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Overall Trends in the Efficacy of Inversion Oxygenation Aeration and

Bioaugmentation as a Treatment for Aquatic Vegetation Growth, Organic Matter

Accumulation, Nuisance Algae, and Water Quality in Indian Lake, Cass County,

Michigan

2012-2014

Notice: This report is © copyrighted and property of Restorative Lake Sciences. No portion of

this report can be duplicated or used without written consent from the Water Resources

Director at Restorative Lake Sciences (Effective January 28, 2015).

Prepared by: Restorative Lake Sciences

Pursuant to MDEQ Permit No: 11-14-0061-P

Jennifer L. Jermalowicz-Jones, PhD Candidate

Water Resources Director

18406 West Spring Lake Road

Spring Lake, Michigan 49456

www.restorativelakesciences.com

http://www.restorativelakesciences.com/

Restorative Lake Sciences

Indian Lake Aeration Report

2014

TABLE OF CONTENTS

SECTION PAGE

1.0 INTRODUCTION & SUMMARY........................................................................................................ 5

1.1 Summary of Indian Lake Aeration Operations ......................................................................... 5

1.2 Summary of Indian Lake Aeration Operation Purpose/Goals ................................................. 5

2.0 INDIAN LAKE WATER QUALITY SAMPLING METHODS ......................................................... 6

2.1 Summary of Equipment/Sampling Devices/Replicates/Parameters ......................................... 6

2.2 Sampling Dates and Locations ................................................................................................. 6

3.0 INDIAN LAKE WATER QUALITY DATA ANALYSIS AND DISCUSSION ............................... 8

3.1 Dissolved Oxygen ...................................................................................................................... 8

3.2 Water Temperature ................................................................................................................. 10

3.3 Conductivity ............................................................................................................................ 10

3.4 Total Dissolved Solids and Total Suspended Solids ............................................................... 12

3.5 Total Phosphorus, Orthophosphorus, and Sediment Nutrients .............................................. 13

3.6 pH ............................................................................................................................................ 16

3.7 Secchi Transparency and Turbidity ........................................................................................ 16

3.8 Oxidative Reduction Potential ................................................................................................ 18

3.9 Algal Composition and Chlorophyll-a .................................................................................... 19

3.10 Organic Matter and Sediment Muck Depth ............................................................................ 21

4.0 INDIAN LAKE HYBRID WATERMILFOIL TREATMENT AND DISTRIBUTION ................... 23

5.0 INDIAN LAKE INLET WATER QUALITY MANAGEMENT & RECOMMEND. ...................... 26



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GRAPHS AND FIGURES

NAME PAGE

Figure 1. Map of Indian Lake Deep Basin Sampling Locations ................................................................... 7

Figure 2. Aquatic Plant Biovolume Map of Milfoil (May 30, 2014) .......................................................... 24

Figure 3. Aquatic Plant Biovolume Map of Milfoil (October 10, 2014) .................................................... 25

Figure 4. Map of Indian Lake Inlet Plume (RLS, 2014) ............................................................................. 26

Figure 5. Map of Indian Lake Inlet Drainage Course (RLS, 2014) ............................................................ 27

Graph 1. North Basin DO June 2012-2014 ................................................................................................... 8

Graph 2. North Basin DO July 2012-2014 ................................................................................................... 9

Graph 3. North Basin DO October 2012-2014 ............................................................................................. 9

Graph 4. North Basin Conductivity 2012-2014 .......................................................................................... 11

Graph 5. South Basin Conductivity 2012-2014 .......................................................................................... 11

Graph 6. North Basin Total Dissolved Solids 2012-2014........................................................................... 12

Graph 7. North Basin Total Phosphorus 2012-2014 ................................................................................... 13

Graph 8. South Basin Total Phosphorus 2012-2014 ................................................................................... 14

Graph 9. North Basin Sediment Total Phosphorus 2012-2014 ................................................................... 15

Graph 10. South Basin Sediment Total Phosphorus 2012-2014 ................................................................. 16

Graph 11. North Basin Secchi Transparency 2012-2014 ............................................................................ 17

Graph 12. South Basin Secchi Transparency 2012-2014............................................................................ 18

Graph 13. Algal Composition of Indian Lake 2012-2014 .......................................................................... 20

