SEARSPORT, Maine — A group of concerned environmental activists took a tour Tuesday afternoon through a piece of Maine’s industrial past — the Penobscot Bay shoreline near a factory that has been producing chemicals for almost 100 years.

Ron Huber, the executive director of Friends of Penobscot Bay, told a crowd of about 20 people who had gathered for a tour and press conference near GAC Chemical Corp. in Searsport that he was concerned about pollution due to past practices that may have left toxins leaching into the bay.

“Because earlier companies on the site in the 20th century thoughtlessly dumped hundreds of tons of industrial wastes on the shore, GAC Chemical’s property is today eroding and leaking these wastes into Penobscot Bay,” Huber said. “This has got to stop.”

However, Jessamine Logan of the Maine Department of Environmental Protection said Tuesday that GAC Chemical Corp. is in compliance with her agency and that the corporation’s permits and licenses are all current.

“It is a priority, to make sure that people are following what we license them to do, and [make sure they are] following environmental law and regulations,” she said.

David Colter of GAC Chemical Corp., who recently was named the company’s CEO by founder James Poure, was out of the office Tuesday but issued a general response to Huber’s current concerns earlier this week in a press release. He said that the company engages in monthly and annual monitoring and reporting and believes it is in compliance with all Maine DEP and U.S. Environmental Protection Agency regulations.

“Our closed-loop operations, ongoing monitoring and evaluation of our waterfront by environmental experts document our operations are not having a detrimental impact on the adjacent harbor,” Colter wrote. “This is further supported by the water quality testing performed by the Department of Marine Resources. The clam flats adjacent to GAC are open and active.”

The site, and the company, have a history of infractions.

In 1998, a state marine biologist found that remediating a discolored clam flat abutting the chemical company, which was then called General Alum & Chemical Corp., would cause more harm than allowing the beach’s natural processes to restore the area, according to BDN archives. The cream-colored sediment found throughout the flat was believed to have originated from erosion of nearby banks, which contain traces of bauxite, an ore once used for chemical processes at the plant.

Then in 2002, the Conservation Law Foundation reached a settlement with GAC Chemical Corp. after the environmental advocacy organization filed a federal Clean Water Act lawsuit against the company in U.S. District Court in Bangor. According to the settlement, GAC contributed $20,000 to a study of the decline of Stockton Harbor and began complying with federal wastewater discharge rules, according to previously published reports in the BDN. The suit alleged a long history of water pollution at the facility, including a serious spill of sulfuric acid in April 2001 and discharges of acid wastewater into the harbor.

On Tuesday, Huber said he has doubts about the health of the clam flats. He had two young interns from Searsport Shores Ocean Campground, located south of the chemical plant, come forward to describe what they found while clamming in the adjacent area. Justin Kirkland of Simi Valley, Calif., and Stephanie Alley of Brewer said that the clams they dug on the south side of the Sears Island causeway were more abundant and healthier-looking. But to the north of the causeway, closer to GAC Chemical Corp., the clams were more sparse and located in flats that seemed “muckier and filmier,” the duo said.

“It’s just gross,” Alley said of those flats.

After the short bivalve show-and-tell, Huber and the environmental group’s president, Harlan McLaughlin, led the group along the cobble beach and mudflats to a section of shore right in front of the factory. They pointed out small yellow chunks in the rocks that they said were pieces of sulphur leftover from the production of chemicals including aluminum sulfate. Huber showed the long pipe that once led from the factory directly into Stockton Springs Harbor. He also led the group to hillsides near the plant that appear to be crumbling into the shorefront.

“Basically, eroding things into the bay is not good. You’re not supposed to do that,” Huber said, taking pains to point out that the company’s current practices do not appear to be environmentally troubling.

He called upon Colter to take an active role in doing some more remediation efforts such as building a berm and planting vegetation to prevent percolating old waste from running off into the harbor.

“We think they can remediate the problems without us taking them to court and make them out to be bad guys,” he said. “As far as the community goes, they’re a good company. They hire a lot of people and keep their noses clean.”

Maryjane Crowe of Belfast, who worried whether walking on the shoreline would be dangerous if, as Huber said, there were toxins present, wants the company to clean up the problems of the past.

“I think that we live in a beautiful place, and the ocean is worth protecting,” she said. “We did bad stuff. But now, it’s a new day — clean it up!”