No guarantee that Missouri River Basin won't flood again

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Flooding risk along the Missouri River Basin can be reduced through repairs to damage caused by floods in 2011 but never can be entirely removed, says the Army Corps of Engineers in a report released this month.

Record levels of snowfall the previous winter in the Rocky Mountains and rainfall caused months of flood conditions along the Missouri River during the summer of 2011, resulting in still uncalculated damages likely to amount to billions of dollars, the Corps notes in a vulnerability assessment report. During March through June, approximately 49 million acre-feet of runoff poured into the system, overwhelming flood plains and overtopping levee systems, although flood control infrastructure did prevent nearly $8.2 billion in damage, the Corps says.

2011 was an "unprecedented 500-year event"--and even were the flood control system to be completely repaired, it would still be vulnerable to flooding during extreme events, the report states.

As a result, "the basin needs to plan and prepare for future flooding events." Those measures may need to include relocating buildings located in the floodplain, the report adds.

Corps engineers also criticize the current approach of responding to major floods, whereby funding is allocated for repair to damaged levees but no overall net improvement to flood protection occurs.

Congress appropriated $1.72 billion in 2012 through a supplemental appropriations bill for the Corps to repair damages caused by major disasters in the Mississippi River Basin and it tributaries (which include the Missouri River), and roughly a third of that is going to the Missouri River Basin, the Corps says.

Repair projects will take some time to complete. For example, the navigation channel established at Sioux City, Iowa to the river mouth suffered damage that in places from Sioux City to Rulo, Neb., has led to significant navigation hazards. Even assuming that adequate funding will exist, repair will require 2 to 4 years, the Corps says.

For more:
- go to an Army Corps of Engineers webpage with the report

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