Volunteers measure Lake Tahoe area water quality in annual Tahoe Truckee Snapshot Day
A volunteer army of citizen scientists fanned out across the Lake Tahoe area watershed on Saturday morning for the annual Tahoe-Truckee Snapshot Day.
The 26th annual spring gathering is the area's longest-running citizen science program, where teams of volunteers of all ages and abilities collect water samples and measure their quality across the across the Truckee River watershed. Data from the lakes, streams and rivers provides a point in time snapshot of the quality of the drinking water and recreational areas.
The volunteers tested the water for dissolved oxygen, pH, and nutrients among other categories. The environmental group Keep Tahoe Blue, which organizes the Upper Truckee River segment of the event, says the information is compiled into long-term data sets on water quality conditions and provides baseline data to be used in ongoing and future environmental projects.
"Snapshot Day is a fan-favorite event because it directly connects people with this beautiful watershed where they live, work or play - but in a completely different way," said Courtney Baumann, Keep Tahoe Blue's engagement manager and event organizer in a prepared statement.
The 2026 event involves some 75 locations across the entire watershed, grouped into North Lake Tahoe, South Lake Tahoe, and Middle Truckee River. Water quality data over the past 25 years are compiled into an interactive StoryMap that you can viewed on the Keep Tahoe Blue website.
Research by the University of California, Davis indicates that sediment from the Upper Truckee River is a primary driver of the Lake Tahoe's clarity, and recent years have seen a shift in algae composition that also contributes to the lake's clarity. The research from the UC Davis Tahoe Environmental Research Center shows that while the lake is no longer losing about a foot of clarity per year as it did from the 1960s to the the 1990s, it has also not yet improved.
