Tahoe created a world-class model for protecting the lake from weeds, fish, and other intruders

By Jim Sloan/Tahoe In Depth

Nicole Cartwright remembers her first summer at Lake Tahoe. It was 2007, and she was working on a pilot project introducing boat inspections at launch sites around the Lake Tahoe Basin.

At the time, natural resource managers throughout California and other parts of the country were scrambling to find ways to battle tenacious aquatic invasive species that were invading lakes and rivers, fouling boat propellers, ruining swimming areas, and clogging domestic water systems. Many lakes around the country had been ecologically decimated by such foreign invaders as quagga mussels, curlyleaf pondweed, and invasive fish.

Although Cartwright had studied the problems posed by invasive species, that summer she was learning how to explain to the public how aquatic invasive plants posed a threat to Tahoe.

“It was so eye-opening for me,” she said. “People were accustomed to having open access to the lake and now we were explaining why we needed to inspect their boats.”

Dennis Zabaglo, the aquatic resources program manager at Tahoe Regional Planning Agency, remembers the summer of 2007 well. That was when invasive mussels were discovered in Lake Mead. Resource managers in the West had been working for years to halt the spread of invasive mussels from the Great Lakes—calling their work the 100th Meridian Initiative— and the discovery of mussels in Mead was a chilling confirmation that the mussel had slipped past them.

“That’s what really drove us to action,” he said. “Quagga and zebra mussels can have a tremendous impact on a lake. They reproduce quickly, clogging dams and water conveyances, and they completely disrupt the food chain. They excrete nutrients that cause algal blooms, and they consume the phytoplankton that native fish rely on.”

With the mussels already established in Lake Mead, Tahoe faced a daunting challenge. Adult mussels cling tenaciously to boats and are difficult to remove. In their juvenile stages, the mussels are microscopic and easily transported in small amounts of water in boat compartments.

The boat inspection program was launched in 2008 and was voluntary. The next year it became mandatory.

An inspector checks a boat for aquatic invasive species prior to launch. Photo: Novus Select

Today, it’s the most comprehensive program in the country. Resource managers from all over the world call TRPA or the Tahoe Resource Conservation District for advice. More than 70,000 boat inspections have been conducted and more than 32,000 boats have been decontaminated at Tahoe. Inspectors have flagged hundreds of watercraft infested with mussels and other invasives and decontaminated them before the boats were launched. Meanwhile, in other areas of the West, the mussels spread to more than 60 other waterbodies.

“If we hadn’t started inspections when we did, it’s very likely Tahoe would be home to mussels today,” Zabaglo said.

10 years of success

A decade after the program launched, Cartwright, now the executive director of the Tahoe Resource Conservation District (Tahoe RCD), has noticed the public’s understanding of the threat from aquatic invasive species has increased.

“People understand about aquatic invasive species now,” Cartwright said. “When we go into the schools and businesses, people understand the importance of aquatic invasive species prevention and also why we work to control them. When boaters come through the inspection stations, their tone is much different than it was in 2007. They get it and have been conditioned to be wary of aquatic invasive species. They want to do the right thing when they come to Lake Tahoe.”

What are aquatic invasive species?

Aquatic species like weeds, nonnative fish, mussels, clams, and other invertebrates can threaten native ecosystems and ruin a resource’s natural beauty and recreation potential. They can cloud the water, foul beaches, and push out native species, causing massive changes to the appearance and quality of a lake or other natural resource.

Aquatic invasive species currently in Lake Tahoe include Eurasian watermilfoil, curlyleaf pondweed, largemouth bass, Asian clams, bluegills, bull frogs, and goldfish. Some of these invaders were introduced by people who either set loose living fish or dumped their aquariums.

Some, such as the nonindigenous Eurasian watermilfoil, were likely introduced over 30 years ago. Mysis shrimp were purposely introduced over 50 years ago, while others, such as the largemouth bass and Asian clams, are fairly recent arrivals. The fish have taken advantage of warmer water and the invasive weeds to make a home in certain areas of Lake Tahoe, such as the Tahoe Keys.

A measure of success

Since the boat inspections began, no new invasive species have been found in the lake. This hasn’t been the result of luck, but of hard work. In 2016 alone, the conservation district conducted 6,800 inspections and required 2,300 decontaminations. Forty vessels that year carried some form of invasive species. Had it not been for the inspections, and TRPA’s lakewide jurisdiction to oversee the program, these contaminated boats would have entered Lake Tahoe.

An inspector peers into the hull of a kayak. Hand-carried watercraft, such as kayaks and paddleboards, are screened at developed recreation sites. Inspections and decontaminations for canoes, kayaks, and paddleboards are free for paddlers who have recently visited infected waters. Visit TahoeKeepers.org to learn how to self-inspect and decontaminate your gear. Photo: Novus Select

The inspections, which take place at four entry points to the Lake Tahoe Region, allow trained and certified employees to examine all areas of the boat including the hull, engine, live well, bilge, and trailer. If anything looks suspicious, the boat is decontaminated with 140-degree water before it can be launched. Annual inspection fees range from $35 for personal watercraft to $101 for vessels over 39 feet. A decontamination, if necessary, is $35.

All boaters should arrive “Clean, Drain, and Dry,” meaning all vegetation, mud, sand, and other contaminants should be cleaned off surfaces; all bilge, ballast, live wells, and sea strainers should be drained; and all compartments of a boat should be dry. Water present in a compartment or engine results in a decontamination.

“TRPA had a challenge in the beginning to either close the lake to outside boating or figure out a way to keep our waters public,” Cartwright said. “The question was, ‘How far are we willing to go and how much money are we willing to spend to keep the lake open and free of invasives?’

“Now all the access points have gates and hours. All boats that come in with water get decontaminated. Not many places have that level of protection.”

Greatest accomplishment

Cartwright and Zabaglo are quick to point out how many agencies have pulled together in the Tahoe Basin to battle aquatic invasive species. The Lake Tahoe Aquatic Invasive Species and Watercraft Inspection Programs are implemented by 40 public and private partner organizations, including federal, state and local jurisdictions, research partners, public utility districts, and private marinas. The Tahoe Regional Planning Agency and the Tahoe Resource Conservation District lead the inspection program through the collaborative framework of the Lake Tahoe Aquatic Invasive Species Coordinating Committee. The Committee provides the leadership, direction, and resources to fulfill this program’s mission of prevention, detection, and control of aquatic invasive species in the Lake Tahoe Region.

The committee’s research, including work from the University of Nevada, Reno, and the U.C. Davis Tahoe Environmental Research Center, has mixed science, management, technology, and regulation to create a multi-pronged strategy to prevent and remove aquatic invasive species from Tahoe.

“That’s where our success starts,” Cartwright said. “We’ve been able to bring all these minds together to tackle this problem and the result has been a nationally recognized program that is the most robust in the United States.”

Zabaglo echoes that.

“Our greatest accomplishment has been the massive support we’ve had in the last 10 years,” he said. “We’ve had buy-in from the marinas, the boating public, legislators, and funders, and that’s really what’s helped our program be successful.”