Not all power lines run on poles. Some rest on the bottom of the deepest Great Lake.
Madeline Island, just 2.5 miles across the water from Bayfield near Wisconsin’s northern tip, is the only inhabited island on Lake Superior. It is home to roughly 450 residents and thousands of summer visitors who depend on reliable electricity for safety, comfort, business and tourism. That's where that important power line plays a critical role.
In October, Xcel Energy completed a major upgrade to strengthen that connection by installing a new 12-kilovolt submarine cable and putting it into service. The new cable replaces the one installed in 1964 and is paired with a secondary cable, installed in 2002, to preserve the island’s energy reliability.
“This is a vibrant, year-round community, but we would not have a community on the island without power,” said Glen Carlson, town board chair of La Pointe, the official town.
Keeping that power flowing meant going beneath the surface — and taking on a project unlike a typical power line replacement.
A big project beneath Lake Superior
Manufactured specifically for this project, the submarine cable stretches 13,000 feet — nearly 2.5 miles — in one continuous length, with no splices. The cable weighs 19 pounds per foot, and the loaded reel weighs 283,000 pounds. It rests on the lake floor at depths reaching approximately 170 feet.
Planning began in 2020 and covered engineering, permitting, environmental review, manufacturing and transportation. In 2025, crews completed much of the supporting construction, including conduits that carry the cable between land and water.
A long journey to serve the island
Strengthening service for the island’s homes and businesses began far from Lake Superior. Before it could be installed, the custom-built cable had to travel thousands of miles to the community it would serve.
“The transportation coordination is immense for something like this,” said Bruce Holzmann, Xcel Energy’s director of distribution operations. “Just getting it here took a team effort.”
The new cable traveled from South Korea to Houston, then headed north by barge through America’s inland waterways. Its route followed the Mississippi River to the St. Louis area and the Illinois River toward Chicago, then continued through Lakes Michigan and Superior.
The journey involved numerous locks and transfers between towing vessels. Near Lemont, Illinois, crews added ballast water to lower the barge enough to clear a bridge. Despite minor delays from lock traffic and routine river operations, the shipment arrived ahead of schedule without a major transportation incident.
By July 2026, the cable was in Duluth, bringing the island one step closer to a renewed electric connection.
Making the connection
Installation in October brought together shore crews, divers and marine crews, powerful tugboats, specialized drilling equipment and a barge carrying the cable. Even with those resources in place, the work depended on Lake Superior’s weather.
“It's not every day that we have a submarine project like this,” said Zach Hughes, Xcel Energy project manager. “We needed the weather to cooperate for two consecutive days. Finding calm days on Lake Superior in October is tricky, but we were able to execute a successful installation.”
Powering island life
Now beneath Lake Superior, the cable serves residents, businesses and visitors with critical, reliable power.
“There is something very special about this island,” Carlson said. “Xcel Energy prepares and plans to ensure this island is taken care of. It means a lot to those who call this place home.”
The new cable, expected to be in service for the next 50 years, is built to handle future energy demand and electrification.
“This highly complex project is an example of our commitment to customers,” said Hughes. “We will go to great lengths to serve them.”
