Great Lakes water levels — which can sway the region’s economy billions of dollars in either direction — are expected to rebound slightly and be a little more stabilized in 2014.
Yet the U.S. Army Corps of Engineers and the National Oceanic and Atmospheric Administration, the main federal agencies on the U.S. side of the border tracking water levels, said Wednesday the lakes likely will stay below long-term averages for the foreseeable future.
Lake levels can affect sailing, fishing, cargo shipping, and other waterborne types of industry. They are especially crucial in western Lake Erie, the shallowest part of the Great Lakes.
When water levels recede, that requires more dredging or lighter cargo loads. That drives up costs.
Scientists also think excessive dredging adds to the basin’s algae woes and impairs water quality in other ways.
Records show Lake Erie, which tends to have more water-level highs and lows, got back in sync with its long-term average in mid-July and continued to follow it through October.
It is expected to recede to 3 inches below its long-term average for the next six months, but be 4 to 5 inches above what it was a year ago.
The depth varies, depending on the monitoring station. There are multiple ones for each lake.
The corps and NOAA made the 2014 projections with help from Environment Canada. Officials underscored it was a cooperative effort because of how the water flow transcends the international boundary.
The five Great Lakes in general — but especially Lakes Superior, Michigan, and Huron — have been mired in a prolonged low-water era since the late 1990s after experiencing a 30-year era of higher-than-normal water levels.
One of the presenters, Drew Gronewold, a hydrologist in NOAA’s Great Lakes Environmental Research Laboratory, said one of the great unknowns is if the lake levels are undergoing a natural fluctuation cycle or if the region is in a new norm of lower levels because of climate change. Scientists have determined Great Lakes water has evaporated at a faster rate since an El Nino event in the late ’80s. They’re not sure why, Mr. Gronewold said.
Data go back to the 1850s. The corps has issued monthly bulletins about Great Lakes water levels since 1918, Keith Kompoltowicz, watershed hydrology branch chief for the corps’ Detroit district, said.
Lakes Michigan and Huron, considered one body of water by hydrologists, hit record lows in December and January, Mr. Kompoltowicz said. “The very wet conditions we saw allowed the lakes to have a seasonal rise, although Michigan, Huron, and Superior are still below their long-term averages,” he said. “We aren’t looking at record-setting conditions by any means over the next six months, but we are looking at long-term below-averages.”
Much depends on how much ice cover the lakes get this winter, a factor which Mr. Gronewold described as “incredibly important.”
Ice helps seal off evaporation. Evaporation is greatest in the winter, just before ice forms, because of the differences between water and air temperatures.
Lake Erie usually is prone to freeze earlier than the other lakes because of its shallowness. In recent years, those freezes have come later and thawed earlier.
“Water levels depend so much on the subtle interplay between precipitation and evaporation,” Mr.Gronewold said. “When we look at projections of both climate and looking into the future, we see a broad range of possibilities.”
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