In September, news outlets announced Winnie Kortemeier found that Lake Tahoe is the oldest lake in North America, and third-oldest in the world. But this was old news to Kortemeier, a volcanologist and Western Nevada College professor who published her research proving Lake Tahoe is at least 2.3 million years old in 2012.
“I was just hoping that maybe somebody would pick up on that and figure out how old Lake Tahoe was in relation to other lakes, but it never really happened,” she said over the phone. “That data just sat there for a decade.”
Though Kortemeier is not a limnologist (aka a studier of lakes), she knew the age of Tahoe is significant, and she wanted to share this knowledge with the public. Most lakes, she said, have lifespans of mere tens of thousands of years before they fill with sediment and die.
Kortemeier did not grow up in the Tahoe region. Her passion for the alpine waters developed when she moved to the area in 1986. Originally from South Carolina, she ventured west for graduate school, earning a master’s in geology at Arizona State University. There, she gained attention for being the first and only person to find co-occurring ongonite and topazite rocks in North America.
“I was famous for a week back then,” she joked. She then turned to volcanology.
Later, while studying for her doctorate at the University of Nevada, Reno, she took a field trip to Skylandia Beach at Lake Tahoe, near Tahoe City, Calif. The professor leading the group said the volcanic rocks lining the northwestern side of Tahoe had never been studied. Kortemeier raised her hand and said she’d do it.
These same rocks became the basis for her Ph.D. studies. She figured that the basalt rocks that formed during volcanic activity interacted with water, proving that a lake was present at the time.
“I was like, ‘Oh, this changes everything; this is just exciting stuff,’” she said. “I knew that Lake Tahoe had to be at least 2.3 million years old.”
Kortemeier finished her Ph.D. in 2012, and her findings slid into the background. In 2018, she tried again to gain traction by publishing part of the findings in a scientific paper. Still nothing.
More recently, a mentor from the United States Geological Survey encouraged her to get the word out about Lake Tahoe’s age. She met with Steve Yingling, the public information officer at WNC, who recommended transforming the data into more palatable terms, suggesting she compare the age to other ancient lakes to learn whether Tahoe was the oldest.
“I’m like, ‘How do you do that? I’m not a lake expert. I can’t go study all the lakes,’” she said. “But then I just decided I’d have to study all the lakes.”
This recommendation led to a year-long sabbatical, during which Kortemeier scrubbed the internet and UNR’s databases for verified information on the world’s oldest lakes. She began by utilizing artificial intelligence to help her search. She asked ChatGPT to make lists of the oldest lakes for her.
“I’d never used ChatGPT before,” she said with a chuckle.
But digging into generated lists and Wiki searches only lead to claims without data to prove them. “That just caused all kinds of issues, because most of the dates that you can find for lakes are estimates,” she said. “They varied wildly. It felt like a lot of dead ends.”
This is when she decided she needed the “good databases” at UNR. To use them, she needed to enroll as a student. She took a graduate-level geology class each semester, and the access her helped her immensely.
At the end of her research, she had data to prove that there are only two lakes in the world that are older than Lake Tahoe: Lake Baikal in Siberia (estimated to be 5-10.3 million years old) and Lake Tanganyika in East Africa (estimated to be 8-10 million years old). Finally, the superlative the publicist had pushed her to find helped her research on Lake Tahoe come to light.
Though Kortemeier achieved her goal, she said the media blitz was a “little scary,” because she is not a limnologist and isn’t very comfortable using superlatives. She also doesn’t mind if someone proves that there is a lake older than Tahoe.
“I don’t care if it becomes not the oldest lake in North America,” she said. “Maybe they’ll find a lake with good evidence that it’s older. That’s OK with me.”
Kortemeier has a few tips for amateur geologists who would like to access the Lake Tahoe Basin’s volcanic rock themselves. Near the wooden boardwalk at Commons Beach in Tahoe City, there’s basaltic tuff, a tan-colored rock that forms when “lava flows into water and then is blown to bits and blows back on shore,” she said.
At Skylandia Beach, keep an eye out for smooth, black pebbles. These are basalt that has interacted with lake water. At Eagle Rock in Homewood, a .4-mile hike leads to incredible lake views from the top of an eroded volcano.
Have you checked little Crater lake off of highway 44 here in Lassen county. It’s a natural volcanic lake approximately above 5500f’ elevation with no drainage, just like the natural Eagle Lake. Where the Eagle lake trout come from here in California only place in the world where they started, only trout with pink meat like a salmon. Kinda rare like a California golden trout. Except I’ve never seen the second fish live in person sad to say the are so rare and elusive to us trout fisherman. There are other small mountain lakes right in that general area that may also be part of that group of volcanic lakes.
I would think lake Baikal might be older so I googled that 25-30 million years old
This is for volcanologist Kortimeier,
If you see this note and are still interested in the study of some of Tahoes past remaining history of Volcanos. Please email me a note and I’ll get back to you.
I green up in Incline Villabe from 1968 to 2016 and was born Reno. Explored every nook and cranny yhe Noth side of the lake has to offer as kids when it was less populus. We know of many spot of huge conglomerate balls of rock and pentacles that stand at least a minimum 100 feet tall. The kind that looks like cement rolled down a beach of quartz and rocks of agate? IDK. We used to chip it off these big globs as kids and drag some home. This is up north side of Incline. You might have been there? It’s a great canyon to experience. We would climb the pentacles and camp for days by them when you could.
Anyways this is for one person only please.
Volcanologist Kortimeier.
Tanganyika and Baikal, if I remember correctly, are both in intracontinental rift basins.
Sounds like at Tahoe: Subaerial basaltic extrusion, flowing INTO surface water. So guessing no pillow basalts, just phreatic activity. But did Tahoe basin also originate from rifting? Is there also associated rhyolitic magmatism ?
When trout bottom feed you will get pink meat, all over the Sierras.
I always wanted to know how old lake tahoe was I find this story very informative. Thank you for your research and data on this beautiful marvel.
How old is clear lake in CA
You are so wrong about your remark about eagle laker trout being the only fish other than salmon to have pink or redish meat. I have been fishing since the age of 4 and I am 67 now, there are trout all over having meat th I started color, fact also in Oregon they have tooley Salmon that have white meat. This is a bad tasting Chinook. Many lakes creeks and rivers have pink meters , I have caught hatchery fish with nice meat the Lassen hatchery has Tasty fish.