Thousands of drivers from Kirkland and other Eastside locations could be affected by a lawsuit filed in federal court in Seattle.

But the filing also could become just one more level of dispute in questions about the Evergreen Point Floating Bridge that date back more than 40 years.

The new filing is a complaint brought by the Coalition for a Sustainable 520, a Seattle-based community organization that’s questioning the building of a new Highway 520 route, which includes the floating bridge.

The filing was made Sept. 2, the last possible day to bring such an action, said David Bricklin, attorney for the coalition.

“They kind of forced our hand,” said Bricklin. “The deadline was the day we filed it.”

The lawsuit argues that an environmental-impact statement prepared for the 520 project was inadequate and had several failures, including not considering alternatives and not properly considering adverse environmental impacts.

Defendants include the United States Department of Transportation through the Federal Highway Administration and the state Department of Transportation. The defendants have 60 days to respond to the filing and no replies have been made to the arguments.

No trial date has been set, and Bricklin estimates it could be six to nine months before the matter comes before a judge.

At the same time, Bricklin also acknowledged the entire matter may be moot.

“They don’t have enough money to build it anyway,” he said.

Bricklin pointed out that a number of factors could affect bridge construction long before the lawsuit reaches a trial stage, including the successful implemention of tolls, now expected to begin in December, and the outcome of a November ballot measure, Initiative 1125, which could curtail tolls.

Bricklin said one possible outcome for the lawsuit is that it could “be put on hold” until funding questions are resolved.

The 520 bridge opened in 1963 and as early as 1970 the state was considering options to increase its capacity. A Translake Study Committee met during the 1990s and considered dozens of options, including a tunnel under, or a suspension bridge over, Lake Washington.

The final decision, which is now proceeding forward, was to replace the present bridge with a six-lane tolled configuration. The state estimates the project cost at $4.65 billion, with some $2.62 billion in funding received so far, and with a planned opening in 2014.

More than 100,000 vehicles use the route between Seattle and the Eastside daily.