Graph 14. North Basin Chlorophyll-a 2012-2014 ...................................................................................... 21

Graph 15. South Basin Chlorophyll-a 2012-2014 ...................................................................................... 21



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TABLES

NAME PAGE

Table 1. Sediment Muck Depth Measurements 2012-2014 ........................................................................ 23

Table 2. North Inlet Water Quality Data 2012 ............................................................................................ 28

Table 3. North Inlet Water Quality Data 2013 ............................................................................................ 28

Table 4. North Inlet Water Quality Data ..................................................................................................... 29



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Overall Trends in the Efficacy of Inversion Oxygenation Aeration and

Bioaugmentation as a Treatment for Aquatic Vegetation Growth, Organic Matter

Accumulation, Nuisance Algae, and Water Quality in Indian Lake, Cass County,

Michigan

2012-2014

1.0 INTRODUCTION AND SUMMARY:

Indian Lake is located in Sections 30 and 31 of Silver Creek Township (T.5S, R.16W) in Cass

County, Michigan. The lake surface area is approximately 499 acres (Michigan Department of

Natural Resources, 2001) and may be classified as a eutrophic aquatic ecosystem with a central deep

basin and a moderate-sized littoral zone. Indian Lake has a maximum depth of 30.0 feet (confirmed

by RLS in 2014 through depth contour mapping). The lake bottom consists primarily of sandy

substrate, along with marl and organic matter deposits. Indian Lake has a lake perimeter of

approximately 4.65 miles.

Indian Lake is a well-recreated lake and is utilized by many for fishing, swimming, boating, and

waterfront living. In recent years, the lake has become dominated by aggressive hybrid watermilfoil

growth and nuisance cyanobacteria algal blooms. Previous aquatic plant herbicide and algae

treatments have proven ineffective and the local residents have desired a more holistic approach to

addressing both the algae and aquatic plant issues as well as the dissolved oxygen depletion issues

associated with lake stratification later in the summer season on the lake.

1.1 Summary of Indian Lake Aeration Operations:

Laminar Flow Aeration (LFA) was installed in the South Basin of Indian Lake in 2010 and was

evaluated and determined to be effective at improving water quality. During July of 2012, a whole-

lake aeration system was installed throughout the North Basin of Indian Lake which consisted of 27

twelve-inch ceramic diffusers that were supplied air from two onshore air compressors. Scientists

evaluated the efficacy of this expanded aeration system in 2012-2013 and are now compiling an

overview of performance data from 2012-2014 to determine overall efficacy of the LFA system on

the entire lake to assist in future lake management decision-making.

1.2 Summary of Indian Lake Aeration Operation Purpose/Goals:

The Indian Lake waterfront residents desired a lake restoration strategy that would make the lake

healthier and accomplish the following objectives:



2014

The primary objectives of the implemented LFA system for Indian Lake include:

1) Reduction of nuisance rooted submersed aquatic vegetation such as milfoil and pondweed

2) Increase in top to bottom dissolved oxygen concentrations

3) Increase in water clarity

4) Reduction of blue-green algae such as Microcystis sp.

5) Reduction of muck accumulation in problem (shallow) areas

2.0 INDIAN LAKE WATER QUALITY SAMPLING METHODS

2.1 Summary of Equipment/Sampling Devices/Replicates/Parameters:

Restorative Lake Sciences has routinely sampled 10 deep basin sampling sites throughout the main

lake (North Basin) and 5 sampling sites in the South Basin in June, July, and October of 2012, 2013,

and 2014 to evaluate the efficacy of the aeration system. Baseline conditions of Indian Lake have

been previously reported and extensively documented and discussed and consisted of excessive

invasive aquatic vegetation growth, nuisance blue-green and green planktonic algal blooms, dissolved

oxygen depletion during stratification (DO < 5.0 mg/l at depths ≥ 10.5 feet), decreased water clarity

(mean secchi transparency ≤ 4.5 feet), and organic muck deposits in shallow recreational areas.

