IDOT released the following explanation Tuesday morning:
First, the Iowa DOT recognizes the importance of Iowa 2 to the economic and social vitality of southwest Iowa, northwest Missouri and southeast Nebraska. It is a critical lifeline for citizens living, working and conducting business between Iowa and Nebraska.
The Iowa DOT also understands the dramatic impact this closure has on the regional transportation system and how the situation is made more difficult due to the closing of the bridge crossings at U.S. 136 near Rock Port, Mo., and U.S. 159 near Rulo, Missouri due to levee breaches and overtopping.
The Missouri River flooding disaster is placing an extraordinary strain on the Midwest transportation system and people who rely on it.
The Iowa DOT has been actively engaged in the flood fight examining each threatened roadway section along the Missouri River corridor to determine what flood mitigation efforts could be used, if any, to prevent a road from being flooded or keep a road open as long as possible.
Each area where a roadway is located has unique characteristics and challenges. Iowa 2 is located within a low-lying area normally susceptible to ground water flooding. It has not been unusual in recent years for a portion of the roadway to be partially covered by water. Agricultural levees are also located not far from the roadway. In an average year, the ground water would not result in a total road closure.
This year is unlike others, as evidenced by the recent rising water levels that were a combination of ground and river water. Water eventually covered the roadway in many locations and the depth was rising. It was no longer safe for travel, and the road had to be closed Sunday.
Before the closure, the Iowa DOT was on the verge of installing a 6-foot tall flood barrier system along the route and using pumps to divert flood waters. Regular sandbagging was not an option because of seeping ground water and roadway distance. The barrier system could have allowed vehicles to use the road in a head-to-head configuration in the westbound lanes.
The Iowa DOT was forced to scrap those plans at the last minute when it learned that the levee system adjacent to the roadway was highly susceptible to a breach. A number of boils have surfaced near the toe of the levee. The levee system will be further weakened by weeks of pressure from the high river water levels.
After consulting local emergency agencies, it was determined that if a breach occurred or the levee was overtopped, the barrier system would not protect the roadway from being immediately inundated. The amount of river water that would rush toward the roadway would threaten the lives and safety of motorists. The Iowa DOT could not risk endangering the lives of highway users by allowing the road to be reopened.
Therefore, Iowa 2 will remain closed until flood waters recede and any damage to the roadway repaired. It may be several months before the water levels are reduced.
Travelers seeking information about alternate routes may call the Iowa DOT’s Flood Hotline at 866-452-8510 from 7 a.m. – 9 p.m. daily