Yashiki Irisawa No. 7 Stone Dam

A Dry-Stone Erosion Control Dam

The Yashiki Irisawa No. 7 Stone Dam (屋敷入沢第七号石堰堤) is a dry-stone erosion control (sabo) dam built between 1910 and 1918 on the Yashiki Irisawa stream at Kamikurokoma, Misaka-cho, Fuefuki City, Yamanashi Prefecture, as a sabo project subsidised by the Home Ministry, and was registered as a Registered Tangible Cultural Property (structure) on August 7, 2009 (Agency for Cultural Affairs, Yamanashi Prefecture).

The Agency for Cultural Affairs records a stone dam 66 metres long and 6.4 metres high, with guide walls and an apron; registration number 19-0061, owned by Yamanashi Prefecture.

The 1907 Floods and Sabo Works

A report by the Yamanashi Prefecture Sabo Division explains that in the Meiji era, as silk reeling grew, forests were cut for firewood and cleared for mulberry fields. Heavy rain in August 1907 sent debris flows down the Yashiki Irisawa and other streams of the Kanegawa basin, sweeping away houses and killing many people.

In 1908 the right-bank basin of the Kanegawa became a designated sabo area, and after further floods in 1910 a plan was made to place sabo works throughout the basin. Work on the Yashiki Irisawa ran from 1910 to 1918, and more than 40 stone dams have been identified (Yamanashi Prefecture).

Value as a Registered Cultural Property

The Yashiki Irisawa No. 7 Stone Dam was registered as a structure contributing to the historic landscape of the country. Yamanashi Prefecture notes that when rain as heavy as that of 1907 fell in 1928, there was little damage, and that the Yashiki Irisawa sabo works have survived later major disasters intact and still function.

What to Look For

The Agency for Cultural Affairs notes that the dam stands in the lower reaches of the Yashiki Irisawa, a right tributary of the Kanegawa in the Fuji River system. From the foot of the dry-stone body, 66 metres long and 6.4 metres high, an apron runs 13 metres downstream. Its gentle slope steadies the channel and protects the village below from landslide debris.

Yamanashi Prefecture sees the skill of the period in the tanizumi masonry, with stones set diagonally. As the lowest stone dam on the stream, it guarded the settlement directly below (Yamanashi Prefecture).

Visiting

The Yashiki Irisawa No. 7 Stone Dam is a working sabo structure managed by Yamanashi Prefecture. According to the Yamanashi Infrastructure Guide, there is no parking; it lies about 12 kilometres from the Ichinomiya-Misaka interchange of the Chuo Expressway.

As it stands in a mountain stream, avoid visiting after heavy rain and watch your footing. Enquiries go to the prefecture's Kyōtō Construction Office in Koshu (0553-20-2710).