The city recently adopted new federal flood maps for first time since 1990. Flood lines exist primarily for flood insurance, and the new maps mostly brought them closer to the coast, dropping the high water mark from 16 feet to 13 feet near the waterline, and to as low as 11 feet in the rest of the flood zone.

At the same time, those who work on the waterfront are reporting more regular flooding, near misses and general uncertainty about how to prepare for changes in the weather and water.

Belfast Harbormaster Katherine Pickering said high tides approaching 13 feet are more frequent now than in years past. Additionally, she said, "weird storms" like the bomb cyclones that have hit the Midcoast several times this winter, are happening more often. When these extreme weather events coincide with high tides, she said, the potential for damage is significant — but it's often hard to know in advance how things will play out.

This past weekend, tides in Belfast reached 12.9 feet, which brought some water into the parking lot near the public landing, but Pickering said the flooding didn't result in much damage, in part because winds were coming from the north, where Belfast Harbor is relatively protected.

"If the winds had been out of the east, this building would have been damaged," she said, referring to her office, a two-room building at the foot of Main Street. The office lies within the floodplain, and to conform with flood zoning, it is classified as a temporary structure. Pickering said the very high tides that used to come twice a year are coming every couple months.

"We were lucky with that last one," Pickering said, "but it's a matter of time. You look at the high tides and the number of weird storms coming up the coast."

A city councilor recently visited the harbormaster's office and recommended raising the building up on stilts to avoid damage from a future storm.

The combination of forces that leads to the worst floods isn't always predictable. An Oct. 30 storm that pulled boats off their moorings and caused flooding along the waterfront happened during a stretch of relatively low high tides of less than 10 feet, according to U.S. Harbors.

Oddly, one of the more flood-prone properties, Marshall Wharf Brewing Co., escaped that storm with relatively little damage. David Carlson, co-owner of the business said the 19th-century grain storage building that houses the brewery had six inches of water on the floor, but the business remained open through the afternoon with workers ferrying beer to customers on higher ground just outside the door.

Carlson said a few inches of water is not uncommon, but knowing how much to expect in any given storm isn't easy. Weather systems can hold in a tide causing a surge when the next one comes, he said; winds, rainfall and spring thaw and other factors play into the tide level. In response, he keeps a close eye on tide charts and stays up nights when the forecast looks dicey.

"When the tide hits 13 feet, that's kinda like flood height for us," he said. "We've definitely dodged a bullet with systems that have gone out to sea, or when the tides cooperated."

Asked if the weather events are worse now, Carlson hesitated. They might not be worse, he said, but they are more frequent.

In 2007, when Carlson and his wife bought the building, neighbors talked about storms that brought flood waters as high as the railroad tracks — now the Harbor Walk promenade on the upland side of the brewery. A stake in the side of the brewery that has since disappeared reputedly indicated the 100-year high-water mark.

Despite these maybe-apocryphal warnings, a December 2009 storm that flooded the first floor of the brewery with 24 inches of water took the new business owners by surprise. Carlson said it was a wake-up call. The business was closed for four months while they raised electrical outlets and other utilities out of the danger zone.

That was the first of three storms to warrant a claim with Montana-based National Flood Services. The most recent was this year, during the Jan. 4 blizzard, he said, and it was the worst to date. The ground floor of the building, which tilts down toward the harbor, was submerged in 30 inches of water at its deepest point.

Carlson is working with an engineering firm to build a seawall for the old brewery building, which now sits on cribbing that is more than 150 years old. The most recent storm is returning some money to help with the renovations, but Carlson said the work has the eager backing of his bank.

"They recognize that if the building fails, they lose their asset," he said.

Nautilus Restaurant sits directly between the brewery and harbormaster's office. And while it doesn't appear to be much higher than either building, co-owner Roz Peters said the business has yet to flood. In the two-plus years since the business moved in, staff members have watched untethered objects float around the parking lot during big storms, but the water has always remained outside, she said. Peters said she wasn't exactly sure why, but she credited good luck, possibly with some help from the pilings that support the building.

"I think it's just the way our foundation is," she said. "The water gets around us. We're just high enough, thankfully. It's all very exciting when it happens, though."

Under the revised flood maps, Nautilus lies within a newly created "low to moderate wave action" area of the flood zone. The building predates federal flood maps and is grandfathered. But if renovations were made to the building equaling 50 percent of the total value within a five-year period, the flood zoning would be triggered and the building would have to come into compliance with current rules.

City Planner Wayne Marshall said the new flood maps are a boon for new developments near the waterfront. He gave the example of the 29,000-square-foot Building 6, planned for construction at Front Street Shipyard. Unlike its older and slightly smaller neighbor, Building 5, which was constructed when the flood lines were higher and includes louvers in the walls to let flood waters pass through, Building 6 will be raised out of the revised flood zone on an 18-inch-high foundation.

Marshall was quick to note that the flood lines aren't binding.

"When you have natural disasters occur," he said, then paused to revise his phrasing. "We'll leave the word 'natural' out of it. Even though you're not in the flood zone, doesn't mean you're not going to experience a flood."