Column: 10 years of fighting invasive species at Tahoe

This summer marks the tenth anniversary of Lake Tahoe’s Watercraft Inspection Program. Under the program, every motorized watercraft is inspected to ensure it is clean, drained, and dry and not carrying aquatic invasive species before launching at Tahoe.

More than 40 local, state, federal, private, and nonprofit partners worked together to create this inspection program a decade ago when invasive and harmful quagga mussels were spreading West. The mussels were being carried to new lakes, rivers, and reservoirs by boats and people recreating on their waters, raising serious concerns they would reach Tahoe.

In the years since then, Tahoe’s inspection program, managed by the Tahoe Regional Planning Agency (TRPA) and Tahoe Resource Conservation District, has grown into a national model for preventing the introduction of harmful invasive species that could damage the environment and degrade recreational experiences that drive the region’s economy. Tahoe’s watercraft inspectors have prevented the launch of hundreds of boats carrying aquatic invasive species. And today, because of this critically-important program, Tahoe remains free of quagga mussels and there have been no detections of new aquatic invasive species in the lake over the last 10 years.

With this front-line defense protecting Tahoe from new invasive species, TRPA and dozens of partners are working to control, if not eradicate, other harmful aquatic invasive species that found their way into the lake decades ago. With the help of research partners, Tahoe has a science-based management plan that details what invasive species should be targeted for control or eradication and how and where they should be targeted with projects.

Through the Lake Tahoe Environmental Improvement Program, partners have treated more than 60 acres of the lake for Eurasian watermilfoil, curlyleaf pondweed, and Asian clams. That includes work to eradicate a six-acre infestation in Emerald Bay, an iconic part of the lake that remains weed-free five years later. Last year, partners treated 14.5 acres for invasive plants and Asian clams and are planning more projects to keep that momentum growing.

Partners at Tahoe are working with the boating industry to help develop new engine, watercraft, and trailer designs that are easier to inspect and less likely to spread aquatic invasive species. They are also testing new ways to treat invasive species, including the ultraviolet light technology tested at Lakeside Beach and Marina. Citizen-science programs like Eyes on the Lake are training people to identify and report invasive species they see while recreating at Tahoe.

TRPA and its partners are now turning their attention to the Tahoe Keys, which is ground-zero for aquatic invasive species. Eurasian watermilfoil and curlyleaf pondweed infest more than 90 percent of the 172 acres of canals and lagoons in the Tahoe Keys each summer. The Tahoe Keys Property Owners Association (TKPOA) has done significant work to develop a comprehensive management plan with projects to thin out the weeds and keep them from growing back or spreading to other parts of the lake.

This summer, TRPA, the Lahontan Regional Water Quality Control Board, and Tahoe Keys are working to launch a broad, collaborative process and environmental analysis to review the comprehensive suite of weed control and eradication proposals submitted by the Tahoe Keys. The review will include looking at one of the most controversial aspects: A proposal to test the use of federally-approved aquatic herbicides in a portion of the canals and lagoons as one way to knock weed populations down to a level that could then be controlled through other methods like bottom barriers and diver pulls.

Herbicides are only one of many treatment approaches under consideration for the Tahoe Keys. While the herbicides are used in other lakes in California and across the country, they have never been used in Tahoe or any other federally-designated Outstanding National Resource Water with the highest levels of protection.

TRPA looks forward to working with agency and community partners to complete this review and to moving forward with a comprehensive plan to address invasive aquatic species in the Tahoe Keys in a way that is effective, protects the surrounding environment, and protects Tahoe’s world-class recreation opportunities.

July was the hottest July on record in California, and climate change is increasing Lake Tahoe’s water temperatures, which threatens to make the lake a more hospitable place for aquatic invasive species in decades to come. By working together to ramp up aquatic invasive species control projects at Tahoe and to find a collaborative solution for the Tahoe Keys we can make continued progress in the fight against aquatic invasive species.

- Joanne S. Marchetta is executive director of the Tahoe Regional Planning Agency