More than 90% of measurable standards for Lake Tahoe’s environmental health are stable or improving, according to a draft report presented by the Tahoe Regional Planning Agency (TRPA) to its governing board. The 2023 Draft Threshold Evaluation, which is peer-reviewed, highlights areas such as aquatic invasive species, regional wildfires, and seasonal lake clarity trends that require further attention, monitoring, or research.
The report, compiled every four years, assesses 140 indicators of environmental quality in the Tahoe Basin and evaluates 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,” said TRPA Executive Director Julie Regan. “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 TRPA adopted measurable threshold standards in the 1980s, covering ten environmental categories, including water quality, wildlife, transportation, and scenic quality. The Tahoe Science Advisory Council conducted a peer review of the evaluation, providing input to aid future assessments.
Significant progress is attributed to the Lake Tahoe Environmental Improvement Program (EIP), recognized as one of the nation’s most successful conservation initiatives. A notable achievement during the reporting period is the restoration of over 1,100 acres of marshes, meadows, and wetlands, crucial for lake clarity and biodiversity.
The report also identifies several overarching issues from 2020 to 2023:
- Wildfires affecting air quality standards.
- Ongoing questions about restoring the lake’s famed clarity, with winter clarity improving but summer clarity declining.
- The discovery of the New Zealand mudsnail in 2023 and new targets for aquatic invasive plants necessitating continued efforts.
- Decreased vehicle miles traveled (VMT) and VMT per capita, with shifting recreation patterns straining popular roadways.
“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,” said Bob Larsen, Program Officer of the Tahoe Science Advisory Council.
TRPA will gather public and partner input on the draft evaluation over the coming months, with a final report to be presented in June. The report will include recommended actions based on findings, changing conditions, public and stakeholder input, and scientific advancements.
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