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Evaluation of Laminar Flow Aeration and Bioaugmentation for Water Quality Improvements in the South Basin of Austin

Lake, Kalamazoo County, Michigan

March 2, 2016

Prepared for: The Austin Lake Governmental Lake Board Attn: Brian Johnson, Chair City of Portage 7900 South Westnedge Portage, MI 49002

Prepared by: Jennifer L. Jermalowicz-Jones, PhD Candidate Water Resources Director Restorative Lake Sciences

18406 West Spring Lake Road Spring Lake, MI 49456 www.restorativelakesciences.com

TABLE OF CONTENTS

SECTION PAGE

LIST OF FIGURES..................................................................................................................................... 6 LIST OF TABLES....................................................................................................................................... 7 1.0 AUSTIN LAKE SOUTH BASIN AERATION & BIOAUGMENTATION SUMMARY .......................... 8 2.0 LAMINAR FLOW AERATION PRIMER ........................................................................................ 9 2.1 The Mechanics of Laminar Flow Aeration ..................................................................... 9 2.2 The Benefits and Limitations of Laminar Flow Aeration ............................................. 10 3.0 LAMINAR FLOW AERATION 2015 WATER QUALITY PARAMETERS ....................................... 11 3.1 Water and Sediment Parameter Methods, Data, and Discussion .............................. 11 3.1.1 Dissolved Oxygen ......................................................................................... 13 3.1.2 Water Temperature ..................................................................................... 13 3.1.3 Conductivity.................................................................................................. 14 3.1.4 pH ................................................................................................................. 14 3.1.5 Secchi Transparency ..................................................................................... 14 3.1.6 Turbidity ....................................................................................................... 15 3.1.7 Oxidative Reduction Potential ..................................................................... 15 3.1.8 Total Phosphorus and Ortho-Phosphorus ................................................... 16 3.1.9 Total Dissolved and Suspended Solids ......................................................... 16 3.1.10 Measurement of Sediment Loss .................................................................. 18 3.2 Phytoplankton Communities ....................................................................................... 19 3.2.1 Phytoplankton Sampling Methods .............................................................. 19 3.2.2 Phytoplankton Data and Discussion ............................................................ 19

3.3 Submersed Aquatic Plant Sampling Methods, Data, and Discussion ......................... 20 3.3.1 Submersed Aquatic Plant Sampling Methods ............................................. 20 3.3.2 Austin Lake Exotic Aquatic Plants ................................................................ 21 3.3.3 Austin Lake Native Aquatic Plants ............................................................... 22 4.0 CONCLUSIONS & RECOMMENDATIONS FOR THE SOUTH BASIN OF AUSTIN LAKE .............. 26 5.0 SCIENTIFIC LITERATURE CITED ................................................................................................ 27 6.0 APPENDIX A ............................................................................................................................. 29

FIGURES

FIGURE PAGE

Figure 1. The South Basin Laminar Flow Aeration System ............................................................ 9 Figure 2. Sampling Locations for all Water Quality Parameters .................................................. 12 Figure 3. Sampling Locations for all Sediment Parameters ......................................................... 13 Figure 4. Photograph of Eurasian Watermilfoil ........................................................................... 23 Figure 5. Photograph of Sago Pondweed .................................................................................... 24 Figure 6. Photograph of Muskgrass (Chara) ................................................................................ 24 Figure 7. Photograph of Brittle Naiad .......................................................................................... 24 Figure 8. Photograph of Wild Celery ............................................................................................ 24 Figure 9. Photograph of Yellow Waterlily .................................................................................... 25

Figure 10. Photograph of White Waterlily ................................................................................... 25

Figure 11. Photograph of Spikerush............................................................................................. 25

Figure 12. Photograph of Cattails ................................................................................................ 25

TABLES

TABLE PAGE

Table 1. South Basin Water Quality Data (June 5, 2015) ............................................................. 17 Table 2. South Basin Water Quality Data (July 17, 2015) ............................................................ 17 Table 3. South Basin “Diffuser” Water Quality Data (November, 2015) ..................................... 18 Table 4. South Basin “Control” Water Quality Data (November, 2015) ...................................... 18 Table 5. South Basin Chlorophyll-a Data (June & July, 2015) ...................................................... 20 Table 6. South Basin Algal Community Composition (June & July, 2015) ................................... 20 Table 7. South Basin Changes in Native Aquatic Plant Species (October 2012-2015) ................ 23

Restorative Lake Sciences Austin Lake LFA Study Progress Report

March 2, 2016

Page 8

Evaluation of Laminar Flow Aeration and Bioaugmentation for Water Quality Improvements in the South Basin of Austin Lake, Kalamazoo

