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Great Lakes heading down after a summer of record highs

An all-time Lake Superior record, and autumn storm damage, still possible.

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U.S. Army Corps of Engineers hydrologists Tuesday said most of the Great Lakes have begun to fall away from summer record high water levels. But they said Lake Superior could still reach all-time high levels if rainfall persists in coming weeks. They also warned that the ongoing high water levels could again spur shoreline damage during autumn storms. News Tribune 2019 file photo.

A summer of record-breaking monthly high-water levels on most of the Great Lakes was the product of a trifecta of recent weather patterns that started last year, officials from the U.S. Army Corp of Engineers said Tuesday.

Corps hydrologists talked with reporters about why the Great Lakes have been so high for so long, including Lake Superior which has broken monthly high-water records from May through August.

The big lake has approached, but probably won’t break, the all-time record high set in October 1985.

Keith Kompoltowicz, chief of watershed hydrology at the U.S. Army Corps of Engineers’ Detroit District, said Tuesday that the autumn of 2018 was unusually wet across much of the Great Lakes watershed. Then heavy winter snows piled up in many areas, unable to soak in to the already wet ground, adding to the available moisture.

Third, even as the snow melted, a spring and early summer of heavy rainfall events began, rapidly increasing runoff, river flow and lake levels.

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And Kompoltowicz said that even before the last year of wetness, the Great Lakes region had seen an unusually wet cycle since about 2012, so the lakes came into the wet period higher than normal.

While the big lake now seems poised to drop, Kompoltowicz said, "the record territory from October 1985 is still within our forecast range — but only if we see a really wet period from now through September.”

The high water continues to cause problems for lakefront property owners, especially along the South Shore and Duluth's Park Point. But it's also spurring erosion on beaches and inundating key wildlife habitat in the Twin Ports harbor.

Even if the record isn’t set, Lake Superior could still cause damage along its shores heading into the gales of autumn.

“We’ve seen this happen before, including last summer, where it looked like Lake Superior was heading into its seasonal decline and then it jumped up again. So we aren’t out of the woods yet,’’ Kompoltowicz said. “With the impact of fall storms, and the lakes still so high, the impacts of this high water are still going to be with us into winter.”

Corps hydrologists pushed back against criticism that the International Joint Commission — which oversees Great Lakes water levels for the U.S. and Canada — could have foreseen the influx of water and manipulated dams to prevent high-water damage on some lakes. Experts said engineers have a limited ability to react to rapid weather pattern changes and have little impact on water levels overall.

Col. Greg Turner, commander of the Corps’ Detroit District, noted that much of the nation’s midsection experienced flooding this spring and summer — not just the Great Lakes — including the Mississippi and Ohio rivers that saw record flood events.

There is good news to report, however, with a drier than normal August so far spurring most of the Great Lakes to start dropping, part of a seasonal pattern which usually sees the lakes drop from late summer through winter. The exception was Lake Superior which has remained fairly stable so far in August.

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Lake Superior started August by breaking the monthly high-water level record, the fourth straight month that's happened, as the big lake continues its high-water trend. The International Lake Superior Board of Control reported earlier this month that Lake Superior rose by 1.2 inches in July, less than the usual 1.6 inches but still enough to push the lake nearly an inch above the previous record high level for August 1 set in 1950.

As of mid-month, the big lake sat 13 inches above the 100-year average for Aug. 1 and 8 inches above the level at this time in 2018.

Lake Superior generally rises from April through August or September and then drops from October through March.

Meanwhile lakes Erie and Ontario were also at record-high August levels, while lakes Michigan-Huron were 2 inches below the record high beginning-of-August level set in 1986. As of mid-August, lakes Michigan-Huron were 30 inches above the long-term average and 15 inches higher than they were Aug. 1, 2018. Those lakes all have begun to drop.

John Myers reports on the outdoors, natural resources and the environment for the Duluth News Tribune. You can reach him at jmyers@duluthnews.com.
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