Water levels in the Great Lakes are swinging bigger and faster. A forecast could help
In June, the wild rice growing on Minnesota’s St. Louis River danced like ribbons on the surface of the water.
Wild rice is a traditionally important Ojibwe food. A millennium ago, when the Ojibwe people migrated west, searching for a new home, a prophecy told of a land where food grows on water: manoomin, or wild rice.
The grassy plant likes the slow-moving waters here that flow into Lake Superior. So, it’s sensitive to how high or low the water is. And those levels — here and across the Great Lakes — are always changing.
“That period when the wild rice is floating, it’s kind of vulnerable to wave action,” said Faith Fitzpatrick, a hydrologist with the U.S. Geological Survey’s Upper Midwest Water Science Center in Madison.
“If it’s in a quiet, backwater zone that’s going to be overtaken by some storm surge, that would be good to know,” said Fitzpatrick, who works with resource managers involved with things like fisheries management and wild rice restoration.
Fluctuating water levels in the Great Lakes come down to three things: precipitation, runoff from all the rivers and streams trickling into the lakes, and evaporation. All of which are affected by human-driven climate change.
The lakes already fluctuate with the seasons, rising in the summer and falling in the winter. With climate change, which drives both extreme precipitation and drought in the region, the highs are higher and the lows are lower. And those swings are coming faster.
A forecast could help coastal communities deal with these changes, not only for things like wild rice restoration, but also navigation, infrastructure and city planning. It’s part of adapting to life in a warming world. When the waters are high, they can drive floods and cause bluffs to slide. When they’re low, they can wreak havoc with navigation and harbor operations.
In January 2020, for instance, a wild winter storm, combined with record high water levels in Lake Michigan, battered the Port of Milwaukee and prompted flooding from Milwaukee to Kenosha, causing millions of dollars in damage.
A forecast would help with making weather-based decisions — something we do all the time, not just during extreme storms, said Meg Palmsten, an oceanographer with the U.S. Geological Survey (USGS) who is leading an effort to build such a tool for coastlines across the country.
“We always have the weather report to decide whether or not we should take our umbrella or make a choice about going to the beach,” Palmsten said. “This is also at that level of forecast. Do you need to make a decision about what road to drive on, because it might be covered in sand or flooded?”
With climate change in the picture, “being able to have that information becomes more and more relevant as those changing water levels are affecting people’s lives every day,” Palmsten added.
The USGS tool provides a forecast of total water level, which describes where water meets the coast, informing the user on sites where erosion or floods could occur. Currently, a six-day forecast is available for the parts of the Gulf Coast and Atlantic, offering a resolution of about six city blocks. The team is working on expanding to the Pacific, as well as the Florida Keys and U.S. territories.
The Great Lakes are the last piece of the puzzle. An initial study published in April found that the data inputs used to build the forecast elsewhere work well for the Great Lakes.
Erdinc Sogut, a postdoctoral researcher at USGS and the Woods Hole Oceanographic Institution, led the April study. Like the current tool, he said, the Great Lakes total water level forecast could be used by planners and emergency responders.
“It can be used to make critical decisions for emergency managers before and after a storm hits an area,” he said. They could direct people away from a road if it’s likely to flood or focus resources on sections of the coast that are most likely to erode.
Currently, there are forecasts available for water levels and waves offshore. And, if Lake Michigan were simply a big bathtub, that would do the job. But it’s more complicated than that.
As geologists, said Walter Barnhardt, one of the USGS researchers, the team is asking questions about where water and land interact. “How does the landform then respond?” he said. “Does it breach a road? Does the dune get overwashed entirely? How is it interacting with the land, which is where people live?”
Their model takes in data on the water, waves and weather, information that comes from the National Oceanic and Atmospheric Administration and the National Weather Service. It also uses information on the surrounding beach and bathymetry.
Then, they project how all of that interacts with the coast. The forecast describes a range of potential impacts, from when waves remove sand from the coast to when they overtop dunes, pushing sand inland, or inundate the beach entirely.
The researchers began work on the Great Lakes model by focusing on Lake Superior, but they plan to eventually tweak their model so it’s specific to each lake. Barnhardt said it was an interesting challenge, after working on the oceans.
“On the Atlantic coast, sea level is only coming up. The only question is, how fast is it rising?” he said. “In the Great Lakes, it comes up and it goes down, and the shoreline responds very differently. It’s a different set of issues in many ways.”
Add to that the diversity of coastlines across the Great Lakes region and one other thing the oceans don’t have: ice.
“There’s a lot of uncertainty around ice cover now because of climate change,” Barnhardt said. “How thick is the ice? How extensive is it? How late in the season does it last? It’s a science project.”
A science project that could help emergency managers in communities like Milwaukee. Or, help people figure out the best places for wild rice and coastal restoration projects.
It will take a few years before the forecast for the Great Lakes is up and running, Palmsten estimated. Next, she said, the scientists will need to get in the water, to collect on-the-ground data that can test the accuracy of their forecasts.
Reporting for this story was made possible, in part, by the Institute for Journalism & Natural Resources.