Elwood ? Some local residents are angry about a decision by the U.S. Army Corps of Engineers that will require some people in Doniphan County, Kan., and Buchanan County, Mo., to buy flood insurance.

The corps decertified the levee surrounding the area because of new, more accurate information about the Missouri River that prompted the government to change formulas for studying floods, said Christopher Purzer, a hydraulic engineer with the corps.

The corps’ decision to decertify the St. Joseph levee forced the Federal Emergency Management Agency to act, said spokeswoman Pam Soper. That means residents of Elwood and Wathena and western Buchanan County, Mo., will have to buy flood insurance.

The new rules don’t take effect for 18 months, Soper said. About 260 Elwood residents already have flood insurance and their rates won’t change if they have a standard policy.

But at an insurance meeting Tuesday, some Elwood residents said they did not understand why they had to have flood insurance.

“The levee didn’t deteriorate,” said Wes Wallick. “The government changed techniques. Nothing changed in protection.”

The corps is waiting for a flow study of the entire Missouri River Basin before finishing its restoration study.

“This is an attempt at avoiding getting to the end of the study and being told we have to redo the whole thing,” said Charles Detrick, project manager for the St. Joseph levee study.