All chemical water samples (such as total phosphorus, orthophosphorus, and total suspended solids)

were collected at the specified depths (one each at the middle depths of each of the sampling sites)

using a 4-liter VanDorn horizontal water sampler with weighted messenger (Wildco® brand). Water

physical parameters (such as water temperature, dissolved oxygen, conductivity, turbidity, total

dissolved solids, oxidative reduction potential and pH) were measured with a calibrated Hanna®

multi-probe meter. Total phosphorus was titrated and analyzed in the laboratory according to the

method by Menzel and Corwin (1965; page 97 in Wetzel and Likens, 2000). Ortho-phosphorus was

titrated and analyzed in the laboratory according to the method by Murphy and Riley (1962; page 94

in Wetzel and Likens, 2000). Total suspended solids were analyzed for each sample using ASTM

Method D5907.

Chlorophyll-a was analyzed with the use of a fluorimeter according to the fluorometric method

described by Welschmeyer (1985).

2.2 Sampling Dates and Locations:

During each sampling year in 2012-2014, samples were collected by RLS staff in June, July, and

October. For these dates, all samples were collected from the sampling locations according to Figure

1.



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Figure 1. Deep basin sampling locations on Indian Lake, Cass Co, MI (2012-2014).



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3.0 INDIAN LAKE WATER QUALITY DATA ANALYSIS AND DISCUSSION

3.1 Dissolved Oxygen

Dissolved oxygen (DO) is a measure of the amount of oxygen that exists in the water column. In

general, DO levels should be greater than 5 mg L-1 to sustain a healthy warm-water fishery or higher

for better overall water quality. DO is generally higher in colder waters. During summer months, DO

at the surface is generally higher due to the exchange of oxygen from the atmosphere with the lake

surface, whereas DO is lower at the lake bottom due to decreased contact with the atmosphere and

increased biochemical oxygen demand (BOD) from microbial activity. A decline in DO may cause

increased release rates of phosphorus (P) from lake bottom sediments if DO levels drop to near zero

milligrams per liter.

Under low DO conditions, the imminent accumulation of NH3+ (ammonia) may result in toxicity to

aquatic organisms (Camargo et al., 2005; Beutel, 2006). Prior to implementation of the aeration

system in Indian Lake, the DO concentrations in the lake declined sharply with depth after around

mid-June from a depth beyond 10 feet which limited the depth of the fishery. Additionally, it allowed

for release of P from bottom sediments. Graphs 1-3 below show the relative stability of the DO

levels in 2013-2014 relative to 2012 due to destratification of the water column and complete

mixing of lake water and uniformity of DO levels which increased DO throughout the entire

lake. The DO levels in the South Basin have been consistently ≥ 8.3 mg/l since the

implementation of the LFA system due to destratification. Elevated of the DO levels

throughout the entire lake has resulted in a decline in overall quantities of blue-green algae.

Graph 1. Changes in Main Lake June DO concentrations 2012-2014.



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Graph 2. Changes in Main Lake July DO concentrations 2012-2014.

Graph 3. Changes in Main Lake October DO concentrations 2012-2014.



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3.2 Water Temperature

The water temperature of lakes varies within and among seasons. When the upper layers of the lake

begin to warm in the spring, the colder, dense layers remain at the bottom. This process results in a

“thermocline” that acts as a transition layer between warmer and colder water layers. During the fall

season, the upper layers begin to cool and become denser than the warmer layers, causing an

inversion known as “fall turnover”. In general, shallow lakes will not stratify while deeper lakes may

experience single or multiple turnover cycles. Water temperature is measured in degrees Celsius (°C)

or degrees Fahrenheit (°F) with the use of a submersible thermometer. Differences in water

temperatures are due to seasonal effects of sunlight penetration, water level changes, and degree of

particles and color in the water that absorb heat. The main challenge with whole-lake aeration is to

aerate the entire waterbody without causing thermal stress throughout the entire water column.

Although water sampling in June, July, and October showed a modest change in overall water

temperature (variation of between 3-7 degrees F) during operation of the aeration system, the

overall water temperatures did not exceed water temperatures that accompany a healthy

warm-water fishery. There were also no fish kills reported during the aeration evaluation period.

3.3 Conductivity

Conductivity is a measure of the amount of mineral ions present in the water, especially those of salts

and other dissolved inorganic substances. Conductivity generally increases as the amount of

dissolved minerals and salts in a lake increases, and also increases as water temperature increases.

Conductivity is measured in micro-Siemens per centimeter (µS cm-1) with the use of a conductivity

probe and meter.

