Shiraiwa Weir, Flood control dam in Toyama Prefecture, Japan.

Shiraiwa Weir is a flood control structure on the Joganji River in Toyama Prefecture that works together with seven smaller counter dams to regulate water flow and manage debris. The dam system forms multiple barriers that slow the river and protect communities downstream from the Tateyama Caldera.

The first weir here, the Yukawa No. 1 sabo dam, was begun in 1913 and finished in 1919 after six years, then damaged by debris flows that same year and again in 1922. Control passed from Toyama Prefecture to the national government in 1926. The present Shiraiwa Weir was completed in 1939 after eight years of work, and its first counter-dam reuses part of the prefectural dam's body.

The first sub-dam reuses part of the body of the Yagawa No. 1 sabo dam, built by Toyama Prefecture and completed in 1919. In 2009 the main dam, its sub-dams, the second sub-dam as a riverbed check and the grid-frame works were designated a National Important Cultural Property as the Shiraiwa Entei Sabo Facility, the first sabo facility to receive that status. In 2017 the Hongu and Dorodani dams were added and the designation renamed Joganji River Sabo Facilities.

The structure is visible from designated viewing areas where you can see the dam and the river system from above. Clear weather provides the best view of how the multiple barriers work together across the landscape.

The first auxiliary dam reuses part of the body of the Yagawa No. 1 sabo dam built by the prefecture, finished in 1919 after six years of work and damaged by debris flows that same year and again in 1922. In 2009 the main dam, its auxiliary dams, the second auxiliary dam and the grid frames were designated a National Important Cultural Property as the Shiraiwa Weir Sabo Facility, the first sabo facility to receive the designation; in 2017 Hongu Weir and Dorodani Weir were added and the name changed to Joganji River Sabo Facility.