County, Michigan

March, 2016

1.0 AUSTIN LAKE SOUTH BASIN AERATION & BIOAUGMENTATION SUMMARY

Austin Lake is a 1,132-acre natural, glacial origin lake with nearly 6.5 miles of shoreline, a maximum water depth of 8.0 feet and an average depth of approximately 5.0 feet. The lake is located sections 23, 24, 25, 26, 35, and 36 in the City of Portage (T.3S, R.11W), in Kalamazoo County, Michigan. Previously, sediments in the South Basin of the lake were very thick, very high in ammonia, low in oxygen, and were an imminent threat to the health of the Austin Lake ecosystem and threatened waterfront property values and lake recreational activities. Over the past three years (2012-2015), Restorative Lake Sciences has scientifically evaluated the efficacy of a laminar flow aeration (inversion oxygenation system) that was placed into the 200-acre South Basin of Austin Lake to biodegrade the toxic ammonia-laden sediments in hopes of reducing organic muck. Overall, the scientific results are promising and include the following general conclusions supported by data within this report and that has been shown in previous reports:

1) In 2015, there was an average gain in sediment in the diffuser areas of approximately 16.9 inches and an average gain in sediment in the control area of 15.5 inches. (Note: the aeration system although implemented from July of 2012 to November of 2015, can only operate per MDEQ permit from April 1-November 30 of each calendar year.) This surprising result may have been attributed to the intense storm events and rainfall that may have transported sediments into the Basin and re-distributed them throughout the basin. Careful monitoring in 2016 is recommended to see if addition of microbes can compensate by increasing losses of new sediment by the end of the 2016 season.

2) The Eurasian Watermilfoil once present in many of the sampling sites at the beginning of the evaluation period was absent throughout the entire South Basin in 2015. This result could have cost-saving to the South Basin riparians and to those of the entire lake in future years if the system is continued as the cost of aquatic herbicides to treat milfoil is very costly and may need to be continuously repeated each year, especially if milfoil had been allowed to propagate and spread.


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3) The water column nutrients were elevated in 2015 compared to previous years and this could also be due to the intense rainfall/runoff and nutrient contributions to the South Basin. These results were also noted on many other aerated and non-aerated lakes during the 2015 season.

Restorative Lake Sciences recommends that the residents around the South Basin of Austin Lake decide on the future of the aeration system but certainly consider the benefits described herein and as summarized above. This basin was severely compromised in 2015 due to historic climatic events or other processes such possible sediment deposition. It is unclear as to whether geologic activity may have also played a role in this significant change. The aeration system apparently cannot process excessive loads of organic sediment in a short period of time if the incoming loads are excessive and possibly burying the microbes that were added to the Basin in 2015.

2.0 LAMINAR FLOW AERATION PRIMER

2.1 The Mechanics of Laminar Flow Aeration

Laminar flow aeration systems are retrofitted to a specific site and account for variables such as water depth and volume, depth contours, water flow rates, and thickness and composition of lake sediment. Figure 1 shows the retrofitted design for the South Basin of Austin Lake (courtesy of Lake-Savers, LLC, 2012). The systems are designed to completely mix the surrounding waters with convectional currents and evenly distribute dissolved oxygen throughout the lake sediments for efficient aerobic microbial utilization.

Figure 1. Retrofitted laminar flow aeration system design for the South Basin of Austin Lake. Photo used with permission from Lake Savers, LLC.


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A laminar flow aeration system utilizes diffusers which are powered by onshore air compressors. The diffusers are connected via extensive self-sinking airlines which help to purge the lake sediment of gasses such as H2S that degrade water quality. In addition to the placement of the diffuser units, the concomitant use of non-pathogenic bacteria and enzymes to facilitate the microbial breakdown of organic sedimentary constituents is also used as a component of bioaugmentation. The need for adequate oxygen levels at the sediment-water interface cannot be overemphasized. The mechanism behind the laminar flow aeration system is to reduce the organic matter in the sediment so that a significant amount of nutrient and rooting medium is removed from the sediments, thus reducing the pool of organic deposits and increasing water depths. 2.2 Benefits and Limitations of Laminar Flow Aeration

