State of the Lake: Tahoe’s average temp rose in 2020

Miranda Jacobson

INCLINE VILLAGE, Nev. — UC Davis Tahoe Environmental Research Center last week released its annual Tahoe: State of the Lake Report which shows the basin is in a warming trend.

The State of the Lake Report is given to help nonscientist understand whatu2019s going on in the lake. The UC Davis Tahoe Environmental Research Center has been working for the last year to put together the results. (Provided / Brandon Berry and UC Davis TERC)

It was presented by TERC Director Geoffrey Schladow on Aug. 12 via Zoom with the aim to provide non-scientists with important information on the factors affecting the lake and on potential restoration tactics and management decisions in the basin.

The report, which was based on data taken in 2020, uses a long-term record of research dating back to 1968 that helps scientists understand the changes of the lake overtime.

One of the glaringly present factors of the presentation was how the overall warming of the planet is affecting the smaller ecosystem at Lake Tahoe. In 2020, the annual average maximum temperature of the lake was 58.2 degrees, which was a 3.2 degree increase from 2019. Overall, climate change has become evident in Tahoe due to rising air temperatures, an increase of rain compared to snow, drier winters, and the growth in algae and populations of invasive species.

Schladow referenced the newest climate report released by the Intergovernmental Panel on Climate Change earlier this month, and broke down one of the major findings for viewers.

“Even if our fairy godmother (which also doesn’t exist) came along with her magic wand and stopped our carbon emissions, now, this minute,” said Schladow, “we’re still going to have those kinds of warming rates continue.”

The warming rates he’s referring to reflect the research done on the emissions of greenhouse gases, which warm the air temperature, and have been widely advised to be reduced on a large scale to avoid an increase of 1.5 to 2 degrees Celsius, which is considered to be the ‘no turning back’ point of the planets climate catastrophe.

“They will eventually abate depending on what we do and which emission scenarios we choose to live in, but climate change is happening,” he said. “Temperature increase is just one manifestation of that.”

Other manifestations of the rising climate were presented as well.

Wildfire smoke is one factor that has affected the overall clarity of the lake by prevent UV light and sunlight from reaching the lake. (Provided / Katie Senft and UC Davis TERC)

One is the clarity of the lake, which is measured by the depth at which a white Secchi disk can be observed. Clarity was at its lowest in May of 2020 which was about 50 feet, with the highest measurement at over 80 feet in February.

In terms of wildfires, it was found that while there were no significant wildfires in the Tahoe basin in 2020, the amount of smoke that blanketed the area in August and September produced a hazardous air quality and lowered the amount of sunlight and UV radiation due to the smoke. Lack of UV radiation along with reduction of sunlight introduces a plethora of nutrients, toxins, and other materials that have the ability to impact the food chain of the lake.

Both above and below the shores of Lake Tahoe, algae and metaphyton are also plaguing the lake, creating a green lake bottom and the introduction of Asian clams. This not only affects the overall clarity, it will over time change the food web of the lake. It’s expected that climate change will bring a great increase to the extent and duration of the algal blooms.

While many solutions to climate change cannot be fulfilled by the scientists and residents of the Lake Tahoe basin alone, Schladow presented many interesting and innovative ways to combat these issues in the basin and potentially improve the health of the lake.

One solution involved mysis shrimp, which have devastated the Lake Tahoe ecosystem in the past, but aren’t completely unbeatable.

“A solution that they [scientists and researchers working on the mysis shrimp crisis] found that seemed to bear out both financially and was practical for the short term,” said Schladow, “was to harvest them and then regenerate them into a useful product.”

Mysis shrimp, which are high in protein and rich in healthy Omega-3 fatty acids, can be made into dog treats. Not only does this solution engage people’s awareness of invasive species, but it can help fund more research on how to help the lake.

“Potentially, based on some of the assumptions in the financial model, this can actually generate funds rather than taking funds exclusively… it could be funds to support further research on the Lake Tahoe ecosystem,” said Schladow.

The State of the Lake Report also included current research project summaries, outreach and education efforts, and data that encompassed weather, physical properties, clarity, nutrients and particles, and the overall biology of Lake Tahoe.

The full report can be found at

The report’s production was funded by the California Tahoe Conservancy, Tahoe Fund, Tahoe Regional Planning Agency, Tahoe Lakefront Owners’ Association, Nevada Division of Environmental Protection, Lake Tahoe Marina Association, Parasol Tahoe Community Foundation, League to Save Lake Tahoe, Tahoe Water Suppliers Association, TruePoint Solutions and Incline Village Waste Not program.

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