U.S. Army Corps of Engineer flood control projects in Hawai'i helped prevent an estimated $23 million in damage last year, officials said yesterday.

Engineers were able to make the estimate by calculating how much flooding would have occurred without the protections, which included reservoirs, levees and emergency operations, according to the Corps' public affairs office at Fort Shafter.

Last year's figures included flood protections that were provided during the nearly 40 straight days of rain in late winter and early spring. In March alone, the state was under 22 days of flash flood warnings and had three verified severe thunderstorms that contributed to some flooding and other heavily soaked areas.

The biggest savings, an estimated $14.1 million, came from a recently completed flood control project along Kahawainui Stream in La'ie. During the peak of the March rain, the stream reached 4.86 feet, more than 2 feet higher than the level that would have caused flooding without the flood control project.

Other projects that paid off in flood damage savings included about $3 million on Hanapepe River in Kaua'i and $5.8 million along Alenaio Stream on the Big Island, the federal agency said.

Officials say there are about 25 flood control projects in Hawai'i that were either built by the Army Corps of Engineers or are frequently inspected by them.

Last week, the Corps reported that three of them, including one on O'ahu, were rated "unacceptable" because of maintenance problems. Officials in Honolulu and Kaua'i said they were making repairs to the projects and hoped to have them approved by inspectors next month.