UPDATE: CEDAR RAPIDS — Mayor Ron Corbett gives the Army Corps of Engineers this: The federal agency has left out new surprises in its draft study report on Cedar Rapids’ flood-protection needs, a report that is now released and ready for the public to comment on.

Corbett on Wednesday said the Corps’ surprises all came earlier in the year as Corps representatives first let the city and the Cedar Rapids public know that it would recommend a no-frills flood-protection system that would protect most of the east side of the Cedar River through Cedar Rapids but leave the west side unprotected.

The Cedar Rapids City Council rejected the Corps’ conclusions at a mayoral flood forum early in the year and again at a public open house in June. Corbett did so again on Wednesday.

“I still can’t support the Corps effort to protect only one side of the river, and many people in this community feel the same way,” the mayor said.

The Corps plans another public open house in Cedar Rapids – at 6 p.m. Sept. 21 in the Crowne Plaza Five Seasons Center ballroom – to take input on the draft report. The report then will be finalized and taken in front of the Corps’ Civil Works Review Board in November. The report should be ready to present to Congress in February, according to the Corps’ latest timeline.

The Corps has emphasized repeatedly that it is bound by federal law and can only recommend a flood-protection system that meets a benefit-cost ratio of 1. In other words, a system can’t cost more than the value of the property it protects.

Corbett said the city will make its case to the review board this fall, but he said the city knows it will need the help of the state’s Congressional delegation to get the kind of flood-protection system that the city feels is necessary to protect against a repeat of the June 2008 flood.

“We’ve known from Day 1 that this is going to be fought out in the halls of Congress,” Corbett said. “Certainly, you’d like to have the Corps standing on your side to get both sides of the river protected.”

The Corps’ three-page executive summary of a report that reaches to more than 1,600 pages with addenda makes it clear that the city of Cedar Rapids needs a new flood-protection system.

The city’s existing system “does not provide protection,” the Corps’ summary states.

However, the Corps says the only system that is economically justifiable is one that uses “utilitarian” design and by and large features basic concrete flood walls to protect the most of the east side of the river. The protection would be for the downtown and include protection for the Quaker Co. plant just above downtown and the Cargill plant downriver from the downtown.

The Corps puts the cost of such a plan at $98.8 million, $34.6 million of which would be the responsibility of the city of Cedar Rapids to come up with.

The Corps’ recommended plan – which it defines as Option 4C – comes with a 91.24 percent probability that the protection system won’t be overtopped by flood water. It has an acceptable benefit cost ratio of 1.15 percent.

The Corps’ recommended system would consist of 2.17 miles of concrete flood walls, .75 miles of earthen levees and .23 miles of closure structures around bridges.

The draft report notes that the Corps studied a variety of flood-protection options as it worked to come up with its recommended option.

The report notes, for instance, that it would cost $600 million and take nearly 50 years to build a large reservoir upstream from Cedar Rapids and $920 million and 40 to 50 years to build multiple reservoirs upstream. Building a diversion channel around the city to the east would cost $5.6 billion and take 20 to 30 years to build while building one to the west of the city would cost $2.8 billion and take the same amount of time to build.

One idea, to use the city’s Jones Park Golf Course as a detention facility to hold flood water, would have zero affect in reducing flooding while dredging the river would cost $26 million and reduce the level of flooding by 2 percent, the Corps concludes.

On Wednesday, the city of Cedar Rapids was encouraging residents to review the Corps report and send comments to the Corps. The report is available in the following locations:

• The Corps’ Rock Island District’s Web site: http://www.mvr.usace.army.mil/PublicAffairsOffice/CedarRapids/CedarRapids.htm

• The Cedar Rapids Public Library

• Through requests to Ms. Marsha Dolan of the USACE, Rock Island District by e-mail at marsha.g.dolan@usace.army.mil or by phone at (309) 794-5648