A pedestrian navigates Portland Pier in the wake of a flooding event. (Courtesy GMRI)
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Spring in Portland is a cherished thing, when 50-degree days in March, though often a false positive, serve as hope for the upcoming warm months.

But with warmer months and melting snow comes an added, though often overlooked, challenge: oceanic impacts, most notably rising sea level.

Though not a problem unique to any coastal city, the rising sea level in Portland and southern Maine continues to be problematic for wildlife, for the economy, and for infrastructure.

Experts say it’s not necessarily the number of storms that present the biggest issue, but instead, the vulnerability created by higher tides. While flooded streets might seem like the result of storms, that’s not always the case. These so-called nuisance floods are a sign of rising sea levels, which leave the city vulnerable to worse flooding if there is a major storm. 

High-water events like this on Somerset Street in Portland’s Bayside neighborhood are viewed by experts as troubling signs of increased coastal flooding. (Courtesy GMRI)

Flooded streets are one of the most quantifiable components of rising sea levels. According to one expert, Peter Slovinsky of the Maine Geological Survey, in the 10 years from 2010 to 2020, the number of hours the city experienced flood-prone streets rose dramatically over the prior average. 

While the average going back over 100 years is under four hours of nuisance flooding annually, during the last decade that number jumped to 13.5 hours. Additionally, with just an additional foot of sea rise, it skyrockets to 142 hours per year. 

Gayle Bowness, manager of Sea Level Rise programming at the Gulf of Maine Research Institute in Portland, said her organization has turned to the public for more help in documenting evidence of rising sea levels. This is in addition to partnering with local municipalities, including Portland and South Portland on their One Climate Future sustainability plan.

That plan, approved by both municipalities, calls for the cities to transition to 100 percent renewable energy for municipal operations by 2040 and reduce greenhouse gas emissions by 80 percent by 2050.

At a statewide level, Bowness said, there is data from the Maine Geological Survey that can be used to make generalizations about sea-level rise. What is lacking is localized data on these impacts, which led to the partnerships.

“We identify and work with communities to identify vulnerable areas, and get people to make those observations and line them up,” Bowness said.

GMRI launched a pilot program in Belfast last September, which has since been expanded to Portland and South Portland, and Vinalhaven, where citizens are asked to upload flood information about coastal areas. Bowness said this doesn’t ask people to wade out into the waters of a storm, but to be on the lookout for obvious signs of flooding and high water, like coastal erosion and seaweed strands higher than usual.

“It’s not just photographic evidence, but we’re looking to get people’s thoughts on how does flooding in that area impact them personally,” she said.

While there’s no timeline on this citizen observation program, Bowness said it will begin in the spring, which is when higher tides are expected. She said an important aspect of the project is to give GMRI more detailed information on these events and to make people more aware and concerned.

“If we’re not aware we’re not going to invest our tax dollars,” she said. “It will be costly to change, and people are resistant to change, so how do we shift the conversation?”

Bowness said as more recognition is given to rising sea levels and these events, the easier it will be to move towards a solution.

“Right now, say we have a year without too many storms,” she said. “We might have 10 to 12 high-water or nuisance flooding events, and they might even happen at night when no one sees them. So right now, it’s just a nuisance, but with 12 extra inches of sea-level rise, we’ll see events like this up to 100 times a year. It becomes a major problem.”

Volunteer approach

GMRI isn’t the only group turning to the public for help in documenting rising seas.

Sarah Lyman, the community engagement coordinator with the nonprofit organization Friends of Casco Bay, said her organization relies on hundreds of volunteers to document evidence of sea-level rise in the area. The program, known as Water Reporters, has been in effect since summer 2018 and has had approximately 250 volunteers contribute more than 1,500 images to a database.

Lyman said the importance of this volunteer program is threefold. First, it increases awareness of various environmental issues, especially for people who may be new to exploring Casco Bay or are looking for reasons to get out into nature.

Second, she said it brings attention to evidence of sea-level rise and other issues that Friends of Casco Bay staff might not be aware of. “The bay is big, and we can’t be aware of everything,” she said.

Finally, Lyman said, it allows the organization to compare images of areas over time and see what the impacts have been. For example, she said, even in just a few years, a popular area like Willard Beach may start to look different.

“Sea-level rise is the thing that gets our attention the most,” Lyman said. “When you see it, it is impactful and it sticks with you.”

