #2 if 874.43 as provided by the
Minnesota Department of Transportation Geodetic Unit. The water surface
elevation of Lake Orono was therefore approximately 871.83 feet (874.43 - 2.6 =
871.83) on May 5, 1970.
The 1996 survey references a gage located at the outlet dam on the southeastern
shore of Lake Orono. The elevation of Lake Orono is obtained by adding the
gage reading to elevation 870.0 as documented in the 1982 Operation and
Maintenance Manual for the Elk River Dam. The gage reading was documented
as being 2.2 feet on August 28, 1996. In reviewing this reading, it became
apparent that it was in error because a 2.2 foot gage reading represents 0.9 feet of
head above the weir crest at elevation 871.30. The resulting flow over the dam
would be approximately 360 cubic feet per second (cfs).
Q = 3.087 L (H)3/2
L = 136 feet
H = 0.9 feet
Q = 358 cfs
The USGS flow record for the Elk River at ERCR 15 indicates flow between
66-111 cfs for a two week period around August 28, 1996 and 82 cfs on
August 28, 1996 (see Appendix E). In addition, the daily operations log for the
dam was obtained and it indicates a lake elevation reading of 871.6 which
corresponds to a gage reading of 1.6 feet (see Appendix F). The above gage
reading is consistent with the USGS flow record.
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DRAFT
The above investigation concluded that the Lake Orono elevation was
approximately 0.23 feet higher on May 5, 1970 than on August 28, 1996 (871.83 -
871.6 = 0.23 feet). The volumetric analysis comparing the 1970 and 1996 DNR
lake surveys takes this difference into account.
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DRAFT
III.
Sedimentation and Water Quality Analyses
A. SEDIMENTATION RATES
Sedimentation rates were calculated by the following two methodologies described below:
Volumetric comparison of 1970 and 1996 DNR lake surveys
Sediment loading analysis based on monitoring data and literature values
1. Volumetric Comparison of 1970 and 1996 DNR Lake Surveys
The following results were calculated as accurately as the available data allow. However, due to
the level of detail associated with the surveys (especially the earlier one), the analysis has only a
limited ability to observe small changes in lake volumes. The calculated sedimentation volumes
and rates should not be viewed as being accurately quantified, but instead providing an indication
of whether or not there have been significant lake volume changes over the 26.3-year time period
between surveys.
The volume comparison implies a net fill within Lake Orono of 181,000 cubic yards. This
represents an annual deposition of approximately 6,900 cubic yards. Spread evenly over the 254-
acre lake, it represents a deposition rate of 0.017 feet/year for a total deposition of 0.44 feet over
the 26.3-year time period between surveys. These results correspond to high deposition for a
lake, but Iow deposition for a reservoir.
N:\0598\01~ELKRIVER.RPT-rlb ] ]
e
Sediment Loading Analysis
DRAFT
The sediment and phosphorus mass flowrates were used to calculate the net annual loadings of
the sediment and phosphorus. The calculations were done for TSS, VSS, TSS-VSS, phosphorus,
and ortho phosphorus. Mass inflows were calculated at ERCR 15 and TBCR 35, and mass
outflows were calculated at the Lake Orono dam. The calculations are shown in Appendix D.
The calculation procedure is explained below:
ao
The average inflow rate (mass/day) for the time interval between two consecutive
sampling events was calculated by adding the two inflow rates, and then dividing the sum
by two. Similarly, the average outflow rate (mass/day) for the time interval between two
consecutive sampling events was calculated by adding the two outflow rates, and dividing
the sum by two.
bo
The mass inflow for the time interval was calculated by multiplying the average inflow
rate (mass/day) by the time duration between the sampling events (days). The mass
outflow for the time interval was calculated by multiplying the average outflow rate
(mass/day) by the time duration between the sampling dates (days).
The mass inflows for all the time intervals were added to get the annual mass inflow. The
mass outflows for all the time intervals were added to get the annual mass outflow.
The annual mass inflow and the annual outflow were divided by the number of days
(365 days) to get the average mass inflow and outflow rates (tons/day) respectively.
eo
The inflow of bed load was calculated as a percent of the inflow of suspended load. No
bed load was assumed for the outflow.
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go
DRAFT
The total inflow was calculated as the sum of the suspended load and the bed load.
The total annual outflow was subtracted from the total annual inflow to get the annual
loading.
