Development and Implementation of an Invasive Aquatic Plant Management Program at Indian Brook Reservoir Essex, Vermont Marc Bellaud VP/Aquatic Biologist

2 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winter 2001/2002 for Sonar (fluridone) herbicide treatment  Milfoil population naturally crashed  Permit application withdrawn  Milfoil has now recovered to nuisance densities

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 was not observed in 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

5 Comparison of milfoil cover

6 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)?

7 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 I ntegrated M anagement P rogram

8 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

9 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.

10 Renovate Concentration Exposure Time Untreated 1 WAT 4 WAT Source: US Army Engineers – ERDC Control Predictions A: % (regrowth likely) B: % (regrowth potential subject to site conditions) C: >85 % (limited regrowth potential)

11 Renovate OTF Renovate 3 Two formulations available

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

13 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

14 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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18 Projected 5-year IMP costs for Indian Brook Reservoir Estimated Program Costs – (2011 dollars) Year 1Year 2Year 3Year 4Year 5 Year Renovate Herbicide Treatment Program $20,000$0$10,000$0 Suction Harvesting / Hand-Pulling$0$5000$2500$3000 Permitting / Notifications$2500$500$2500$500 Monitoring / Reporting$5000$3000 $2500 Education (newsletter, etc.)pending In-Kindpending TOTALS $27,500  $8,500  $18,000  $6,000 

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