Where the Mountain Stream Drops Its Silt
The Heisakubara Power Station Endo River Settling Basin (平作原発電所遠藤川沈砂池, Endō River) is a reinforced concrete settling basin built in 1928 on the right bank of the Endō River intake weir in Kamisaibara, Kagamino Town, Okayama Prefecture, and registered as a Registered Tangible Cultural Property on 29 November 2006.
It measures 51 metres long and 7.3 metres wide, with an area of 506 square metres. Water diverted by the weir passes through this long tank, slows down and drops its sand and gravel before moving on into the channel.
Turbines hate grit. Even fine sand wears down a runner, so removing silt close to the intake is basic practice at any hydro plant. At Heisakubara, this basin has done that job right beside the stream since the plant opened.
Concrete Inside, Granite Outside
The Heisakubara Power Station Endo River Settling Basin was registered as a structure that contributes to the historic scenery of the country. The Agency for Cultural Affairs notes that it was built on the fast, silt-laden upper reach of a mountain stream to clean water for generation.
The key element is the west wall, which separates the channel from the river. On its river face it is clad in granite laid in the Tanizumi style, with stones set diagonally so the face that takes the brunt of floods is protected by stone.
A sluice for flushing sediment is set in the north wall. When silt builds up on the floor, opening this gate sends it back into the river.
What to Look For
Look at the wall that faces the river. One side is smooth reinforced concrete, the other diagonal granite masonry. That single wall shows how the engineers of 1928 paired a new material with a much older way of building.
Then consider the plan. The basin is 51 metres long but only 7.3 metres wide, giving the water a long, slow run in which to drop its load.
The Endōbara River settling basin at the same plant is even slimmer, at 55 metres by 5.5 metres. Comparing the two shows how each was fitted to its own valley.
Visiting the Endo River Settling Basin
The Heisakubara Power Station Endo River Settling Basin is a working facility run by Chugoku Electric Power, and no visitor facilities are advertised. The basin edge, the sluice and any gated or fenced area are off limits; you can only see the exterior from places where access is permitted.
It sits in the mountains of the Endō district, directly beside the Endō River intake weir. Keep away from the water's edge, as levels and currents can change quickly. Deep snow covers the valley in winter.
Chugoku Electric's page for the station gives no restriction on photographing exteriors, but operational areas cannot be entered for photos.
- 📍 Plan Your Visit to Okayama
- Find tours, activities & transport passes near Heisakubara Power Station Endo River Settling Basin
- [ Kurashiki Bikan District & Korakuen Garden Tours ]
Q&A
- What is the Heisakubara Power Station Endo River Settling Basin?
- It is a reinforced concrete basin built in 1928 to remove sand and gravel from water taken in at the Endō River weir. It became a Registered Tangible Cultural Property in 2006.
- How big is the Heisakubara Power Station Endo River Settling Basin?
- It is 51 metres long and 7.3 metres wide, with an area of 506 square metres.
- What are the main design features of the Heisakubara Power Station Endo River Settling Basin?
- Its west wall is faced with diagonally laid granite on the river side, and a sediment sluice is built into the north wall.
- Can visitors see the Heisakubara Power Station Endo 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.
- Where is the Heisakubara Power Station Endo River Settling Basin?
- It is beside the Endō River in the Endō district of Kamisaibara, Kagamino Town, Okayama Prefecture, directly against the right bank of the intake weir.
Basic Information
| Name | Heisakubara Power Station Endo 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 | 51 metres long, 7.3 metres wide, area 506 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 Endo River Settling Basin
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006047
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Endo River Intake Weir
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006045
- 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
- 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
