Above: A map of the proposed bridge and tunnel through the Chain of Lakes area. The orange indicates the tunnel, while yellow shows the bridge. The map is approximately 90 degrees clockwise from normal north-south alignment.

Updated at 7:32 p.m.

A local group has so far made compelling arguments that the Metropolitan Council acted too quickly securing Southwest light rail approvals without proper environmental reviews, a federal judge ruled Friday.

Judge John Tunheim agreed to allow core components of the Lakes and Parks Alliance’s lawsuit against the Met Council proceed in federal court, setting up a weighty hearing on the case Monday afternoon. He simultaneously dismissed the group’s claims against the Federal Transit Administration.

The lawsuit argues the Met Council violated federal and state laws by securing municipal consent from cities along the 16-mile route before the completing a study on the environmental impacts of a new tunnel plan. That tunnel in the Chain of Lakes was added late in the project to accomodate trains and recreational trails at a pinch point, after plans to reroute freight rail to St. Louis Park were abandoned.

Tunheim said the lack of an updated environmental review “would seem to give cities less than they need to provide informed municipal consent.” He also agreed to hear further arguments that the approval process violated federal law by, in effect, limiting alternatives before the environmental analysis was complete.

“The [Lakes and Parks Alliance] has made significant allegations regarding the Met Council’s actions; namely that the Council has led a municipal consent process and spearheaded negotiations with specific cities, and has for all intents and purposes dramatically reduced the number of realistically available routes for the SWLRT, despite the FTA and Met Council’s continued environmental review,” Tunheim wrote of the federal law.

He cautioned, however, that the Friday ruling was merely a determination that the court will hear the claims — not a judgment on the outcome of the case.

The decision is nonetheless a blow to the project just one week after the Met Council struck a deal with the Minneapolis Park and Recreation Board, whose opposition to a bridge directly north of the tunnel also threatened to hold up the project. Met Council spokeswoman Laura Baenen declined to comment on the ruling Friday afternoon.

Representatives of the Lakes and Parks Alliance could not be reached for comment.

The proposed Southwest line would run from downtown Minneapolis to Eden Prairie, costing about $1.6 billion. It is expected to open for service at the end of 2019.

The lawsuit is steeped in the timeline of Southwest approvals and route changes, which are crucial to determining whether the Met Council is at fault.

The original draft environmental review, completed in 2012, examined three methods for accomodating light rail through tight spots in the Kenilworth corridor: moving freight rail to St. Louis Park, moving freight rail and sending light rail down the Midtown Corridor, or “co-locating” both trains alongside recreational traffic.

The review concluded that co-location would “not adquately preserve the environment and protect the quality of life in the area,” according to Tunheim’s opinion. But a subsequent review by the U.S. Army Corps of Engineers also concluded that re-locating freight rail — an option opposed by many St. Louis Park residents — was not feasible.

The Met Council later approved a plan for co-location with two light rail tunnels on either side of a new bridge, in order to handle all three modes of traffic through the narrow corridor. The north tunnel was then eliminated as part of an agreement with the city of Minneapolis, allowing for an extra station at 21st Street.

The Met Council is currently working on the supplemental environmental report. Despite a February statement that it would be released in the second quarter or 2015, Baenen declined Friday to say approximately when it will be released.

The full order is below:

Tunheim Order