Relevance

Maintaining the biological integrity of Lake Tahoe’s nearshore environment is a longtime goal of resource managers in the region and has been set forth in a variety of planning documents. Submerged aquatic vegetation is an important biological component within Lake Tahoe’s nearshore context. Knowing the status of submerged aquatic plant populations at Lake Tahoe has become increasingly important to nearshore managers due to the introduction and spread of invasive species such as Eurasian watermilfoil (Myriophyllum spicatum) and curly-leaf pondweed (Potamogeton crispus). Aquatic invasive plants when left unchecked can impact water quality, fish and wildlife habitat conditions, recreational fishing, human and animal health, vessel navigation, and the recreation values of water bodies. The threshold standard establishes a goal for aquatic invasive plant infestations in Lake Tahoe and associated areas. The standard establishes the goal that all aquatic invasive plant infestations in Lake Tahoe (not including the Tahoe Keys, which has a separate standard) be in the surveillance category. The goal aligns with the management categories that are utilized by the Lake Tahoe Aquatic Invasive Species Coordinating Committee and conveys the reality of long-term management of aquatic invasive species. Due to aquatic invasive plants’ proclivity towards spreading and establishing new infestations through fragmentation throughout connected waterbodies, all completely treated AIP sites are at risk of re-establishment if there is source of AIP fragments within Lake Tahoe. The goal acknowledges that because of this risk, complete eradication is unlikely, and control will likely require continued surveillance and vigilance. The threshold standard formally adopts the phase one vision laid out in the Lake Tahoe Region AIS Action Agenda.

Human and Environmental Drivers

Non-native species have been both intentionally and unintentionally introduced to Lake Tahoe over the last 150 years. Habitat modification such as channelization and modification of the Upper Truckee Marsh for the Tahoe Keys also created micro-environments within the lake that may be more suitable for colonization by AIS. Climate change further threatens to alter the lake’s physical environment, with the potential for making further AIS establishment more likely. Three management categories are used to evaluate the status of individual infestations. Planning – Active infestation. Active planning and procurement of funds to treat. Site Assessments, coordination with landowners, Containment, marina-led maintenance treatment, or pilot methods testing projects may be implemented. Active control methods (barriers, diver-assisted suction, or UV-C) will likely be needed to treat this site. Control – Active infestation. Active control methods (barriers, diver-assisted suction, or UV-C, site preparation, or methods testing) were implemented throughout the season. Also includes first-time or previously treated control sites that only required hand removal to maintain the weed-free status. Surveillance - Previously treated control site, not an active infestation. Throughout one season, no more than 20 diver hours over the expected surveillance effort was required at this site to maintain weed-free status. Also includes sites where consecutive surveys over have revealed no detections.

EIP Action Priorities

• Prevent, Control, or Eradicate Aquatic Invasive Species

  Projects aim to reduce and eradicate populations of invasive aquatic weeds.

EIP Indicators

• Acres of Invasive Species Inventoried
• Acres Treated for Invasive Species

Example EIP Projects

• Crystal Shores Aquatic Invasive Plant Control
• Early Detection and Rapid Response to New Aquatic Invasive Species Infestations
• Emerald Bay Aquatic Invasive Plant Control
• Taylor and Tallac Ecosystem Restoration

  17 acre invasive weed infestation treat in in South Lake Tahoe

• Truckee River AIS Plant Control

Local and Regional Plans

• Aquatic Invasive Species Action Agenda 2021-2030

  The Lake Tahoe Region Aquatic Invasive Species Action Agenda 2021-2030 implements a well-funded, comprehensive, robust, simultaneous, science based, and aggressive suite of AIS control actions.

Monitoring Programs

• Aquatic Invasive Species Monitoring
• Lake Tahoe Aquatic Plant Monitoring Program: Aquatic Plant Monitoring and Evaluation Plan

  Protocols to gather, analyze, and report information relative to aquatic plant populations in Lake Tahoe, with an emphasis on guide control efforts for AIS.

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