Lyman said Water Reporters are also on the lookout for evidence of impacts from several other things: wildlife, trash, erosion, and eelgrass, and to report pollution.

“We feel really supported by the community that they want to take part in this way,” she said. “It just helps us so much to have all of this information coming in.”

‘This is occurring now’

While the Water Reporters and the GMRI citizen coastal flooding study are concerned with the more obvious impacts of sea-level rise, Mike Doan is concerned with the less obvious warning signs.

“It’s not just the stuff you notice,” Doan, a staff scientist with the Friends of Casco Bay,  said. “With increased precipitation, we’re seeing more storms, we’re seeing more nutrients run off (into the Bay). It gets into the water, which leads to reduced water quality.”

Doan said there are “concerns everywhere” about sea-level rise, although it’s hard to always figure out the impetus, from the precipitation and storm frequency to increased temperatures.

“Everything works together to bring about these nuisance flood tides we’re seeing more and more of,” he said.

Doan’s work focuses on the impacts the rising sea level can have on the region, often on less obvious things than erosion. For example, he studies how wildlife is impacted by the effect sea-level rise has on marsh grass, which tends to grow above the water, and eelgrass, which is submerged.

“Both are important habitats,” Doan said. “They prevent things from getting into the water, clean it for lack of a better term, and reduce the amount of nitrogen in the water. These are two types of habitats we can’t afford to lose.”

The nuisance flooding that Doan and Bowness identified, the worst of which can often be seen around the piers on Commercial Street, on Marginal Way, or in the Bayside neighborhood, might seem like just that: a nuisance. But Bowness said these floods can be damaging to people’s cars and the infrastructure because it is backed up ocean water making its way into the city.

“Essentially it just looks like a large puddle, but it’s saltwater,” Bowness said. “On Marginal Way that can be up to a foot deep.”

She said Commercial Street, where the piers and wharf are, are also notorious culprits for water coming up and flooding the infrastructure. 

Doan said there’s also an economic and ecological impact for the amount of beach habitat the region stands to lose, which not only threatens wildlife but sweeps bacteria into the bay through runoff after storms.

“There are more intense and frequent storms,” he said. “It’s all part of the same picture, it’s all reducing water quality.”

Doan said there are some obvious examples, like green algae blooms that appear in Casco Bay, that you can point to as evidence of sea-level rise. He said the most important thing his organization can do is raise awareness.

“This is occurring now, we’re in this,” he said. “We’re not looking at what might happen in 50 years, we’re dealing with impacts of climate change and sea-level rise now. The rate of those changes is only getting worse. It’s important to be able to do something about it now.”

‘We have our work cut out for us’

Sea-level rise is often one of the many symptoms cited for climate change, along with increased temperatures, prolonged droughts, extreme heat that threatens agriculture, and prominent natural features being put at risk.

That was part of the reason Portland and South Portland created the One Climate Future plan.

Troy Moon, Portland’s sustainability director, said the plan aims to sharply reduce both cities’ carbon footprints over the next 30 years, and transition to total renewable energy dependence.

Moon said part of the plan involved a vulnerability assessment for expected sea-level rise, which indicated an “intermediate scenario” where sea levels will rise almost 2 feet by 2050, and 4 feet by the year 2100.

“We need to be conscious,” he said. “More extreme scenarios could bring over 10 feet of sea-level rise by 2100 if globally we aren’t taking care of our emissions.”

That 2-foot rise doesn’t mean Commercial Street, which often sees the most visible flooding moments, will be totally underwater. But he said it does mean it will be more vulnerable if a high-level storm moves through.

“We have our work cut out for us,” Moon said.

He said Portland is lucky that the city is somewhat elevated, but said the vulnerable places are the ones that have the most obvious flooding impacts: Marginal Way, Commercial Street, and parts of the Bayside neighborhood. And if the city doesn’t take appropriate steps to combat climate change, he added, rising sea levels could also impact East Deering.

Moon said the city’s Public Works Department routinely keeps an eye out for nuisance floods and often puts up barricades in anticipation of a storm to keep drivers out of areas prone to flooded areas.

But in addition to cars being damaged by driving through saltwater, Moon said seawater that comes back through the city’s drain systems and creates floods can damage those systems. Part of One Climate Future addresses infrastructure concerns, he said, since those sewer systems are vulnerable to flooding.

“We don’t want to see our streets underwater,” he said. “It doesn’t do any good to be flooded.”