Plans for a dam on the Sagami River were submitted to the Home Ministry in 1935, but approval was delayed in favor of other projects.

Instead, the Kanagawa Prefectural Assembly passed the necessary regulations and secured a special budget to begin work in 1938.

Construction work did not begin immediately, due to strong opposition from 196 families who needed to be relocated from the area to be flooded by the dam.

It was designed to provide flood control, and industrial and drinking water to the cities of Yokohama, Kawasaki, Yokosuka and the Shōnan area.

The reservoir created by the dam, Lake Sagami is a major recreational location for Kanagawa Prefecture.