Recent History at Indian Brook Reservoir

1. Development and Implementation of an Invasive Aquatic Plant Management Program at Indian Brook ReservoirEssex, VermontMarc BellaudVP/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winter 2001/2002 for Sonar (fluridone) herbicide treatment • Milfoil population naturally crashed • Permit application withdrawn • Milfoil has now recovered to nuisance densities

3. 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

4. 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. 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

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. 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)

11. Two formulations available Renovate 3 Renovate OTF

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 ppm 72 hr 0.5 ppm 48 hr 1 ppm 36 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

18. Projected 5-year IMP costs for Indian Brook Reservoir

19. 2001

20. 2011…