Download - 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Permit application withdrawn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…