Considerations

• Limited to small areas since labor intensive and costly to install and maintain
• Needs to be secured to prevent lifting from gas bubbles or wave action
  • Permeable fabric or small cuts may allow gas to escape
• Control plants prior to installation to secure to lake bottom
• Deeper water installation may require SCUBA
• Non-selective and may kill all plants and other organisms trapped underneath

Examples of Feasible Control

• Apply to swimming areas or bottoms of ponds

Silt Curtains

Reduce water flow or exchange to facilitate chemical or mechanical control

Considerations

• Not an aquatic plant control method alone, but critical component in some integrated plans
• Expensive and labor intensive to install and remove
• Use curtain, if possible, around harvesting or shredding
  • To contain turbidity or fragments
  • Yo reduce wave action and flow within control area
  • May not be feasible in flowing water around bridges or near flood control structures
  • Install commercial fabric barrier
    • May not be feasible for locations far from access points
  • Use existing band of emergent plants to contain plant fragments or turbidity
    • Harvest or shred natural barrier last
• Accommodates some herbicide applications by reducing dissipation / dilution
  • Install along shore of spring runs or river to isolate flow
  • Install across mouth of cove to isolate from main body of lake or river

Examples of Feasible Control

• Shredding and harvesting is conducted leaving a 25-foot band of emergent plants on the outside edge to contain turbidity and fragments – harvesting the band last
• Silt barriers have been installed to separate herbicide treated areas from the flow in Salt and Sanlando Springs

Fences, Booms, Chains

Devices to prevent floating plants, tussocks and islands from entering or impacting selected areas

Considerations

• May need state or federal permits and appropriate marking or warnings
  • May impede navigation or flood control
  • Installation may disturb sediments
• Ensure that barrier is sufficiently strong to hold back floating plants
  • Floating PVC or log boom may be sufficient to exclude water hyacinth
  • Pilings and steel cables may be required to hold back drifting islands
• Require frequent inspection and may be expansive to keep clear and maintain intact

Examples of Feasible Control

• Floating PVC booms prevent water hyacinth from drifting into canals from the St Johns River
• Pilings and cables prevent drifting floating tussocks and islands from blocking the outfall canal and flood control structure on Lakes Hancock and Apopka