The Great Lakes are 5 of the 13 largest fresh bodies of water in the world by area, but over the last several years, water levels have been very slowly receding. Even though overall water levels really haven't changed much in the last 50 years, with population continuing to grow, and the threat of fresh drinking water becoming more scarce in the years to come, the last thing anyone wants to see are the Great Lakes dwindling. But some very good news over the past year as water levels have rebounded quite nicely, showing a larger rise in water levels than we have seen in many years. Here now is an article about the issue from The Detroit Free Press.
"A snowy winter and wet spring and summer led to an almost unprecedented recovery of Great Lakes levels this year, officials with the U.S. Army Corps of Engineers and National Oceanic and Atmospheric Association said.
Lake Michigan and Sleeping Bear Dunes National Lakeshore Park are shown in Empire in 2006. Lake Michigan is among the Great Lakes seeing a rise in water levels, according to a U.S. Army Corps of Engineers report Wednesday, Nov. 20, 2013. / Douglas Tesner/Traverse City Record-Eagle/AP
But because they were at or near record lows, several of the lakes continue to have below-average water levels even after the recovery.
"That's going to continue to affect Great Lakes shipping, shoreline property owners, marina owners and the recreational boater," said Keith Kompoltowicz, watershed hydrology branch chief of the Army Corps' Detroit district.
Great Lakes levels typically do whatever rising they will have in a normal year during snow melt and spring rains, a period from late winter to early summer. Lakes Michigan and Huron, which are connected at the Straits of Mackinac, had a nearly 20-inch rise from late February to early June in 2013, compared to just a 4-inch seasonal rise the year before, Kompoltowicz said. The average seasonal rise from late winter to early summer is closer to a foot, he said.
"Going back to 1918, the seasonal rises on Lake Superior and Lakes Michigan and Huron were in the top percentages of seasonal rises ever recorded" this year, Kompoltowicz said.
The better-but-not-normal theme played out across the Great Lakes basin:
■ Lakes Michigan and Huron remain 17 inches below their long-term average as of the end of October, but are up 11 inches from this time a year ago;
■ Lake Superior is 2 inches below its long-term average, but up 13 inches from its levels of a year ago;
■ Lake St. Clair is 6 inches below its long-term average; but up 10 inches from a year ago;
■ Lake Erie is near its long-term average and up 10 inches from this time last year.
■ Lake Ontario is also near average and up 14 inches from the previous year.
Precipitation levels are only part of the equation, said Drew Gronewold, a hydrologist with NOAA's Great Lakes Environmental Research Laboratory. How much evaporation occurs in the summer is also key to lake levels, he said.
"Right now we are in a period, since an El Niño period in the late 1990s, of exceptionally high evaporation," he said. El Niño refers to a pattern of extended warming of the Pacific Ocean that leads to climate changes across the globe.
The forecast over the next six months calls for Lake Superior to remain 2 to 3 inches below its long-term average, but a foot or more above its levels of a year ago.
"With a wet winter, mean monthly Lake Superior water levels could rise above their long-term average, which would be the first time in 14 years that has occurred," Kompoltowicz said.
The six-month forecast calls for water levels about a foot above those of a year ago on lakes Michigan and Huron.
"Even with very dry conditions, we don't see any further threat for record lows on Lakes Michigan and Huron," Kompoltowicz said.
Lake Erie is expected to remain near its long-term average and 4 to 5 inches above its levels of last year, he said. Lake Ontario is projected at about 10 inches above its levels of the previous year over the next six months.
Kompoltowicz noted the difficulty in even short-term projections of lake depths.
"At the end of 2012, we were projecting several months in a row of record-low water levels on lakes Michigan and Huron," he said. "That ended with only a 2-month stretch, and lakes Michigan and Huron then rose very quickly.
"Something could change to make these forecasts complete busts."