The fraction of bed load depends on the characteristics of the stream bed material, texture of
suspended material, and the suspended sediment concentration. The bed load correction factors
given in Table A-3 (Design of Small Dams, Bureau of the Reclamation, Department of the
Interior 1987) were used to estimate the percent bed load in terms of suspended load. For
concentrations less than 1,000 mg/1, the table gives a bed load correction factor of 25 to
150 percent of suspended load for sandy stream bed material.
The trap efficiency of the lake was also calculated assuming different bed load concentrations
(Appendix D). The trap efficiency of the lake is the percent of the total sediment inflow that is
deposited in the lake
The trap efficiencies calculated were compared with Brune's trap efficiency curve (Brune, "Trap
Efficiency of Reservoirs" June 1953) (Appendix D). Brune's curve gives trap efficiencies of
normal ponded reservoirs as a function of detention time (lake volume divided by the annual
inflow). Lake Orono has a volume of about 1,249 acre-ft. The annual inflow rate into the lake
based on 1996 data is 222, 410 acre ft/yr (USGS data for Elk River near Big Lake). This gives a
detention time of 0.0056 years. The corresponding trap efficiency per Brune's curve is in the
range of 15-40 percent. This is comparable to the calculated values with bed loads of 50-100
percent of suspended load. Total sediment deposition was calculated to be between 880 and
2,500 tons per year assuming bedload contribution in the above range. Based.on bedload at 75
percent of the total suspended load, net deposition is approximately 1,700 tons, or approximately
1,700 cubic yards, per year in Lake Orono. Spread evenly over the lake's 254 acres, it represents
a deposition rate of 0.004 feet/year. This is about one fourth of the deposition rate previously
calculated by comparing the 1970 and 1996 DNR lake surveys. The sediment deposition is,
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DRAFT
however, likely to occur primarily in the upper portions of the lake and is probably not evenly
distributed over the whole lake.
B. WATER QUALITY ASSESSMENT
1. Suspended Solids and Phosphorus
Flow- and time-weighted averages were calculated for total phosphorus, ortho-phosphorus, TSS,
VSS and TSS-VSS at monitoring stations: ERCR 15, TBCR 35, and the Lake Orono Dam (see
Appendix D). Average total phosphorus and TSS concentrations were 0.12 milligrams per liter
(mg/1) and 9 mg/l at ERCR 15, 0.15 mg/1 and 9 mg/1 at TBCR 35, and 0.11 mg/1 and 11 mg/1 at
the Lake Orono Dam. The MPCA has developed a water quality database from monitoring
minimally impacted streams from various ecoregions across Minnesota. The Elk River
watershed is within the North Central Hardwood Forest (NCHF) ecoregion. "Typical" values for
total phosphorus and TSS, within the NCHF ecoregion, range from 0.06 - 0.15 mg/1 and 4.8 - 16
mg/l respectively. The above average concentrations are all within the "typical" ranges provided
by the MPCA. The average total phosphorus concentration monitored at TBCR 35 is on the high
end of the "typical" range for total phosphorus and is 25 percent higher than the average total
phosphorus concentration monitored at ERCR 15.
Storm event monitoring of minor tributaries to Lake Orono overall showed reasonably low total
phosphorus and TSS concentrations (See Table 2). Due to the very small local drainage
contribution to Lake Orono, the lake's water quality is dominated by the Elk River flow.
In-lake total phosphorus and TSS concentrations in Lake Orono are very high compared to
minimally impacted lakes within the NCHF ecoregion. "Typical" summer values for total
phosphorus and TSS, within the NCHF ecoregion, range from 0.023 - 0.050 mg/1 and 2-6 mg/1
N :\0S 98\0 I~ELKRIVER. RPT-rlb 14
DRAFT
respectively. Average summer values for total phosphorus and TSS in Lake Orono, based on
five summer samples collected as part of this study, were 0.171 mg/l and 27 mg/1 respectively.
Based on total phosphorus data Lake Orono is classified as hypereutrophic. Poor water quality in
Lake Orono is largely due to a very high watershed drainage area to lake volume ratio resulting
in average residence times of only three days. Total phosphorus removal efficiencies within
Lake Orono were calculated to be less than 10 percent. This is much lower than lakes with
longer residence times where removal efficiencies can be on the order of 90 percent.
2. Fecal Coliform and Fecal Streptococci
The City of Elk River collected fecal coliform samples at the Lake Orono City Beach during six
sampling events in July - August 1997. Results indicated fecal coliform concentrations between
800 and 4,600 organisms/100 milliliters (ml), significantly above the National Public Health
Association Guideline of 200 organisms/100 ml (see Table 3). Additional sampling was
conducted on August 19, 1997 at various locations along the Elk River and at the Lake Orono
City Beach. Results indicate very high concentrations of fecal coliform and streptococci bacteria
for an inflow to Elk Rivef at Wapiti Campground and an inflow to Lake Orono from a
subdivision sedimentation pond with adjacent lands containing recently spread manure. The
concentration of fecal coliforms at the Lake Orono Beach was 70 organisms/100 ml.
