Lake Mendota Discovery Reveals Dugout Canoes Thousands of Years Old

Tamara Thomsen, a Maritime Archaeologist for the Wisconsin Historical Society, has been involved in the discovery of more than 100 shipwrecks across the Great Lakes. In 2014, she was inducted into the Women Divers Hall of Fame. In 2021, an afternoon dive in Lake Mendota near the University of Wisconsin-Madison campus added a new discovery to her resume and launched a major, nationally recognized research project.

Swimming near Lake Mendota’s shore in almost 30 feet of water, Thomsen noticed a partially buried length of wood. On the surface, she told her diving partner she thought she had found a dugout canoe. Days later, the finding was confirmed.

In November, a complicated, meticulously planned recovery project in collaboration with the Ho-Chunk and Menominee nations brought the dugout canoe to the surface. During the recovery, Thomsen and her team noticed a collection of small rocks on the canoe. Anthropologists identified the stones as net sinkers used for fishing. The thrill of the discovery increased dramatically when radiocarbon analysis indicated the canoe was 1,200 years old.

A year later, in September 2022, Thomsen and her team discovered a second 14.5-ft dugout canoe within 100 yards of the first discovery. Radiocarbon dating determined that the second canoe was 3,000 years old. While recovering the second canoe, researchers realized that the canoe was placed on top of another canoe, this one 4,500 years old.

The discoveries intensified, and a careful survey of Lake Mendota (called Tee Waksikhominak in the Ho-Chunk vocabulary) identified almost a dozen more sunken hulls within 800 feet of shoreline. Some were intact, others in fragments. Radiocarbon dating yielded a range of 800 to 4,500 years. The 4,500-year-old dugout has been called the oldest canoe in the Great Lakes region.

The Wisconsin Dugout Canoe Survey

The Wisconsin Dugout Canoe Survey began in 2018, when Ryan Smazal, an undergraduate student majoring in History, approached the Underwater Archaeology Program at the Wisconsin Historical Society to inquire about research opportunities in underwater archaeology. That request evolved into a senior thesis under the direction of Sissel Schroeder in the Department of Anthropology at the University of Wisconsin-Madison. Thomsen worked closely with him to locate and identify dugout canoes held by small museums, historical societies, tribal collections, small businesses, and collectors across Wisconsin.

After Ryan graduated from UW-Madison in 2019, Thomsen and Schroeder continued their research documenting dugouts around Wisconsin. By 2024, the researchers confirmed the existence of 73 dugout canoes, with at least two of the canoes ranking in the top ten of the oldest dugout canoes found in North America.

Combining resources and expertise, the survey functions as a collaboration between Shroeder’s Archaeology Lab at UW–Madison and the Wisconsin Historical Society. Thomsen’s experience with Ryan Smazal’s senior thesis inspired her to continue the search for ancient dugout canoes. Her discovery of the sunken dugout canoe on a recreational dive in 2021 launched the Lake Mendota research project.

Construction & Design

The canoes recovered from the waters of Lake Mendota differ in design and construction from the upturned-bow, high-sided models found on most Midwestern lakes today. The ancient dugouts were constructed from a single log. The long and flat hulls of the ancient dugouts resemble today’s stand-up paddleboards.

Dugout builders used fire and tools to remove wood from the centers of the logs, creating a long, flat platform well-suited to carrying supplies on quiet, flat waters.

Scientists studying the recovered canoes have identified cottonwood, elm, red oak, and white oak as the trees used to build the canoes. The variety of trees used reflects thousands of years of environmental change, where the canoes were submerged.

Small wood samples from the recovered dugout canoes were sent for radiocarbon dating. At the USDA’s Forest Products Laboratory in Madison, WI, a strontium isotope analysis studied the cellular structure of the wood to identify where ancient builders found the trees used to craft the canoes.

Researchers also documented each recovered dugout canoe with 3D imaging. The team scanned the canoes with an iPhone 13 Pro and the Scaniverse app or via GoPro timelapse photography processed in MetaShapePro. The files are available on the “Dugout Canoe 3D Models” page hosted by the UW-Madison Anthropology lab. Viewers can rotate interactive models of specific canoes to learn more about their discovery, construction, and restoration status.

