A short stretch up the Mystic River from Boston Harbor, an oil transfer and storage station operated by ExxonMobil sits at the verge of a high-tide mark that is plainly visible along the blackened shoreline.

That terminal in Everett, Mass., according to the Conservation Law Foundation, routinely violates the legal limits of the company's federal operating permits, usually because of stormy weather. What's more, the New England advocacy group says, the company is knowingly putting local people at risk in the face of imminent climate risks that could someday wash the Everett terminal away—storage tanks, impoundments, oil stockpiles, rickety docks, contaminated soils and all.

The CLF and a coalition of local green groups contend that the company has understood for years the global risks posed to its business and to the public by climate change. Even so, it has failed to fortify this soft local underbelly of a sprawling oil distribution network against increasingly likely inundation from rising tides and intensifying rains.

On Tuesday, the CLF took the first legal step toward lodging a civil complaint against Exxon in federal court, a move that introduces a new twist into the company's escalating legal battles over climate change.

The complaint, to be filed under clean water and hazardous waste statutes, will say that if Exxon knew about rising climate risks to installations like Everett, it was legally bound to take protective steps—but has not done so.

"ExxonMobil knowingly and unlawfully misled regulators about whether its Everett facility can withstand rising seas, more intense precipitation, and other climate impacts without spewing oil and other toxic pollutants into adjoining neighborhoods, the Mystic River, and the Boston Harbor," said Brad Campbell, president of CLF. "Today's lawsuit—the first of its kind—aims to hold ExxonMobil accountable for decades of dishonesty and require that the Everett facility meet the legal standards for climate-readiness."

Exxon did not respond to a request for comment. It has repeatedly said that it considers legal actions based on its early understanding of the emerging science of climate change, a history described in a series of articles by InsideClimate News last year, to be the product of a conspiracy driven by advocacy organizations.

The CLF's approach, which it said was sparked by ICN's reports, is unlike investigations by the attorneys general of Massachusetts, New York and the Virgin Islands, among others, which are probing whether Exxon misled investors or the public about climate risks. Those have produced subpoenas, but have not leveled any specific charges.

This lawsuit, brought by outside parties including citizens who say they are being put at risk by the company's negligence, will ask the federal court in Boston to find that Exxon has not lived up to its legal obligations to protect a local community against a very specific and perhaps even imminent danger.

The CLF is bringing suit on behalf of the Mystic River Watershed Association and a coalition of local advocacy groups from communities that are among the Boston area's least prosperous and most heavily impacted by industrial pollution.

They claim that even in routine rainstorms the wastewater impoundments at the site have allowed pollution to spill into the Mystic and its tributaries, and that under the effects of climate change the situation is bound to worsen and invites calamity. Already, they say, there have been narrow escapes when the timing of powerful storms and high tides just missed a worst-case outcome.

"The first significant storm surge that makes landfall at the Everett Terminal at or near high tide is going to further flush your hazardous and solid waste into the Island End and Mystic Rivers and through those communities, and a significant rise in sea level will put the majority of the Everett Terminal, including soils, groundwater, and treatment works, under water," contended a letter delivered to Exxon by the plaintiffs on Tuesday, a legally required shot across the bow required a few months before a lawsuit may be filed. "You know all this, and yet have not taken appropriate steps to protect the public and the environment from this certain risk."

That is the novelty of this litigation: It connects the big picture of Exxon's record on the science of climate change to the local damages that the plaintiffs say they will incur.

"Your obfuscation and denial is not and has not been limited to the imminent and substantial endangerment to health or the environment you have created at theEverett Terminal," the letter from CLF to Exxon states. "You have also engaged in a decades-long scheme to conceal and sow doubt regarding the effects of climate change and your role, as the largest oil refiner on the planet, causing the anthropogenic climate change that is resulting in a greater frequency of storm surges and extreme weather events and rising sea levels."