Joanne Marchetta: Beating aquatic invasive species at Tahoe

Around the world, invasive species are notorious for their ability to out-compete native plants and animals. Once introduced to an area, they can spread out of control and fundamentally change both landscapes and ecologies, and then pose incredible challenges to manage or eradicate.

With another boating season underway at Lake Tahoe, invasive species remain one of the greatest and most persistent threats to our mountain lake’s unique environment and clear blue waters, as well as the recreation-based economy that it supports. Fortunately, Tahoe is a national leader in the fight against invasive species.

Our region has taken major steps to protect Lake Tahoe. More than 40 agencies and private and nonprofit partners are working together to prevent new introductions of invasive species and control populations of invasive species already in the lake. But we can and must do more.

Last month, TRPA received an update on plans to fight invasive aquatic weeds in the Tahoe Keys. The canals, lagoons and marina are ground-zero for invasive weeds and warm-water fish. The Tahoe Keys Property Owners Association is spearheading a plan, which has generated significant discussion because of its proposal to test and potentially use herbicides to fight the weeds that choke the lagoon’s waterways.

While specially-designed herbicides are used to fight invasive weeds in other lakes, some of which likely couldn’t be cost-effectively controlled or eradicated in any other way, their use would be a first for the Lake Tahoe region. And the subject has rightly prompted serious discussions about potential impacts to drinking water, other plants and animals, and the environment at large.

While conversations continue about whether herbicide use is appropriate for lagoons so close to Lake Tahoe, there’s no doubt a problem with invasive species in the Tahoe Keys. Every summer, weeds must be cleared from its waterways to keep them open. The harvesting or “mowing” process costs hundreds of thousands of dollars. It also creates small weed fragments that threaten to spread and colonize the lake and leave the weeds growing back year after year.

This is a difficult issue to work through. But it should inspire each of us to see Tahoe Keys property owners cooperating with agencies, scientists, researchers and community members to find innovative solutions to the problem.

Once fully analyzed and approved, the comprehensive weed management plan for the Tahoe Keys will contain a suite of options. For example, the plan calls for better ways of using barrier mats to block out sunlight and kill weeds, improving harvesting methods to reduce the number of weed fragments, and reducing the amount of nitrogen and phosphorus pollution from lawn fertilizer and other sources that washes into the lake and helps weeds grow. One researcher is even testing new ways to use ultraviolet lighting systems to kill the underwater weeds.

The community and agencies are embracing innovation and new technologies along with more cost-effective ways to fight invasive species at Tahoe. Our work is already paying off.

Tahoe’s boat inspection program is nationally recognized as a model for the rest of the country. This frontline defense has successfully stopped any new introductions of invasive species since its launch in 2008. Boater outreach and education is paying off, too, with fewer boats needing to be decontaminated because they are showing up “Cleaned, Drained and Dry.” The Tahoe Keepers program has educated more than 3,000 people with kayaks, paddleboards and canoes about how they can ensure their boats and fishing equipment aren’t spreading invasive species.

Researchers at University of Nevada, Reno, have created a lake-wide plan to control existing invasive species populations before they do any more harm to Tahoe’s environment and ecology. The plan will guide future control projects, outlining what invasive species we have the best chances to manage or eradicate, treatment techniques, research needs and locations where projects will be most successful.

Nonprofit groups and research partners at Tahoe have also launched innovative new programs for people to get involved. The League to Save Lake Tahoe’s Eyes on the Lake program trains people to spot and report invasive species infestations while they are recreating at Lake Tahoe, compiling information that helps monitoring programs and guides future removal projects. The Lake Tahoe Citizen Science App created by the UC Davis Tahoe Environmental Research Center helps people report all sorts of useful information about invasive species and beach and water quality conditions.

There are many ways for people to get involved to protect Tahoe from the harms of aquatic invasive species. To learn more, please attend an upcoming public event about the past, present, and future of aquatic invasive species control and prevention work at Lake Tahoe. The event is scheduled for Tuesday, June 14, from 5:30-7:30 p.m. at the Tahoe Center for Environmental Sciences in Incline Village. By working together and bringing forward our best ideas for innovative solutions we can and will make a difference, and help ensure the lake we all treasure is passed on for future generations to enjoy. Please join us in this important work.

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