The First Step in a Mountain Water System
The Heisakubara Power Station Endo River Intake Weir (平作原発電所遠藤川取水堰堤, Endō River) is a concrete gravity weir built in 1928 across the Endō River in Kamisaibara, Kagamino Town, Okayama Prefecture, and registered as a Registered Tangible Cultural Property on 29 November 2006.
It is small: 18 metres long and 3.0 metres high. Its job is to raise the stream enough to divert water into the Endō River channel that feeds the power station. The Agency for Cultural Affairs describes it as the uppermost of all the hydropower facilities on the Yoshii River system, so this is where the water's journey to the turbines begins.
A settling basin built the same year sits against its right bank, and the Onbara Reservoir Dam stands about 1.7 kilometres to the north.
Curves Where You Might Expect Corners
The Heisakubara Power Station Endo River Intake Weir was registered as a structure that contributes to the historic scenery of the country. The listing covers the sluice gates and the stone revetment along the bank as well as the weir itself.
Like any gravity weir, it resists the water with its own mass, and its downstream face slopes back at a ratio of 0.8 to 1. What the agency singles out is the detailing: both the crest and the joint between the weir body and the apron below are formed as curves. With no sharp edges, water spilling over the top is guided down smoothly instead of crashing onto a corner.
Two sluice gates on the right bank are set parallel to the current, not square to the weir, so water is drawn off from the side of the flow into the intake.
What to Look For
Start with the profile. The flat crest rolls over into a curve, runs down the face and bends again into the apron. Seen side on, the two curves read as a single continuous line.
Then look at the gates. Because they line up with the river, the intake opens along the flank of the stream. The Endō River settling basin right beside it completes the sequence of intake, desilting and dispatch into the channel.
For comparison, the Endōbara River weir at the same power station is only 8.2 metres long, less than half this one. Seeing both shows how the designers scaled each structure to its stream.
Visiting the Endo River Intake Weir
The Heisakubara Power Station Endo River Intake Weir is a working intake managed by Chugoku Electric Power, and no visitor facilities are advertised. The weir, the gates and any gated or fenced operational area are closed to the public, so you can only see the exterior from places where access is permitted.
The site is in the mountains south of the Onbara Reservoir, in the Endō district. Water levels around an intake can change quickly, so stay off the riverbank. In winter the area is buried under deep snow.
The company's page for the station says nothing to restrict photographing the exteriors, but you cannot enter private land or operational areas to take pictures.
- 📍 Plan Your Visit to Okayama
- Find tours, activities & transport passes near Heisakubara Power Station Endo River Intake Weir
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Q&A
- What is the Heisakubara Power Station Endo River Intake Weir?
- It is a concrete gravity weir built in 1928 to divert water from the Endō River for Heisakubara Power Station. It is 18 metres long and 3.0 metres high, and it became a Registered Tangible Cultural Property in 2006.
- Can I visit the Heisakubara Power Station Endo River Intake Weir?
- You can look at the exterior from places where access is allowed. The weir itself and the operational areas are closed because the facility is still in use.
- What is special about the design of the Heisakubara Power Station Endo River Intake Weir?
- Its crest and the joint between the weir and the apron below are both shaped as curves, and its two sluice gates run parallel to the river.
- Where is the Heisakubara Power Station Endo River Intake Weir?
- It is in the Endō district of Kamisaibara, Kagamino Town, Okayama Prefecture, about 1.7 kilometres south of the Onbara Reservoir Dam. You will need a car.
- How is the Endo River Intake Weir related to the Endo River Settling Basin?
- The settling basin sits against the weir's right bank. Water taken in by the weir drops its silt there before entering the channel. Both were registered on the same day.
Basic Information
| Name | Heisakubara Power Station Endo River Intake Weir |
|---|---|
| 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 |
| Dimensions | Crest length 18 metres, height 3.0 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 Intake Weir
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006045
- 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 Endobara River Intake Weir
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006048
- 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
