Model program prevents, controls, and monitors aquatic invasive species
Billboards help remind paddlers to clean their gear before launching at Lake Tahoe. Image by Tahoe Regional Planning Agency.
This article was originally published in Tahoe In Depth, Issue 33, Summit 2026.
Strolling along the shore of Lake Tahoe, you may stumble across white, ribbed shells and be tempted to pocket them as a memento of Tahoe. However, these algal-bloom-promoting clams aren’t representative of Tahoe at all, they are an aquatic invasive species, or AIS. Corbicula clams (previously known as Asian clams) were discovered near Nevada Beach in 2002, likely transported as fishing bait or in ballast water before live bait was outlawed and boat inspections were required.
Aquatic invasive species are notorious for hitching a ride between waterbodies on watercraft. Once introduced, they wreak havoc on native biodiversity, decrease water clarity, hinder recreation opportunities, and are often impossible to eradicate. Corbicula clams weren’t the first species to sneak into Lake Tahoe—crayfish, weeds, and warm-water fish were already established—but the discovery of an even more insidious invader in Southern Nevada rallied local leaders to prevent any new introductions.
The detection of quagga mussels in Lake Mead in 2007 was the first detection of these invaders in the western U.S. It sparked action to establish one of the first mandatory boat inspection programs in the nation in 2008. Invasive quagga, zebra, and golden mussels encrust rocks, boats, and piers, decimate fish populations, and, if introduced, would irreversibly alter Lake Tahoe’s ecosystem. The Tahoe Regional Planning Agency (TRPA) and Tahoe Resource Conservation District (Tahoe RCD), coleaders of the Lake Tahoe Watercraft Inspection Program, knew this was not a risk Tahoe was willing to take, and with the groundwork for collaboration established by the Environmental Improvement Program (EIP), partners were prepared to respond.
Since 2008, the Lake Tahoe Invasive Species Program has invested $85 million to prevent, detect, and control aquatic invasive species in the Tahoe Basin, a cornerstone program for achieving water quality thresholds in Lake Tahoe.
Prevention
Today, stations at Spooner Summit, Nev., Meyers, Calif., and Alpine Meadows, Calif., serve as a nationwide model for watercraft inspections. Inspectors have performed as many as 9,300 inspections and intercepted 129 vessels with invasive species in a single year. Dedicated partnerships between 40 organizations, including non-profits, marinas, boaters, shoreline property owners, and state, federal, and local agencies create strong protection from new invaders. New programs across the West consult with the watercraft inspection program for best practices on vessel inspection and decontamination at stations, seal inspection at boat ramps, and Clean, Drain, Dry outreach on the beaches.
The program’s tagline “Clean, Drain, Dry” can be seen on posters, billboards, murals, and stickers. It is a call to action for boaters, paddlers, anglers, and beachgoers to become Tahoe Keepers, and do their part to prevent the spread of invasive species.
“Prevention is the best investment to preserve Tahoe’s unique beauty,” says Dennis Zabaglo, aquatic invasive species program manager at TRPA. “The success of the inspection program set the stage for all that we do to protect Lake Tahoe from AIS,” Zabaglo said.
Control
With measures in place to prevent the introduction of new species, EIP partners set their eyes on a lofty goal to eradicate populations of existing invaders.
Over 90 percent of boat trips include a visit to Emerald Bay, an iconic state park and landmark. The deep blue waters weren’t always pristine, however. In 2007, invasive weeds like Eurasian watermilfoil and curlyleaf pondweed had taken over portions of the popular shoreline. EIP partners embarked on a several-year journey to eradicate the plants and restore previous clarity. Private and public investment funded bottom barriers and diver hand pulling to
remove the weeds and keep them at bay.
“The control project in Emerald Bay was important for the program to understand the effort needed to maintain its pristine, weed-free status,” explains Mollie Hurt, director of programs at Tahoe RCD. “It’s an ongoing practice that takes work and collaboration to ensure Emerald Bay remains clear for years to come.”
The success of the Emerald Bay plant control project laid the groundwork for larger control efforts in the basin, like the Taylor and Tallac Creek Restoration
Project, which removed 17 acres of invasive plants from critical wetlands from 2021 to 2024.
Monitoring
Part of the lesson learned in Emerald Bay was the importance of ongoing surveillance—checking restored areas to prevent re-establishment of invasive species spreading from areas like the Tahoe Keys. The AIS program has implemented a wide range of monitoring techniques—including lake-wide dive surveys, environmental DNA (eDNA) sampling, aerial imagery, lasers, sonar, and community science—to protect investments and maintain environmental thresholds. A diverse set of monitoring tools helps partners better understand progress being made, or where more focus is necessary. Ongoing early detection monitoring also reveals that prevention is working. “Secret shoppers” are also used to make sure science based protocols are being followed at
the inspection stations, and only cleared boats are allowed to launch at ramps.
Looking to the future, the threat of invasive species continues to grow, but so do Tahoe’s protections. Golden mussels, discovered in the Port of Stockton, California, have now spread from as far south as San Diego. Fortunately, the Tahoe Basin is equipped for prevention. From pioneering UV light control technology to guiding policy at a national level to groundbreaking on a permanent watercraft inspection station at Spooner Summit, the Lake Tahoe Invasive Species Program will continue to meet the demands of the future so everyone can do their part and enjoy all of Tahoe’s splendor.
McKenzie Koch is the AIS outreach and education specialist at TRPA.
Click here to read more articles from the 33rd issue of TRPA’s environmental newspaper, celebrating decades of remarkable progress through the Lake Tahoe Environmental Improvement Program.