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Snapshot Day

Connecting the Tahoe community to its watershed

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About
Snapshot Day is a citizen science water quality monitoring event that takes place each May. Volunteers fan out across the Truckee River Watershed to take samples from creeks, streams and lakes – including Lake Tahoe – to capture a snapshot of Tahoe’s water quality at a moment in time.

 

View the storymap to learn more about the citizen science in action over the last 25 years.

snapshot day storymap, keep tahoe blue

Click to view the StoryMap

What do volunteers monitor at Snapshot Day?

Dissolved oxygen
Microscopic bubbles of oxygen available for aquatic organisms
Total dissolved solids
The combined inorganic and organic content of the water
pH
A measure of the water's acidity or alkalinity, which can show if the stream is a healthy habitat
Temperature
Of the air and the water at each sampling site
Water samples
To be tested in the lab for turbidity (cloudiness), nutrients and bacteria
Site-specific disturbances
Erosion or sources of pollution visible to the naked eye

Snapshot Day Report: A Community-Powered Look at Tahoe’s Water Quality

 

Each spring, volunteers fan out across the Lake Tahoe watershed to measure water quality for Snapshot Day, Tahoe’s longest-running citizen science program. Dive into the 2025 Snapshot Day report to uncover the methods of data collection, what volunteers found, and the health of Tahoe’s lakes, streams, and rivers through in-depth data and trends.

 

View the 2025 interactive map below to explore each sample site’s info, including photos, and discover how each sample fits into the bigger picture of water quality.

Read 2025 report

Snapshot Day Sampling Sites Map

Click any icon on the map to explore a sampling site, view photos of the volunteer teams, and see the waterways they helped monitor. From creeks in South Lake Tahoe to the Truckee River, every site tells a story.

The information gathered by volunteers is compiled into long-term data sets on water quality conditions within the Truckee River watershed. Snapshot Day also provides baseline data that can be used in ongoing and future environmental projects.

If you are interested in viewing data and analyses from previous Snapshot Day events, please visit tahoetruckeesnapshotday.org. You can also contact us at protect@keeptahoeblue.org for more information about Snapshot Day and to learn how you can get involved.