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 (or 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 in the mere ten-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 PhD at the University of Nevada, Reno, she took a field trip to Skylandia Beach on Lake Tahoe, near Tahoe City, Calif. The professor leading the group said that 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 PhD 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 PhD 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 relate 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 AI 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 Search 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 this granted her helped her work immensely.
At the end of her research, she had data to prove that there are only two other 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 her 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.