The overall conductivity of Indian Lake have traditionally been moderate for an inland lake.

Mean values for the North Basin (main lake) for 2012-2014 were 231 mS/cm and mean values

for the South Basin were 217 mS/cm for 2012-2014. The overall trend for both regions of the

lake is that the conductivity has declined slightly with time with use of the LFA system. The

reason for this effect is unclear but the result may be beneficial. Graphs 4 and 5 show the

relative changes over time in conductivity for the North Basin and South Basin, respectively.



2014

Graph 4. Changes in Main Lake conductivity 2012-2014.

Graph 5. Changes in South Basin conductivity 2012-2014.



2014

3.4 Total Dissolved Solids and Total Suspended Solids

Total Dissolved Solids (TDS) is a measure of the amount of dissolved organic and inorganic particles

in the water column. Particles dissolved in the water column absorb heat from the sun and raise the

water temperature and increase conductivity. Total dissolved solids are often measured with the use

of a calibrated meter in mg L-1. TDS measurements have fluctuated in Indian Lake both in the North

Basin and in the South Basin and ranged from 55-174 mg/l. This number can fluctuate numerous

times daily due to scattering of light on particles in the water and re-suspension of fine particles from

the lake bottom during the time of measurement.

Total Suspended Solids (TSS) is a measure of the amount of suspended particles in the water column.

Particles suspended in the water column absorb heat from the sun and raise the water temperature.

Total suspended solids is often measured in mg L-1 and analyzed in the laboratory. The lake bottom

contains many fine sediment particles that are easily perturbed from winds and wave turbulence. All

of the TSS samples collected in Indian Lake between 2012-2014 in the South Basin and Main

Portion of the lake were < 10 mg/l which is low. Graph 6 below shows the decline in TDS from

2012-2013. There was a negligible increase in 2014 which is within normal fluctuations for an

inland lake.

Graph 6. Changes in North Basin TDS 2012-2014.



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3.5 Total Phosphorus, Ortho-Phosphorus, and Sediment Nutrients

Total phosphorus (TP) is a measure of the amount of phosphorus (P) present in the water column.

Phosphorus is the primary nutrient necessary for abundant algae and aquatic plant growth. Lakes

which contain greater than 20 µg L-1 of TP are defined as eutrophic or nutrient-enriched. TP

concentrations are usually higher at increased depths due to higher release rates of P from lake

sediments under low oxygen (anoxic) conditions. Phosphorus may also be released from sediments

as pH increases. Total phosphorus is measured in micrograms per liter (µg L-1) or in milligrams per

liter (mg L-1). Orthophosphorus refers to the soluble reactive portion of phosphorus that is

bioavailable to algae and other biota. Higher concentrations of orthophosphorus concentrations in the

lake result in increased uptake of the nutrient by aquatic plants and algae.

Most of the orthophosphorus samples collected in the lake have been < 0.010 mg/l which is the

lowest detectable level. This is not uncommon for many inland lakes that are P-limited. The

TP values show an interesting response in both the South Basin and North Basin of Indian Lake

in that there was a slight increase in 2014 due to the release of nutrients from the massive

nutrient release associated with natural and herbicide-related milfoil death in both regions of

the lake.

Graph 7. Changes in North Basin water column TP 2012-2014.



2014

Graph 8. Changes in South Basin water column TP 2012-2014.

When phosphorus enters Indian Lake from the atmosphere, runoff, the inlet, or wetlands, it

falls to the bottom and seeps into the sediment pore water where it is assimilated by the aquatic

plant roots, especially milfoil, pondweeds, and lily pads. This is why the sediment TP and TKN

(nitrogen) concentrations are much higher than the water column concentrations throughout

the entire lake. Nutrients adhere to sediment particles and solubilize in the pore water where

they can be directly assimilated by plant roots for metabolism and growth. Sediment TP is

measured in milligrams per kilogram (mg kg-1) with EPA method 6010B. A study by Krogerus and

Ekholm (2003) measured the release rates of P from sediment in shallow, open, agriculturally-

impacted lakes and found that the mean daily rate of gross sedimentation was 0.04-0.18 g m-2 day-1 of

phosphorus.

The sediment TP concentrations of both the South Basin and North Basin have however,

declined with time due to assimilation by rooted aquatic vegetation for growth. It will be

interesting to see if these values continue to decline if rooted aquatic vegetation also declines over

time given that they would not be present to utilize the sediment phosphorus and nitrogen sources.