There are different forms of aeration, including laminar flow aeration, hypolimnetic aeration, fountain aeration, and ozonation aeration (Verma and Dixit, 2006) among others. Furthermore, the technologies used for these aeration devices are designed to deliver aerated water to different regions of lake systems. For optimum performance, designs should be retrofitted to the bathymetry of the lake (such as the laminar flow aeration system that Clean-Flo® designs). Johnson (1984) emphasized the importance of matching the appropriate aeration system design to the lake management application. Installation of a retrofitted aeration system allowed for a basin-wide complete mixing of the water volume. The use of microbial applications (bioaugmentation) with laminar flow aeration has been studied and has determined that the bioaugmentation is critical. Bacteria are the primary decomposers of organic matter in lakes (Fenchel and Blackburn, 1971). Research on the colony counts of microbes added to lake sediments through bioaugmentation is scarce but would be valuable for determining ideal doses given known background microbial populations for a particular lake ecosystem. Duvall et al. (2001) found significant augmentations for microbial applications using certain products of microbes. Historically, bacteria have been used to biodegrade sewage and toxic pollutants (Madigan et al., 1997). Furthermore, laminar flow aeration may reduce the total lake ecosystem respiration in that a constant supply of air can override the accumulated respiratory demands of aerobes that degrade organic materials and use oxygen and also oxidation of reduced compounds resulting from anaerobic respiration. Thus, laminar flow may be an effective tool in maintaining a balance in lake metabolism for sites where respiration activities exceed gross primary production. Staehr and Sand-Jensen (2007) define a balanced lake metabolism as one where the gross primary production (GPP) to Respiration (R) ratio is equal to 1.0. Lastly, laminar flow aeration may also offer benefits that traditional methods such as dredging cannot provide.


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These benefits usually include the manipulation of nutrients that may not be successfully reduced from sediments after dredging activities due to the presence of more sediment with anoxic properties. Annadotter et al. (1999) mentioned that dredging activities previously implemented in Lake Finjasjön, a shallow eutrophic lake in Sweden, were terminated when sediments left after removal failed to halt the release of phosphorus into the water column. Since many lakes contain several meters of sediments, it is unlikely that dredging could affordably remove all sediments and some degree of continual phosphorus release from sediments will occur in eutrophic systems where the sediment layer is anoxic. This particular realization strengthens the argument for the use of laminar flow aeration as a restorative technique to reduce phosphorus release from sediments. The laminar flow aeration system has some limitations including the inability to biodegrade mineral sediments (such as marl), the requirement of a constant single phase electrical energy source to power the units, and unpredictable response by various species of rooted aquatic plants. Thus, the main objective of laminar flow aeration system use should be related primarily to sediment parameters and secondarily in aquatic plant control. However, in lakes with both prominent algal blooms and nuisance aquatic plants, laminar flow aeration offers continuous and sustainable benefits relative to other management methods that are executed only a few times per season or that need to be re-applied.

3.0 LAMINAR FLOW AERATION 2015 WATER QUALITY PARAMETERS

The quality of water is highly variable among Michigan inland lakes, although some characteristics are common among particular lake classification types. The water quality of each lake is affected by both land use practices and climatic events. Climatic factors (i.e., spring runoff, heavy rainfall) may alter water quality in the short term; whereas, anthropogenic (man-induced) factors (i.e., shoreline development or lawn fertilizer use) alter water quality over longer time periods. Since many lakes have a fairly long hydraulic residence time, the water may remain in the lake for years and is therefore sensitive to nutrient loading and pollutants. Furthermore, lake water quality helps to determine the classification of particular lakes. Lakes that are high in nutrients (such as phosphorus and nitrogen) and chlorophyll-a (the primary pigment of algae), and low in transparency are classified as eutrophic; whereas those that are low in nutrients and chlorophyll-a, and high in transparency are classified as oligotrophic. Lakes that fall in between these two categories are classified as mesotrophic. Austin Lake is considered mesotrophic due to its clear water and low nutrients and chlorophyll-a, but moderate aquatic plant growth.

3.1 Water and Sediment Parameter Methods, Data, and Discussion

Water quality parameters such as dissolved oxygen, water temperature, conductivity, pH, oxidation-reduction potential (ORP), turbidity, Secchi transparency, water column total phosphorus and ortho-phosphorus, total suspended and total dissolved solids all respond to changes in water quality and consequently serve as indicators of water quality change. An aerial map showing the deep basin


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water quality sampling locations is shown below in Figure 2. Additionally, an aerial map showing the locations of sediment sampling is shown in Figure 3. Water quality data for the South Basin can be found in Tables 1-4. The sections below describe the methods used to measure the parameters, along with measured data and discussion of results.

Figure 2. Sampling location map of parameters collected at water quality sampling sites in June and July of 2015.


