TRAVERSE CITY, Mich. (AP) -- Water levels are surging in the Great Lakes and likely will set records this summer, forecasters said Monday --- a remarkable turnaround from earlier this decade that's bringing welcome relief to shippers and marina owners, but causing flooding and heavy erosion in some areas.
A six-month bulletin from the U.S. Army Corps of Engineers predicted Lake Superior and Lake Erie soon will reach unprecedented high points, as a heavy winter snowpack across the region's northern section melts and mingles with water gushing into the lakes from rivers swollen with spring rainfall.
Levels have been trending upward at varying rates since 2013, when Lakes Huron and Michigan fell to their lowest points and the other Great Lakes were significantly below normal. That was the nadir of a nearly 15-year slump that stranded pleasure boats, forced cargo vessels to lighten loads, dried up wetlands and fueled conspiracy theories that water was somehow being siphoned off to the parched West.
"It's quite the shift," said Keith Kompoltowicz, chief of watershed hydrology with the Corps' district office in Detroit. "Now we're at the other extreme."
Lake Superior, which holds more water than the other four combined and sends them a continuous flow through its southern outlet, is about 15 inches (38.1 centimeters) above its long-term average level for this time of year, and nine inches (22.9 centimeters) higher than a year ago. Lake Erie is 26 inches (66 centimeters) over its long-term average.
Michigan, Huron and Ontario aren't expected to set records but are well above average, Kompoltowicz said.
Great Lakes levels are known to fluctuate over time. But experts said the prolonged drop-off of the past decade and the more recent rise likely result at least in part from a warming climate.
"These events are quite consistent with what scientists have been expecting with long-term climate change patterns," said Drew Gronewold of the University of Michigan's School for Environment and Sustainability. "The challenge is that it's very hard to forecast when those extremes are going to occur and when the transition between them might occur."
Kolleen Jones, co-owner of the Betsie Bay Marina in Elberta, Michigan, said the recovery was a blessing. The previous owners were hammered when levels dropped so low that many of the 95 boat slips were unusable.
"We were considering not even buying it," Jones said. "Now, we're working our tails off to raise our docks to get them out of the water."
The low water was costly for ships that haul iron ore, coal and other bulk commodities between Great Lakes ports. Things are much better now, although with water so high, vessels must slow down on rivers and channels to avoid creating wakes that damage shoreline docks, said Glen Nekvasil of the Cleveland-based Lake Carriers' Association.
"These vessels have very high operating costs and anything that lengthens a voyage adds to those costs," Nekvasil said.
Another sign that the pendulum may have swung too far for comfort: flooding and erosion, which the Corps expects to worsen. The agency dispatched a technical team Monday to help with proper placement of sandbags in Sodus, New York, where Lake Ontario overflows loom. Gov. Gretchen Whitmer declared an emergency last week because of flooding in southeastern Michigan.
Storms that have battered the central U.S. this spring have filled Great Lakes tributary waters while kicking up big waves that are eroding shorelines, said Guy Meadows, director of the Great Lakes Research Center at Michigan Technological University.
"We expect lake levels to fall again but this episode of high water is going to take a couple of years to work its way through the system," Meadows said. "It's going to be a big hit."