Sediment nitrogen was measured in the South Basin during the 2012 study and showed a steady



2014

decline with the effects of the LFA system due to denitrification which is a commonly observed

effect of the aeration on oxidation of lake sediments.

Graph 9. Changes in North Basin sediment TP 2012-2014.



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Graph 10. Changes in South Basin sediment TP 2012-2014.

3.6 pH

pH is the measure of acidity or basicity of water. The standard pH scale ranges from 0 (acidic) to 14

(alkaline), with neutral values around 7. Most Michigan lakes have pH values that range from 6.5 to

9.5. Acidic lakes (pH < 7) are rare in Michigan and are most sensitive to inputs of acidic substances

due to a low acid neutralizing capacity (ANC). pH is measured with a pH electrode and pH-meter in

Standard Units (S.U). The pH of Indian Lake water has remained remarkably consistent

throughout the evaluation of the LFA system with a mean of 8.5 S.U. and a range of 8.3-8.5 S.U.

Thus, the LFA system does not appear to be influencing pH.

3.7 Secchi Transparency and Turbidity

Secchi transparency is a measure of the clarity or transparency of lake water, and is measured with

the use of an 8-inch diameter standardized Secchi disk. Secchi disk transparency is measured in feet

(ft.) or meters (m) by lowering the disk over the shaded side of a boat around noon and taking the

mean of the measurements of disappearance and reappearance of the disk.



2014

Elevated Secchi transparency readings allow for more aquatic plant and algae growth. Eutrophic

systems generally have Secchi disk transparency measurements less than 7.5 feet due to turbidity

caused by excessive planktonic algae growth. These Secchi transparency values are adequate to

allow abundant growth of algae and aquatic plants to a depth of 12 feet in Indian Lake. Secchi

transparency is variable and depends on the amount of suspended particles in the water (often due to

windy conditions of lake water mixing) and the amount of sunlight present at the time of

measurement. The overall mean secchi transparency measurements in Indian Lake have

increased since implementation of the LFA system, largely due to a decline in blue-green algal

blooms. Graph 11 shows the significant increase (nearly 5.5 feet) in clarity in the North Basin

and Graph 12 shows the nearly 4.5 increase in clarity in the South Basin since the

implementation of the LFA system.

Graph 11. Changes in North Basin secchi transparency 2012-2014.



2014

Graph 12. Changes in South Basin secchi transparency 2012-2014.

Turbidity is a measure of the loss of water transparency due to the presence of suspended particles.

The turbidity of water increases as the number of total suspended particles increases. Turbidity may

be caused by erosion inputs, phytoplankton blooms, storm water discharge, urban runoff, re-

suspension of bottom sediments, and by large bottom-feeding fish such as carp. Particles suspended

in the water column absorb heat from the sun and raise water temperatures. Since higher water

temperatures generally hold less oxygen, shallow turbid waters are usually lower in dissolved oxygen.

Turbidity is measured in Nephelometric Turbidity Units (NTU’s) with the use of a turbimeter. The

World Health Organization (WHO) requires that drinking water be less than 5 NTU’s; however,

recreational waters may be significantly higher than that. The turbidity of Indian Lake water is

moderate to low and has ranged from 0.4-1.6 NTU’s at mid-depth during the 2012-2014

evaluation period and was highest during 2012 prior to LFA implementation due to increased

blue-green algal blooms and values were also higher in June than in October due to seasonal

growth of algae.

3.8 Oxidative Reduction Potential

The oxidation-reduction potential (Eh) of lake water describes the effectiveness of certain atoms to

serve as potential oxidizers and indicates the degree of reductants present within the water. In



2014

general, the Eh level (measured in millivolts) decreases in anoxic (low oxygen) waters. Low Eh

values are therefore indicative of reducing environments where sulfates (if present in the lake water)

may be reduced to hydrogen sulfide (H2S). Decomposition by microorganisms in the hypolimnion

may also cause the Eh value to decline with depth during periods of thermal stratification. The Eh

values in Indian Lake fluctuate substantially within a single day, seasonally, and annually. Typical

values have ranged as low as between -25.0 mV to 390.0 mV with lowest values recoded during

June of 2010 near the lake bottom. In general, most of the Eh values recorded today are (+) due

to oxidative effects of the LFA system, especially at the sediment water interface.

