Unlocking Tahoe’s dirty secret: Data from a multiyear litter and debris monitoring project
Submitted by Jeff Munson on Tue, 03/05/2024 - 6:02pm
Clean Up The Lake, the environmental non-profit responsible for the 72-mile cleanup of Lake Tahoe, has recently completed a two-year monitoring effort on the lake. CUTL conservation dive teams revisited 20 litter hot spots in the 0 to 25-foot depths along the Nevada shoreline that were identified during the 72-mile cleanup of Lake Tahoe in 2021.
The primary purpose of this project was to survey these nearshore zones along the Nevada shoreline to observe changes in litter accumulation and perform surveillance for aquatic invasive species (AIS) that may have progressed since 2021. By revisiting places that were already cleaned, the data collected helped determine the status of litter accumulation in Lake Tahoe, its rate of change since the 72-mile cleanup, and the efficacy of CUTL's SCUBA-enabled cleanup methodology.
A secondary purpose of this monitoring project was to perform 40 additional deep dive surveys between the 35 and 70-foot depths near each hot spot location to better assess litter loads and AIS at deeper depths.
“The findings of what is very likely one of the largest freshwater submerged litter studies in the world are proving to yield extremely promising results, and I could not be any more excited to share our findings,” said Clean Up The Lake Founder and CEO Colin West.
Lake Tahoe Monitoring Nevada - Project Report Video from Colin West on Vimeo.
The 0-25 ft zone of these 20 hot spots around Lake Tahoe's Nevada shoreline produced 2,937 pounds of litter in 2021, compared to only 879.5 pounds of submerged litter in 2023. The totals from the initial clean-up and monitoring efforts indicate that CUTL divers removed 77% of the litter in the zero to 25- foot zone of Lake Tahoe's nearshore environment in 2021.
Despite the reality of newly deposited litter each year and the likelihood that some litter may have been missed on the first pass, the monitoring data suggests that the remediation performed during the 72-mile SCUBA cleanup has proven to be long-lasting. These findings also suggest that SCUBA-enabled cleanup can be a low impact solution to bring freshwater and marine environments closer to their natural state.
Additionally, the data collected from the dives performed at 35 and 70-foot depths has brought a new story to the surface. With video and photo documentation, observations, and dive summaries completed by professional divers, the organization has concluded that a high concentration of litter still exists in Lake Tahoe within the 35 to 55-foot zone. These findings have already begun to inform future CUTL projects.
"In Lake Tahoe, 0-25-foot dives have a bottom time of 45 minutes to 1 hour, whereas the dives down to 70 feet have a maximum bottom time of 11 minutes,” explains Director of Programs, Sadye Easler.
“While this results in a significant decrease in distance covered by divers at these depths, 737.5 pounds of litter were still pulled from this zone.”
While the data analysis from the hot spot monitoring project on the California side of the lake has yet to be finalized, results appear similar to those of the Nevada side, showing that Lake Tahoe is significantly cleaner than it was in 2021. With that data also supporting the efficacy of SCUBA-enabled cleanup, CUTL plans on tackling litter that has accumulated in the 35 to 55-foot zone in future projects.
Clean Up The Lake would like to acknowledge the funding partners who made this project possible. This has included new partners like Boatworks at Lake Tahoe but also many of the original core partners to the 72-mile cleanup who continued to support this research & cleanup effort, including Tahoe Blue Vodka, Tahoe Fund, Nevada Division of State Lands & the Lake Tahoe License Plate Grant Program, The American Century Championship, The Nature Fund provided by the Tahoe Truckee Community Foundation and the Martis Fund.
