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The Army Corps of Engineers on Friday begins 12 consecutive days of reducing the amount of water being released from Gavins Point Dam on the Nebraska-South Dakota border.
By late August or early September, the water should be substantially off Missouri River levees in the Omaha-Council Bluffs metropolitan area. By late September, the water could be below Omaha's flood stage of 29 feet, said John Remus, chief of the hydrologic engineering branch for the corps' Omaha district.
Work is under way to assess and repair flood damage.
"Once it starts to approach 31 feet, I think (Omaha and Council Bluffs) can start breathing a little easier," Remus said.
That can come none too soon, especially in Council Bluffs, where the homes of about 30,000 people are vulnerable to flooding should a levee break.
"It is obviously going to reduce risk, and a lot of people are going to be very pleased with getting water off levees," said Don Gross, a spokesman for the City of Council Bluffs.
Should heavy rain occur, Bluffs neighborhoods will still be at risk of flooding behind the levees, he said. Gross said the river level will have to drop to between 23 feet and 25 feet before the water table drops, ponding disappears and the drainage system functions properly.
"We're going to be dealing with that all through September," he said.
On Monday, the Council Bluffs City Council is scheduled to vote on a resolution authorizing a team of engineering firms to do an extensive assessment of damage in the city, Gross said. Two large engineering firms, HDR Inc. and CDM, are competing for the contract.
Matt Cox, Council Bluffs' city engineer, said the contract will probably be for about $500,000. The size of the contract, he said, is an indication of how involved the process will be.
The consultants also will assist Council Bluffs in applying for federal reimbursement.
Levees, pump stations, gates, streets and sewers all will be studied.
Omaha officials are also looking forward to the drop in river levels.
"There remains uncertainty about how long it will take for the floodwaters to drain from the flood plains, but if the corps maintains their schedule and rainfall is normal, we expect to see the water off our levees and in the range of 30 to 32 feet by the end of the month," Marty Grate of the Omaha Public Works Department said via email. "Top priority then will be damage assessment."
Cox, of Council Bluffs, said it's possible that damage will continue to occur as river and groundwater levels drop. Pipes could fail, pavement could settle unevenly and levees could slough off soil, he said.
Kim Thomas, readiness branch chief for the corps in Omaha, said levee and dam assessment has begun wherever the water has dropped low enough.
"Obviously, the water is still up on those levees, so if there is damage, it's hard to see right now," Thomas said.
The corps is planning daily reductions of 5,000 cubic feet per second, which will take releases at Gavins Point Dam from 150,000 cubic feet per second to 90,000 cfs by the end of August.
At that point, the corps is planning a two-week pause in releases as it assesses the condition of the levees.
At their highest, releases from Gavins Point reached 160,000 cfs. The corps stair-stepped that down by 10,000 cfs several weeks ago.
Contact the writer:
402-444-1102, nancy.gaarder@owh.com
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