Visitors to the Mississippi River in northeast Minneapolis may one day be able to stroll two footbridges from a new riverside park to an island under Plymouth Avenue and along a boardwalk through habitat for migrating birds and other animals, if river boosters get their way.

But the island doesn't exist, and creating it by 2020 comes with a cost: almost $25 million to sculpt the island and adjoining park. That's including the price of buying the land and other costs to date, but not $14 million more for park buildings. About $10 million has been spent so far.

"It's expensive," one lobbyist for the Minneapolis Park and Recreation Board admitted to state senators who toured the site last week. The Park Board is asking for $12 million in state bonding for the project, one of its largest requests ever.

It's also complicated. The board hasn't yet applied for permits that will be reviewed by multiple agencies that regulate the river. One of them, the state Department of Natural Resources (DNR), warned in early 2013 that state rules prohibit filling waters to create upland areas like islands.

But area legislators got a law passed directing the DNR to issue a state permit, the second time that lawmakers have passed special legislation to help the project. However, lawmakers lack similar power to direct U.S. Army Corps of Engineers, which will decide on issuing permits after reviewing navigational and environmental impacts.

Proponents of the island, such as lobbyist Brian Rice, who will seek the bonding imply that the state owes the project a favor. That's because a predecessor to the DNR granted a permit in the 1960s that allowed the Scherer Bros. Lumber Co. to erase what was known as Hall's Island offshore from its yard. Portions of the island were dredged to fill a channel between the shore and island so that the firm could install a barge wharf.

"They were the ones that caused the problem. We're just undoing the desecration they did 50 years earlier," Rice said of the state.

Reshaping the riverfront

The project is a major bridgehead in the drive by the Park Board and the city to reshape the upper river over several decades. The Park Board bought the 10-acre Scherer Bros. site in 2010 for $7.7 million, largely obtained from the state, with plans to create a park.

The proposed island would be 4.4 acres in size, the equivalent of four football fields but long and skinny. A boardwalk would run down its spine for wildlife observation. Engineers are modeling designs for a shape that allows the island to withstand flooding and the erosive power of the river, while minimizing the silting of the new channel. The upstream end would be armored with boulders and plants, while a bioengineered shore that relies more on vegetation would surround the rest of the island.

The island would front a gravel beach on the mainland that's intended primarily for launching kayaks and other human-powered craft, a complement to the launch for bigger craft on Boom Island just downstream. The site would also have buildings that might house a cafe or kayak rental and storage space.

The project has evolved in response to regulatory pressures. Originally, the DNR noted, the island was intended for recreation and scenic purposes, but was revamped toward habitat because that's a possible exception to rules prohibiting filling state waters. However, DNR biologists in 2013 opined that "any habitat benefits would be inconsequential." That's when legislators mandated the agency issue a permit.

But Sen. LeRoy Stumpf, DFL-Plummer, chairman of the Senate's bonding committee, noted during the tour this week that in his northwestern Minnesota district such a project might be considered filling wetlands. Although project backers suggest that the agency has relaxed its skepticism, Julie Ekman, a DNR manager, said she's not aware of any change.

Habitat vs. recreation

But it may be tricky to attract wildlife when park officials also have sold the project as a place "to touch the river and get on the river" in Park Board President Liz Wielinski's description. Drawing people, including school groups, potentially conflicts with the goal of attracting migratory birds. Moreover, the mainland's pebbled shore won't be like beaches at city lakes, intended for swimming and sunning, planners say.

Yet the island's history includes about 20 years when it was used as a swimming hole with city-owned bathhouses in the early 20th century, after previous owner Dr. P.M. Hall, after whom the isle is named, was thwarted in his plan to put a trash incinerator there.

The upper river has been considered more of an industrial trench than nature habitat after a succession of sawmills, a major power plant, truck gardens and heavy industrial uses like scrap and gravel yards. But advocates say that now that barges have been banished from the upper river by the closing of the upper lock at St. Anthony Falls, it's time for nature to re-emerge.

"Someday this will be the national example of how to do it right," said John Anfinson, superintendent of the National Park Service unit straddling the river in the Twin Cities area.

Steve Brandt • 612-673-4438

Twitter: @brandtstrib