The Hanapepe River Flood Control Project is located on the southern coast of the island of Kauai and flows through the town of Hanapēpē into Hanapēpē Bay. It was authorized by the 1944 Flood Act. The project consists of a floodwall atop a levee (2,200 feet long) and an I-Wall (185 feet long) on the left bank commencing at the new Kaua‘i Belt Highway Bridge located about 0.4 mile above the river mouth and extending to the cliffs at the northeast corner of the town of Hanapēpē; and riprap-lined earth-fill levee (4,465 feet long) on the right bank commencing at the old highway bridge about 0.5 mile above the river mouth and extending upstream to high ground.
The Honolulu District completed improvements to the left and right banks in 1959 and 1963, respectively, and completed additional improvements to raise the height of the levees and construct the floodwalls in 1966. The local sponsor, the County of Kaua‘i, operates and maintains the project. Approximately 859 homes and commercial buildings are currently protected by the project. To date, the project has prevented more than $23.7 million in projected damages, within the project area.