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

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 MONITORINGPUBLIC EDUCATION

Northeast Aquatic Research - Approximately 52 acres of problematic growth

Variable Watermilfoil Myriophyllum heterophyllum Target Invasive Aquatic Plant in Lake Quassapaug

Variable Watermilfoil Myriophyllum heterophyllum Acid waters 7-10 pairs of leaflets Vegetative propagation

POTENTIAL IMPACTS OF EXOTIC OR INVASIVE PLANTS 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 Source: A report from the Milfoil Study Committee on the Use of Aquatic Herbicides to Control Eurasian Watermilfoil in Vermont. VTDEC, March 1993

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

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

HABITAT MANIPULATION OR PHYSICAL CONTROL

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

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

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

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

MECHANICAL CONTROLS

Dredging

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

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

CHEMICAL CONTROL

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

Concentration Exposure Time (CET) 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)

Registered Aquatic Herbicides Effective for Milfoil Control CompoundYear RegisteredMode of Action 2,4-D Ester 2,4-D Amine Auxin – Systemic Copper1950’sContact – phs – membrane Diquat1962Contact – PSII – membrane Endothall1960Contact – Resp. – membrane Glyphosate1982Growth – protein synthesis Fluridone1986Growth – Enzyme inhibitor Triclopyr2002Auxin - Systemic Imazapyr2003Growth – AHAS inhibitor Carfentrazone2004Contact – Enzyme- membrane Source: USACE, ERDC

ChemicalFormulationTrade NameAttributesLimitations 2,4-D BEE esterGranularNavigate  Best activity on variable milfoil  Selective for dicots, so less potential for non-target native plant impacts  Dense granule can “plug” in mucky bottom sediments, resulting in incomplete release of active ingredient 2,4-D amineLiquidDMA 4 IVM; Clean Amine, etc.  Low cost  Initial concentration can be established immediately  Selective for dicots, so less potential for non-target native plant impacts  Subject to dilution  Less effective for spot-treatment 2,4-D amineGranularSculpin G  Less dense granule will not sink into the mud  Complete herbicide release within 24 hours  Selective for dicots, so less potential for non-target native plant impacts  Subject to dilution  Not effective for spot-treatment  Higher cost than liquid 2,4-D amine & triclopyr amine GranularRenovate Max G  Less dense granule will not sink into the mud  Complete herbicide release within 24 hours  Good control when whole-lake concentrations are established and maintained for 2 weeks+  Selective for dicots, so less potential for non-target native plant impacts  Long restriction on irrigation for gardens and ornamentals  Subject to dilution  Not effective for spot-treatment  Higher cost than liquid TriclopyrGranular & LiquidRenovate OTF & Renovate 3  Less dense granule will not sink into the mud  Complete herbicide release within 24 hours  Good control when whole-lake concentrations are established and maintained for 2 weeks+  Selective for dicots, so less potential for non-target native plant impacts  Long restriction on irrigation for gardens and ornamentals (120 days or <1 ppb)  Subject to dilution  Not effective for spot-treatment  At least 3x more expensive than 2,4-D DiquatLiquidReward  Low cost  Rapid mode of action, effective for spot- treatments  Controls bladderwort and milfoil  Short water use restrictions (maximum 5 day irrigation)  Not systemic-acting so it does not kill the roots  Greater potential for non-target native plant impacts FlumioxazinLiquidClipper  Rapid mode of action, effective for spot- treatments  Low toxicity, no drinking restriction, maximum 5-day irrigation restriction  High cost  Does not provide complete control of variable milfoil alone, but works well in combination with Diquat FluridoneLiquid & GranularSonar  Systemic-action provides complete plant control  Effective on multiple species  High cost  Requires long contact time (60-90 days)  Long restriction on using water for irrigation  Less effective on variable milfoil

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

Keith Gazaille, Senior Biologist Aquatic Control Technology 11 John Road Sutton, MA phone fax Web: