Lake Superior and Lake Erie both broke records for average water height in May, as did Lake St. Clair on Detroit’s eastern edge, according to the Army Corps of Engineers.
The two Great Lakes in May also reached their highest levels on record for any month.
Record or near-record high water levels are forecast to continue in the summer before making the usual downturn into fall.
The effects of this high water have been wide-reaching. Beaches have shrunk, while water has inundated docks and destroyed roads.
Damage to lakeshore property was reported this week along Lake Ontario in Henderson, N.Y.
“There’s houses surrounded by water, water going into houses and lake water in the roads,” Eric Anderson, an operations coordinator for the Henderson Fire District, told the Watertown Daily News. “Carp are feeding in people’s front lawns.”
This kind of flooding has occurred along the shores of the Great Lakes for months, in some places repeatedly, and intensifies during high wind events and storms.
A combination of major winter snowfalls and excessive rainfall are primary drivers for this year’s high water.
Normal water levels in the Great Lakes are largely modulated by precipitation, natural springs and rivers. Great Lakes water levels typically rise during the spring into summer, but this year has taken it to an extreme.
Year-to-date precipitation in much of the lakes region is running 150 to 200-plus percent of normal (only the Lake Ontario region has seen somewhat lesser amounts, while still enduring flooding).
While rainfall surpluses have continued to be significant in recent months, the last few weeks have seen a drier pattern take hold. But this drier spell may not last, and only persistent dryness would meaningfully reduce the risk of future flooding.
The outlook from the U.S. Army Corps of Engineers indicates monthly mean water levels for June are likely to meet or surpass highs for that month.
Water levels are forecast to continue rising through June on Lake Superior and continue through the heart of summer. For Superior, levels are anticipated to stay near or above prior monthly records every month through September.
Lakes Michigan and Huron are also likely to see additional rises of several inches through June. Elsewhere, lake levels are anticipated to fall but remain near or above record levels for the time of year.
Although water levels in the Great Lakes are in constant flux, the recent shifts have been particularly extreme.
“Over the past two decades, water levels on the Great Lakes have gone through an unprecedented period of persistent below-average conditions, a record-setting rate of water level rise and, now, a series of record-setting high levels,” said Drew Gronewold, a hydrologist at the University of Michigan.
While experts work to better understand effects of climate change on Great Lakes water levels, they are seeing increased evidence of a new normal characterized by rapid shifts between extreme high and low levels.
“We are undoubtedly observing the effects of a warming climate in the Great Lakes,” wrote Richard Rood, a University of Michigan climate scientist. “We are at the beginning of what’s going to be a number of decades where the climate is going to be changing very fast. During that time, we will have many unexpected weather events, and we need to learn from these events to better prepare for the future.”