Officials keeping close eye on flood stage

Jul 2, 2010 — Ottumwa Courier

Mark Newman

Jul. 2, 2010 (McClatchy-Tribune Regional News delivered by Newstex) -- OTTUMWA -- Flood stage means the river is out of its banks, not that the town is flooded. But with flood stage being exceeded along the Des Moines River, those numbers are being closely watched.

The National Weather Service pegs flood stage at 11 feet in Ottumwa and considers 15 feet to be "major flooding." On Thursday, the Des Moines River was measured at 15.3 feet in Ottumwa.

"We're a long way from panic," said Tom Rodgers, the city's public information officer. "We are seeing some flooding outside of city limits. In town, our levee is designed to protect up to a 25-foot river stage, so we have a long way to go before we're in any real trouble. I'm looking at the river right now from the top of [a tower]."

Rabbit Run Road is still flooded, and there are other places in similar situations in low-lying areas of Wapello County.

"Our situation here in Ottumwa is that the river is at about 15 feet, and Red Rock [Dam] is outflowing about 50,000 cubic feet per second," said Rodgers. "The forecast shows no real change in either of those numbers in the next week."

But he has been getting worried phone calls.

"I've been getting a lot of calls about Saylorville flooding [around] Des Moines. We have the buffer of Red Rock. And they tell us they can hold it steady," Rodgers said.

Significant rainfall could cause fluctuations, however.

"You'll notice there's a pump that's been pre-positioned near Market Street. If we were to get a forecast [the Des Moines River] would go up to 20 feet, you'd probably see some additional measures being taken," said Rodgers. "In the meantime, we're just holding steady."

The NWS also said the city of Eddyville is considered to have flooding, though they are in the minor flooding category. Flood stage is 61 feet, with the river running at 65.5 feet.

Things aren't too bad at that level, said Eddyville's mayor.

"We're looking good right now," said John Johnson. "It's flooding the low lands pretty good, in the rural parts. [In town], we've got a lot of levee left."

It'd have to get "pretty bad" before the mayor would recommend sandbagging. Like in 2008?

"In 2008, we had a little bit of levee left," he said.

In fact, he said, 61 feet is probably a bit pessimistic.

"That's what time they give a warning, when it's coming out of its banks [somewhere locally]," he said. "They want to raise ours, maybe, to around 64 feet. And I think Ottumwa could go [from 11 feet] to 12."

After weeks of fighting a rising river in 2008, he said, the people of Eddyville have a good idea of what needs to be done, especially with the river lower than major flood stage.

"We've got all the angles figured out now," said Johnson.

Both he and Rodgers said they are not surprised that Iowans are paying such close attention to the river.

"For local residents, vigilance is important," said Rodgers. "Pay attention, see the forecasts and check the local media. That's how we get our information out."

Johnson still remember the rumors that started floating around in 2008, claiming a levee had broke in Ottumwa or in Eddyville, or "official word" there were no more sandbags in Iowa.

"And it's already starting again," said Johnson, who recommended area residents focus on official reports. "Call City Hall. Somebody is always starting something. Call us; we'll give you the true figures."

County roadways flooded

The Wapello County Secondary Road Department is reporting road closures due to flooding:

--River Road, from Eldon bridge to the Davis County line.

--South Walnut Avenue/120th Avenue from Highway 34 to the river.

--Cemetery Road from the intersection of Cemetery Road and Cliffland Road to Fox Hills Road.

--28th Street from 42nd Avenue to 48th Avenue.

--Rabbit Run Road, from Highway 63 to 120th Avenue.

--125th Street from 198th Avenue to 180th Avenue.

Roadways will remain closed until further notice.

What is flood stage?

When the forecasters call "flood stage" 11 feet in Ottumwa, or 61 feet in Eddyville, they are measuring from a fixed point based on sea level. John Holt, the U.S. Army Corps of Engineers' assistant operations manager for Lake Red Rock said the point chosen for each measuring point on the Des Moines River -- like Ottumwa or Eddyville -- rarely changes..

The starting point for Ottumwa is 665 feet above sea level. That place is what engineers call the "Gauge Zero." So if the Des Moines River surface was at 670 feet above sea level, readers in Ottumwa would see a river stage listing of 5 feet.

Not all gauge zeroes are the same. The terrain around Eddyville puts the Des Moines River in their part of the state at 600 feet above sea level. So 600 feet above sea level is zero, 610 feet above sea level is read as a stage of 10 feet.

"It's a way of measuring vertical distance, a known, certifiable elevation. Then we want to know the change. That's the important thing," said Holt.

By measuring the stage of the river and how much water is flowing through at that point, Holt said, they are able to see a relationship between the flow and the stage.

"We have two ways to measure," he said.

By knowing the stage, they know the flow. By knowing what the flow is, they can figure the stage.

Late Thursday, Gov. Chet Culver issued a disaster proclamation for Wapello County.

Newstex ID: KRTB-0395-46644992