For centuries it has been one lakes has the cleanest waters in the world, but climate change and wildfires have muddied it. for several years, TahoeThe largest mountain lake in the United States, with a width of 500 square kilometers and a length of 35 kilometers, becomes clear. It begins to show its usual cobalt blue color. Scientists are clear why.
A team from the University of California at Davis studied the process extensively and concluded: The ‘culprit’ for recovery is native zooplankton.especially those belonging to the species water flea And bosminasmall crustaceans popularly known water fleas.
Lake Tahoe, located on the Nevada-California border in the last half of last year, displayed a transparency not seen since the eighties of the last century. Visibility from the surface reached a depth of almost 22 meters14 less than the results collected in 1969, a year after the start of measurements, but best of 40 years.
The worst record came in 2017, when the 25.4-metre-diameter white disc used for measurements was only visible to a depth of 18.4 metres. The loss of the lake’s clarity alarmed environmental groups, scientists, tourism professionals and officials.
Among the reasons for this turbidity, climate change And heavy rains winter 2016-17 they dragged a lot of sand and mud (according to some studies 12.000 tons of sediment) five-year drought registered in the field. All this turned Tahoe into a greenish lake filled with mud, algae and silt.
a desperate attempt
In recent years, there have been many attempts to ‘clean’ Tahoe’s waters. While verifying that the treatment plants are not working, collectors to remove the sewage from the basin. it happened a desperate attempt to save the lake. And it worked. Among other reasons, because from that moment the zooplankton population began to increase and the color of the water began to improve.
HE native zooplanktona group of small and microscopic animals “natural cleaning team helps restore the lake’s famous blue waters”given feeds on particles that cloud itresearchers point out.
Since the 1960s, Lake Tahoe’s zooplankton populations had declined due to the growth of shrimp, their main predator. Mysis. Daphnia and Bosmina populations have dropped to dangerously low levels over the years, reaching an all-time low in 2021, when the second-worst record for clarity was observed: just over 18 meters.
This particle levels The lake also reached a record level in 2021 mainly due to forest fires. Everything started to improve from that moment on.
Researchers believe the impact of Daphnia and Bosmina in Lake Tahoe will increase this year and beyond, restoring clarity to previous levels. Well The scientists’ goal: to restore the lake’s clarity to 36.3 meters in 1969, if possible.
The authors of the study stress that the road will be long and complex, but “necessary”, The clarity of Tahoe’s waters is the best indicator of the environmental health of its watershed.adds up to about 800 square kilometers.
millionaire spending
The danger to Tahoe will continue to be Mysis populations. In fact, the study authors believe the species will recover and put zooplankton at risk, meaning that “practice” may be necessary. population control measures “To preserve the clarity of the lake,” they warned.
Although the measurements started 55 years ago, the problems in Tahoe started much earlier. HE developmentalism This event, recorded in the 20s of the 20th century, was the beginning of the phase of water quality and clarity loss that accelerated in the fifties.
Tahoe has lost most of its transparency. construction erosion, golf course manures, loss of wetlands that leak pollutants, and other man-made disturbances.
So far this century, state and federal governments have spent hundreds of millions of dollars inside wetland restorationThey toughened building regulations and passed several laws trying to stop the second deepest lake in the United States (501 meters) from deteriorating just behind Crater Lake (594 meters).
Another great enemy of Tahoe’s clarity is Climate change disrupting the normal mix of shallow and deep waters, causing it to warm earlier than historically.
“Climate change is affecting not only the lake’s water quality, but also the lake’s water quality. health of nearby forests and economy based on recreation“, warned those in charge of the Tahoe Regional Planning Agency in 2017. Zooplankton is now back to give hope to lovers of the legendary cobalt blue lake.
Reference website: https://tahoe.ucdavis.edu/
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Contact address of the environment department: [email protected]