SEATTLE — The coal industry, shaken by dropping global demand and tighter air quality regulations, took another major hit on Monday when the United States Army Corps of Engineers said it would deny the permit for what could have been nation’s largest coal export terminal here in Washington.

The $665 million project, called the Gateway Pacific Terminal, was already hitting headwinds. The developer asked last month that the state environmental review on the project be delayed, citing “uncertainty and related costs.” And one of the largest potential suppliers of coal, Peabody Energy, filed for bankruptcy protection last month.

But in the end, the decision came down to fish.

The Lummi Nation of American Indians had said the terminal, about 90 miles north of Seattle, would threaten the tribe’s ancestral fishing rights, which are legally protected by treaties dating to the mid-1800s. Spills or maritime accidents, the tribe said, could permanently destroy fishing beds.

In its decision, the corps agreed, saying the developer’s plan to extend docks across 144 acres over the water could have restricted access to the water by the tribe. That concern was enough to stop the terminal, corps officials said, without even considering potential environmental harm.