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3.1.1 Dissolved Oxygen

3.1.1 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. DO concentrations may decline if there is a high biochemical oxygen demand (BOD) where organismal consumption of oxygen is high due to respiration. DO is generally higher in colder waters. DO was measured in milligrams per liter (mg L-1) with the use of a calibrated dissolved oxygen meter (Hanna® Model HI 9828). The DO concentrations in Austin Lake ranged from 8.2-8.6 mg L-1 in June-July of 2015 and 9.2-10.6 mg L-1 in November of 2015. The DO concentrations were higher in October due to lower water temperatures which hold more dissolved oxygen. These values were lower than the previous ones and may indicate that the microbial community in the sediment was elevated due to the influx of sediment and need for decomposition of the organic matter which increases BOD in the water and reduces oxygen. 3.1.2 Water Temperature

The water temperature of lakes varies within and among seasons and is nearly uniform with depth under winter ice cover because lake mixing is reduced when waters are not exposed to wind. When the upper layers of water begin to warm in the spring after ice-off, the colder, dense layers remain at the bottom. This process results in a “thermocline” that acts as a transition layer between

DB #1 Figure 3. Sampling location map of sediment and water quality parameters collected at diffuser and control sites on November 2, 2015.


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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 such as Austin Lake will not exhibit a major thermal stratification while deeper lakes may experience marked stratification. Water temperature was measured at depth (just above the lake bottom) in degrees Fahrenheit (°F) with the use of a calibrated submersible thermometer probe (Hanna® Model HI 9828). Water temperatures at sampling sites in the South Basin ranged from 70.5-72.1°F in June to 74.9-75.3°F in July and from 50.2-51.0°F in November. The values for 2015 were slightly lower in 2015 than in 2013-2014 due to a cooler. Differences in water temperatures among sampling sites may be due to variations in solar irradiance, aquatic plant biomass, or relative position to surface water movements.

3.1.3 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 and temperature in a lake increases. Conductivity was measured in micro-Siemens per centimeter (µS cm-1) with the use of a calibrated conductivity probe (Hanna® Model HI 9828). Conductivity values for the South Basin of Austin Lake ranged from 698-726 µS cm-1 in 2015. These values are high for an inland lake and reflect a high concentration of ions in the water column. The conductivity values of Austin Lake waters have traditionally been elevated and are due to runoff and not to the effects of the aeration system.

3.1.4 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 was measured with a calibrated pH electrode (Hanna® Model HI 9828) in Standard Units (S.U). The pH of Austin Lake South Basin water in 2015 ranged from 8.0-8.2 S.U., which is similar to recent years and demonstrated that the aeration system is not having an effect on the pH of the South Basin. The pH of lakes is generally dependent on submersed aquatic plant growth and underlying geological features. From a limnological perspective, Austin Lake is considered above neutral on the pH scale.

3.1.5 Secchi Transparency

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 was measured in feet (ft.) at each individual sampling site 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.


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Elevated Secchi transparency allows 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. 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 Secchi transparency in the South Basin was beyond the maximum depth at each sampling site in 2015 as well as in 2013-2014. These transparency measurements are moderately high for a shallow inland lake and have increased from filtration of the water by zebra mussels.

3.1.6 Turbidity

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 in the South Basin during 2015 was low and averaged 0.5 NTU’s throughout the season, which is slightly higher than observed in 2012-2014. This may be due to sediment re-suspension in the water column.

3.1.7 Oxidation-Reduction Potential

The oxidation-reduction potential (ORP or 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 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 for the South Basin of Austin Lake ranged from 80.4-141.2 mV. The high variability could be due to numerous factors such as degree of microbial activity near the sediment-water interface, quantity of phytoplankton in the water, or mixing of the lake water. The mean ORP values have increased significantly after aeration which was expected since the dissolved oxygen creates an oxidized environment which raises Eh.


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3.1.8 Total Phosphorus and Ortho-Phosphorus

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 or 0.020 mg 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 milligrams per liter (mg L-1) with the use of a chemical auto-analyzer or titration methods. The TP values for the South Basin of Austin Lake in 2015 ranged from 0.025-0.030 mg L-1, which indicates that there was a moderate amount of phosphorus in the water column in 2015. These numbers are nearly double the concentration noted in 2014 and may also be attributed to increased sedimentation. Ortho-phosphorus or “soluble reactive phosphorus” refers to the proportion of phosphorus that is bioavailable to aquatic life. Higher concentrations of ortho-phosphorus concentrations in the lake result in increased uptake of the nutrient by aquatic plants and algae. The Ortho-phosphorus values for the South Basin of Austin Lake in 2015 were between 0.010-0.020 mg L-1, which indicates that there is a moderate bioavailability of phosphorus to biota in the water column. These numbers were also higher than in previous years and may also be attributed to sedimentation.

3.1.9 Total Dissolved Solids and Total Suspended Solids

Total Dissolved Solids (TDS) refers to 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. The concentration of TDS in the South Basin of Austin Lake ranged from 186-282 mg L-1 in 2015, which has declined significantly after operation of the laminar flow aeration system but was higher in November than in the summer months which may have been a seasonal effect. Total Suspended Solids (TSS) is the 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 samples were collected with a VanDorn water sampler and were measured in mg L-1 and analyzed in the laboratory (Analysis Method SM 2540 D-97). The lake bottom contains many fine sediment particles which are easily perturbed from winds and wave turbulence. The concentrations of TSS in the South Basin of Austin Lake were between 13.0-20.0 mg L-1 in 2015 which is elevated compared to in 2013-2014. The acceptable standard for drinking water is 100 mg L-1 and a freshwater environment is 1,500 mg L-1.


