Strengthening levees not worth the expense, corps says

Protecting vast tracts of agricultural land with bigger, stronger levees along the upper Mississippi and Illinois rivers would not justify the multibillion-dollar expense, according to a new federal study. The U.S. Army Corps of Engineers has concluded that the existing flood protection system along nearly 1,100 river miles north of Cairo, Ill., generally holds its own most of the time, although some segments have "varying structural integrity."

By contrast, building up levees to protect against a so-called 500-year flood would cost more than $8 billion. Even upgrades to survive less-severe 100-year floods would cost roughly $3.7 billion.

from the St Louis Post-Dispatch