The Ottumwa Courier

December 10, 2013

Pending freeze boosts river level

By MATT MILNER
Courier staff writer

---- — OTTUMWA — If you’ve driven over the Market Street Bridge or the Jefferson Street Viaduct in the past couple days, you’ve probably noticed that the river has more water in it.

A lot more.

After months of staying mostly below one foot, the river has jumped up in just a couple days. The area has seen snow in that time but not enough to change the level on its own. And, let’s face it, it has been far too cold for most of it to melt anyway.

From Sept. 1 through Dec. 6, the river spent only 21 days with more than a foot of water flowing through Ottumwa. You have to go back to Aug. 23 to find the last time the river was over 1.5 feet here.

If anyone should know why things changed, it’s Perry Thostenson, the assistant operations manager for the U.S. Army Corps of Engineers at Lake Red Rock. The lake controls water flow for a large area downstream, including Ottumwa.

Thostenson said a combination of factors helped change conditions. The first is the season. Fall means large-scale bird migrations, and many of those birds use large bodies of water as rest stops on their trips.

“Our regulation plan allows for a fall raise in the conservation pool to benefit and coincide with the fall migration of waterfowl and other birds,” he said.

Winter’s arrival changes the situation, though.

“With the impending ice-over of the lake we opted to increase outflow to draw the pool down to ‘normal’ conservation pool before substantial ice is formed,” said Thostenson.

This summer’s drought played a role in dropping river levels even before any of this took place. It was the second consecutive summer of drought conditions in Iowa, and at Ottumwa, some months saw even less rain than in 2012.

More than half the state, including all of southeast Iowa, remains in drought. But the window for recharging the soil is closing. The winter freeze means soil moisture levels are unlikely to change much until next spring.

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NOTE: This version of the story has been corrected to eliminate inaccurate information.