Using Biomanipulation to Achieve and Sustain Long-term Water Quality Improvements in a Shallow Lake

Brian Vlach

Rich Brasch

Alternative Stable States Theory

Turbid and Clearwater States Competing Equilibria in Shallow Lakes

• Turbid State – High algal productivity – Low rooted aquatic plant productivity – Low grazer (zooplankton) population – Higher nutrient concentrations

• Clear-water State – Robust rooted native aquatic plant community – Low algal productivity – Large grazer population – Lower nutrient concentrations

A Tale of Two Shallow Lakes

Turbid State Algal Dominated Condition

Clear-water State Plant Dominated Conditions

Overview of Cleary Lake

• Natural Environmental Lake • Surface Area = 157 acres • Watershed Area = 5102 acres • Watershed : Lake Area Ratio = 32:1 • Cleary Lake Regional Park = 1123 acres • Max Depth = 8.9 feet • Mean Depth = 2.8 feet • Classified as “shallow” lake • Listed as “impaired” by MPCA in 2008

for excessive nutrients. • Average Water Quality Conditions

June-Sept 1998-2003 Average: – Total Phosphorus = 184.2 µg/L – Chlorophyll-a = 61.4 µg/L – Secchi Depth = 1.13 m

• Turbid – Algal dominated condition

Lake Name: Cleary Lake

Lake ID: 70-002200

Surface Area 157.03 acres 63.55 hectares

Littoral Area 157.03 acres 63.55 hectares

Average Depth 2.79 ft 0.85 m

Maximum Depth 8.89 ft 2.71 m

Fetch 1.01 miles 1.63 km

23.8

0.8

11.3

0.6

17.4

25.3

13.5

7.3

Cleary Lake %Watershed Land Use

Agricultural

Farmstead

Single Family

Industrial/Commercial

Park Reserve

Undeveloped

Public Water

Wetland

LandUse Acres %

Agricultural 1213.5 23.8 Farmstead 38.8 0.8 Single Family 579.0 11.3 Industrial/Commercial 28.3 0.6 Park Reserve 888.9 17.4 Undeveloped 1292.3 25.3 Public Water 686.6 13.5 Wetland 374.4 7.3 Total 5101.8 100.0

2.5

55.8 41.6

Cleary Lake Percent Loading

Atmospheric

Watershed

Internal

Cleary Lake (70-002200)

Watershed : Lake Area Ratio: 32:1

Load

Load

lbs kg %

Atmospheric 40.6 18.4 2.5 Watershed 892.4 404.8 55.8

Internal 665.4 301.8 41.6 Total 1598.4 725.0 100

Potential Sources of Internal Load Fish Community

• Cleary Lake has a substantial population of black bullhead. Black Bullheads

have the potential to degrade water quality.

• Cleary Lake was used as a walleye rearing lake by the Minnesota Department of Natural resources prior to 1999.

• The lake has been primarily managed for pan fish (i.e. Bluegill).

• Cleary Lake had a severe fish kill in the winter of 2002-2003. The fish community was dominated by black bullheads following the winterkill.

Fish Sampled for 1999 Survey Year

Species Gear Used

Fish Caught/Net Average Fish Weight (lbs)

Sampled

Normal

Sampled

Normal

Range Range

Black Bullhead Gill Net 35 9.6-91.4 0.88 0.2-0.5

Trap Net 1.4 2.2-60.5 0.66 0.2-0.5

Bluegill Gill Net 74 NA 0.12 NA

Trap Net 95.8 1.9-29.5 ND 0.2-0.3

Green Sunfish Trap Net 2 0.2-2.0 ND 0.1-0.2

Hybrid Sunfish Trap Net 4.1 NA 0.05 NA

Largemouth Bass Trap Net 1.3 0.3-1.2 0.61 0.4-1.2

Walleye Gill Net 31 1.0-7.3 0.81 1.0-2.8

Trap Net 1.3 0.4-1.9 0.65 0.6-2.6

Normal Ranges represent typical catches for lakes with similar physical and chemical characteristics.