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Sample

Location

Depth

ft.

Water

Temp ºF

DO

mg L-1

pH

S.U.

Cond.

µS cm-1

TDS

mg L-1

TSS

mg L-1

Total Phos.

mg L-1

Ortho-P

mg L-1

1 2.5 72.1 8.6 8.1 715 219 13 0.030 0.020

2 4.2 70.5 8.2 8.1 722 242 18 0.025 0.020

3 3.9 71.8 8.2 8.1 711 249 18 0.025 0.020

Table 1. Water quality parameters collected in the South Basin of Austin Lake on June 5, 2015.

Sample

Location

Depth

ft.

Water

Temp ºF

DO

mg L-1

pH

S.U.

Cond.

µS cm-1

TDS

mg L-1

TSS

mg L-1

Total Phos.

mg L-1

Ortho-P

mg L-1

1 2.5 75.2 8.4 8.0 723 251 16 0.025 0.020

2 4.1 74.9 8.4 8.1 709 267 20 0.030 0.010

3 3.9 75.3 8.6 8.2 716 282 18 0.025 0.020

Table 2. Water quality parameters collected in the South Basin of Austin Lake on July 17, 2015.


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Table 3. Water quality parameters collected in diffuser sampling locations of the South Basin (November 2, 2015).

Table 4. Water quality parameters collected in control sampling locations of the South Basin (November 2, 2015).

3.1.10 Measurement of Sediment Loss

A special device was used to measure the distance from the top of the sediment to the water surface in each of the n=45 control and n=19 diffuser sampling locations on November 2, 2015. On both occasions, the staff gauge level (in feet) was recorded at exactly 6.25 feet (USGS data). The instrument consisted of a flat plate approximately ½” in thickness tethered to a retractable metered tape measure. The instrument was lowered to the bottom during calm wind conditions and the distance was recorded. A mean increase in inches of sediment was confirmed in the control region of approximately 15.54 inches. The range of sediment gain or loss in control region samples ranged from a loss of -43.52 inches to a gain of 3.38 inches. A mean gain of 16.93 inches of sediment was confirmed in the diffuser region. The range of sediment gain in the diffuser region ranged from a gain of -7.0 inches to – 30 inches. This data was surprising given the previous amount of loss and

Water

Column

Descriptive

Statistic

Water

Temp.

°F

pH

S.U.

ORP

mV

Diss.

Oxygen

mg L-1

TDS

mg L-1

Cond

µS cm-1

Mean ± SD

Max

Min

50.8±0.1

50.9

50.6

8.1±0.1

8.2

8.0

103.0± 5.0

111.4

92.7

10.1±0.1

10.3

9.8

201±4.6

215

192

709±7.8

721

698

Water

Column

Descriptive

Statistic

Water

Temp.

°F

pH

S.U.

ORP

mV

Diss.

Oxygen

mg L-1

TDS

mg L-1

Cond

µS cm-1

Mean ± SD

Max

Min

50.7±0.3

51.0

50.2

8.1± 0.1

8.2

8.0

104.7 12.0

141.2

80.4

10.1±0.3

10.6

9.2

203±7.9

220

186

714±6.3

726

701


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not gain in previous years. As mentioned above, the sediment deposition has hindered progress and was likely due to unprecedented (historical) climatic events that were encountered in 2015. Individual sampling site data for this parameter is present in Appendix A. 3.2 Phytoplankton Sampling

