A proposed extension of a multi-use trail at Sleeping Bear Dunes National Lakeshore in Michigan is raising concerns even before the design work is finished.

The Grand Portage Band of Ottawa and Chippewa Indians, the Leelanau County's Cleveland Township Board of Trustees, and the National Parks Conservation Association all have concerns with the cost to the environment the segment's construction would inflict.

As envisioned by the Park Service more than a decade ago, the Sleeping Bear Heritage Trail would be a "hard-surfaced, multi-use trail paralleling state highways M-22 and M-109 for 27 miles through the Lakeshore. It will provide a safe, non-motorized, multi-use transportation alternative connecting the lakeshore’s main visitor destinations with the neighboring communities of Glen Arbor and Empire."

Twenty-two miles of the trail have been finished. The 4-mile extension now being planned, called Segment 9, would require a significant construction footprint, according to opponents.

Back in the spring, NPCA submitted comments to the Park Service on the plan, saying that "under the current alternative, the trail will need to be constructed in the State of Michigan’s regulated critical dunes requiring a 15-foot retaining wall, extensive boardwalks through wetlands, reduction of canopy cover and habitat through the removal of 7,300 trees some culturally significant to the Odawa. A trail within this area would exacerbate impacts to forest diversity and water quality."

The Grand Portage Band wrote Interior Secretary Deb Haaland and Michigan's two U.S. senators to voice concerns over the segment's "potential impacts on wetlands, tree removal, and the treaty gathering rights of our tribal members." And the Cleveland Township withdrew its support of the project, citing concerns over impacts to dunes in the lakeshore and cost estimates showing the project could reach $15 million.

Sleeping Bear Dunes Superintendent Scott Tucker, however, said the route and cost of the extension have not been finalized.

"There's a lot of speculation of what the trail is going to be, how it's going to be built, the materials and the alignment and all of that," Tucker said this week during a phone call. "The design right now is at about 40 percent and so there's a lot of speculation of what it's going to be. My position is we have a contract in place that's going to tell us what their recommendation is, and then that design has to meet National Park Service standards, federal regulations. ... and it has to be fiscally responsible."

At the present time, he added, there's not a completed design that can accurately be discussed.

The superintendent did say the trail would involve retaining walls and that it would "go through areas of the park that have not been developed. It's the continuation of a 20-mile trail that was built very specific and intentional to resource protection [and], at the same time, provide access to everyone to this amazing park."

Once the design work is completed, the superintendent said he intends to meet with the Grand Portage Band.

"I'm going to go visit with the Grand Traverse Band tribal council, the tribal chair, and talk through any concerns they may have with the final piece of the puzzle," he said.