They are the kind of floods that are only predicted to happen every 100 years. But St. Paul has seen three of them over the past 15 years.
Each one has shut down Holman Field, a small airport on the Mississippi River in St. Paul's urban center.
The Metropolitan Airports Commission's Gary Warren says the airport cannot sustain another flood like the ones in 1993, 1997, and 2001.
"The airport closes here every four to six years, or it has in recent past, for up to two months," Warren says. "And some people like the peace and quiet that comes with that. I think that's unfortunate, because it's at the expense of millions of dollars to businesses and tenants who use the airport."
Holman Field tenants are mostly corporate customers, including 3M, the St. Paul Companies, and United Health. The Minnesota National Guard also rents airport access at Holman, and stores about a dozen Black Hawk helicopters there.
Warren says if flood protection isn't built now, his projections show another big flood would cost $7 million, or $24,000 a day for each day the airport is shut down. That financial loss would be incurred mostly by the airport's corporate customers.
Larry Dowell, president of the St. Paul Area Chamber of Commerce, says protecting Holman Field is essential because the conveniently located airport spurs economic development across the state.
"Clearly, an airport is not a seasonal thing, not a temporary thing. It needs to be a permanent piece of infrastructure that's not closed down for nearly three months," says Dowell. "The dislocation of business and jobs, and so on, and future economic development is what we care about -- the ability to signal that St. Paul is open for business, and that includes its transportation infrastructure."
The MAC's proposal includes a 1,000-foot earthen levee, a temporary dike system, and a 5,700-foot permanent floodwall. It also calls for a subterranean draining system, and for dredging the river to accommodate displaced water during floods.
The total cost estimate is nearly $42 million. None of that would come from the city of St. Paul. Nearly half is pledged from the Federal Aviation Administration.
So far, the state has kicked in $1 million in bonding money, and the Minnesota Department of Transportation is pledging $6 million. 3M is supporting the proposal with a $1 million pledge. The remaining $14 million will probably come from MAC-issued bonds.
For the MAC and its business customers, it is the right proposal for long overdue flood protection.
But there are many who say the project will not be good for the river or the city.
Opponents have been beating the drum against the project at every step, testifying against it at public hearings, and mobilizing detractors at protest rallies, including one held last weekend at Holman Field.
On the river bank, they constructed a nine foot mock flood wall out of 2-by-4s and black cloth.
State Rep. Sheldon Johnson, DFL-St. Paul, was at the rally. Johnson says he opposes building the dike and wall largely because his constituents believe it would be ugly, and block off access to the river. He says he also objects to the MAC's intention to widen the river at the wall's location.
"The strategy they're talking about is a strategy that was used in terms of dealing with the river and transportation issues 50 and 100 years ago," Johnson says. "This isn't the way we should be taking care of the river, and providing stewardship, in this day and age."
Nearby resident Carol Carey says she opposes the plan because she thinks it will make noise around the airport worse than it already is.
"That's the fear -- that this floodwall isn't so much about however many days in a 10-year period there might be flooding that would create problems with air traffic," says Carey, "but what does this mean about what the overall plan for the airport is, in growth at the airport?"
MAC officials insist there are no plans to increase air traffic at Holman Field.
The St. Paul Planning Commission already approved the MAC proposal. It now moves on to the City Council. Currently it looks like a slim majority of the council opposes the MAC's plan. Whatever the council decides, the issue will end up on the desk of Mayor Chris Coleman.
The mayor says he hasn't decided whether he supports the project or not. At a recent town meeting, he said he needs more time to make up his mind.
"I won't make a decision unless I feel like I fully understood the information and what's been presented, and feel like the information has been vetted to the point where I can trust it," Coleman said.
Coleman says he's listening to both the opponents of the project and the businesses who depend on the airport.
Questions recently surfaced about who owns the sliver of property where the dike and wall would be built, which means the MAC would have to come up with a revised proposal.
That means Coleman may be able to spend a little more time vetting, and dodge, at least for now, the first really tough decision of his term.