Potential Sources of Internal Load Anoxic and Oxic Sediment Release

• Cleary Lake is a shallow lake in an algal dominated condition. The lake did

not have a diverse native plant community to stabilize sediments and nutrients from re-suspension.

• Cleary Lake had 3 to 5 submersed native plant species from 2000-2003.

Coontail and Elodea were the dominate native plant species and have decreased in frequency of occurrence.

• Curlyleaf pondweed increased in frequency of occurrence.

Data collected and analyzed by John Skogerboe – U.S. Army Corp of Engineers.

Species

Percent Occurrence

2000 2001 2002 2003

Apr Jun Aug Apr Jun Aug Jun Aug Apr Jun Aug

Potamogeton crispus 74 85 11 54 72 4 91 0 100 94 0

Ceratophyllum demersum 61 72 83 85 72 91 61 32 43 44 32

Elodea canadensis 33 22 69 46 26 32 11 13 13 9 15

Najas flexilis 0 0 0 0 2 0 0 0 0 0 0

Potamogeton foliosus 0 0 0 0 18 0 11 0 0 0 0

Stuckenia pectinata 0 28 7 0 41 11 11 0 0 7 0

Zannichellia palustris 0 0 0 2 0 6 6 0 0 0 0

Potential Sources of Internal Load Curlyleaf Pondweed

• Curlyleaf Pondweed Senescence – The percent occurrence of curlyleaf

pondweed increased substantially from 2000-2003.

• The senescence of curlyleaf pondweed resulted in a total phosphorus spike that occurred at the end of June and the beginning of July.

• The release of nutrients from senescence and the onset of warmer water temperatures were conducive for the development of algal blooms.

Drawdown Most Desirable Option

In-lake management approach to improve water quality conditions by controlling the various sources of internal load

• Drawdown would eliminate any remaining rough fish and reduce potential water quality impacts from the fish community. Provides an opportunity to re-establish a desirable fish community.

• Drawdown would control curlyleaf pondweed by effectively freezing out the residual seed bank (turions) and reduce the potential for internal loading from senescence.

• Establish a diverse native plant community-requires the transition from algal to plant dominated condition Inhibit the growth of curlyleaf pondweed Stabilize in-lake sediments to reduce the potential for internal load

from sediment-nutrient release. Provide beneficial habitat for the aquatic community.

Outlet Structure Installation

Channel Excavation

Outlet Structure Installation 2002

Installation of outlet structure = $16,750 Excavation of outlet channel = $30,000

Lake Response to Drawdown

Annual Water Quality

Annual Water Quality

Clam Shrimp (Caenestheriella sp.)

Changes in Aquatic Vegetation

Point intercept survey was not completed in 2007.

Changes in the % Occurrence for

Curlyleaf pondweed and Submersed Natives

Changes in % Curlyleaf pondweed Occurrence relative to Snow Fall

Changes in Average Total Phosphorus Concentration

Changes in Average Chlorophyll-a Concentration and Secchi Depth

Changes in Total Phosphorus relative to % Frequency of Curlyleaf pondweed

Algal Dominated Plant Dominated

Changes in Fish Community

Fish Stocking Activity

Year Species Size Number Pounds

2004 Walleye Fry 800,000 6.8

2005 Walleye Fry 1,287,000 11.3

2006 Largemouth Bass Adults 8 6.8

2006 Bluegill Adults 100 24

Electrofishing Data 9/24/2012

Conclusions • There have been beneficial improvements in Cleary Lake water

quality and native plant community 8 years following the drawdown.

• The drawdown was effective at temporarily controlling curlyleaf pondweed. Variations in annual curlyleaf pondweed growth appear to be dependent upon snow cover.

• Clear-water conditions following the drawdown (i.e. Clam Shrimp)

was critical for establishment of a more diverse native plant community (switch from algal to plant dominated condition).

• Total phosphorus concentrations correspond with the changes in % frequency of curlyleaf pondweed during the turbid-algal dominated condition.

• Total phosphorus concentrations decreased during the clear water/plant dominated condition. Total phosphorus concentrations were stable relative to changes in curlyleaf pondweed growth.

