Keeping invasive species out of Lake Tahoe
While it felt like spring had finally arrived, we all know Mother Nature can be fickle, especially at Lake Tahoe. For those who love to play in the snow, it was a fantastic winter, and a banner year for the Sierra snowpack. Despite some cooler weather now, steady warmer temperatures are on the way and our attention is shifting from the mountains to the lake.
Boating season is here, and our ongoing battle in the fight against aquatic invasive species continues. For 11 years, more than 40 agencies and private nonprofit partners have worked to prevent the further spread of aquatic invasives.
TRPA and our partners at the Tahoe Resource Conservation District are operating boat inspection stations around the Basin. To date, we have been successful in this critical program. No discoveries of new aquatic invasive species have been detected over the last 10 years.
In no small measure, that’s thanks to the engagement of the boating community. Mandatory inspections have so far stopped the spread of aquatic invasive species like quagga and zebra mussels from entering Tahoe’s waters.
The mantra is simple: Clean, Drain, Dry. Everyone launching a vessel at Lake Tahoe, whether it’s motorized or muscle powered, should be proactive in cleaning watercraft thoroughly. Once you clean it, make sure it’s drained and then fully dry before setting out. Research has shown that adult zebra mussels can survive for days out of water.
During the 2018 boating season, inspectors examined some eight thousand watercraft. Forty-four percent of those had been cleaned, drained, and dried. But that means 56 percent of boaters and their vessels arrived at inspection stations with the potential to spread aquatic invasive species to Tahoe’s waters.
Were either of these invasive mussels able to take hold in Tahoe’s waters, their impacts could be catastrophic. Invasive mussels starve native aquatic species of nutrients they need to survive. Both quagga and zebra mussels are prolific procreators, quickly accumulating on underwater surfaces, encrusting docks, boats, and buoys. Their razor-like shells can carpet shallow waters and beaches, making for a painful encounter with the human foot.
There are harrowing examples of what could have been. Last July, Tahoe Resource Conservation District inspectors intercepted a boat infested with multiple aquatic invasive species. An undetected crack in the boat’s pontoon was allowing water to seep in. Inspectors found adult quagga and zebra mussels, and other aquatic plants and snails – a glaring example of how easy it is for an unsuspecting boater to introduce aquatic invasive species to Tahoe’s ecosystem.
While powerboats get most of the attention, local kayakers, paddle boarders, and other nonmotorized watercraft users can also unintentionally introduce invasives to the lake. The League to Save Lake Tahoe’s “Eyes on the Lake” program has educated thousands of lake lovers, enlisting an army of citizen scientists to help monitor the lake’s shoreline and report sightings of invasive plants like watermilfoil and curlyleaf pondweed. The League will offer several “Eyes on the Lake” training classes throughout the summer. Already, 3,000 people have been trained to keep an eye on Tahoe, helping to protect our clear and pristine waters. The Tahoe Keepers program also has enlisted thousands of paddlers in the quest to protect the lake.
Ground zero in the fight against invasive plants is the Tahoe Keys. The area continues to see large-scale infestations of invasive plants so severe that it’s threatening the entire lake.
In a genuinely collaborative undertaking, the Tahoe Keys Property Owners Association (TKPOA) has partnered with multiple organizations to develop a comprehensive plan to stop the spread of invasive plants. Last month, the property association provided the Tahoe Regional Planning Agency’s Governing Board with an update on the testing to be done in the Tahoe Keys over the next two years.
Test bed studies will be undertaken, using a variety of methods, including the continued application of underwater barriers and the testing of ultraviolet light treatments. The question of whether to use EPA-approved aquatic herbicides is still under discussion and review as part of the testing process over the next few years.
In the meantime, TKPOA and its partners are taking proactive measures to contain these invasive plants within the Keys’ borders. For a second summer, a bubble curtain will operate at the entrance to the Keys. Using a powerful stream of air, this curtain technology dislodges pieces of plant material attached to the bottom of watercraft. Pairing with the bubble curtains, TKPOA has also invested in autonomous sea bins to gather the plant material dislodged from boats leaving the marina.
Protecting and preserving Lake Tahoe’s waters is paramount to TRPA’s mission. Stopping the spread of aquatic invasive species at the lake is a daunting task, and collaborative actions will continue to pave the path to success. Please join us in this fight and learn more at http://www.tahoeboatinspections.com.
Joanne S. Marchetta is executive director of the Tahoe Regional Planning Agency.