Pursuant to a congressional request, GAO examined the operations of levees involved in the 1993 Midwest flood, focusing on: (1) whether the Army Corps of Engineers' flood control levees prevented flooding and reduced damage or increased the flooding and added to the damage; and (2) the governments exercise control over the design, construction, placement, and maintenance of nonfederal levees.

GAO found that: (1) 157 of the 193 Army Corps of Engineers levees found in the areas affected by the 1993 flood prevented rivers from flooding and $7.4 billion in damages; (2) 32 of the Corps levees withstood floodwaters until the water rose above the levees and overtopped them; (3) 4 of the Corps levees allowed water into protected areas before their design capacity was exceeded; (4) the Corps estimated that the breaching of these levees caused about $450 million in damages; (5) although levees allow floodwater to rise higher than it normally would because they confine a flood to a portion of a floodplain, the Corps believe that its levees have the net effect of reducing flooding; (6) no federal programs specifically regulate the design, placement, construction, or maintenance of nonfederal levees, however, flood insurance and disaster assistance programs may exercise control over certain levees; and (7) 17 states and various local governments have programs to regulate levees, many of which are in response to the requirements of the National Flood Insurance Program.