Turns out, cleaning up a lake can help spruce up a city.

Federal money poured into environmental restoration of the Great Lakes will benefit regional economies more than threefold, including the twin port cities of Duluth and Superior, Wis., a study released Tuesday says.

Every dollar of the Great Lakes Restoration Initiative, which the federal government funded to the tune of $1.4 billion between 2010 and 2016, will spur an additional $3.35 in economic activity by 2036, research led by the University of Michigan found.

Nearly half the projected boost would come from increased tourism, with much of the rest from new waterfront real estate and commercial development as well as rising home values and an improved quality of life, which attracts and keeps young people in Great Lakes communities, the study found.

It's a strategy that leaders in Duluth have been embracing in recent years, investing in and promoting the city's rugged outdoor amenities — including access to increasingly clean bodies of water — as part of its plan for economic growth.

"I think the two go hand in hand," said former Duluth Mayor Don Ness, who now represents Minnesota on the board of the Great Lakes Protection Fund, a foundation that grants money for environmental cleanup. "As time goes on, a freshwater resource becomes increasingly valuable and important economically … I think Duluth has made a real commitment to an environment-led strategy to say, as we clean up the [St. Louis River] … that we believe that will result in more human recreational use of the river and some positive economic activity surrounding that."

Case study cities

The Great Lakes Restoration Initiative's focus was environmental: cleaning up contaminated areas, preventing and controlling invasive species, reducing polluted runoff, restoring habitat and promoting long-term stewardship of the lakes.

But the program's economic effect hadn't been measured until now, and researchers found that it was similar to a federal stimulus program in the number of jobs it created or supported.

"This study describes what we already know … cleaning up legacy pollution and restoring aquatic habitat on the Great Lakes isn't only good for the environment, it creates jobs and fuels the regional economy," Minnesota Pollution Control Agency Commissioner John Linc Stine said in a statement.

Led by the intergovernmental Great Lakes Commission and the Council of Great Lakes Industries, the study was funded by several foundations and cited developments in several "case study" cities.

In Duluth-Superior, for instance, Great Lakes Restoration Initiative projects included dredging 300,000 cubic yards of contaminated sediment, cleaning up and restoring 257 acres of wildlife habitat and creating 350 acres of new habitat decades after industrial and municipal discharges contaminated the St. Louis River estuary and harbor.

The projects are credited with helping to boost lodging, recreation, craft brewing and distilling.

The study cited a 10 percent increase in the number of hotel rooms in the Twin Ports over a decade, highlighting Duluth's $32 million Pier B Resort Hotel, which sits on 27 acres of once-industrial land on the Duluth-Superior Harbor and now boasts a hotel, restaurant, convention space and boat launch.

"State and local agencies contributed $5.5 million to the site cleanup, enabling waterfront development where it wasn't possible before," the report said.

The proliferation of waterfront hotels helped fuel a 4.4 percent increase in leisure and hospitality jobs in the city between 2008 and 2017, the report pointed out, and tourism tax revenue in the city doubled in the last decade.

Lake Superior's water quality is often promoted by brewery and distillery owners, according to the study. And water cleanup has "catalyzed" renewed interest in water-based recreation for locals and tourists.

Both cities have grown in the percentage of residents age 20 to 34, the study said, with each hosting above-average concentrations of millennials for their states.

Uncovering a jewel

Despite the study's findings, some might argue that Duluth's renaissance started decades ago.

Like many cities along the Great Lakes, much of Duluth's prime waterfront was once industrial and closed off to the public. In a 1985 plan to redevelop the downtown waterfront, then-Mayor John Fedo wrote that the city had "an opportunity to uncover a jewel."

The area now known as Canal Park was among the first to be cleaned up. The work included clearing away junked cars to make way for hotels, restaurants and shops. More recently, the city has invested in mountain biking, rock climbing and other park features, marketing its outdoors-rich attributes, including water activities.

Researchers found that several cities studied along the Great Lakes have seen a recent resurgence in recreational activity such as boating, sailing, fishing and canoeing, as well as new focuses on kayaking, kitesurfing and paddleboarding. Businesses are now serving more people visiting waterfronts, they said.

In a phone interview Tuesday, an official with one of the groups that led the study acknowledged that some of the economic growth would have happened regardless.

"We can't honestly say — and we're not saying — that everything that's happened along the waterfront, whether the estuary or Lake Superior in Duluth, is a result of the [Great Lakes Restoration Initiative], but that there definitely is evidence of increased spending and recreational activities — tourism and whatnot — along the waterfront," said Matt Doss, policy director for the Great Lakes Commission.

"According to the people we interviewed, at least some of that is reflective of the environmental improvements that are happening in the area."

Pam Louwagie • 612-673-7102