Conclusions • The shallow lake standards for water clarity (chlorophyll-a and

secchi depth) can be met or exceeded by establishing a more diverse native plant community. However, we can’t meet the TP standard and will require additional management efforts (i.e. watershed or alum).

• The public perception is that there have been minimal

improvements in the water quality. Managing shallow lakes to the MPCA state standards supports the “plant dominated condition” to improve water quality. There needs to be better education for the general public with regards to water quality expectations when dealing with shallow lakes.

Acknowledgments

• Minnesota Department of Natural Resources • Gerald Johnson • Daryl Ellison

• Minnesota Pollution Control Agency

• Chip Welling

• U.S. Army Corp of Engineers • John Skogerboe

• Three Rivers Park District

• John Barten • James Johnson • Dean Almquist

Managing Curlyleaf Pondweed with

Herbicides: Experiences with Whole

Lake and Partial Lake Treatments

Minnesota Water Resources Conference October 17, 2012

Yvette Christianson, MS

Steve McComas, MSCE

Udai Singh, Ph.D., PE

Kelly Dooley, MS

Gleason Lake Cities:

•Plymouth (95%) •Wayzata •Orono •Minnetonka

•160 Acre •Main Lake Area: 129 acres •North Basin Area: 31 acres

•Average to poor water quality

•Gleason Lake Improvement Association (GLIA) formed in 1980

Gleason Lake

Curlyleaf pondweed (Potamogeton crispus)

Early season maturation Crowds out native plants Hinders recreational

activities Contributes to high

internal phosphorus

Gleason Lake Management Program Study design:

2007-2009: 3 years of whole lake herbicide treatment 2010-2012: 3 years of herbicide spot treatment

Funding Agreement

MCWD GLIA 2007 Surveys, Herbicide Application, Fees $6,000.00 contribution 2008 Surveys, Herbicide Application, Fees $6,000.00 contribution 2009 Surveys, Herbicide Application, Fees $6,000.00 contribution 2010 Surveys Herbicide Application, Fees 2011 Surveys Herbicide Application, Fees 2012 Surveys Herbicide Application, Fees

Gleason Lake Objectives Determine if herbicide treatments with Aquathol® K can

control and manage for curlyleaf pondweed

Gleason Lake Objectives Determine if herbicide treatments are a viable long-term

solution for Gleason Lake

•Selected certified contractor to apply the herbicide treatment.

Methods: Project Steps

•Obtained signatures from the homeowners

•Applied for MNDNR Permit

•Monitored the water temperature (50°-60° F optimal temps for herbicide effectiveness)

•128 locations on Main lake •31 locations on North Bay

Method: Point Locations for the Aquatic Plant Survey

Methods: Curlyleaf Abundance Density Scale

Rake Density: 4

Rake Density: 1 Rake Density: 2

Rake Density: 3

Stem Densities were determined by counting the number of curlyleaf stems within a 0.10 m² quadrat.

Methods: Curlyleaf Stem Density

Lake Sediment Characteristics: •pH •Fe:Mn Ratio •Bulk Density •Organic Matter

Curlyleaf pondweed growth was predicted to produce mostly moderate growth

Methods: Lake Sediment Samples

Methods: Fish & Macroinvertebrate Survey

Methods: Lake Water Quality Monitoring YSI multi-probe sonde measures:

Water temperature Dissolved Oxygen pH Conductivity

Nutrients: Total Phosphorus Soluble reactive phosphorus Total Nitrogen

Algal abundance: Chlorophyll-a

• Water transparency: Secchi disk depth

Ions: Chloride

2007 2008

2009 2010 2011

Results: Curlyleaf Pondweed Distribution (spring surveys)

