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Summary
Scientists and employees say they need to understand why the famous Alpine Lake does not improve despite decades and billions of dollars in efforts. Last year’s clarity was about 40 feet greater than in the late 1960s. Road flow and air pollution are leading causes.
The iconic blue waters of Lake Taho were the third deadly record last year and the worst they have been for several years, according to scientists who have studied the lake for decades.
Clarity of Lake Alpine – measured by putting a white disc into the water and noting when it disappears from vision – is a signal for its overall health. Small particles are the main culprits for reduced clarity, including the sediment and other pollutants, which are washed in the lake from the runoff and the air pollution and plankton that grow in its waters.
Researchers from the UC Davis Environmental Research Center report today that the average murmur in 2024 was exceeded only in 2021, When the fires darken the lake with smoke and ashand in 2017, when the lake was blurred by Sludge during almost record a wet yearS
Thehe Report says the levels of clarity are “highly variable and generally do not improve” and recommends “future studies focus on the study of the nature of particles that affect the clarity of water.”
In 2024, the white measuring disk disappeared 62.3 feet from the surface -about six feet faster than the previous year and only 1.9 feet deeper than the highest record set in 2017.
The average clarity of last year was about 40 feet greater than at the end of the 60s, when scientists began to track a long decline.
Taho Lake, surrounded by snowy slopes in winter and wooded paths in the summer, attracts 15 million visitors every year to enjoy boats, skiing and tourism – three times more than the Yosemite National Park.
It’s the most clear large lake in the world and one of the deepestS But in spite of Billions in state and federal dollars spent on improving the health of Lake TahoHis known clarity dropped steeply in the 90s and although he was equal, he did not improveS The levels of 2024 fall about 16 feet Short of the goals of the state for 2031And it will have to be improved by 35 feet to return to historical levels by 2081, according to the State Regional Council for the Water Quality Control in Lahontan.
“The clarity of water is not noticeable, but it is also not improving. So the big question for us now is why.”
Stephanie Hampton, UC Davis
“I see something we must celebrate, which is the success of management and recovery in delay or potential stopping the decline,” Stephanie HamptonDirector of the Center for Environment Research of Taho and Professor of Science and Environment Policy at UC Davis.
Still, she added, “The clarity of water is not getting worse, but it is also not improving. So the big question for us now is why.”
The lake is more clear in winter than in the summer. But last year, both winter and summer measurements were the third oldest seasonal records of records.
Winter murmur came a year after the lake showed an unusually dramatic improvement in winter – nearly 92 feet clarity in the winter of 2023, compared to about 72 feet in the winter of 2022 – because of a deep mixing that led clear water to the surface.
However, the gloom appeared again this summer. And in 2024, the summer measurements brought a mystery: even after particle levels dropped, the lake was not more clear, “suggesting unnoticed factors or more complex dynamics affecting the summer clarity,” the report said.
“This caught our eye because it made us wonder, is there anything we don’t measure, which affects clarity?” said Hampton. One possibility is that a tiny plankton – less than those that scientists are tracing – can keep the water more dark than expected.
“Taho is changing in several ways at once,” Hampton said. As the climate change continues, “the water is getting worse, the summer becomes longer and this can enhance some of this growth.”
Sudeep Chandra, director of Global water center At the University of Nevada, Renault said that the ongoing decline in summer clarity means that things are more complicated than they have been thought so far and more research is needed.
“Scientists continue to sound an alarm in Tahoe and elsewhere that we need support so that we do not only measure the heart or pulse of the lake by measuring clarity, but also other vital organs,” says Chandra, who is not involved in the UC Davis clarity. This includes the catchment area and the flows and the ability of the lake to process the nutrients and other materials that are washed in it and the effect of climate change on the snow package and land.
Many environmental and community groups criticize the Regional Planning Agency for the Taho-Government Agency in California-Nevada, established in 1969 to protect Lake Taho-to allow commercial development, tourism and growth.
For example, Tahoe Blue event centerWho opened in Nevada last year is a multi-purpose, 5200-seat arena with expansive luxury condominium development planned on the other side of the street. Also, the village at Palisades Tahoe Project in Placer County will add 850 condoms and hotel units-close 1500 bedrooms-in the resort throughout the year. The developer designs that the resort will attract 300,000 visitors a year.
But employees of the Tahoe Planning Agency said that development projects did not make their efforts to understand and restore the lake and its environment.
“The lake is still visible to 60 feet of clarity – this is incredibly clear and this is something we were able to stop from more damage,” says Jeff Cowen, a public information employee at the Tahon Regional Agency.
“The loss of clarity is like a locomotive in which they removed the steam from the engine, but it still rolls. And see it stabilization is … a pretty good sign of progress.”
Cowen said the work of the roadway helped to keep more than Half a million pounds of sludge from reaching the lake. The nutrients that charge algae growth are also reduced by thousands of kilograms each year, and over 1400 acres improved or restored wet areas help filter pollutants and reduce erosion.
“It’s concerned, for sure … We rely on science and research and it is worried to see that there are trends that do not respond to investment,” Cowen said. “We want to know what more we need to do.”