The Park Board has decided to spend $500,000 to hire an engineer to help make a legal case against a light-rail crossing at the Kenilworth channel in south Minneapolis.

Park officials want to explore a potentially more costly option to route the proposed Southwest rail transit line under the languid channel that connects Cedar Lake and Lake of the Isles.

The current plan would put the rail line over the channel, which is populated by giant snapping turtles.

Park Superintendent Jayne Miller and board President Liz Wielinski met Wednesday with Metropolitan Council officials to discuss their tunneling option.

Later that afternoon, Wielinski said, the Metro Council sent an e-mail saying it had no intention of pursuing the board's tunnel proposal.

The council said in a statement it has been "working with the Park Board for the last two years and is committed to continuing to work with them on the landscape design of the Kenilworth corridor, the design of the bridge over the channel and the design of the Penn, 21st and West Lake Stations."

That night, the Park Board voted to pull $500,000 out of its reserves to conduct an engineering analysis of the tunnel option.

Park officials have been girding for a clash for about two years.

In late August, the Minneapolis City Council gave a crucial final approval for the rail line. Two weeks later, the Park Board voted to hire outside legal help for $22,000 to evaluate its options for fighting the proposed crossing.

Park Board attorney Byron Starns advised the board to do the tunnel analysis before an environmental review is released early in 2015. The board then potentially could go to court to argue that there is a feasible and prudent alternative to the bridge.

The decision to spend up to $500,000 for the analysis comes with plenty of risk. That amount is almost 1 percent of the annual parks operating budget and is more than one-third of next year's projected budget shortfall.

The plan did not require Park Board approval, and the board has not had much success in other fights with transportation agencies.

The board lost in 1995 when it sued to try to keep the Minnesota Department of Transportation from widening the Interstate 35W bridges over Minnehaha Creek, the adjoining parkway and recreational paths.

At the Kenilworth crossing, the Park Board obtained an easement from a railroad to dredge the channel connecting the two lakes.

The Park Board could be able to utilize a federal law that gives it considerable clout when a federally funded transportation project affects parkland. That law bars such projects from taking parkland unless there's no "feasible and prudent" alternative.

It also requires all planning to minimize the harm of a project on parks.

That protection was not yet in place when the Park Board lost a court bid in the 1960s to force a proposed freeway to cross Minnehaha Creek west of the main park. But the court fight prompted negotiations that produced the above-ground tunnel that now carries Hwy. 55 and the Blue Line.

The Park Board also opposes the current proposal to build side-by-side bridges over the channel 9 feet apart, one for freight, and one for transit and recreation.

More than a year ago, park officials opposed an alternative of spending an extra $160 million for shallow tunnels on either side of a bridged crossing of the channel in favor of a deeper tunnel that would be far more expensive.

One of the shallow tunnels has since been dropped, leaving a shorter 2,200-foot tunnel south of the channel. That tunnel adds $100 million to project costs, project officials said Thursday. Extending it to run under the channel would cost $75 million and the delay would increase the overall project cost by another $50 million to $55 million, they said.

Steve Brandt • 612-673-4438

Twitter: @brandtstrib