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Development and Implementation of an Invasive Aquatic Plant Management Program at Indian Brook Reservoir Essex, Vermont Marc Bellaud VP/Aquatic Biologist. Recent History at Indian Brook Reservoir. Eurasian watermilfoil identified in 1999

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Recent History at Indian Brook Reservoir

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Recent history at indian brook reservoir

Development and Implementation of an Invasive Aquatic Plant Management Program at Indian Brook ReservoirEssex, VermontMarc BellaudVP/Aquatic Biologist


Recent history at indian brook reservoir

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  • Permit application withdrawn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


2001 plant distribution

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


2011 survey findings

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


Comparison of milfoil cover

Comparison of milfoil cover


Current management recommendations

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)?


Recent history at indian brook reservoir

Integrated Management Program

  • 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


Why renovate herbicide

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


Jurisdiction

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.


Renovate concentration exposure time

Untreated 1 WAT 4 WAT

Renovate Concentration Exposure Time

Source: US Army Engineers – ERDC

Control Predictions

A: 0 - 70 % (regrowth likely)

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

C: >85 % (limited regrowth potential)


Recent history at indian brook reservoir

Two formulations available

Renovate 3

Renovate OTF


Recent history at indian brook reservoir

  • Initial flash (~50% in 1 hr)

  • Peaks at ~24 hr


Cet relationship

CET Relationship

  • Renovate OTF alters the classical concentration-exposure time relationship

    • Increases the exposure component

    • Decreases the concentration component

      >85% Control of EWM achieved:

      ConcentrationExposure (hr)

      0.25 ppm72 hr

      0.5 ppm48 hr

      1 ppm36 hr

      1.5 ppm 24 hr

      2 to 2.5 ppm 18 hr

Renovate OTF

Renovate 3


Renovate otf treatment recommendations

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


Projected 5 year imp costs for indian brook reservoir

Projected 5-year IMP costs for Indian Brook Reservoir


Recent history at indian brook reservoir

2001


Recent history at indian brook reservoir

2011…


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