3.2.1 Phytoplankton Sampling Methods

Water samples for phytoplankton (algae) analysis were collected at the n=45 control sites and n=19 diffuser sites via a composite sample from above the sediment to the surface using a composite sampler as described by Nicholls (1979). Chlorophyll-a readings were collected in situ with a Turner Designs in situ fluorimeter. Three samples were collected at three distinct sampling regions in the South Basin for chlorophyll-a analysis on June 5, 2015 and July 17, 2015. 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-ml aliquots was used under a bright-field compound microscope to determine the identity and quantity of the most dominant phytoplankton genera in the South Basin. For identification of the individual dominant algal taxa, algal samples were keyed to genus level with Prescott (1970). 3.2.2 Phytoplankton Data and Discussion Algal genera present in Austin Lake include the following as determined through analysis under a compound bright-field microscope. The genera present included the Chlorophyta (green algae): Chlorella sp., Chloromonas sp., Scenedesmus sp., Mougeotia sp., Micrasterias sp., Euglena sp., and Ulothrix sp., Staurastrum sp.; the Cyanophyta (blue-green algae): Gleocapsa sp. and Oscillatoria sp.; the Bascillariophyta (diatoms): Synedra sp., Navicula sp., Cymbella sp., and Tabellaria sp. The aforementioned species indicate a diverse algal flora and represent a relatively balanced freshwater ecosystem. Tables 5 and 6 below show the chlorophyll-a concentrations in three regions of the South Basin, as well as the overall dominant algal genera in the South Basin (i.e., diatoms). The chlorophyll-a concentrations in the South Basin were elevated in 2015 compared to in 2012-2013 and may be attributed to increased nutrients despite the cooler water temperatures. The dominant algae measured consisted of diatoms, followed by the single-celled and multi-celled (colonial) green algae. The blue-green algae were quite scarce which is good since they are not favorable. In many lakes that are aerated, this finding is almost universal with diatoms showing the highest rate of increase and the blue-green algae showing a decline over time. The diatoms and green algae are the preferred food sources of the zooplankton which are the food chain base.


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Sample Location June Chl-a

(µg L-1)

July Chl-a

(µg L-1)

1 1.0 2.0

2 2.0 1.0

3 2.0 1.0

Table 5. Chlorophyll-a concentrations in areas of the South Basin of Austin Lake on June 5, 2015 and July 17, 2015.

Sample Location Mean #

Blue-Green

Algae

Mean #

Green

Algae

Mean #

Diatoms

1 4 42 105

2 6 34 110

3 5 39 122

Table 6. Mean number of algal taxa in 1 ml sample of lake water from areas of the South Basin in Austin Lake on June 5, 2015 and July 17, 2015.

3.3 Submersed Aquatic Plant Sampling Methods, Data, and Discussion

3.3.1 Submersed Aquatic Plant Sampling Methods

The GPS Point-Intercept Survey method was developed by the Army Corps of Engineers to assess the presence and relative abundance of submersed and floating-leaved aquatic plants within the littoral zones of Michigan lakes. With this survey method, individual GPS points are sampled for relative abundance of aquatic plant species. Each aquatic plant species corresponds to an assigned number designated by the MDEQ. In addition to the particular species observed (via assigned numbers), a relative abundance scale is used to estimate the percent coverage of each species within the GPS site. The survey on November 2, 2015 consisted of 64 sampling locations in the South Basin of Austin Lake. A combination of rake tosses and visual observations were executed to sample the aquatic vegetation communities throughout the South Basin area. The majority of the


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aquatic vegetation in Austin Lake is viable until the middle to end of November. The primary objective of these surveys was to assess the conditions of the submersed aquatic plant communities before and after annual implementation of the laminar flow aeration system with bioaugmentation.

3.3.2 Austin Lake Exotic Aquatic Plants

Exotic aquatic plants (aquatic plants) are not native to a particular site and are introduced by some biotic (living) or abiotic (non-living) vector. Such vectors include the transfer of aquatic plant seeds and fragments by boats and trailers (especially if the lake has public access sites), waterfowl, or by wind dispersal. In addition, exotic species may be introduced into aquatic systems through the release of aquarium or water garden plants into a water body. An aquatic exotic species may have profound impacts on the aquatic ecosystem. The majority of exotic aquatic plants do not depend on high water column nutrients for growth, as they are well-adapted to using sunlight and minimal nutrients for successful growth. These species have similar detrimental impacts to lakes in that they decrease the quantity and abundance of native aquatic plants and associated macroinvertebrates and consequently alter the lake fishery. There were no invasive submersed aquatic plants found in the South Basin of Austin Lake and the previously abundant aquatic plant Eurasian Watermilfoil (Myriophyllum spicatum; Figure 4) was completely absent. The amount of Eurasian Watermilfoil declined from 16.5% in 2012 to 0% of sampling sites (n=64 total control and aeration sites) in 2015. This is a substantial reduction over the past three years. Eurasian Watermilfoil was first documented in the United States in the 1880’s (Reed 1997), although other reports (Couch and Nelson 1985) suggest it was first found in the 1940’s. Eurasian Watermilfoil has since spread to thousands of inland lakes in various states through the use of boats and trailers, waterfowl, seed dispersal, and intentional introduction for fish habitat. Eurasian Watermilfoil is a major threat to the ecological balance of an aquatic ecosystem through causation of significant declines in favorable native vegetation communities within lakes (Madsen et al. 1991), and may limit light from reaching native plant species (Newroth 1985; Aiken et al. 1979). Additionally, Eurasian Watermilfoil can alter the macroinvertebrate populations associated with particular native plants of certain structural architecture (Newroth 1985). Within the past decade, research has been conducted on the genotype of hybrid watermilfoil species (Moody and Les, 2002; 2007) which are commonly a result of cross-pollination between Eurasian Watermilfoil and other native species such as Northern Watermilfoil (M. sibiricum), and Variable Watermilfoil (M. heterophyllum). Since the introduction of Eurasian Watermilfoil, many nuisance aquatic plant management techniques such as chemical herbicides, mechanical harvesting, and biological control have been implemented. Mechanical harvesting is generally not recommended for the control of Eurasian Watermilfoil since it causes fragmentation of the plant which dramatically increases the