By monitoring both fecal coliform (FC) and fecal streptococci (FS) concentrations and
evaluating the ratio of FC/FS, information regarding the origin of the fecal contamination can be
obtained. The FC/FS ratio for domestic animals is less than 1.0, whereas the ratio for human
beings is more than 4.0 (Wastewater Engineering Treatment/Disposal/Reuse, Metcalf and Eddy,
Inc., 1979). The data show low FC/FS ratios indicating fecal material from non-human sources.
FC/FS ratios from "Lake Orono City Beach" and "Inflow to Lake Orono from Subdivision" are
1.17 and _ 2.86 respectively. This could indicate a differential die-off of indicator organisms
N:\O$ 98\01XELKRI VER.RPT-db ] 5
DRAFT
where the fecal streptococci die off more rapidly than the fecal coliforms. High fecal coliform
concentrations at Lake Orono City Beach may be due to a high goose population in and around
the beach, or it may be related to precipitation events flushing fecal coliforms into the Elk River
from an upstream source. Additional monitoring is required to better evaluate the source of the
fecal coliform contamination.
N:\0598\01 kELKR1VER.P~T-rlb 16
DRAFT
IV.
Conclusions
o
o
o
Sedimentation rates within Lake Orono appear to be in the range of 1,700 to 6,900 tons per
year, equivalent to 0.004 to 0.017 feet per year over the whole lake area.
Total phosphorus and total suspended solids concentrations in the Elk River are within the
typical range for minimally impacted streams within the same part of the state.
Total phosphorus concentrations in Tibbits Brook are 25 percent higher than in the Elk River
and are on the high end of the typical range for minimally impacted streams within the same
part of the state.
In-lake total phosphorus concentrations in Lake Orono are very high compared to minimally
impacted lakes within the same part of the state. Based on total phosphorus data Lake Orono
is classified as hypereutrophic.
Poor water quality in Lake Orono is largely due to a very high watershed drainage area to
lake volume ratio, resulting in average water residence times of approximately three days.
Monitoring in the swimming area of the city beach indicated high levels of fecal coliform
bacteria above national public health association guidelines.
N :\059s\01 ~ELKKIVEK. KPT-rlb 17
DRAFT
Vo
Recommendations
Develop a lake management plan for dredging parts of the lake based on usage.
Dredge an in-lake sedimentation basin where the Elk River enters Lake Orono to provide
a reservoir for coarser fraction of the river's sediment load to be deposited in.
Develop a water quality action plan to address
· fecal coliform contamination in Lake Orono
· best management practices within the Elk River watershed
· on-going water quality monitoring in Lake Orono
N :~0 $ 9 8\01 ~EL KR.I VEK P,.PT-rIb 1 8
Tables
Table 1
City of Elk River
Water Quality Data
Sample Site Sample Total Ortho- Total Volatile
Date Phosphorus Phosphorus Suspended Suspended
Solids Solids
mg/l mga mg/l mg/1
Elk River 8/27/96 0.132 0.022 23.2
~ CR 15 10/2/96 0.087 0.023 16
10/18/96 0.076 0.021 7.6
11/13/96 0.06 0.01 4.8
12/10/96 0.055 0.033 2.6
3/27/97 0.106 0.064 16.4
4/3/97 0.178 0.105 14
4/9/97 0.117 0.069 3.3 1
4/16/97 0.067 0.035 2.6 1
4/23/97 0. I 1 0.017 16 7.1
4/30/97 0.096 0.01 12.4 7
5/14/97 0.07 0.01 10.2 5.2
5/28/97 0.075 0.01 12.6 5.6
6/11/97 0.075 0.01 12.6 6.8
6/25/97 0.105 0.049 13 7.8
6/30/97 0.161 0.058 5.8 2.6
