Recent History at Indian Brook Reservoir

Development and Implementation of an Invasive Aquatic Plant Management Program at

Indian Brook ReservoirEssex, Vermont

Marc BellaudVP/Aquatic Biologist

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Recent History at Indian Brook Reservoir

Eurasian watermilfoil identified in 1999

Comprehensive survey performed in 2001 and 5-year IMP developed

Permit filed in winter 2001/2002 for Sonar (fluridone) herbicide treatment

Milfoil population naturally crashed

Permit application withdrawn

Milfoil has now recovered to nuisance densities

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2001 Plant Distribution

EWM growth pattern changed in 2004 and infestation rapidly expanded

Total lake area = 50 acres

Milfoil cover estimated in 22 acres

Possible milfoil expansion to 30 acres or 60% of lake based on bathymetry

Milfoil disappeared?

Elodea was dominant native plant in 2001 - was not observed in 2011

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2011 Survey Findings

Surveyed same points

Used GPS technology

Milfoil found at 36% of sample locations in 2011 (50% in 2001)

12 species in 2011 (10 species in 2001)

6 species were found during both surveys

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Comparison of milfoil cover

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Current management recommendations

Agree on Management Objectives - Define Control• Control milfoil• Prevent introduction/establishment of other invasives• Preserve diverse plant assemblage for habitat• Maintain water quality• Improve recreational access

Initiate new 5-year IMP

Recommended herbicide: Renovate (triclopyr)

Why the switch in herbicides: from Sonar (fluridone) to Renovate (triclopyr)?

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5-Year program integrating chemical treatment with non-chemical controls

The Town must commit to continuing with non-chemical controls as part of this integrated milfoil management program. Techniques that should be considered:

Suction harvesting (DASH)

SCUBA diver hand-pulling (paid)

Snorkel hand-pulling (volunteer)

Volunteer monitoring

Boat launch inspections

Education

Integrated Management Program

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Why Renovate herbicide?

SONAR (fluridone)

In 2001 only Sonar (fluridone) had been permitted for use in Vermont and

>40% of lake supported milfoil

Whole-lake treatment would be required

In 2011 less than 20% of lake supported dense milfoil growth

RENOVATE (triclopyr)

Renovate has been the primary herbicide used for milfoil control in VT since

2006

Provides highly selective control of milfoil

Effective for partial-lake or spot treatments

Lower cost

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Jurisdiction

VTDEC can issue a permit for pesticide use when the following five findings are made:

1) There is no reasonable non-chemical alternative available;

2) There is acceptable risk to the non-target environment;

3) There is negligible risk to public health;

4) A long-range management plan has been developed which incorporates a schedule of pesticide minimization

5) There is a public benefit to be achieved from the application of the pesticide, or in the case of a pond located entirely on a landowner’s property, no undue adverse effect upon the public good.

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Renovate Concentration Exposure Time

Untreated 1 WAT 4 WAT

Source: US Army Engineers – ERDC

Control PredictionsA: 0 - 70 % (regrowth likely)

B: 70 - 85 % (regrowth potential subject to site conditions)

C: >85 % (limited regrowth potential)

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Renovate OTF

Renovate 3

Two formulations available

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OTF Pond Residue Profile (n=3) vs. Theoretical Renovate 3SePRO Research Campus (2006)0.15 A, 3 feet average depth

Hous after treatment

1 2 4 8 24 32 48 96 168 336 672

Con

cent

ratio

n (p

pm)

0.0

0.5

1.0

1.5

2.0

2.5

Actual OTF Theoretical Renovate 3 (7 d linear half-life)

Initial flash (~50% in 1 hr) Peaks at ~24 hr

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CET Relationship

Renovate OTF alters the classical concentration-exposure time relationship

Increases the exposure component Decreases the concentration component

>85% Control of EWM achieved:

Concentration Exposure (hr) 0.25 ppm 72 hr 0.5 ppm 48 hr 1 ppm 36 hr 1.5 ppm 24 hr2 to 2.5 ppm 18 hr

Renovate OTF

Renovate 3

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Renovate OTF treatment recommendations

Target treatment of all dense beds which is estimated at 16 acres

Dose 2.0 to 2.5 ppm in bottom 4 feet

Timing – mid June

Water use restrictions: • No swimming for 2 days• Drinking resumes <75 ppb

(~ 1 week) • Irrigation varies

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Projected 5-year IMP costs for Indian Brook Reservoir

Estimated Program Costs – (2011 dollars)

Year 1 Year 2 Year 3 Year 4 Year 5

Year 2012 2013 2014 2015 2016

Renovate Herbicide Treatment Program

$20,000 $0 $10,000 $0 $0

Suction Harvesting / Hand-Pulling $0 $5000 $2500 $3000 $3000

Permitting / Notifications $2500 $500 $2500 $500 $500

Monitoring / Reporting $5000 $3000 $3000 $2500 $2500

Education (newsletter, etc.) pending pending pending pending pending

In-Kind pending pending pending pending pending

TOTALS $27,500 $8,500 $18,000 $6,000 $6,000

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2001

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2011…