The debate over flood risk has implications for hundreds of thousands of people living near major rivers in the Midwest.

Several academic researchers say that the Missouri and Mississippi Rivers have become increasingly flood-prone. The Army Corps of Engineers says there is no cause for alarm.

Even slight increases in flood levels could spell trouble for communities that narrowly escaped inundation in the Flood of 1993.

Here's a tale of two cities living on the edge of a hard-to-predict river.

HANNIBAL:

The city of Hannibal has capitalized on its Mississippi River location since the steamboat era. Residents in the boyhood hometown of Mark Twain initially balked at funding a levee, saying it would ruin the scenic riverfront.

Then, merchants in the historic downtown, with the help of the city, put a down payment on a new levee funded mainly by the corps. The 100-year levee was barely finished when the 1993 flood hit. The levee had been built to withstand a flood the size of the 1973 flood, the previous record-breaker, but it wasn't enough.

With water rising dangerously high, former city emergency director John Hark ordered crews to pile sand and dirt on top of the levee, and sandbags on top of that. To raise the concrete flood wall portion, crews attached plywood sheets to both sides of the wall, lined them with plastic, and filled the gap with sand.

High water lapped at the plywood, but the temporary reinforcements held. The charming downtown, with its tourist shops, bank and car dealership, stayed dry.

Hark believes the failure of levees across the river from Hannibal helped save the day.

"I think we were at our limit," Hark said. "Should we ever top that '93 flood stage here in Hannibal, I think it's going to be a real serious situation."

The corps' latest study on Mississippi River flood heights says a 100-year flood would rise 1.8 feet higher at Hannibal than previously estimated. If the city's levee no longer offers 100-year flood protection, the Federal Emergency Management Agency may decide to withdraw levee certification and flood insurance.

Now the city faces questions: Is the levee still good enough? Should it be raised, just a decade after its completion?

City engineer James Burns isn't sure, but he does have the sense that flood levels are going up. "As you go through and build more levees and channelize water more, it's got less area to spread out over. That results in more water through a smaller channel, and that water has to be higher," he said.



St. Louis




Former St. Louis Fire Chief Neil Svetanics will never forget the war he nearly lost in the summer of 1993. Rising water on the Mississippi, Missouri and Illinois rivers converged at St. Louis, where it funneled through an hourglass shape, pinched in by the St. Louis flood wall on one side and the East St. Louis flood wall on the other.

The city was in a state of emergency for 41 days. It started raining in April, and by summer, the ground was saturated and the river banks were full.

The flood wall that had protected low-lying areas north and south of downtown since 1974 started to fail. One section of the wall shifted out of place. The river began to scour underneath the wall in several places, threatening chemical companies, manufacturing plants, trucking companies and a city prison.

Workers controlled the damage by building ring levees around sand boils and dumping truckload after truckload of rock to shore up the wall.

By early July, sandbag levees along the River Des Peres began to fail. Neighborhoods flooded.

Concern grew that 51 giant propane tanks along South Broadway, each holding 30,000 gallons of flammable gas, would float off their moorings and explode in a fire big enough to consume 2,500 buildings. The tanks were lashed down with half-inch thick steel cables and bolts, and a security guard patrolled the area day and night.

Thousands of people were ordered to evacuate on both sides of the river, because of the explosion threat.

Bolts snapped off propane tanks, sounding like shotgun blasts. "Everything was going to hell in a handbasket," Svetanics said.

He remembers gathering with city, state and federal emergency leaders in the basement of Soldiers Memorial one night, trying to figure out how to stop the unstoppable. "We had just about surrendered, because we were losing on every front," Svetanics said.

Then, like a miracle, the water started going down.

A levee broke about 10 miles downstream in Illinois on Aug. 1, flooding thousands of acres of farmland. Within hours, the water level in St. Louis dropped 2 feet, as if it were being siphoned off, Svetanics said. More importantly, it didn't go back up.

The floodwater had risen to about 2 feet from the top of the flood wall in places, and it had been forecasted to go even higher.

"If that levee hadn't broken, I believe we would have lost the north riverfront. We would have lost south city, Carondelet and River Des Peres," he said.

Today, some residents and businesses have been moved out of some of the low-lying neighborhoods. Sewer improvements make backup flooding less likely. The propane tanks have been dismantled and removed.

But the same flood walls are still there, and most of the same industries are behind them.

Svetanics, now chief of the Lemay Fire Protection District in south St. Louis County, doesn't feel secure that St. Louis is protected from such a threat again.

"I'm not as optimistic as a lot of people," he said. "The river has been here for millions of years. That flood happened because of unusual circumstances, but those unusual circumstances could happen again."



Reporter Sara Shipley:
E-mail: sshipley@post-dispatch.com
Phone: 314-340-8215