3.9 Algal Composition and Chlorophyll-a

Water samples for phytoplankton (algae) and chlorophyll-a analysis were collected at all sites via a

composite sample from above the sediment to the surface using a composite sampler as described by

Nicholls (1979). Samples were placed in dark brown polyethylene bottles and maintained at 4°C

until microscopic analysis could be executed. All samples were preserved with buffered

glutaraldehyde and analyzed within 48 hours of collection. Prior to microscopic analysis, each

sample bottle was inverted twenty times prior to selection of each aliquot to evenly distribute

phytoplankton in the sample. A calibrated Sedgwick-Rafter counting cell (50 mm x 20 mm in area

with etched squares in mm) with 1-µl aliquots was used under a bright-field compound microscope to

determine the identity and quantity of the most dominant phytoplankton genera at the sampling sites.

For identification of the individual dominant algal taxa, algal samples were keyed to genus level with

Prescott (1970).

Algal genera were analyzed under a compound bright field microscope. Genera were recorded by

abundance and are listed in order of abundance. The genera present included the Chlorophyta (green

algae): Chlorella sp., Gleocystis sp., Pandorina sp., Scenedesmus sp., Euglena sp., Protococcus sp.,

Zygnema sp., Chroococcus sp., Aphanothece sp., Ulothrix sp., Rhizoclonium sp., Pediastrum sp., and

Chloromonas sp.; the Cyanophyta (blue-green algae): Microcystis sp., and Gleocapsa sp., and

Oscillatoria sp.; the Bascillariophyta (diatoms): Navicula sp., Cymbella sp., Eunotia sp., Cyclotella

sp., Fragilaria sp., Nitzschia sp., Synedra sp., Asterionella sp., Tabellaria sp., and Stephanodiscus sp.

Graph 13 below shows the changes in relative abundance of algal taxa before and after

implementation of the LFA system. There was a significant decline in blue-green algae from

2012 (pre-aeration) to 2014 and a significant increase in beneficial diatoms post-aeration. Also,

the relative abundance of green algae has declined over the past two years.



2014

Graph 13. Changes in Indian Lake algal taxa 2012-2014.

Chlorophyll-a is a measure of the amount of green plant pigment present in the water, often in the

form of planktonic algae. High chlorophyll-a concentrations are indicative of nutrient-enriched lakes.

Chlorophyll-a concentrations greater than 6 µg L-1 are found in eutrophic or nutrient-enriched aquatic

systems, whereas chlorophyll-a concentrations less than 2.2 µg L-1 are found in nutrient-poor or

oligotrophic lakes. Chlorophyll-a is measured in micrograms per liter (µg L-1) with the use of an

acetone extraction method and a spectrometer. The chlorophyll-a concentrations in Indian Lake were

determined by collecting a composite sample of the algae throughout the water column at each of the

sampling sites from just above the lake bottom to the lake surface. Chlorophyll-a concentrations

have declined over the past few years but increased in 2014 due to nutrient release from the

decaying milfoil biomass. Graphs 14 and 15 below show the changes in chlorophyll-a in the



2014

North and South Basins, respectively.

Graph 14. Changes in North Basin chlorophyll-a 2012-2014.



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Graph 15. Changes in South Basin chlorophyll-a 2012-2014.

3.10 Organic Matter and Sediment Muck Depth

Organic matter (OM) contains a high amount of carbon that is derived from biota such as decayed

plant and animal matter. Detritus is the term for all dead organic matter which is different than living

organic and inorganic matter. OM may be autochthonous or allochthonus in nature where it

originates from within the system or external to the system, respectively. Sediment OM is measured

with the ASTM D2974 method and is usually expressed in a percentage (%) of total bulk volume.

Indian Lake sediment samples were collected at the sampling locations with the use of an Ekman

hand dredge. Sediment OM has steadily declined in sampling areas in both the South Basin and

North Basin since implementation of the LFA system. In the North Basin, there has been a net

loss of 8% OM in South Basin sediment samples since 2012 and a net loss of 14.8% OM in

North Basin sediment samples since 2012.

