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Timeline of AIS in Tahoe Keys



  • Tahoe Keys Lagoons Restoration Project application for herbicide use submitted to TRPA and Lahontan Water Board in 2018
  • Collaborative stakeholder process begins Fall 2018 resulting in a modified Application for the Tahoe Keys Lagoons Aquatic Weeds Control Methods Test Spring 2019.  The application is again revised in 2021.
  • Independent technical team begins design and implementation of environmental analysis (EIS/EIR) and field studies and tests 2019 – 2021
  • Approval and implementation of Aquatic Weed Control Methods Test 2022.
  • Non-herbicide combination control methods evaluation 2018-2022
    • Ultraviolet (UV) light tests
    • Broader bottom barrier use
    • Diver assisted pulling
    • Bubble Curtain + Sea Bins for fragment containment and collection
    • Laminar Flow Aeration (LFA) to improve water quality


Research & Collaboration

  • Education and outreach to homeowners, landscaping companies and other land owners for Nonpoint Source Plan
  • Independent Scientific Panel review of Integrated Management Plan
  • Fragment Control method evaluation including new boats, boat backup station
  • Alternative methods research and field study
  • Water quality monitoring and study
  • Collaboration with stakeholders in planning process, including the Lake Tahoe Water Suppliers Association, League to Save Lake Tahoe, Sierra Club, Tahoe Resource Conservation District, Tahoe Regional Planning Agency, Lahontan Regional Water Quality Control Board
a scuba diver in the water speaking to a man on shore


Research & Coordination

  • Initial collaboration with Tahoe Regional Planning Agency and Tahoe Resource Conservation District
  • Initial experiments with bottom barriers
  • Comprehensive literature research on control methods
  • Informational consultations with Lahontan Regional Water Quality Control Board, Lake Tahoe Aquatic Invasive Species Coordinating Committee and others
  • Waste Discharge Requirement (WDR) Permit issued in 2014, necessitating
    Integrated Management Plan and Nonpoint Source Water Quality Management Plan


Investigation & Harvesting

  • Curlyleaf pondweed is discovered in Lake Tahoe in 2003
  • The harvesting and fragment control programs continue and grow as the infestation grows
Underwater image of curlyleaf pondweed PC: Novus Select
a metal grate filtering weeds out of the water

1980- 1990

Infestation & Response

  • Native to Europe and Asia, Eurasian watermilfoil was introduced to Lake Tahoe and the Tahoe Keys in the 1980s. No one knows how specifically, but it is likely from home aquarium dumping, or transported accidentally by boat.
  • Harvesting begins
eurasian watermilfoil with four branches
fingers holding milfoil out of the water