It’s taken a decade of starts and stops, contentious debates and delicate negotiations, but this month a new era begins for the treasured 72-mile stretch of the Mississippi River that winds through the Twin Cities.

For the first time since 1976, Minnesota has adopted a uniform framework for how the 21 cities and five counties along the Mississippi’s banks will manage the river to protect the water, the increasingly fragile bluffs and the spectacular views that provide the Twin Cities its singular sense of place. Now each community, from Dayton to Hastings, must come up with plans that fit the new rules governing building heights, setbacks and open space — a process that will define life along the river for decades to come.

Though the path has been long and fractious — and some players remain critical of the constraints on business and development — others say the framework is an extraordinary accomplishment that will protect the Mississippi corridor for the next generation.

“This is one of the world’s greatest rivers. And it’s a national park,” said John Anfinson, superintendent of the Mississippi National River and Recreation Area. Now the Twin Cities has a chance to create an urban riverfront that “could become an international model for how to do it right,” he said.

But business interests say the final results, while great for the river, impose too high a price on existing and future businesses.

“The [state] did a good of job protecting the river’s scenic and environmental values, but they failed on protecting economic value,” said Marie Ellis, director of public policy for the St. Paul Area Chamber of Commerce.

The new rules stem from the special status the state gave that stretch of the river in 1976, calling it a “critical corridor,” followed 12 years later with an even higher status as a national park of sorts. The National Park Service owns just 64 of the 54,000 acres in the corridor — mostly islands in the stream — but the river valley and bluffs are managed cooperatively by the Park Service, the state and local governments.

Part of that deal, Anfinson said, calls for the state and local governments to provide the kind of management that a national park would get: to preserve things unimpaired for future generations.

That turned out to be a tall order for a working river with locks and dams that flows through agricultural lands, industrial areas, downtowns and neighborhoods.

‘Like a sore thumb’

The concept dates to an executive order signed in 1976 by Gov. Wendell Anderson, which laid down what many now describe as a one-size-fits-all set of rules that cities found unworkable. Over the years, local officials often granted exemptions and variances, resulting in some eyesores. A large stand of mature oaks was clear-cut along the river in Mendota, for example, and a row of townhouses was carved into the bluffs near Lilydale that were clearly visible from Fort Snelling.

“They stuck out like a sore thumb,” said Jennifer Shillcox, a land use manager for the state Department of Natural Resources who helped develop the new rules.

Finally in 2009, after pressure from local residents, some legislators and advocacy groups, the Legislature instructed the DNR to come up with something new.

It didn’t go well.

Homeowners and city officials revolted in fear that the state would take control of their property, dictate zoning rules or quash development. There was talk that the DNR would rip out docks and patrol the river in canoes.

“Vegetation cops,” Shillcox said. “It got really contentious.”

In 2013 the DNR started over, this time with clearer instructions from the Legislature to work with local governments and to accommodate business and existing structures.

The result is a 66-page document, signed in December by Gov. Mark Dayton, that spells out things like the definition of a bluff (an 18 percent slope) and creates six different types of river districts, from industrial to rural, each with its own set of setbacks and building heights. Cities have some flexibility as they draw up development plans and zoning ordinances in the next five years, but they must still bow to the primary mission of protecting the river and the corridor.

Cities can deviate from height limits, for instance, through a public process that gives citizens a voice. But they also have to consider whether a proposed structure will interfere with the view from other perspectives. In short — does the building stick up above the tree canopy? Can you see it from the river bottom? Does it ruin the scenery from across the river or the park next door?

“Maybe you can go higher in some places and lower in others,” said Whitney Clark, executive director of Friends of the Mississippi River. “If you can’t see it, who cares?”

The plan also requires specific amounts of open space and conservation areas for new developments, which Clark described as “a huge advance.”

“Over time, there will be a lot of land that is set aside that is never developed,” he said.

Which is itself controversial. The stretch that includes 1,400 acres on Grey Cloud Island, in the river near Cottage Grove, was given a designation of rural open space. Both the city and landowners on the island fought it unsuccessfully because it would limit future development. “We don’t see [the entire island] as a park,” said John Burbank, Cottage Grove’s city planner. “That would take 1,400 acres off the tax rolls.”

But the upside, he added, is that the new rules give the city much more flexibility to make that case compared to the old one.

“This is my 29th year with the city,” he said. “And I think they are an improvement.”

Landslide alert

One of the most significant changes, many say, is the extraordinary level of protection for the corridor’s many bluffs. The rules prohibit building on them, and in some districts require a 100-foot setback for new structures, sharply limit removal of trees and other vegetation, and require native plantings as much as possible.

The reasons for that are far more than aesthetic.

Bluff failures — landslides — are increasingly common and damaging. In 2013, two children were killed at Lilydale Regional Park when the slope gave way. Another bluff failure in 2014 shut down Mississippi River Road below the University of Minnesota Medical Center for two years.

Carrie Jennings, research director for the Freshwater Society who studied bluff failures while working for the DNR, said a number of densely packed urban areas are already built out to the top of bluffs, and that’s not going to change. But the new 18 percent slope definition is still likely to save lives and property in less developed areas.

“It’s nice to have an overarching rule,” she said.

Not everyone thinks the rules hit the mark.

Ellis of the St. Paul Chamber objected that the bluff restrictions cover slopes that are near, but not on, the river. And, she said, uncertainty over costs and winning exemptions is already having a chilling effect on local businesses. Last year Johnson Bros. Liquor Co. pulled back from a proposed six-story apartment building on Shepard Road near the confluence of the Minnesota and Mississippi rivers. Neighbors and conservationists complained that it would be too high. And under the new rules it would be.

“That could be a multimillion [dollar] development in an area that’s being unused,” Ellis said.

Existing structures along the corridor can stay as they are but, depending where they are, can’t expand forward without an exemption. “That hampers their ability to expand,” she said. “And that’s what businesses do.”

Nonetheless, the new rules are already having their intended effect. Preliminary designs for the former Ford Motor Co. site in St. Paul call for a tiered structure with four-story buildings close to the river, rising to 65 and 75 feet farther back — all within the new guidelines. They also include roads, walking and bike paths that lead to the parks already fronting the river.

And at this point it appears to be financially viable, said Merritt Clapp-Smith, St. Paul’s project leader.

“We can have a really successful development that fits within this community and the intent of the critical area,” she said.