A lobster boat motors across Casco Bay under a rising, haze-obscured sun in September 2017. A Maine boatyard is building the nation's first lobster boat exempt from modern clean-air rules, a boon for lobstermen but a concern for clean-air advocates. (Ben McCanna/Staff Photographer)

A Maine boatyard is building the nation’s first lobster boat exempt from modern clean-air rules thanks to a waiver program designed to offer financial relief to the state lobster fleet, but that opens the door to more diesel pollution in fast-warming New England waters.

The exempted vessel taking shape in the yard at Wesmac Custom Boats in Surry is heading south to a Massachusetts buyer, but it sets a powerful example for Maine, home to the country’s largest lobster fleet.

The U.S. Environmental Protection Agency rolled out Tier 4 diesel engine restrictions in phases, starting in 2008. Under these rules, heavy trucks, trains and ships must install advanced exhaust systems that remove smog-forming gases and fine black soot before they leave the tailpipe.

For ferries or shipping vessels, finding room for the scrubber gear is easy. But lobster boats have shallow, flat bottoms and cramped engine rooms. Limited space under the deck is used to house seawater tanks that keep high-value lobsters alive on long trips.

The Wesmac Super 46 — an extra-wide, Downeast-style vessel measuring 46 feet, 9 inches long with a 17-foot, 1-inch beam — didn’t have room under its deck for a Tier 4 exhaust system unless the live lobster tanks were removed, said Wesmac President Steve Wessel.

“The Tier 4 will simply not fit in the boat,” Wessel said.

The bulky cleanup gear required by the modern diesel engine rules generates intense heat. Boat builders say trapping that heat inside a small engine room would warm the live tanks, killing the catch before the boat ever made it back to the dock.

Only lobster boats powered by engines with more than 800 horsepower must have the scrubber systems. As climate change pushes lobsters farther offshore into cooler, deeper waters, however, fishermen need higher-horsepower engines to make the longer trips safely.

Despite multiple extensions by the U.S. Environmental Protection Agency, boatyards said they could not build new offshore boats that complied with the clean engine standards. In 2024, the EPA decided to offer waivers to those who could prove a T-4 engine would not work for them.

Many lobstermen have considered applying for a waiver but were discouraged with how much time and paperwork was involved in the process, Wessel said. But he said the EPA has been easy to work with and has been offering assistance at every turn.

Supporters say the waiver program protects maritime jobs. Without it, custom boatyards would lose business, and lobster fishermen would have no choice but to keep running the older, dirtier vessels rather than buying new ones, according to Mark Sanborn, the EPA’s regional administrator.

“Balancing it all out, this meets the administration’s goal of protecting the environment and human health while also being reasonable and realistic in terms of supporting industry,” said Sanborn, the former deputy commissioner of New Hampshire’s state environmental agency.

Sanborn is promoting the waiver program as a “blueprint” for other Maine boatbuilders and lobstermen who have been vocal advocates for this flexibility. The agency has launched a new website to guide applicants through the case-by-case review process.

When the waiver program was first rolled out, the EPA estimated that no more than 92 pilot, lobster or law enforcement vessels would be eligible for the exemption over the course of the program’s lifespan through 2035.

Environmental advocates, however, view the decision with alarm. The older model engines that can be allowed by the waiver release up to 80% more nitrogen oxides and almost double the amount of soot compared to new cleaner models.

Nitrogen oxides are the primary ingredient in ground-level smog, which triggers asthma and air quality warnings along the coast. Exhaust fumes settle into the ocean, adding excess nitrogen to coastal waters that can fuel toxic algae blooms and speed up ocean acidification.

Ocean acidification can make it harder for shell-building creatures like young lobsters to survive.

By using Tier 3 engines instead of Tier 4 models, the EPA calculated at the outset of the waiver program that exempted boats will miss out on cutting about 3,764 tons of nitrogen oxide and 79 tons of soot over the lifespan of the engines.

Even if all the exempted boats were based in Maine, however, they’d represent just 0.4% of the state’s smog-forming emissions and 0.1% of its soot, according to the EPA. The emissions would be released 40 miles out at sea, where the winds often blow away from the populated coastal areas.

But it wouldn’t help the fast-warming Gulf of Maine, environmental groups say. Although the warming rate has slowed, climate change is still heating up the gulf faster than most ocean bodies.

Critics say giving high-powered boats a pass on air pollution undermines Maine’s climate goals.

Clean-air groups argue that granting one waiver makes it easy for other fishermen to claim they need relief, too. If waivers become routine, engine manufacturers will have little reason to spend money designing smaller, cooler models with scrubber systems that actually fit on lobster boats.

Lobstermen are the backbone of Maine coastal communities, and it makes sense that they want stronger engines to chase lobster into cold offshore waters, said Meredith Moore, senior director of Ocean Conservancy‘s fish conservation program.

“This is a missed opportunity to provide cleaner engine alternatives, rather than lock in a new generation of boats using old, dirty engines,” Moore said. “Maine coastal businesses are already leaders in electrifying boat engines, and we should lean into that innovation.”

Moore said the T-4 waivers prove how little is being done to address the impacts on our fisheries. Until the U.S. starts managing fisheries with climate change in mind, fishermen will be pushed to the brink to keep supporting their families, she said.

The EPA insists the program will remain limited, reviewing requests one boat at a time.

Wessel said Friday he’s heard the EPA is going to roll back the T-4 rules for everyone, from heavy trucks to fishing boats. The EPA didn’t respond to questions about the future of the T-4 rule.

For now, the hull under construction in Surry — which won’t be finished until next year — represents a relief valve for a multimillion-dollar fishing industry trying to adapt to changing waters and a rollback of clean air standards put in place to protect the sea where they fish.