A Basin Squeezed Into a Narrow Valley
The Heisakubara Power Station Endobara River Settling Basin (平作原発電所遠藤原川沈砂池, Endōbara River) is a reinforced concrete settling basin built in 1928 on the right bank of the Endōbara River intake weir in Kamisaibara, Kagamino Town, Okayama Prefecture, and registered as a Registered Tangible Cultural Property on 29 November 2006.
It is 55 metres long but only 5.5 metres wide, with an area of 370 square metres. Water from the weir moves slowly down this slender tank, drops its sand and gravel, and leaves for the channel much cleaner than it arrived.
The valley here is tight. The basin fills a thin strip of level ground pinned between the stream and the mountainside.
Guarding Against Silt From Two Directions
The Heisakubara Power Station Endobara River Settling Basin was registered as a structure that contributes to the historic scenery of the country.
Its design deals with sediment coming from two sides. Silt carried in by the river settles on the floor and is flushed back out through a sluice set in the middle of the west wall, the wall that divides the basin from the stream.
The other threat comes down the slope. On the east and south, where the mountainside presses close, the builders stacked Tanizumi stone retaining walls on top of the concrete side walls to keep debris out. The Agency for Cultural Affairs singles this out in its description.
One side is defended against water, the other against the hill.
What to Look For
Study the east and south walls. Concrete below and stone above, the two-tier section shows how the builders prepared for earth pressure and rockfall from the slope.
Notice, too, where the sediment sluice sits: in the middle of the west wall, not at one end. On such a long, narrow basin, that placement likely makes it easier to flush silt from anywhere along the floor.
The Endō River basin in the next valley measures 51 metres by 7.3 metres, shorter and wider than this one. Seeing both makes it plain that valley width shaped each plan.
Visiting the Endobara River Settling Basin
The Heisakubara Power Station Endobara River Settling Basin is a working facility run by Chugoku Electric Power, and no visitor facilities are advertised. Its edges, the sluice and any gated or fenced area are closed; only the exterior can be seen from places where access is permitted.
It sits in the Endō district just below the Endōbara River weir. The valley is steep and narrow, so watch your footing and look out for falling rock. Snow closes in during winter.
Chugoku Electric's page for the station gives no restriction on photographing exteriors, but you cannot enter operational areas for photos.
- 📍 Plan Your Visit to Okayama
- Find tours, activities & transport passes near Heisakubara Power Station Endobara River Settling Basin
- [ Kurashiki Bikan District & Korakuen Garden Tours ]
Q&A
- What is the Heisakubara Power Station Endobara River Settling Basin?
- It is a reinforced concrete basin built in 1928 to remove sand and gravel from water taken in at the Endōbara River weir. It became a Registered Tangible Cultural Property in 2006.
- How large is the Heisakubara Power Station Endobara River Settling Basin?
- It is 55 metres long and 5.5 metres wide, with an area of 370 square metres.
- What are the design features of the Heisakubara Power Station Endobara River Settling Basin?
- A sediment sluice sits in the middle of the west wall, and stone retaining walls are built on top of the east and south side walls to block debris from the slope.
- Can visitors see the Heisakubara Power Station Endobara River Settling Basin?
- Only the exterior, from places where access is allowed. The basin is part of a working plant, so its edges and operational areas are closed.
- How does the Heisakubara Power Station Endobara River Settling Basin differ from the Endo River basin?
- This basin is 55 metres by 5.5 metres, while the Endō River basin is 51 metres by 7.3 metres. Each was shaped to fit its valley.
Basic Information
| Name | Heisakubara Power Station Endobara River Settling Basin |
|---|---|
| Location | Endo area, Kamisaibara, Kagamino Town, Tomata District, Okayama Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2006/11/29 (Heisei 18) |
| Quantity | 1 site |
| Dimensions | 55 metres long, 5.5 metres wide, area 370 square metres |
| Owner | Chugoku Electric Power Co., Inc. |
| Public Access | Exterior viewing only; operational areas closed |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Endobara River Settling Basin
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006049
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Endobara River Intake Weir
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006048
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Endo River Settling Basin
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006047
- Chugoku Electric Power: History of Heisakubara Power Station (Japanese)
- https://www.energia.co.jp/isan/heisakubara_history.html
- Chugoku Electric Power: Heisakubara Power Station, Historic Electric Power Heritage (Japanese)
- https://www.energia.co.jp/isan/heisakubara.html
- Kagamino Town Tourism: Lake Onbara (Japanese)
- https://www.kagamino.holiday/spot/entry-322.html
Last verified: 2026.09.25
