HENDERSON HARBOR — Ronald J. Ditch has spent the past 57 years chartering Lake Ontario. But the veteran fishing guide and owner of Ron Ditch & Sons Charter Service and Marina has been noticing rocks emerging above the water that he’s never seen before.
“I’ve never seen the lake anything near this low,” Mr. Ditch said. “Water is normally on its way back this time of the year, but it seems to be getting even lower.”
Lake Ontario’s water level neared an all-time low for November and was at its lowest since 1964.
According to the U.S. Army Corps of Engineers in Detroit, Lake Ontario was at 243.73 feet last month, only 8.7 inches higher than the historic minimum recorded in 1934.
As of Dec. 20, the mean water level on the lake was 243.62 feet — 10.5 inches below the long-term average for December but 20.6 inches above the record low.
The International St. Lawrence River Board of Control, which determines the outflow at Moses-Saunders hydroelectric dam at Massena, attributes this largely to “dry conditions experienced since last spring.”
“The lake would be about 5 inches below long-term average in May 2013 if the basin receives average water supplies,” said Frank A. Bevaqua, spokesman for the International Joint Commission, a binational entity established to manage shared U.S.-Canadian waters.
Lake Ontario received only 30 percent of its average November precipitation. And over the past 12 months, Ontario received 18 percent less than its long-term average precipitation, according to the Corps of Engineers.
In its most recent outflow strategy report, the River Board of Control said the lake is only 4.3 inches above the lower limit and about 0.4 of an inch below what it tries to meet under an international water regulation plan.
Over the past couple of months, the St. Lawrence Seaway has been warning shippers of “near alert levels” in sections of the Great Lakes-St. Lawrence shipping channel, and recreational boaters and marinas had to pull vessels out of the water at the end of September, almost a month earlier than usual, because of the low water.
Supply from Lake Erie — Lake Ontario’s primary water source — also has been low because of the drought. Like Ontario, Lake Erie received only 30 percent of its average precipitation last month, according to the Corps of Engineers.
Experts also point out that the decline in ice cover in the Great Lakes has led to more evaporation.
Using satellite measurements from 1973 to 2010, researchers at National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory have found that the Great Lakes’ average ice coverage is down by 71 percent — with the highest loss, 88 percent, seen in Lake Ontario.
Historic water data show that in both 1934 and 1964, it took at least two years for Lake Ontario to recover to its long-term average levels following low summer and winter water levels.
But the recovery rate ultimately would depend on the water supply — mainly precipitation — between now and spring, Mr. Bevaqua said, adding that the Corps of Engineers predicts that under the “high-supply” scenario, Lake Ontario in May could rise to about 5 inches above its long-term average level.