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spread of the plant, with each fragment possessing the potential to root into the sediment and grow as a new plant. Chemical aquatic herbicides are commonly used but require a permit from the Michigan Department of Environmental Quality and must be registered with the U.S. EPA and U.S. Department of Agriculture.

3.3.3 Austin Lake Native Aquatic Plants

There are hundreds of native aquatic plant species in the waters of the United States. The most diverse native genera include the Potamogetonaceae (Pondweeds) and the Haloragaceae (Milfoils). Native aquatic plants may grow to nuisance levels in lakes with abundant nutrients (both water column and sediment) such as phosphorus, and in sites with high water transparency. The South Basin of Austin Lake contains low to moderate levels of phosphorus in the water column but has high sediment phosphorus concentrations. The diversity of native aquatic plants is essential for the balance of aquatic ecosystems, because each plant harbors different macroinvertebrate communities and varies in fish habitat structure.

The South Basin of Austin Lake contains 4 submersed, 2 floating-leaved, and 2 emergent aquatic plant species, for a total of 8 native aquatic plant species. The majority of the emergent macrophytes may be found along the shoreline of the lake. Additionally, the majority of the floating-leaved macrophyte species can be found near the perimeter of the lake. This is likely due to reduced wave energy near shore, which facilitates the growth of floating-leaved and emergent aquatic plants. Changes in dominant aquatic plant species are shown in Table 7. The dominant native submersed aquatic plants included Sago Pondweed (Stuckenia pectinatus; Figure 5) which occupied approximately 10.5% of sampled areas in 2015. The most abundant submersed “macro-alga” was Muskgrass (Chara vulgaris; Figure 6), which carpets the lake bottom and serves as fish spawning habitat. The most abundant aquatic plant was Brittle Naiad (Najas marina; Figure 7), which is a low-growing annual that also serves as favorable fish forage habitat but has spiny leaves that can poke those that may contact it. The submersed Wild Celery (Vallisneria americana; Figure 8) was noted in 0.2% of the sites in 2015 where it was previously absent. Lastly, the presence of the floating-leaved, Yellow Water lily (Nuphar variegata; Figure 9) was dominant only near the west and south shorelines of the South Basin of Austin Lake. White Water lily (Nymphaea odorata; Figure 10) was also present in 0.2% of the sampling areas but has been reduced by the aeration system over time. The dominance of rooted submersed aquatic plants in the lake suggests that the lake sediments are the primary source of nutrients (especially ammonia nitrogen and phosphorus), since most submersed aquatic plants obtain most of their nutrition from the sediments.


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Submersed

Aquatic

Plant Species

Aquatic Plant

Common

Name

% South Basin Covered

(November 2, 2015)

Chara vulgaris Muskgrass 7.6 Myriophyllum spicatum Eurasian Watermilfoil 0.0

Stuckenia pectinatus Thin leaf Pondweed 10.5 Najas marina Brittle Naiad 12.7

Vallisneria americana Wild Celery 0.2 Nuphar variegata Yellow Waterlily 0.6

Nymphaea odorata White Waterlily 0.2 Eleocharis sp. Spikerush 0.3

Typha sp. Cattails 0.2

Table 7. Austin Lake changes in aquatic plant species and relative abundance on November 2, 2015.

Figure 4. Eurasian Watermilfoil (Myriophyllum spicatum) © RLS


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Figure 5. Sago Pondweed (Stuckenia pectinatus)

Figure 6. Muskgrass (Chara vulgaris)

Figure 7. Brittle Naiad (Najas marina) © RLS

Figure 8. Wild Celery (Vallisneria americana) © RLS


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Figure 9. Yellow Waterlily (Nuphar variegata) © RLS

Figure 10. White Waterlily (Nymphaea odorata) © RLS

Figure 11. Spikerush (Eleocharis sp.) Figure 12. Cattails (Typha sp.)


