Three of the five Great Lakes are at or above record high water levels for May and the other two are getting close as a winter of heavy snow and a spring of heavy rains continues to flow downstream.
And with wet weather now expected to continue for at least the short term, new all-time record lake levels are possible in late summer or early fall when the lakes hit their usual yearly peaks.
Lake Superior sat at 183.8 meters at mid-week, above the record May average of 183.7 set in 1986.
"We don't have a final average yet, obviously, because the month isn't over. But it's not going down," said Charles Sidick, U.S. Army Corps of Engineers hydrologist in Detroit who oversees Lake Superior levels.
Meanwhile Lake Erie (and Lake St. Claire) already have surpassed their all-time May highs. Lake Ontario is right at the all-time high set just two years ago and Lakes Huron/Michigan are just 3 inches short of their record May high.
Lake Superior is so high that, when northeast winds push toward Duluth, the water is flowing upstream against the St. Louis River, flooding boat landings and docks well away from the lake. The high water is eroding clay banks on the South Shore and erasing sand beaches in Duluth and Superior while once again raising the water table in low areas, filling sumps and basements along Park Point.
There have been some calls to release more water from Lake Superior through dams and gates on the St. Marys River. But that would have little effect on the big lake, Sidick noted, and would only send more flooding problems downstream where problems already are more dire.
"Even if we could, there's nowhere for the water to go. They're all full," Sidick noted of the Great Lakes.
New York Gov. Andrew Cuomo earlier this week declared a state of emergency around Lake Ontario, warning people living along the lake to prepare for flooding and saying the region was "at the precipice of a disaster."
Flooding is already occurring in northwestern Ohio and southeastern Michigan, as western Lake Erie is in "uncharted territory" for high levels, according to the National Weather Service.
The Great Lakes have been high for years and the Corps of Engineers said all of the region received above-average precipitation in April. Each lake exceeded its average April precipitation by at least 24 percent; Lake Erie's April precipitation was 37 percent higher than normal.
"We've seen a region-wide wet period that doesn't seem to want to end," Sidick said. "There's some connectivity between the lakes, obviously. But local impacts (weather events) really are the biggest driver for each specific lake. But we do have a system-wide trend right now that has made all of the lakes high at the same time."
As recently as 2013 all of the Great Lakes were at or near all-time low levels, and had been low for more than a decade, causing headaches for Great Lakes freighters in low-water ports and spurring concerns that the lakes may have entered a permanent period of water shortages. But just the opposite occurred: Wet conditions returned and settled in. Since September 2014, all of the Great Lakes have been above their monthly average levels.
Sidick said that with just average rainfall during the upcoming summer, it's likely Lake Superior will set monthly high-water records in June, July and August as well. Whether the big lake breaks its all-time record, set in October 1985, will depend on how much rain falls. That record - 183.91 meters - is only 4.3 inches higher than this week's level.
"It's certainly possible if this wet pattern continues," Sidick said.