Push to map Great Lakes bottom gaining momentum with promises that efforts will help fishing and shipping

What lies beneath the waves of the Great Lakes is largely unknown, but there is new impetus to learn more about the thousands of shipwrecks, underwater infrastructure and the effects of climate change on the bottom of the world’s largest freshwater system.

According to the Great Lakes Observing System (GLOS), only 15 percent of the lake bottoms have been mapped. Since 2018, the organization has been pushing to secure funding for high-resolution mapping of the entire lakebed.

Proponents argue that it would provide a detailed picture of shipwrecks, infrastructure such as pipelines and topography that would be used to develop storm surge models as the climate warms.

Jennifer Boehme grew up scouring the beaches around her home in St. Petersburg, Florida, searching for anything she could find. Rocks, sand dollars, coquina mollusks – everything the ocean has given up.

Now, 40 years later, Boehme wants to start another treasure hunt. He is the executive director of GLOS.

She says the map will also help ships avoid submerged hazards, identify fishing spots and provide information on erosion, storm surge and flooding patterns as climate change intensifies.

“One of the things that motivates me is the idea of ​​the discovery aspect of it,” Boehme said.

“There’s a lot we don’t know about lakes. We know more about the lunar surface.”

Mapping all five Great Lakes bottoms is a difficult task. The lakes cover an area of ​​244,106 square kilometers, and depths range from 64 meters in Lake Erie to over 396 meters in some parts of Lake Superior.

The idea has been gaining traction since technology improved, and scientists have completed high-resolution mapping of the coast of Florida and the Gulf of Mexico over the past three years.

Two Michigan congressional representatives — Republican Lisa McClain and Democrat Debbie Dingell — introduced a bill this year that would allocate $200 million to map the bottom of the Great Lakes by 2030.

“I believe it’s time to take the exploration and discovery of the Great Lakes into our own hands,” McClain said during a March hearing before a House subcommittee.

The last attempt to map the lakes took place in the 1970s. The maps were created largely using single-beam sonar technology, similar to today’s commercially available echo sounders and fish finders.

They also had extremely low resolution and could miss depressions, canyons, dunes, shipwrecks and infrastructure such as pipelines, cables and intake pipes, according to the Great Lakes Observing System.

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Let’s fast forward almost half a century. Today, scientists and engineers have a range of new mapping tools at their disposal.

One of them is multi-beam sonar. Instead of sending out a single sound wave, these systems bounce potentially in hundreds off the bottom.

According to the US National Oceanic and Atmospheric Administration (NOAA), this technology is so sensitive that it can detect air bubbles in water

The only drawback is that the systems must be mounted on submarines or towed under ships to obtain high-resolution images in deep waters.

Another tool is laser imaging, in which scientists measure the time it takes for a laser beam fired from an aircraft to reach an object and bounce back, producing a three-dimensional image of the bottom topography.

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A high-resolution map of the lake floor would provide many benefits, said Steven Murawski, a biological oceanographer at the University of South Florida who has extensively mapped the bottom of the Florida coast and the Gulf of Mexico.

A map of the Great Lakes would provide a more complete picture of bottom features that have changed over the past 50 years due to erosion and shifting sands, giving navigators new depth determinations that would improve navigation safety, Murawski said.

The map would also help predict how seabed features will affect storm surges and flooding as climate change progresses, which he says will be invaluable information for insurance companies and city planners.

Improved seabed maps would also provide accurate locations of infrastructure such as pipelines that have changed over time, as well as information crucial for dredging and construction projects, Murawski said.

Additionally, high-resolution maps would identify underwater outcrops and rock ledges where fish usually congregate, allowing scientists to obtain better estimates of fish populations, the oceanographer added.

Fully mapping the lakes for the first time could also reveal the locations of hundreds of shipwrecks – some estimates put the number of shipwrecks in the Great Lakes at about 6,000 – and relics of ancient coastal civilizations, Boehme said.

While mapping momentum is gaining momentum, Congress has not taken action on a funding bill since a March hearing before the House Natural Resources Subcommittee on Water, Wildlife and Fisheries.

The subcommittee’s chairman, Rep. Cliff Bentz, R-Ore., suggested during the hearing that supporters of the new map would better articulate the value of the new map.

“I know ranking members have suggested that finding the Edmund Fitzgerald would be a valuable thing, but it has to mean something more,” Bentz said, referring to the freighter that sank in Lake Superior in 1975.

The wreck was found a few days after the ship sank.

Bentz spokeswoman Alexia Stenpzas did not respond to an email from The Associated Press seeking comment on the bill’s prospects.

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Boehme expressed doubts that the bill would pass in an election year, but the Great Lakes Observing System is still working toward its 2030 mapping goal.

The group holds an annual conference in Traverse City, Michigan, to discuss progress and test mapping technology, and contacts any boaters who want to rent mapping equipment to look at small sections of the lake floor.

“This research is for the public good,” Boehme said.

“The key is to be persistent and keep coming back to the issue (before Congress).… We have to understand the system so we can protect it.”