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4.0 Conclusions & Recommendations for the South Basin of Austin Lake

It is important that any improvement method used on Austin Lake be sustainable to allow for the best long-term results. A lake management method that is sustainable means that it will continuously drive its functions with little maintenance while allowing the lake ecosystem to maintain a healthy balance. Previously, sediments in the South Basin of the lake were very thick, very high in ammonia, low in oxygen, and had high odors and thus were an imminent threat to the health of the Austin Lake ecosystem and threatened waterfront property values and lake recreational activities. Over the past three years (2012-2015), Restorative Lake Sciences has scientifically evaluated the efficacy of a laminar flow aeration (inversion oxygenation system) that was placed into the 200-acre South Basin of Austin Lake to biodegrade the toxic ammonia-laden sediments in hopes of reducing organic muck. Until 2015, the scientific results were promising relative to sediment reduction. This was likely attributed to unprecedented climatic conditions in 2015. RLS summarizes the key findings of 2015 below:

1) To date, there has been a total mean gain of approximately 0.93 inches of muck in “diffuser” sampling sites and a mean gain of 3.94 inches of muck in “control” sampling sites. (Note: the aeration system although implemented from July of 2012 to November of 2014, can only operate per MDEQ permit from April 1-November 30 of each calendar year.). This is unfortunate due to unforeseen climatic conditions and runoff and hopefully these weather conditions will not be present in 2016 to allow for another set of sediment-decreasing data as in previous years.

2) An additional “pilot” study funded by RLS has demonstrated that sediment ammonia (once toxic) in the sediments is now at negligible levels as is sediment nitrogen due to the aeration system. RLS is currently submitting this information to a peer-review journal. This finding has major ecological significance since it demonstrates the ability of the aeration system to penetrate into the sediment pore water and alter the biogeochemistry of the lake sediments in a positive manner.

3) The Eurasian Watermilfoil once present in many of the sampling sites at the

beginning of the evaluation period has completely disappeared. This is important since the finding of the ammonia reduction may be related. This result could have cost-savings to the South Basin riparians and riparians in other areas of the lake in future years if the system is continued as the cost of aquatic herbicides to treat milfoil is very costly and may need to be continuously repeated each year.


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4) There was an increase in nutrients such as phosphorus and ortho-phosphorus in the

South Basin in 2015 relative to previous years. As noted above, this is likely due to the climatic activity which likely contributed nutrient-rich runoff to the Basin in 2015.

5) The total suspended solids of the South Basin also increased in 2015 which may have been attributed to the historic climatic conditions.

5.0 SCIENTIFIC LITERATURE CITED

American Public Health Association. 1965. Standard methods for the examination of water and

wastewater, 12th ed. APHA. 759 p. Annadotter, H., G. Cronberg, R. Aagren, B. Lundstedt, P. Nilsson, and S. Ströbeck. 1999. Multiple

techniques for lake restoration. Hydrobiologia 395/396:77-85. Beutel, M.W. 2006. Inhibition of ammonia release from anoxic profundel sediments in lakes

using hypolimnetic oxygenation. Ecological Engineering 28(3): 271-279. Couch, R., and E. Nelson 1985. Myriophyllum spicatum in North America. Pp. 8-18. In:

Proc. First Int. Symp. On watermilfoil (Myriophyllum spicatum) and related Haloragaceae species. July 23-24, 1985. Vancouver, BC, Canada. Aquatic Plant Management Society, Inc.

Duvall, R.J., L.W.J. Anderson, and C.R. Goldman. 2001. Pond enclosure evaluations of microbial products and chemical algaecides used in lake management. Journal of Aquatic Plant Management 39:99-106.

Fenchel, T., and T.H. Blackburn. 1979. Bacteria and mineral cycling. Academic. Johnson, P.L. 1984. Thoughts in selection and design of reservoir aeration devices. Lake and

Reservoir Management 1(1):537-541. Madigan, M. T., J. M. Martinko and J. Parker. 1997. Brock, The biology of Microorganisms.

Prentice-Hall, Inc. Upper Saddle River. 986 pp. Mason C. A., G. Hamer and J. D. Bryers. 1986. The death and lysis of microorganisms.

Madsen, J.D., J.W. Sutherland, J.A. Bloomfield, L.W. Eichler, and C.W. Boylen. 1991. The decline of native vegetation under dense Eurasian watermilfoil canopies. J. Aquat. Plant Manage. 29: 94-99.

Newroth, P.R. 1985. A review of Eurasian water milfoil impacts and management in British Columbia. Pp. 139-153. In: Proc. First Int. Symp. On watermilfoil (Myriophyllum spicatum) and related Haloragaceae species. July 23-24, 1985. Vancouver, BC, Canada. Aquatic Plant Management Society, Inc.

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.

Staehr, P.A., and K. Sand-Jensen. 2007. Temporal dynamics and regulation of lake metabolism.


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Limnology and Oceanography 52(1):108-120. 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.


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6.0 APPENDIX A SEDIMENT DATA 2015


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