The U.S. Army Corps of Engineers anticipates that water levels across the Great Lakes, including Lake Ontario, will decline, but remain higher than average for the remainder of the year.
All of the lakes reached elevations that were significantly above average this year, with Lakes Ontario, Erie and Superior breaking various height records, said Lauren M. Schifferle, a civil engineer with the Corps’ Buffalo District. Higher water levels, primarily caused by excessive precipitation, runoff and inflows from adjoining lakes and tributaries, means an overabundance of water in the basin.
The more water that enters the system, the longer it takes to leave, and it can only leave so fast under the limitations of the waterways and regulations governing the two control systems, an interconnected series of hydropower plants, locks and a dam on the St. Mary’s River, Michigan; and the Robert Moses-Robert H. Saunders Power Dam in Massena and Cornwall, Ontario, Ms. Schifferle said. More water could flow through the St. Lawrence River if it were three times wider and four times deeper, she said.
“We can guide what nature gives to us, but we can’t change what nature puts in our path,” she said. “It’s a very complex system and we are at the winds of nature.”
How much higher water levels will remain above the historic averages for each lake remains uncertain and can vary depending on the weather, but the Army Corps has released some projections based on historic data in its August bulletin, although it does not account for extreme weather events.
For Lake Ontario, the chart shown in the bulletin reports depict levels remaining any amount between a few inches to almost three feet above the historic average height by December depending on the weather. Dry weather could allow the water level to drop as much as three feet, while wet weather could inhibit the amount of reduction.
“Nobody, unfortunately, can accurately predict the weather more than a few days out,” Ms. Schifferle said.
The effects of persistent elevated water levels through the rest of the year, including the extent of erosion, may vary depending on location and weather, Ms. Schifferle said, although higher levels in the fall can elongate the recreational boating season in the lake and river. The Army Corps has no water level predictions past the winter.
Persistent high waters, however, can delay repairs to docks, boathouses and other structures damaged by inundation by blocking equipment, said Bridget Brown, a team leader of the Army Corps’ Auburn office. The Army Corps has streamlined the process for obtaining permits needed to make repairs to shoreline amenities, but the high waters have also delayed permitting by masking the full extent of the damage done to them.
“You can’t really do the work when the water’s that high,” Ms. Brown said.
As the Army Corps and regulators continue monitoring water levels, the agency that manages outflows from Lake Ontario has decided to reduce them Wednesday after lake levels fell to 247.7 feet.
The International Lake Ontario-St. Lawrence River Board announced its decision on Facebook to end the 69-day stretch of maintaining outflows through the Robert Moses-Robert H. Saunders Power Dam in Massena and Cornwall, Ontario at 10,400-cubic-meters-per-second and reduce them to 10,110-cubic-meters-per-second, a 3 percent reduction.
Engineer Robert J. Campany, a member of the river board from Clayton, said the board elected to lower outflows to provide safer conditions for commercial shipping freighters. Both he and Ms. Schifferle said higher outflows at lower lake levels creates a more dangerous velocity of currents for shippers.
The new outflows remain above the safe navigation flow limit for commercial shipping, according to the board, and will be kept above the limit “for the foreseeable future.”
“While we’re above the H-14 trigger, we do have the ability to increase outflows beyond the Plan (2014) to provide maxim relief to riparians,” Mr. Campany said, “of which we are doing.”
The board has virtually no ability to predict future outflows through the dam because outflows depend on the amount of water in the system, fueled by precipitation and runoff, Mr. Campany said.
It typically lowers outflows at a gradual rate through the fall and into winter so the water can form a stable ice cover during the winter and prevent ice jams. Outflows then increase once more.
“If we’re able to build a stable ice sheet and maintain a stable ice sheet, it gives the ability to increase flows in the winter months,” Mr. Campany said.