The Dam That Gave Onomichi Its Water Supply
The Hisayamada Reservoir Dam (久山田貯水池堰堤, Hisayamada Chosuichi Entei) is a stone-faced concrete dam completed in 1925 in Hisayamadacho, Onomichi City, Hiroshima Prefecture, which in 2004 was registered as a Registered Tangible Cultural Property.
The Agency for Cultural Affairs describes it as part of Onomichi's original waterworks, built on the Monden River in the southwest of the city. It is 75 metres long and 22 metres high, with a secondary dam, and belongs to Onomichi City.
Onomichi City notes that water began flowing from the Nagae purification plant, fed by the Hisayamada reservoir, in 1925, and that the city's waterworks marked their centenary in 2025.
The Dam and Onomichi's Water
According to Onomichi City, there is no large river in the city, and much of the town stands on reclaimed land where groundwater is salty, so drinking water was scarce before the waterworks. Water sellers are said to have walked the streets.
With city finances stretched, Yamaguchi Gendo, a native of Onomichi who sat in the House of Peers, offered to donate three-quarters of the construction cost. Approval came in March 1922, work began the following January, and water began flowing in April 1925.
The city says no other waterworks in Japan was founded on a single person's donation. The Hisayamada Reservoir Dam was built to secure the source of that supply.
What to Look For
The Agency notes a spillway at the centre of the dam and a semicircular intake tower projecting near the right bank.
In plan the dam is an arc concentric with the secondary dam, combining gravity and arch construction. Curving a gravity dam upstream helps it resist the pressure of the water.
From the reservoir side, the curve of the dam and the semicircular intake tower jutting from it are easy to see.
Visiting the Hisayamada Reservoir Dam
The Hisayamada Reservoir Dam is a working waterworks facility. Access to the dam and intake tower may be restricted, so view it from outside.
Enquiries go to the Onomichi City waterworks and sewerage bureau.
Q&A
- When was the Hisayamada Reservoir Dam built?
- It was completed in 1925, and Onomichi's water supply began that April.
- How is 久山田 read?
- Hisayamada.
- How big is the Hisayamada Reservoir Dam?
- 75 metres long and 22 metres high, with a secondary dam.
- What is special about the structure of the Hisayamada dam?
- An arc-shaped plan concentric with the secondary dam, combining gravity and arch construction.
- Who funded Onomichi's first waterworks?
- According to Onomichi City, Yamaguchi Gendo donated three-quarters of the construction cost.
Basic Information
| Name | Hisayamada Reservoir Dam (久山田貯水池堰堤) |
|---|---|
| Location | Hisayamadacho, Onomichi City, Hiroshima Prefecture |
| Designation | Registered Tangible Cultural Property (structure) |
| Year Designated | Registered 2004/11/8 (Heisei 16) |
| Quantity | 1 structure |
| Dimensions | Concrete dam, 75 metres long, 22 metres high, with secondary dam |
| Owner | Onomichi City |
| Public Access | Working waterworks; view from outside |
References
- Agency for Cultural Affairs Database: Hisayamada Reservoir Dam (Japanese)
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00004407
- Cultural Heritage Online: Hisayamada Reservoir Dam (Japanese)
- https://online.bunka.go.jp/heritages/detail/117487
- Onomichi City: Waterworks Centenary (Japanese)
- https://water-onomichi-anniv100th.jp/
Last verified: 2026.09.28