Lake Tahoe, also known as the "Lake of the Sky", is an alpine lake that is world famous for its deep, clear water. Over the last half century, clarity in Lake Tahoe has declined by 30–40 feet or 1 foot per year. This decline in clarity has been attributed, in part, to nutrients and sediments delivered to the lake by its tributary streams and nutrients from groundwater inflow.
For decades, USGS has been involved with a wide range of scientific research and monitoring activities in the Lake Tahoe Basin. Water-related activities include stream quantity and quality, groundwater levels and quality, and lake levels and quality. Mapping activities include topographic, bathymetric, and geologic; land-cover and land-use change delineation; and socioeconomic modeling.
USGS Nevada Water Science Center currently has 14 streamflow gages on tributaries to Lake Tahoe.
DataReal-Time Streamflow :: Daily Values :: Peak-Flow :: Water Quality
Lake Tahoe Bibliography: List of USGS Nevada WSC publications about Lake Tahoe, including cooperative State publications.
How Do We Measure Lake Clarity?
In Lake Tahoe, the clarity of the water is usually measured using a device called a Secchi Disk. The Secchi disk can be a white or white and black, circular disk that is suspended on the end of a rope or cable. Scientists lower the disk from the side of a boat at different locations within the lake. The point at which the disk is no longer visible is known at the Secchi depth.