Sediment Muck Depth Measurements

Sediment depths have been monitored by RLS scientists in GPS locations in the South and North

Basins of Indian Lake. Table 1 below shows some of the original sampling locations with recent

sediment measurements collected in October of 2014. The values in brackets indicate the net loss of

sediment since the LFA system has been in operation. There has been a mean muck reduction of

7.2” in the North Basin over the past two seasons and mean muck reduction of 7.0” in the South

Basin. These numbers are satisfactory considering the amount of mineral in the bottom mixed

in with the organic faction of sediment.



2014

North Basin

Sediment Sampling

Site

Sediment

Thickness

(feet)

South Basin

Sediment

Sampling

Site

Sediment

Thickness

(feet)

1611 9.5 [6”] 1601 9.4 [7.2”]

1612 9.6 [4.8”] 1602 6.2 [9.6”]

1613 7.2 [9.6”] 1603 9.2 [9.6”]

1614 7.5 [6”] 1606 9.3 [8.4”]

1617 6.7 [3.6”] 1608 9.7 [3.6”]

1619 7.8 [14.4”] 1609 9.5 [6”]

1620 9.5 [6”] 1610 9.6 [4.8”]

Table 1. Sediment depth measurements showing relative initial measurements

and losses in brackets due to LFA activity.

4.0 Indian Lake Hybrid Watermilfoil Treatment and Distribution

On May 30 of 2014, a Lowrance® 50-satellite GPS HDS 8 WAAS-enabled unit (accuracy within 2

feet) was used to scan the entire bottom of Indian Lake and record all of the aquatic vegetation

throughout Indian Lake and to generate a complete lake aquatic vegetation aquatic biovolume map

(Figure 2). The red and orange colors indicate dense growth, while the yellow is moderate growth and

green is light growth and blue color is no growth.

On June 20, 2014, approximately 155 acres of hybrid Eurasian Watermilfoil were treated in Indian

Lake using the systemic aquatic herbicide, Triclopyr (liquid Navitrol®) at a dose of 3.0 gallons per

acre. Some additional milfoil and pondweed acreage (Approx. 3 acres was treated with the contact

herbicides diquat, hydrothol, and chelated copper algaecide) in the small canals due to watering

restrictions associated with triclopyr. Figure 3 shows the relative change in milfoil biovolume after

systemic herbicide treatment. It is evident that the treatment was highly effective at reducing milfoil

but the lake will be re-surveyed in 2015 to determine if further treatment is needed and to assess

impact of the 2014 treatment on the germination on native aquatic plant species.



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Figure 2. Indian Lake aquatic plant biovolume map showing EWM locations (5/30/14).



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Figure 3. Indian Lake (post-treatment) aquatic plant biovolume map (October, 2014).



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5.0 Indian Lake Inlet Water Quality and Management Recommendations

The inlet flowing into the northern region of Indian Lake continues to contribute nutrient-rich water

to the lake that is rich in nitrogen, phosphorus, chlorophyll-a pigment, total dissolved solids, and

conductivity. The water that is entering the lake is also lower in dissolved oxygen which is likely due

to the increased water temperature and increased biochemical oxygen demand (BOD) from the

nearby farmland and wetland effluents. Figure 4 shows the marked plume of solids that enter the lake

from the inlet, especially after a heavy rainfall event. Figure 5 shows the drainage path to Indian Lake

as it traverses the landscape through farmland, wetlands, and urban land. A loading rate of

approximately 0.35 kg/L/day of phosphorus was estimated based on a mean flow rate of

approximately 2.0 cfs from the inlet during the sampling dates and the mean of the phosphorus

prior to implementation of the buffer.

Figure 4. A close-up aerial view of the inlet plume at the north end of Indian Lake (RLS, 2014).



2014

Figure 5. Drainage path of the north inlet to Indian Lake.