7/23/97 0.241 0.06 26 14
8/5/97 0.165 0.117 5.4 2.6
Tibbets Br 8/27/96 0. t26 0.112 2.5 -
~ CR35 10/2/96 0.332 0.298 3
10/18/96 0.126 0.096 4.3
11/13/96 0.074 0.062 2.9
12/10/96 0.071 0.057 4.1
3/27/97 0.134 0.1 9.4
4/3/97 0.13 0.083 5.6
4/9/97 0.093 0.053 5.1 1
4/16/97 0.07 0.056 5.4 2
4/23/97 0.274 0.231 5.8 2.2
4/30/97 0.162 0.143 4.2 2.2
5/14/97 0.069 0.03 4.4 1.6
5/28/97 0.359 0.226 13.6 6.6
6/11/97 0.174 0.14 5.2 3.2
6/25/97 0.248 0.2 10.6 7.4
6/30/97 0.202 0.194 10.1 7
7/23/97 0.268 0.122 22 15.2
8/5/97 0.103 0.078 -;.4 2.6
Elk River 8/27/96 0.212 0.046 :2
~ Dam 10/2/96 0.039 0.01 17.1 -
10/18/96 0.082 0.01 17.4 -
11/13/96 0.057 0.01 7.1 -
12/10/96 0.051 0.033 1 -
3/27/97 0.066 0.041 2.3 -
4/3/97 0.131 0.081 10.6 -
4/9/97 0.141 0.083 12.5 4.1
4/16/97 0.072 0.037 4.4 1
4/23/97 0.092 0.038 11.9 4.8
4/30/97 0.081 0.021 17 9.8
5/14/97 0.067 0.01 14.9 6.6
5/28/97 0.101 0.01 25.6 9.6
6/11/97 0.124 0.01 19 8.3
6/25/97 0. I11 0.022 20.1 12
6/30/97 0.151 0.01 23 13
7/23/97 0.227 0.033 33.2 20.8
8/5/97 0.154 0. ! 8.4 4.6
N:\0598\01 \TABLE I.XLS
Table 2
City of Elk River
Storm Event Monitoring Data
Sample Site
Sample Date Sample Time Flow (cfs)
Total Phosphorus Ortho= Pbospborus Total Suspended Solids
lslandview Drive
Highw~.y 10
189~ and Concord
Omno Road and Mississippi Road
Omno Road at City H~dl
10/17/96 12:50 3.60 0.078 0.056 5.9
10/17/96 13:50 3.24 0.070 0.048 4.3
10/17/96 14:30 3.24 0.071 0048 4.5
7/2/97 12:25 4.55 0.181 0.105 25.4
7/7./97 14:25 4.50 0.159 0. I00 20.2
10/17/96 14:00 <l 0.133 0.035 6.4
10/17/96 14:45 <1 0.141 0.038 12. I
10/17/96 12:30 trickle only
7/2/97 12:40 1.08
7/2/97 14:45 1.00
8/19/97
8/19/97
0.75
0.79
0.652 0.594 15
0.065 0.045 <2
0.069 0.044 <2
Table 3
City of Elk River
Fecal Coliform and Fecal Streptococci Data
Sample Site Sampled By
Fecal Coliform°) Fecal Streptocel R~tio Preclpitationc~t
Sample Date (# organisms/10Oml) (# organisms/lOOml) FC/FS (inches)
7/I/97
7/2/97
7/3/97
7/4/97
7/5/97
7/6197
7/7/97
7/8/97
7/9/97
7/10/97
7/11/97
7/12/97
7/13/97
Lake Orono City Beach City of Elk River 7/14/97 2,300
Lake Orono City Beach City of Elk River 7/14/97 2,700
7/15/97
7/16/97
Lake Orono City Beach City of Elk River 7/17/97 1,600
7/18/97
7/19/97
7/20/97
Lake Orono City Beach City of Elk River 7/21/97 1,700
7/22/97
7/23/97
7/'24/97
7/23/97
7/26/97
7/27/97
Lake Orono City Beach City of Elk River 7/28/97 2,200
7/29/97
7/30/97
7/31/97
8/1/97
8/3/97
Lake Orono City Beach City of Elk River 8/4/97 800
8/5/97
8/6/97
8/7/97
8/8/97
8/9/97
8/10/97
Lake Orono City Beach City of Elk River 8/I 1/97 4,600
8/12/97
8/13/97
8/14/97
8/15/97
8/16/97
g/17/97
8/18/97
8/19/97 --
8/20/97
8/I 1/97
Lake Orono City Beach Wenck 70 60 1.17
Elk River City of Elk River 1,400 --
Elk River Upstxeam of Wapiti Campground Wenck 8/19/97 140 530 0.26
Elk River Downsm~am of Wapiti Campground Wenck 8/19/97 220 1,$O0 0.15
Elk River Downstream of Camp Cozy Wenck 8/19/97 150 1,200 0.13
Inflow to Elk River at Wapiti Campground Wcnck g/19/97 29,000 270,000 O. 11
laflow to Lake Orono from Subdivisionm Wenck 8/19/97 ~200,000 70,000 >9.86
National Public Health Association Guideline 200 org/100 mi as g~ometric mean of not less than 5 samples
in any calendar month nor shall more than 10% of all samples taken during any calendar month individually exceed
2000 org/100 mi (March 1 - October 31). Minnesota Pollution Consol Agency (MPCA) has adopted this standard for Class 2 waters.
