This indicator tracks the transparency of Lake Tahoe as measured by the annual average Secchi depth at the Lake Tahoe Index Station. Restoring Lake Tahoe's transparency is important to maintaining both ecological function, and its values to local and regional economies as a recreational destination and drinking water source. The decline in transparency is a result of the additions of fine sediment particles and the growth of phytoplankton (algae). Drivers influencing the delivery of fine sediment and nutrients include urban development, anthropogenic and natural disturbance in the undeveloped portions of the watershed and local and regional climate. Many programs throughout the Tahoe Region are aimed at improving lake clarity such as stormwater reduction and stream restoration projects. Lake clarity has been measured at Lake Tahoe by UC Davis since 1968.
Lake Clarity Monitoring Locations
Example EIP Projects
TRPA assists local jurisdictions to plan and design area-wide infrastructure within key watersheds to enable more efficient and effective stormwater treatment for local neighborhoods.
Caltrans completed this roadway retrofit project in 2017 to improve collection and treatment of stormwater runoff along 8.6 miles of roadway, some portions adjacent to Lake Tahoe.
Lake Clarity Indicators
Total Maximum Daily Load implementers collectively prevent roughly 477,000 pounds per year of fine sediment from reaching Lake Tahoe.
Local and Regional Plans
The Lake Tahoe TMDL Program is a science-based plan with stormwater load reduction for implementers to reinstate historic clarity levels in Lake Tahoe.
UC Davis has monitored the clarity of Lake Tahoe with a Secchi disc since the late 1960s.
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