By Debora Van Brenk, The London Free Press
Wednesday, September 17, 2014 10:25:59 EDT AM
Water levels in the Great Lakes are up this year, thanks to an abundance of rainfall. It’s a welcome rebound — levels haven’t been this high since 1999 — but it would take several more years of extra rain before the region’s wetlands begin to recover and diversify. Debora Van Brenk reports.
Yes, more rain dropped on your favourite lake this year and spoiled your picnics. Yes, the water in that same lake was chillier.
But the summer swim you might have lost also translated into a huge gain for Great Lakes levels. Not since February 1999 have water levels been this high — “high” this time meaning they’re finally at levels at or close to the century average.
The rebound in lake levels, particularly in Michigan and Huron, has all been enough to blow experts’ more modest forecasts out of the water.
The one big reason: “lots of precipitation,” says Derrick Beach, water resources engineer with Environment Canada’s boundary waters issues unit.
Lake Superior, for example, experienced 142% of the rain it normally sees in August and September. And some of that naturally flowed to lakes Michigan-Huron (hydrologists consider them one lake system) and to the lower lakes.
Mary Muter, head of the Great Lakes section of the Sierra Club, said it would take several years of this before wetlands begin to recover and diversify.
Only a few years ago — as the lakes dropped to record levels and belied navigational numbers on the charts — many environmental and commercial groups sounded the alarm about the consequences of long-term low lakes.
But Muter says one rainy year does not make a trend.
“We have a blip right now due to high (water) supply,” she said.
Muter is part of a U.S.-Canadian group called Restore Our Waters International that’s still advocating to place “sills,” adjustable speed bumps, in the St. Clair River where dredging took place in 1962. Groups concerned about low levels in Michigan-Huron contend the dredging has created a fast funnel for water to drain out of the lakes.
She said other human-made structures such as canals, locks, hydro-electric dams and the seaway itself make it impossible for the lake ever to be naturalized.
But steps can be taken to manage the extreme highs and lows, she said.
The U.S. Army Corps of Engineers has been commissioned to do a study on the feasibility of putting a structure or structures in the St. Clair River to alter the flow when needed.
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Lower water levels mean loss of wetlands and fish habitat.
Exposed shorelines are taken over by invasive (non-North American) plants that crowd out native species and habitat.
Smaller lake basin warms more quickly and evaporates more quickly, meaning some colder water species have smaller (and more vulnerable) habitat; potential loss of diversity of species.
Commercial ships — the main mode for shipping ore, wood products and salt — must carry lighter loads and make more trips.
Cottagers have more beach-front but recreational boaters, charters and commercial fishers may need to extend their docks farther from shore.
Superior: 15 cm higher than the 1918-2013 average; 20 cm higher than this time last year.
Michigan-Huron: 2 cm below average; 42 cm higher than this time last year.
St. Clair: 13 cm above average; 21 cm above this time last year.
Erie: 11 cm above average; 7 cm above this time last year.
Ontario: 7 cm above average; 2 cm below this time last year.