Port Bay, N.Y. – Sean Martin bends down next to the concrete wall encasing a fuel tank behind The Bayfront restaurant and points to the high-water stains left by Lake Ontario.

Like sedimentary strata, the darker, lower line shows the 2017 lake level; the higher, lighter layer shows this year’s record-breaking level. Martin, who owns the restaurant in Wayne County, hopes there won’t be a third line on that concrete wall next year.

But he’s not taking chances; Martin is already fortifying the shoreline against a potential flood next year. He said he’s going to raise the nearly 300-foot long steel seawall by 16 inches this fall to avoid the arduous work of hauling and stacking hundreds of sand bags.

“It was debilitating,” said Martin, who bought the restaurant in 2017. “We’re preparing for next year already.”

Lakeshore residents and business owners who endured record-breaking water levels two of the past three years are nervously looking toward 2020. While the lake has dropped more about 3 feet from its summer peak, it remains substantially higher than it was a year ago. Rick Cavallaro, who owns a camp on Port Bay, estimates the water is 16 inches higher than last year. He fears that could give spring flooding a head start.

“If we start 16 inches higher now, does that mean it’s going to be 16 inches higher next year?” Cavallaro asks as he pilots his boat through the narrow bay, toward the open lake. “Then we’d have catastrophic flooding.”

The forecast isn’t good for Martin, Cavallaro and thousands of other people who own property along Lake Ontario and its network of bays and inlets. The U.S. Army Corps of Engineers predicts that levels of the Great Lakes will still be about a foot higher than normal in January.

That doesn’t necessarily mean flooding next year, however, said Keith Koralewski, a technical adviser with the Army corps office in Buffalo.

“The lake levels that we see now and even into early spring are no indication whether there will be flooding," Koralewski said. “The main factor is the supply that comes into Lake Ontario.”

Ontario is the lowest of the Great Lakes, and the excess water from the upper lakes eventually flows through over Niagara Falls and into Lake Ontario. About 80% of the lake’s water comes in that way, with the remaining 20% either falling on the lake itself or flowing in from the lake’s watershed.

This year, the Great Lakes hit record levels, and water poured into Ontario at a record pace, too. Lake Erie reached record levels five straight months, Koralewski said.

Lake Ontario peaked in June at 249.08 feet above sea level, the highest level ever measured in the more than 100 years of record-keeping.

Since then, the lake has fallen 3 feet, to 246.1 feet. That’s about still about 14 inches above the long-term average for mid-October, and within an inch of the level recorded one year ago. Two years ago, after the disastrous 2017 flooding, the lake remained about where it is now, but there was no flooding in the spring of 2018.

“2016 and 2018 were not bad years, and 2017 and 2019 were, so it really depends upon that supply,” Koralewski said.

Lake levels generally peak in spring, when snow melts and rain is heaviest, and then fall throughout the rest of the year. The International Joint Commission, a U.S.-Canada partnership, regulates the lake levels by releasing water through the Moses-Saunders power dam, at Cornwall, into the St. Lawrence River.

The commission is nervous about 2020.

“The possibility of a flood next year is very real,” said IJC spokesman Frank Bevacqua. “The lake is high for this time of year. The upper lakes are at record or near-record highs, so the supplies coming in from Lake Erie will be high for the foreseeable future.”

Bevacqua agrees that whether 2020 becomes another flood year depends largely on how amount of winter snow and spring rain. There are three scenarios the commission worries about most, he said:

-- Heavy rain and snow melt in the Lake Ontario watershed early next year, which could raise the lake level faster than water could be released through the power dam.

-- Flooding along the Ottawa River, which merges with the St. Lawrence at Montreal. The river hit record levels in 2017 and again in 2109, restricting how much water the commission could release from Lake Ontario without flooding Montreal. Letting out enough water to lower Lake Ontario by 1 inch raises the level of the St. Lawrence by 11 inches.

-- A wetter-than-normal spring in the Lake Erie watershed, because that water flows faster into Lake Ontario than excess water from the upper lakes.

Flood-weary residents and business owners say they can’t take another year like 2017 and 2019. The high waters this year took a heavy toll on business, Martin said, with sales of marine fuel down 60% from 2018.

“I attribute that 100% to the higher waters and people not putting their boats in the water,” he said.

Martin said he and friends will build the higher seawall project, but it will still cost $5,000 in supplies. A contractor would charge at least $40,000, he said.

Cavallaro, a retired principal of Westhill High School, said he usually puts his boat in the water in late April or May. His dock was under water for so long in 2017 that he didn’t start boating until July 28 that year. This year it was even later: Aug. 4.

Cavallaro and Martin want to see the commission let water out faster to keep water levels lower. They say the commission’s adherence to the regulation plan known as Plan 2014 helped cause the flooding in 2017 and 2019. The plan went into effect in January 2017, about the same time record rainfalls began.

“There’s no doubt it’s controllable,” Martin said.

New York state thinks so, too. The Department of Environmental Conservation filed a lawsuit Oct. 9 against the IJC, alleging that the commission’s “sluggish” response to the high water levels of 2017 and 2019 “wrought millions of dollars in damage.”

The commission and Army corps say the flooding was caused by rain, not the plan. The Upper Great Lakes and the Ottawa River, which are not controlled by Plan 2014, hit record levels this year because of heavy spring rains and snow melt.