When ground is symbolically broken Tuesday at Stillwater's Lowell Park for a new bridge over the St. Croix, it will signal the beginning of a promised transformation of communities on both sides of the scenic waterway.

It also will represent a laying to rest of decades-long controversy, lawsuits and political struggle that culminated 14 months ago when President Obama signed the bill authorizing construction of the $629 million project.

Preliminary work on the bridge began last year, and huge cranes borne on barges soon will begin work on the five sets of massive steel-reinforced piers that will support the four-lane span linking Minnesota and Wisconsin along Hwy. 36. In Oak Park Heights, the bridge's Minnesota jumping-off point, a four-year-long construction zone is taking shape.

Now that the bridge is a reality, U.S. Sen. Amy Klobuchar, D-Minn., said she hopes it will come to be seen as a symbol of unity, rather than divisiveness.

"This was supposed to be the bridge that couldn't be built," she said Monday. "I think a lot of people believed that we couldn't get this done."

The bridge binds the common economic and transit interests of two states, she said, and pulling together the complex and disparate local, county, state and federal interests — not to mention spanning the bipartisan divide in Congress — to reach this point of construction shows how urgently needed the project has been.

"People on both sides of the St. Croix deserve to have a bridge that works," she said. The Stillwater Lift Bridge — completed in 1931 and destined to become part of a hiking/biking trail once the new span is done — is outmoded for the amount of traffic it carries, costly and difficult to maintain, and dangerous, she added. "There are literally chunks falling out of it. We've already seen one bridge fall down in Minnesota. We don't need to see another fall as well."

Klobuchar's support for the bridge put her at odds with environmentalists, an important constituency. It also placed her on the opposite side of two important political allies and friends, U.S. Rep. Betty McCollum, D-Minn., and former Vice President Walter Mondale. She joined forces with U.S. Rep. Michele Bachmann, R-Minn., to get the bill through on the House side.

McCollum opposed the scope of the bridge — now in her congressional district after lines were redrawn — fearing the effects of increased traffic to communities along Hwy. 36. Mondale called the bridge an assault on 1968's Wild and Scenic Rivers Act, of which he was co-author when he was a U.S. senator. It governs the St. Croix and 202 other rivers nationwide, and Klobuchar's legislation creating the bridge exempted it from that law.

"Our relationships are much bigger than one issue," Klobuchar said. She still is close to McCollum and Mondale, who escorted her down the Senate aisle when she was sworn in for her second term in January.

McCollum said that, now that the bridge is here, her focus is on moving forward. "While it is no secret that I opposed the size and cost of the new bridge, now that it is being built, my goal is to ensure taxpayers get the best, most cost-effective bridge possible," she said.

Klobuchar said the bridge design is environmentally sensitive despite its size, and will help curb pollution in Stillwater by eliminating gridlocked traffic. "The people in Stillwater will get their town back," she said.

She is also convinced that, given the enormous difficulty getting the exemption to the Wild and Scenic Rivers Act passed, it won't open the floodgates to other developments the law is intended to prevent.

The bill creating and funding the bridge reached a dramatic, now-or-never moment in the Senate, Klobuchar said. With time running out, and with Senate rules requiring unanimous consent for the bill, her door-to-door campaigning of her 99 colleagues came down to one last holdout: Republican Sen. Thomas Coburn of Oklahoma, a well-known budget hawk.

"What a lot of people don't know is that the vote all came down to one senator," Klobuchar said. "One person — literally one person — had the power to derail us."

Senate Majority Leader Harry Reid took the rare step of presiding over the Senate from Klobuchar during her turn to do so to allow her to go lobby Coburn. In a rare show of accord, Reid and Senate Minority Leader Mitch McConnell also used their influence as well, and the final vote was the needed 99-0.

Jim Anderson • 651-925-5039 Twitter: @StribJAnderson