More than 90 percent of measurable standards of Lake Tahoe’s environmental health are stable or improving, according to a draft report the Tahoe Regional Planning Agency (TRPA) presented to the agency’s Governing Board today. The peer-reviewed 2023 Draft Threshold Evaluation identifies several areas, including aquatic invasive species, regional wildfires, and seasonal lake clarity trends that need more attention, better monitoring, or more research. The four-year report compiles scientific data on 140 indicators of environmental quality in the Tahoe Basin and measures the progress of science-based policies and restoration programs under the bi-state Tahoe Regional Plan.
“It’s incredible to see the hard work of public agencies and property owners making steady progress and making historic achievements in restoring Lake Tahoe and enhancing our communities,” TRPA Executive Director Julie Regan said. “Science-based policies and regional partnerships are essential to restoration on this scale. Many challenges are ahead, but the Regional Plan remains the blueprint for continued progress in the Tahoe Basin.”
The agency adopted measurable threshold standards in the 1980s that today encompass ten environmental categories, from water quality to wildlife, transportation, and scenic quality. The independent Tahoe Science Advisory Council conducted a peer review of the evaluation and provided input that will help future evaluations.
In addition to TRPA’s growth management system and limits on development, findings in the report show significant progress is coming from the Lake Tahoe Environmental Improvement Program, or EIP, which is considered one of the most successful conservation programs in the nation.
A key example during the reporting period is the historic achievement of a wetland restoration target set more than 40 years ago. Today, EIP partners and private property owners have restored more than 1,100 acres of previously disturbed marshes, meadows, and wetlands that are critical to lake clarity and biodiversity. As partners began approaching the target, TRPA strengthened its goals with a new threshold standard that looks beyond acreage and focuses on improving the overall condition and quality of restoration projects.
Several overarching issues emerged during the 2020-2023 reporting period, according to the report:
- Wildfires in and outside the basin are impacting single-day and short-term air quality standards.
- Questions for scientists remain around restoring the lake’s famed clarity; winter clarity measurements continue to improve while clarity in summer declines.
- The New Zealand mudsnail discovery in 2023 and newly adopted targets for aquatic invasive plants require continued work.
- Vehicle miles traveled (VMT) and VMT per capita have decreased, while shifting recreation patterns strained popular roadway corridors.
The 2023 Threshold Evaluation is the eighth four-year evaluation conducted since TRPA adopted measurable targets in the 1980s. The Tahoe Science Advisory Council coordinates a peer review process to ensure that appropriate methods and the best available science are applied in the threshold evaluation.
“The Council is committed to maintaining a strong bridge between science and management, and the Threshold Evaluation peer review effort is a great example of how independent science advice can continue to support TRPA’s important work,” Tahoe Science Advisory Council Program Officer Bob Larsen said.
TRPA will be collecting public and partner input on the draft evaluation over the next few months. The agency will present a final report to the TRPA Governing Board in June that will include recommended actions in response to the findings, changing conditions, public and stakeholder input, and advancements in science. The threshold evaluation summary, detailed findings, and feedback survey are available at thresholds.laketahoeinfo.org/ThresholdEvaluation/Index/2023.
Images:
Spring East Shore Drone
Caption: A national scenic byway stretches along the East Shore of Lake Tahoe, Nev. Transportation and parking improvements are planned for the roadway corridor that can see thousands of visitors a day.
Image Credit: Drone Promotions
Tahoe Conservancy Upper Truckee Marsh
Caption: That California Tahoe Conservancy restored the Upper Truckee River Marsh in 2023. Restoration partners have restored more than 1,100 acres of critical marsh, meadow, and wetland habitat, surpassing a landmark goal adopted in 1982.
Image Credit: California Tahoe Conservancy
Pier Drought South Lake Tahoe
Caption: A pier on Lake Tahoe’s South Shore sits high and dry during a drought year. Extreme weather events, hotter temperatures and prolonged droughts are impacting Tahoe’s forests and water quality.
The Tahoe Regional Planning Agency leads the cooperative effort to preserve, restore, and enhance the unique natural and human environment of the Lake Tahoe Region, while improving local communities, and people’s interactions with our irreplaceable environment.
