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LAKE QUASSAPAUG

LAKE QUASSAPAUG. Review of Variable Watermilfoil Control Program for Lake Quassapaug – Middlebury, CT. Prepared For: Lake Quassapaug Association Meeting March 25, 2014. Presenter: Keith Gazaille, Senior Biologist.

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LAKE QUASSAPAUG

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  1. LAKE QUASSAPAUG Review of Variable Watermilfoil Control Program for Lake Quassapaug – Middlebury, CT Prepared For: Lake Quassapaug Association Meeting March 25, 2014 Presenter: Keith Gazaille, Senior Biologist

  2. DEVELOPMENT OF A COMPREHENSIVE AQUATIC VEGETATION MANAGEMENT PLAN LAKE ASSESSMENT * Water Quality * Biology * Watershed * Morphometry MANAGEMENT OBJECTIVES * Fisheries/Wildlife * Recreation * Aesthetics EVALUATION OF MANAGEMENT TECHNIQUES * Effectiveness * Environmental Effects * Compatibility with Other Uses * Cost * Social Acceptability FINAL DESIGN & PERMITTING IMPLEMENTATION MONITORING PUBLIC EDUCATION

  3. - Approximately 52 acres of problematic growth Northeast Aquatic Research

  4. Target Invasive Aquatic Plant in Lake Quassapaug - 2014 Variable Watermilfoil Myriophyllum heterophyllum

  5. Variable WatermilfoilMyriophyllum heterophyllum • Acid waters • 7-10 pairs of leaflets • Vegetative propagation

  6. FISH, WILDLIFE & NATIVE PLANTS Displacement of native plants Displacement of endangered, threatened or rare aquatic plants Habitat loss for fish & wildlife Change in spawning site availability Change in fish distribution Reduction in feeding success of predatory fish Reduction of open-water WATER QUALITY Temperature & oxygen fluctuations Increased phosphorus (nutrient) loading Alteration in plant and algae communities Accelerated eutrophication rates POTENTIAL IMPACTS OF EXOTIC OR INVASIVE PLANTS Source: A report from the Milfoil Study Committee on the Use of Aquatic Herbicides to Control Eurasian Watermilfoil in Vermont. VTDEC, March 1993

  7. POTENTIAL IMPACTS OF EXOTIC OR INVASIVE PLANTS (continued) RECREATION • Risk of swimmer entanglement • Reduced access for boating & fishing • Reduced aesthetics LOCAL COMMERCE & REAL ESTATE • Reduced property taxes • Declining property values • Renters fail to return for a second season • Slowed business for marinas, etc. • Declining attendance at lakefront beaches and parks Source: A report from the Milfoil Study Committee on the Use of Aquatic Herbicides to Control Eurasian Watermilfoil in Vermont. VTDEC, March 1993

  8. MANAGEMENT TECHNIQUES Different Approaches • Physical/Manual • Mechanical • Chemical • Biological Determining Which One to Use • Program goals and objectives • Accurate plant identification • Environmental constraints • Social acceptability • Cost

  9. HABITAT MANIPULATION OR PHYSICAL CONTROL

  10. Drawdown • Outlet structure required • Effective on plants that propagate through vegetative means • Milfoil, Fanwort, Brazilian Elodea are generally susceptible

  11. Benthic Barriers • Compression and blocking sunlight • Effective for small areas • Swim areas / dense patches • Leave in place for >6 weeks

  12. Hand-Pulling • Sparse or widely scattered growth • Effective for small areas • Follow-up strategy • Labor intensive

  13. Suction-Harvesting • Diver-Assisted-Suction-Harvesting (DASH) • Improves efficiency of hand-pulling • High unit cost

  14. MECHANICAL CONTROLS

  15. Dredging

  16. Harvesting • Effective for seed producing plants • Water chestnut, pondweeds • Material handling issue

  17. Hydro-Raking • Removing plants and root structures • Most effective on plants with well-defined roots like waterlilies and emergents • Slower than harvesting

  18. CHEMICAL CONTROL

  19. FACTORS FOR HERBICIDE SELECTION… • Target species • Size & configuration of treatment area • Selectivity desired or required • Water uses • Flow considerations • Timing • Cost

  20. Untreated 1 WAT 4 WAT Concentration Exposure Time (CET) 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)

  21. Registered Aquatic Herbicides Effective for Milfoil Control Source: USACE, ERDC

  22. Formulation: Granular (BEE) (Navigate) – Amine liquid & granular (Sculpin) Mode of Action: Systemic – auxin mimic, inhibits cell division in new tissue and stimulates growth of existing tissue Environmental Fate: Hydrolosis, microbial degradation, photolysis Water Use Restrictions: Drinking < 70 ppb, Irrigation < 100 ppb Advantages: Selective for broad-leaf (dicot) species, multiple year control, effective for spot-treatments Limitations: long irrigation restrictions, negative public perception Plants Controlled: Milfoil, Water Chestnut, Waterlilies, Watershield 2,4-D

  23. Keith Gazaille, Senior Biologist Aquatic Control Technology 11 John Road Sutton, MA 01590 508-865-1000 phone 508-865-1220 fax Web: www.aquaticcontroltech.com E-mail: KGazaille@aquaticcontroltech.com

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