Scientists from RLS have collaborated with the Cass County Drain Commissioner and it is likely that

funds for improvement of the inlet would have to come from a drain assessment. This assessment

district would require a formal petition process. This poses a challenge since many of the residents

within the drainage district also currently pay for the existing special assessment district for current

lake improvements. This will be evaluated in 2015 to determine the possible feasibility of a double

assessment since it could significantly raise taxes on many with a fixed income. Grant opportunities

for small drainage repairs are scarce but RLS is actively seeking opportunities. A specialized buffer

was installed near the inlet after July 16 of 2013 and has demonstrated a nearly 38% reduction

in phosphorus since its operation began. Thus far, the buffer installed at the confluence of the inlet

and the lake seems to be reducing phosphorus and can remove nitrogen but is less effective in



2014

removing nitrogen especially with very heavy rainfall. This remains the largest challenge in

managing nitrogen reduction. Fortunately, the LFA system is highly efficient at reducing all forms of

nitrogen within the lake and sediments. Thus, reduction of other parameters such as phosphorus

would be a higher priority relative to the activity of the buffer. The data in tables 2-4 below

show the baseline data of multiple water quality parameters in the inlet (pre-buffer) in 2012-

July 2013 and post-buffer in late July 2013-October of 2014.

Inlet

Sampling

Date

Water

Temp

ºF

DO

mg L-1

pH

S.U

Cond.

µS

cm-1

Total

Diss.

Solids

mg L-1

Total

Phos.

mg L-1

Total

Nitr.

mg L-1

Chl-a

µgL-1

TSS

mg L-1

June 6 86.1 5.0 8.3 415 121 0.080 0.50 11.6 45

July 10

October 20

88.0

68.7

4.1

6.9

8.4

8.2

392

406

148

167

0.065

0.070

1.50

3.90

15.9

7.5

61

33

Inlet

Sampling

Date

Water

Temp

ºF

DO

mg L-1

pH

S.U

Cond.

µS

cm-1

Total

Diss.

Solids

mg L-1

Total

Phos.

mg L-1

Total

Nitr.

mg L-1

Chl-a

µgL-1

TSS

mg L-1

June 11 84.3 5.3 8.4 422 125 0.075 0.65 10.2 30

July 16

October 25

86.8

61.4

5.0

7.5

8.4

8.3

405

381

156

122

0.068

0.040

1.55

1.65

13.6

4.1

35

21

Table 2. Indian Lake inlet water quality data (June 6, July 10, and October 20,

2012). Note: Due to the high flow during sampling, ORP values fluctuated from

-44.7 to -88.4 mV.

Table 3. Indian Lake inlet water quality data (June 11, July 16, and October 25,

2013). Note: Due to the high flow during sampling, ORP values fluctuated from -25.4

to -59 mV.



2014

Inlet

Sampling

Date

Water

Temp

ºF

DO

mg L-1

pH

S.U

Cond.

µS

cm-1

Total

Diss.

Solids

mg L-1

Total

Phos.

mg L-1

Total

Nitr.

mg L-1

Chl-a

µgL-1

TSS

mg L-1

May 30 74.7 7.8 8.4 377 110 0.045 0.55 4.7 12

July 18

October 11

85.1

65.5

8.2

8.8

8.4

8.4

345

371

95

107

0.040

0.050

1.00

3.50

6.2

3.6

10

13

6.0 SCIENTIFIC LITERATURE CITED

Beutel, M.W. 2006. Inhibition of ammonia release from anoxic profundal sediments in lakes

using hypolimnetic oxygenation. Ecological Engineering 28(3): 271-279.

Camargo, J.A., A. Alonso, and A. Salmanca. 2005. Nitrate toxicity to aquatic animals: a review with

new data for freshwater invertebrates. Chemosphere 58: 1255-1267.

Krogerus, K., and P. Ekholm. 2003. Phosphorus in settling matter and bottom sediments in lakes

loaded by agriculture. Hydrobiologia 429: 15-28.

Nicholls, K.H. 1979. A simple tubular phytoplankton sampler for vertical profiling in lakes.

Freshwater Biology 9:85-89.

Prescott, G.W. 1970. Algae of the western great lakes areas. Pub. Cranbrook Institute of Science

Bulletin 33:1-496.

Verma, N. and S. Dixit. 2006. Effectiveness of aeration units in improving water quality of Lower

Lake, Bhopal, India. Asian Journal of Experimental Science 20(1): 87-95.

Wetzel, R. G. 2001. Limnology: Lake and River Ecosystems. Third Edition. Academic Press, 1006

pgs.

Table 4. Indian Lake inlet water quality data (May 30, July 18, and October 11, 2014).

Note: Due to the high flow during sampling, ORP values fluctuated from -16.3 to -58.1

mV.

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