PBS’ “Lake Tahoe, Can We Save It” 26-minute documentary
Lake Tahoe is the clearest lake of its size in the USA. It’s also one of the deepest lakes in the USA at 1,645-feet deep (deeper than the Empire State building is tall) and holds over 39 trillion gallons of water. In 1968, you could see a 10-inch diameter disk (Secchi disk) 97 feet down in Lake Tahoe’s crystal clear waters.
Today, you can only see a 10-inch diameter disk 75 feet down in Lake Tahoe.
Clarity is key in Lake Tahoe for an amazing reason that we’d never heard of:
“Under clear conditions, we get a lot of penetration of UV radiation deep into the lake. It probably has some of the highest UV penetration of any lake in world.” – Geoffrey Schladow, director of the Tahoe Environmental Research Center & professor of Water Resources and Environmental Engineering at the University of California, Davis.
Without this deep UV penetration, invasive species (carp, bluegill, big mouth bass, crawdads) are thriving in Lake Tahoe.
“When these invasives reproduce, their young can’t stand that UV radiation and they die. But native fish are adapted to it.” – Geoffrey Schladow
Lake Tahoe’s famously blue waters – which make it the clearest lake of its size in the United States – attract three million visitors to California and Nevada each year. But decades of development, and now climate change, threaten this national treasure. This QUEST half-hour documentary takes you behind the scenes with the scientists working to keep the lake pristine and protect it for generations to come.
But Lake Tahoe isn’t the only body of water that comes to mind when we think about America’s most treasured lakes. The Great Lakes, an interconnected set of five lakes which include lakes Erie, Superior, Huron, Michigan and Ontario, hold 18% of the water on the face of the Earth. Both Lake Tahoe and the Great Lakes face environmental challenges, but are differently equipped to handle them because of their particular characteristics. – PBS