Green circles = light growth

Yellow circles = moderate growth

Red circles = heavy growth

2012

Results: Curlyleaf Stem Densities Prior to Herbicide Treatment

2007: 817 stems/m2 2008: 411 stems/m2 2009: 329 stems/m2

2010: 73 stems/m2 2011: 21 stems/m2 2012: 77 stems/m2

Results: Curlyleaf Pondweed Stem Densities

817

411 329

73 21

77

0

100

200

300

400

500

600

700

800

900

2007 2008 2009 2010 2011 2012

Ste

ms/m

²

2007* 2008* 2009* 2010 2011 2012

Acres Treated 137 137 140 27.9 16.3 45 Gallons of

Herbicide 521 521 517 98 39 164 *Whole lake treatments

Results: Herbicide Treatment History

Results: Native Vegetation Gleason Lake

Coontail

Gleason Lake August

Coontail 2007-2012

2007 2008

2009 2010 2011

Green squares = light growth

Yellow squares = moderate growth

Red squares = heavy growth

2012

Results: Annual Mean Secchi Disk Depth

1.08 0.91

0.77

1.11 1.23 1.24

1.38

1.93

0.00

0.50

1.00

1.50

2.00

2.50

2005 2006 2007* 2008 2009 2010 2011 2012

Se

cc

hi D

isk

De

pth

(m

)

*Began herbicide treatment

Results: Annual Mean Total Phosphorus

116

133 125

96 105

65

50 41

0

20

40

60

80

100

120

140

2005 2006 2007* 2008 2009 2010 2011 2012

To

tal P

ho

sp

ho

rus

(µ

g/L

)

*Began herbicide treatment

Results: Annual Mean Chlorophyll A

61 53

60

69

52

37 29

14

0

10

20

30

40

50

60

70

80

2005 2006 2007* 2008 2009 2010 2011 2012

Ch

lA (

µg

/L)

*Began herbicide treatment

Did We Meet Objectives? Determine if herbicide treatments with Aquathol® K can

control and manage for curlyleaf pondweed

2007

Yes

2012

Did We Meet Objectives? Determine if herbicide treatments are a viable long-term

solution for Gleason Lake:

•Native Vegetation

•Water Transparency

•Phosphorus Concentrations •Chlorophyll a Concentrations

Yes, but

Other Factors: •Increased size of storm pond •Aerated during winter

Post Project Gleason Lake Improvement Association plans to continue

applying spot treatments each spring MCWD will continue monitoring Gleason Lake to see if

the lake’s water quality continues to improve

MCWD/Blue Water Science will analyze fish and macroinvertebrate data

Lake residents concerns over increase in coontail may lead to additional vegetation management projects

Thanks to our partners & consultants:

Questions?

Yvette Christianson, Water Quality Specialist Minnehaha Creek Watershed District ychristianson@minnehahacreek.org

www.minnehahacreek.org

Acres Treated for Curlyleaf

2011 2012 2010

28 Acres 16 Acres 45 Acres

References Emmons and Olivier Resources. 2003. Gleason

Lake Management Plan.

McComas, Steve and Jo Stuckert, 2009. Curlyleaf Pondweed and Eurasian Watermilfoil Growth Potential Based on Gleason Lake Sediment Characteristics.

McComas, Steve and Jo Stuckert, 2011. Aquatic Plant Surveys for Gleason Lake, Hennepin, Co, Minnesota for 2011.

Endothall Herbicide General purpose aquatic herbicide. Some other trade names for the acid form of

Endothall include: Aquathol, Hydrothal-47, Hydrothal-191

Trade names for Disodium salt of Endothall include: Accelerate, Des-I-Cate, Tri-endothal, Ripenthol, Niagrathol.

LD50 is much higher then the doses used for lake treatment.

Half life 7-21 days in soil and 4 to 7 days in water.

Vegetation in Gleason Lake

Coontail Curly-leaf pondweed

White water lilies

Elodea Duckweed & Watermeal Filamentous Algae

Results: Water Quality Annual Averages Years

Average Secchi

Disk Depth (m)

Average Total

Phosphorus (µg/L)

Average

Chlorophyll-a

(µg/L)

2005 1.08 116.33 62.72 2006 0.91 133.29 53.06 2007* 0.77 125.29 59.83 2008 1.11 95.56 69.44 2009 1.23 109.60 54.50 2010 1.24 65.44 36.89 2011 1.38 48.78 27.11 2012

*First year of Aquathol K treatment