Officials from Coralville, Iowa City, and the University of Iowa asked the Army Corps of Engineers to increase the discharge rate to 10,000 cubic feet per second earlier this week. The Corps responded by raising the outflow from 6,000 to 8,000 cubic feet per second on Wednesday.

Johnson country emergency-management coordinator Dave Wilson recommended to the Board of Supervisors at its meeting Thursday that the Corps review its regulation plan for the Coralville Reservoir.

“We can’t keep regulating on a plan that’s 20 years old when we’ve had two floods,” Wilson said.

A number of factors necessitate the revision, he noted, including weather patterns, siltation in the Reservoir, and other changes downstream.

Recent rainfall has the supervisors especially concerned about lake levels.

“It was particularly concerning when a town [upriver] got 10 inches,” said Supervisor Janelle Rettig.

Four more inches of rain are expected in the Coralville Reservoir’s watershed Sunday through Wednesday, and the water level is expected to reach 705 feet on July 8. Water flows over the spillway at 712 feet.

Officials hope a revised regulation plan could change water output to mitigate future flooding events.

“We would probably continue letting water out at a little higher rate until a little later in the season,” Wilson said.

But letting more water out isn’t always the answer, some officials say.

“That can be negative if you have a dry year,” said Supervisor Pat Harney.

Harney believes a revision could be necessary, however.

“I don’t think it hurts anybody to review it and update it,” he said. “We just kind of like to review it to see if there’s something different that can be done.”

Though “relatively minor” changes were made to the regulation plan in 2001, there have been no big changes since the 1990s, said Jim Stiman, the chief of the water-control section in the Rock Island District of the Army Corps of Engineers.

An environmental assessment will be required for a revision in the plan, Stiman said, and several other factors will need to be taken into account, like downstream real estate.

Wilson said the next step is to form a partnership with the East Central Iowa and Johnson County Councils of Governments to approach the Corps to review the plan.

An assessment may cost up to $1 million. The cost would be shared among the local councils of governments and the federal government.