Monday, October 3, 2022

Devastating wildfires could destroy the iconic blue waters of Lake Tahoe

Researchers say smoke and ash from wildfires near Lake Tahoe (one of the deepest lakes in the world) have clouded the lake’s famous clear waters.

Although the long-term effects are not yet known, volcanic ash and soot now cover the surface of High Sierra Lake and obscure the sun, which can damage the lake’s ecosystem and its clarity. This fall and winter, more debris and sediments may be washed into the lake from runoff and rain.

“In my opinion, it will not turn the lake water into green or something like that. But what is certain is that the clarity of the lake water, how deep the lake water you can see, may be affected in a few years,” Randy Dahlgren, Professor Emeritus of Soil and Biogeochemistry, University of California, Davis. “It all depends on nature.”

Researchers are now trying to figure out what the remnants and flames of the Kaldor Fire that now threaten the Tahoe Basin mean to the iconic cobalt blue lake.

“We have never had such a serious fire before…this time beyond the chart,” said Jeffrey SchraderDirector of the Tahoe Environmental Research Center at the University of California, Davis.

The research center’s tests on the lake have shown that its clarity has declined in recent days, although Schrado said it may be temporary. These changes may be caused by a combination of factors: smoke prevents sunlight from penetrating the depths of the lake, ash makes the lake water turbid, or more algae grow near the lake surface.

“Usually at this time of the year, we expect to drop 65 feet. Now what we see may be 50 feet,” Schrader said.

In the past half century, the clarity of mountain lakes has dropped by 40%, mainly due to runoff Contains particulate and plant-based nitrogen and phosphorus. In recent years, its clarity-a sign of improved health- Has started to stabilize As state and local officials in California and Nevada took steps to protect the lake.

The degree of damage to Lake Tahoe depends on the degree of damage to the forest and surrounding buildings. This will also depend on the next few months: the heavy rains after the fire forced more sediment and nutrients into the runoff and eventually into the lake.

For fine particles, nutrients, and toxic chemicals, “most of the sediments occur on land, and when the fire comes back in the winter, the fire is extinguished for a few months and continues to be washed into the lake,” 2020 report from the Tahoe Environmental Research Center at the University of California, Davis.

Located between California and Nevada, Lake Tahoe is an outdoor recreation center in summer and winter, attracting more than $3 billion in tourism revenue each year. Tahoe Prosperity Center.

During the fire, Schladow’s team would take measurements every few days, risk collecting water samples on the water surface and measuring ultraviolet radiation, water transparency, nutrients and algae.

“The strangest thing is that we came here at the end of August on Lake Tahoe. You can’t hear the sound of another boat on the lake. This is unheard of at noon on Lake Tahoe in August,” Schrader said.

Lake Tahoe and the surrounding land and waters are Abundant wild animals, Including the threatened species Lahuntan trout, as well as mountain white fish, black bears, beavers, marmots, deer, birds of prey, rare flowering plants and A stone fly without wings Live at the bottom of the deep lake and provide Fish food.

“I’m not worried about the clarity, but the sensitive, endemic (found in only one place) species floating in the lake… The clarity may rebound, but will we lose those that have passed the difficult time? Species?” said Sudip Chandra, Professor of Biology at the University of Nevada, Reno.

On August 25, 2021, as the Kaldor fire filled the air, researcher Brandon Berry replaced the particle sampler on a research buoy at the University of California, Davis on Lake Tahoe. (Brand Allen/University of California Davis provided by S Geoffrey Schladow)

Alexander ForrestAn associate professor at the University of California, Davis launched an autonomous underwater vehicle that moves on a seesaw in a water column and traverses the lake every 15 hours to measure particle size and concentration. His team hopes to collect robots and retrieve their data within a few weeks.

“There is this layer on the surface and underneath, and you stir it with your hands, and you can see these particles floating in the water,” Forrest said. “What we are trying to clarify or try to understand is, what does it mean?”

If soot and ashes fall into a wide watershed, they will wash into the lake and have different effects on the algae of Lake Tahoe at different depths. The particles darken the water and cool the lake water-making it unsuitable for certain algae. But it can also introduce nutrients that algae and other organisms rely on, such as nitrogen, which may encourage the proliferation of surface algae.

“I expect that the entire food web is undergoing a reversal,” Schrader said. “The measures we are taking (yes) to see if this is true and how things change.”

This happened after a team of researchers from the University of Nevada, Reno, in the summer of 2018, suffocated the area for 55 days. Recent report. The light in the water dims and the temperature drops. Algae thrives in shallow waters, but decreases to nearly zero in deep waters. The trout disappeared from the lake.

“As a result, you completely reorganized the internal structure of the lake,” said Chandra, one of the authors of the study. “The question for Lake Tahoe has become, will the internal structure be reorganized and rebound in a short time? Or will it be reorganized more permanently?”

Recent weeks, The area has been enveloped by the burning smoke of the entire Northern California, making the air dangerous. on Monday, Forced evacuation From the Fire of Kaldor Spread to South Lake Tahoe, There are resorts that are usually full at the end of summer.

Kaldor’s Fire is already burning Over 290 square miles El Dorado County for the past 15 days.Fire has overflowed Into the Tahoe Basin And grind on the edges Upper Truckee River Basin, this The biggest contributor to water Lake Tahoe.

“It is conceivable that most of the upper Truckee basin could be burned,” Dahlgren said. “This is the worst-case scenario.”

Fire is ok Contaminated water used for drinking water.

Scientists worry that the extreme wildfire season may be a sign that climate change will damage Lake Tahoe and other waterways in the next few years.

“This may be a warning or a harbinger of Lake Tahoe and other lakes in the future,” Schrader said.

“If we have these fires every summer, and we start to be affected by these temporary effects every year, when will such temporary effects become the norm?”

Nation World News Desk
Nation World News Desk
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