Media Releases

2018 Snapshot Day data shows Tahoe-Truckee water clarity improvements, and highlights aquatic life concerns

League to Save Lake Tahoe
April 30, 2019

South Lake Tahoe, Calif. –  Snapshot Day is one of the longest-running watershed monitoring events on the West Coast of the United States, and is now in its 19th year.  Each May, hundreds of volunteers disperse to collect data about the health of streams and lakes in the Tahoe-Truckee watershed, which includes Lake Tahoe. The data collected from Snapshot Day 2018 has been analyzed and is now available. It paints a picture of a healthy, vibrant watershed with a few notable exceptions.

One positive finding was that only 22 percent of the sites monitored in 2018 showed elevated levels of turbidity, down from 30 percent of the sites in 2017. Turbidity is a measure of the water’s cloudiness and an indicator of the presence of fine sediment pollution, the leading cause of clarity loss in Lake Tahoe.

“This is a positive trend and one we hope continues in 2019. But it needs to be tempered by the fact that prior to this, we had four years of drought followed by a big winter in 2017 and significant spring runoff,” said Emily Frey, natural resources associate for the League to Save Lake Tahoe. “Measuring consistently year after year is critical for getting an accurate read on this and other water quality trends,” she added.

But not all water quality trends were positive. More than 50 percent of the samples taken by citizen-scientists during Snapshot Day showed less-than-optimal dissolved oxygen levels. Dissolved oxygen is a measure of the amount of oxygen dissolved in water, and is used as an indicator of stream health because a certain amount of dissolved oxygen is necessary to support aquatic life, like mountain whitefish and Lahontan cutthroat trout.

“If dissolved oxygen levels drop too low, we start to see significant impacts on our native aquatic life,” said Zack Bradford, natural resources manager for the League to Save Lake Tahoe, “which is why the League’s work is critical.” The League is working to control the spread of aquatic invasive plants and inputs like Nitrogen and Phosphorus, which drive algal growth in Lake Tahoe. When algae and invasive plants die and decay, they consume oxygen, robbing it from our wildlife.

Snapshot Day has been held in the morning of the second Saturday of May for the past 18 years. It is a collaborative effort between the League to Save Lake Tahoe, the Nevada Division of Environmental Protection (NDEP), the Tahoe Water Suppliers Association (TWSA), and the Truckee River Watershed Council (TRWC). Additional agencies that assist include: The Pyramid Lake Paiute Tribe, the South Tahoe Public Utility District, the Lahontan Water Quality Control Water Board, and the Tahoe Regional Planning Agency (TRPA).

“We want to collect as much relevant data as possible each year and to do that we depend on dedicated volunteers. They are critical to the success of Snapshot Day,” said Darcie Goodman Collins, Ph.D., CEO of the League to Save Lake Tahoe. “This event is a great opportunity for our community to come together for one day to Keep Tahoe Blue.”

Snapshot Day will be held this year on Saturday, May 18th from 9 am to noon, at various sites around the Lake. Volunteers wishing to participate are invited to RSVP ( and join in efforts to collect data and create a “snapshot” in time of the Tahoe-Truckee watershed. No experience is necessary, and all are welcome to attend.


The League to Save Lake Tahoe, also known by the slogan “Keep Tahoe Blue,” is Tahoe’s oldest and largest nonprofit environmental advocacy organization. The League is dedicated to community engagement and education, and collaborating to find solutions to Tahoe’s environmental challenges. The League’s main campaigns include combating pollution, promoting restoration, tackling invasive species and protecting Tahoe’s shoreline.

The mission of the Tahoe Water Suppliers Association (TWSA) is to develop, implement and maintain an effective watershed control program in order to satisfy recommendations in watershed sanitary surveys, advocate for the protection of Lake Tahoe as a viable source of drinking water, and to satisfy additional state and federal requirements.

IVGID Waste Not’s mission is to empower sustainable living by providing conservation programs and services for our community in the areas of watershed protection, water conservation, recycling, household hazardous waste, living with wildlife and the Tahoe environment. Waste Not is part of IVGID’s Public Works Department, it also serves as the home agency for the Tahoe Water Suppliers Association.

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