WHAT THE CORPS LEARNED FROM THE 1993 FLOODING
The unprecedented flooding in 1993 led the Corps of Engineers to review
the management of Coralville Dam for flood control.
The following is brief chronology of the steps that have been taken.
February 1994: In a joint meeting of the Iowa City and
Coralville City Councils, the Corps announced plans to reassess the
regulation manual. They would "look at many options" and "optimize
benefits". Following this, there would be a period of public input
and hearings. Final implementation was expected to take many years.
May 1994: The US Geological Survey installed automated gages
(with financial underwriting from Iowa City, Coralville, and the
University of Iowa) to monitor the development of flash floods.
The Corps coordinated a standard operating procedure (SOP) for
disseminating this information. In addition, the Corps promised
to develop (at a future date) a written contingency plan for lake
operation in the event of a flash flood.
January 1995: An "Initial Appraisal" of lake operations was
published which found "evidence of a significantly changed physical,
hydrologic, and economic condition upstream and downstream of
Coralville Lake." Further study was recommended.
August 1995: A "Report on Data Collection 1993 Flood Damage"
was completed, updating the stage-damage data upon which a regulation
study could be based. (The current regulation plan is based on
economic data that had been collected in the 1950's.)
August 1997: The "Review of Completed Works Reconnaissance
Report" was announced. Surprisingly, the results contradicted all
A review of some of the major procedural and
technical flaws of this Report was written by Larry Molnar and
Charles Newsom. This has been forwarded to the Corps of Engineers and
is under consideration.
- After studying two unrealistic options (one that did not attempt
downstream flood control), it was determined that despite the enormous
physical and economic changes found in the previous studies there is
no Federal interest in a study of the optimal regulation of the
- No public input or hearings were scheduled to review this decision.
- Development of a written contingency plan for lake
operation in the event of a flash flood was no longer recommended.
Last updated on September 18, 1997 by CRN