Restoration

Sitting on the bottom of Lake Mendota undisturbed for thousands of years, the dugout canoes are extremely fragile. The first two canoes discovered are undergoing a years-long preservation process.

After the recovery process, the dugout canoes were initially placed in a tank of deionized water to protect the waterlogged wood. Next, the dugouts were lowered into a large vat of polyethylene glycol (PEG), a chemical commonly used to preserve shipwrecks and recovered wooden artifacts. The PEG stabilizes the wood by filling up the spaces currently filled with water.

Thomsen explains, “If you think about the cellular structure of wood, the only thing that’s holding a wood cell up in waterlogged wood is the water that’s inside it. Once the wood starts drying out, it collapses and falls apart.

“If you’re thinking about a 1,200-year-old canoe when it comes out of the water, it’s kind of like a bagel. It has a hard shell on the outside and is soft and spongy on the inside. As soon as that wood starts breaking down, it would just shrivel like wet cardboard.”

The PEG chemical serves as a bulking agent, replacing water in the cells and hardening the wood, thereby making the wood shelf-stable. After a long multi-year process, the canoes will be freeze-dried to strengthen the wood. The new History Center, in Madison, WI, expected to open in 2027, will display the restored canoes.

Plans to recover the discovered dugout canoes still in Lake Mendota are under careful consideration.  The location of the submerged canoes has been designated an archaeological site, and a National Register of Historic Places application is planned.

The restoration work is being carried out in partnership with Wisconsin’s Ho-Chunk Nation and the Bad River Band of Lake Superior Chippewa. Tribal historic preservation officers have been directly involved in research, restoration, and cultural interpretation.

An Ancient Parking Lot

The canoes were found in Lake Mendota, a 15-square-mile body of water located on the north side of the isthmus in downtown Madison that is sometimes called "the most studied lake in the world," thanks to the proximity of the UW-Madison Center for Limnology.

As more ancient canoes were discovered, tagged, and recovered, the number of questions grew. One of the major questions, “Why are these canoes here?” brought together experts from across the state. Thomsen worked with Sissel Schroeder, Bradshaw Knight Professor of Environmental Humanities at the University of Wisconsin-Madison; Dr. Amy Rosebrough, Assistant State Archaeologist of Wisconsin; and Bill Quackenbush, the Ho-Chunk Nation tribal preservation officer, to explore ancient cultures for clues.

Although the natural landscape has evolved over thousands of years, there remain high bluffs on the southern shore of Lake Mendota that Thomsen suggests may have served as navigation points for ancient paddlers. “We believe that when you’re paddling, especially on big water, you’re sighting on the horizon. They were probably paddling toward the big bluffs that are on that south shore. These canoes are parked in clusters grouped around three cuts or gullies that go through those bluffs,” said Thomsen.

State archaeologists suggest there may have been a village in this area, and the canoes were shared with other community members and stored for future use. Long and heavy, these canoes would have been difficult to transport between villages.

Researchers believe the dugout canoes were intentionally buried near the lakeshores in waist- to chest-deep water to protect the wood from drying out or being broken by the movement of winter ice. In familiar locations, the canoes were removed from the lake bottoms and paddled to their next destination.

Since the recovered canoes at the same location have been dated thousands of years apart, Lake Mendota appears to have served as a storage or transfer point for hundreds of generations.

Rosebrough posited that paddlers stored the canoes on their way to Lake Wingra, a small 312-acre lake on the south side of Madison. Lake Wingra plays an important role in the cultural history of the Ho-Chunk Nation.

Next Steps

The discovery of the sunken canoes has significantly influenced the future of maritime archaeology and research. Bringing the ancient canoes to the surface brought financial resources to the historical society. An American Museum grant and matching funds from other institutions helped cover the costs of the expensive preservation process.

There are no plans to move the remaining 14 canoes sitting at the bottom of Lake Mendota, a decision made collaboratively by Thomsen and Wisconsin’s Native nations with the goal of responsible stewardship.

The Wisconsin Historical Society will display a collection of ancient canoes in a new History Center opening in 2027. To follow the progress of the recovered canoe restoration process and announcements of new discoveries, visit the Wisconsin Dugout Canoe Survey Project at https://schroeder.labs.wisc.edu/research-projects/the-wisconsin-dugout-canoe-survey-project/