Where the Waterway Meets the Penstock
The Heisakubara Power Station Head Tank (平作原発電所水槽) is a reinforced concrete head tank built in 1928 on a hillside in Kamisaibara, Kagamino Town, Okayama Prefecture, and registered as a Registered Tangible Cultural Property on 29 November 2006.
Roughly rectangular, about 25 metres by 10 metres, it covers 355 square metres. Water arrives here after a run of about 2.3 kilometres from the main waterway settling basin, pauses, and is then fed into the steel pipe that plunges down the slope. The main building of the power station stands about 330 metres below.
In a conduit-type plant, water gains height by running along a gently graded channel and is then dropped all at once through a penstock onto the turbines. The head tank is the buffer between the slow channel and the high-pressure pipe. Chugoku Electric gives the plant's maximum effective head as 143.64 metres.
Clean Water, Good Cement
The Heisakubara Power Station Head Tank was registered as a structure that contributes to the historic scenery of the country.
The Agency for Cultural Affairs notes a sediment sluice in the middle of the north wall, which runs parallel to the spillway channel. Grit picked up along the 2.3-kilometre waterway can be flushed out here before it reaches the penstock, even though the water has already passed through a settling basin upstream.
The agency also points out the cement: like the plant's other structures, the tank was built with high-grade cement from the Asano and Onoda companies. On a site where every sack had to be hauled into the mountains, the builders still paid attention to quality.
As the starting point of both the penstock and the overflow channel, the tank is a pivot in the plant's water system.
What to Look For
Picture the line that links three registered structures. The main building stands about 330 metres downstream of the tank, the penstock runs between them, and granite retaining walls brace the slope beside it.
Notice, too, how the north wall runs parallel to the spillway channel, so surplus water and flushed sediment can go straight into it.
From outside, a concrete box of 25 by 10 metres is easy to overlook. Yet every drop of water that turns the turbines passes through it.
Visiting the Head Tank
The Heisakubara Power Station Head Tank is a working facility run by Chugoku Electric Power; its interior and the surrounding operational area are closed. The company says the station's exteriors can be viewed at any time, but the tank sits on the hillside above the main building and no path leading close to it is advertised.
Chugoku Electric gives about 70 minutes by car for the station address (Heisakubara 1878, Kamisaibara) via the Innoshō Interchange on the Chūgoku Expressway, and about 75 minutes by car via JR Innoshō Station on the Kishin Line. Deep snow covers the area in winter.
The company's page gives no restriction on photographing exteriors, but operational areas cannot be entered for pictures.
- 📍 Plan Your Visit to Okayama
- Find tours, activities & transport passes near Heisakubara Power Station Head Tank
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Q&A
- What is the Heisakubara Power Station Head Tank?
- It is a reinforced concrete head tank built in 1928 to hold water arriving by channel and feed it through the penstock to the main building. It became a Registered Tangible Cultural Property in 2006.
- How large is the Heisakubara Power Station Head Tank?
- It is roughly rectangular, about 25 metres by 10 metres, with an area of 355 square metres.
- What is distinctive about the Heisakubara Power Station Head Tank?
- A sediment sluice sits in the middle of the north wall, which runs parallel to the spillway channel. It was built with high-grade Asano and Onoda cement.
- Can I visit the Heisakubara Power Station Head Tank?
- It is part of a working plant, so its interior and operational area are closed, and no path to it is advertised.
- How far is the Heisakubara Power Station Head Tank from the main building?
- The main building stands about 330 metres below the tank, connected by the penstock.
Basic Information
| Name | Heisakubara Power Station Head Tank |
|---|---|
| Location | Heisakubara 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 | About 25 metres by 10 metres, area 355 square metres |
| Owner | Chugoku Electric Power Co., Inc. |
| Public Access | Exterior only; operational areas closed |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Head Tank
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006050
- Cultural Heritage Online: Heisakubara Power Station Head Tank (Japanese)
- https://bunka.nii.ac.jp/heritages/detail/152655
- Agency for Cultural Affairs, Database of National Cultural Properties: Heisakubara Power Station Main Building
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00006051
- 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