Precipitation readings submitted to thc Slate Climatology Office by an observer at the Municipal Power Plant in Elk River.
Stormsewer inflow from subdivision sedimentation pond with adjacent lands containing recently spread manure.
0.00
2.08
0.11
0.13
0.31
0.00
0.00
1.43
0.00
0.O0
0.00
0.O0
0.88
T
T
0. O0
0.00
0.14
0.00
0.00
0.73
0.03
1.24
0.29
0.00
0.43
0.O0
0.O0
0. O0
0.O0
0.O0
0.O0
0.57
0.34
0.27
0.15
0.80
1.53
Figures
*Ol8
T 33N
T 32N
,o1'~
T 171 N.
17'30"
1192/ l, .~ .!.
872
I 32
Park
888
Gem
Powerl
~ 10
/
/
Wa.~er.
*. Tn.n k ,
· '111 ~
Ih ·
---5
SCALE 1:24000
o
1 ~LE
I
I000 0 t000 2000 3000 4000 5000
///i ~ .s o
CONTOUR INTERVAL 10 FElT
NATIONAL GEODETIC VERTICAL DATUM OF 1929
6000 7000 FE~
I KILOMETER
CITY OF ELK RIVER
Site Location Map
Wenck SEPT 1997
WenckAssociates, lnc. 1800 PioneerCreek Ctr. Figure 1
Environmental Enginoem Maple Plain, MN 55359
-!
!
06.'
I
-CUM-7
07
N
MINN -
O?~
02 ,
~ J f ELK RIVER WATERSHED
""" --/ I
/r/.' --' FISHERBUR~E ,...~ .. ~' ",,..,.
%70 ~'I" J-"' '?~-, l°?'
k. , . - ,. ,o¢_..
' "" MINN -UM-ELK-S
,..~-~' I ;" ¢.~ / ISAN'
11 ~ 69 t /
Elk River '- --.-- --- - t -
(miaor watersheds) SQ/~I County \
Benton (79.7) Morrison (1.5) ·
Upper Elk River (01) -81.2
Mayhew Creek (02) 54.0
Stoney Brook River (03) 53.7
Lower Elk River (04) 120.5
Snake River (05) 42.1
Upper St. Francis (06) 85.1
Battle Brook (07) 45.4
St. Francis River (08) 84.6
Tibbits Creek (09) 40.2
606.8
Benton (52.7) Morrison (1.3)
Benton (34.4) Sherbume (19.3)
Benton (10.0) Sherbume (1 I0.5)
Sherbume (42.1)
Benton (85.1)
Benton (5.7) Sherbume (22.7)
Mille Lacs (17.0)
Sherburne (84.6)
Sherbume (40.2)
J
LAKE ORONO
INN-UM-CROW-6~''
CITY OF ELK RIVER
Elk River Watershed
Wenck
WenckAssociates, Inc. 1800 PioneerCreek Ctr.
Environmental Engineers Maple Plain, MN 55359
SEPT 1997
Figure 2
ERCR 15
N
~ 922
I ~'~-~.~"~s~o
Sediment Sampling Locations
Water Quality Monitoring Locations
· Elk
' Inflow to E!
!'
Nt':~ ·
Elk River
x. '....~ '~o~
S-1, S-2, S-3, S-4
Elk River at County~
Tibbits Brook at Co
Lake Orono at the d ,- -
I
Storm Event Monitoring Locations IslandviewDfive ~ : __,;~,.
Highway I0 -.
189th and Concord '/"~ , - :'
Orono Road and Mi ' ,'.~.
Coliform Monitoring Locations Lake Orono City B( / it .- ,,, ~ . ,,
ElkRiverDownstre ::/" "~ ff ~' ' r.~
...... Inflow Lo Lake Oroc....-'
-,Sub-
.i. sta
Wenck
· .iatel, IIle. 1800 Pioneer Cre~lk Center
l~aglneerl Mople Pioin, MN 55359
SEPT 1997
Figure 3