Tahoe Resource Conservation District

News & Updates

CSV_flowering Eurasian watermilfoil

Headway made in fight against aquatic invasive plants

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Lake Tahoe, CA

In 2010, the Tahoe Resource Conservation District (Tahoe RCD), in collaboration with the Lake Tahoe Aquatic Invasive Species Program, began treatment of approximately six acres of aquatic invasive plants in the nearshore by Vikingsholm in the iconic Emerald Bay. The control methods included bottom barriers, which kill plants by eliminating light, and diver-assisted suction removal, which physically removes plants and roots. After four years of comprehensive treatment, Emerald Bay remains free of aquatic invasive plants.

Using this integrated approach, other locations around the Lake Tahoe Basin are being addressed. An Implementation Plan for the Control of Aquatic Invasive Species within Lake Tahoe developed by University of Nevada Reno in 2015 is guiding the way. The Implementation Plan uses an ecological and scientifically-based framework to determine site prioritization, which calls for controlling satellite populations in an effort to achieve containment. In 2016 Tahoe RCD treated 4.5 acres at Lakeside Marina and Beach, Crystal Shores marinas, Fleur du Lac’s outer harbor and in the Truckee River. This winter a new infestation at the Tahoe Vista boat launch will be tackled. Treatment of Eurasian watermilfoil is important for water quality because the invasive plant raises pH, decreases oxygen, and increases water temperature, all of which alter the ecosystem and negatively impact recreation and public safety.

“From our efforts in Emerald Bay, we know that invasive plant populations can be reduced, and with continued treatments, we will be able to better manage populations around the lake in the future,” said Tahoe RCD District Manager Kim Boyd.

Tahoe RCD anticipates the continuation of aquatic plant control efforts in Lake Tahoe and the Truckee River for years to come. While bottom barriers and diver-assisted suction removal have proven to be successful, there is a need to identify other techniques that could help us get ahead of the battle, particularly with persistent plant species such as curlyleaf pondweed. The potential to use ultra-violet light will increase the effective techniques available to Tahoe RCD especially in low water years and in tight spaces within marinas. Ultra-violet light has proven in lab studies and small field tests to damage the DNA and cellular structure of aquatic plants causing it to die back. Tahoe RCD will continue to work with partners this winter to finalize environmental documentation and permitting so UV light can be tested in Lake Tahoe in 2017.

“We are excited about working with our partners to explore new technology that can be added to the toolbox,” said Boyd, “A project using UV light to reduce aquatic plant infestations is being developed and is expected to launch in spring 2017.”

Funding for these projects has been provided by the Truckee River Fund, the Tahoe Fund, the Rotary Club of Tahoe City, California Tahoe Conservancy, and Nevada Division of State Lands.