Three Portland organizations are suing the federal government in an attempt to stop, or at least delay, a plan to widen a 1.7-mile stretch of Interstate 5 in Northeast Portland.

A legal complaint filed Friday by advocacy group No More Freeways, environmental organization Neighbors For Clean Air, and Portland’s Eliot Neighborhood Association aims to have the project put on hold until the Oregon Department of Transportation (ODOT) conducts a rigorous study into the environmental impacts of the project—something the complaint claims ODOT failed to do in the years-long planning phase of freeway widening.

The lawsuit lists the United States Department of Transportation and the United States Federal Highway Administration as defendants, as these federal agencies gave ODOT the go-ahead last year to break ground on the project without first completing an environmental impact statement (EIS), which would have been an more in-depth alternative to the environmental assessment ODOT put forward for the plan. Some experts have cast doubt on the data ODOT used in that environmental assessment, and say it was more limited in scope than a full EIS would be.

The lawsuit claims that this failure to conduct an EIS violates the National Environmental Policy Act (NEPA), a piece of 1970 legislation which provided the groundwork for most legal environmental protections in the United States.

Under the NEPA, the complaint states, federal agencies must “analyze and disclose the environmental impact of the proposed action, any adverse environmental effects which cannot be avoided should the proposal be implemented, [and] alternatives to the proposed action.”

The federal government’s approval of the I-5 widening, the lawsuit continues, “violates NEPA because the Project is a major federal action significantly affecting the quality of the human environment.”

The I-5 widening plan, which ODOT and other proponents say is necessary to improve auto safety and fix a traffic bottleneck in Portland’s Rose Quarter, has been the subject of controversy in Portland since its inception. It’s drawn the ire of environmentalists and transportation advocates; an organization seeking to preserve Portland’s historically Black Albina neighborhood, which was already disrupted by the original I-5 construction in the 1960s; Portland Public Schools board members concerned about the environmental impact on nearby Harriet Tubman Middle School; and numerous local elected leaders who say ODOT has failed to properly weigh their concerns when shaping the plan—including Mayor Ted Wheeler and Metro Council President Lynn Peterson.

If this lawsuit is successful, ODOT will be forced to conduct an EIS before breaking ground—a process that could take years to complete.

“Transportation infrastructure projects like the original I-5 freeway have created an environmental justice catastrophe for the surrounding Albina neighborhood,” said Mary Peveto, executive director for Neighbors for Clean Air, in a press release sent Monday. “Now, instead of learning from the past and putting community voices at the center of decision-making, ODOT is not only planning an expansion based on flawed analysis, but looks to build it right at the backyard of Harriet Tubman Middle School.”

“We're eager to join this legal action,” Peveto continued, “to hold this agency accountable for the air pollution they are clearly intending to add to this already polluted neighborhood.”