A Reservoir Buried Under a Lawn
The Midoricho Distribution Plant Reservoir (緑町配水場配水池, Midoricho Haisuijo Haisuichi) at 1-3780 Midoricho in Ashikaga City, Tochigi Prefecture, is a reinforced concrete water reservoir completed in December 1930 and entered on the national register of Tangible Cultural Properties on 2 March 2006 under register number 09-0134.
Most visitors walk over it without noticing. The tank measures roughly 60 metres by 27 and covers 1,606.73 square metres, but it is sunk into the summit of the hill above Ashikaga Park and its roof is turfed, deliberately, so that the structure reads as lawn rather than infrastructure. What breaks the surface are two small concrete buildings on the east side, set almost symmetrically, and those are worth the climb.
Water reached the city from here in April 1931, four months after the tank was finished. The arrangement has not changed since. Groundwater is gathered through infiltration galleries at the Imafuku Purification Plant on the flat ground to the west, pumped up the hill, held in this tank, and released to households by gravity alone, using the fall between a stored water level of 72.4 to 76.0 metres and the town below. No pumps at this end. The hill does the work.
Three Chambers, and the Decade That Added the Third
The interior is divided into three basins. That number is the result of a later campaign rather than the original design. As first built the reservoir held about 120,000 cubic shaku, roughly 3,340 cubic metres, sized against a city population of some 43,000 and a first-phase target of 55,000 served. Postwar demand outran it. A further basin was raised alongside the original tank on its northeast side, bringing the plant to its present capacity of 5,100 cubic metres in three basins of 1,700 each, at a water depth of 3.6 metres.
Sources differ slightly on when. The Agency for Cultural Affairs records the extension as around 1955; Ashikaga City, citing its own waterworks department records, gives 1953 to 1956, and places the work within a first expansion project said to have run from 1953 to 1958. The discrepancy is narrow and both accounts put the job in the mid-1950s.
The two structures on the lawn are the water-level gauge house and the maintenance and inspection entrance. Both are handled in a heavy geometric idiom that Japanese architectural writing calls Secession style, after the Viennese movement whose vocabulary reached Japan in the 1910s and lingered in public works long after it had faded in Europe. Each has a hexagonal plan with pilaster forms worked into every corner, and above the cornice moulding a parapet rises with its joints left visible as a pattern. They are small buildings given the treatment of monuments, which is roughly how the city of 1930 felt about its water.
Two Inscriptions Worth Finding
On the west face of the maintenance and inspection entrance is a stone tablet reading Gensen konkon, an image of a spring welling up without end, composed by Ogyu Shin, mayor at the time the founding waterworks project was completed. On the west face of the water-level gauge house is a second tablet, Seicho muhi, praising the clarity of Ashikaga's groundwater beyond comparison, written by Kimura Asashichi, mayor when the expansion finished. The two stones bracket a quarter of a century of municipal effort, and they sit about thirty metres apart.
Practical points. The plant is in service and the grounds are not open for casual inspection; Ashikaga City lists the site as normally closed, and any interior access depends on a special-viewing day announced by the municipal government. Enquiries go to the Cultural Affairs Division of the Board of Education, or to the waterworks section for questions about the plant itself. No photography rule has been published, so ask when you arrive. The hill is the same one that carries Ashikaga Park and its burial mounds, about thirty minutes on foot from JR Ashikaga Station or Tobu Ashikagashi Station and under ten by taxi, and the view east over the Watarase River is free to anyone who walks up.
Three more registered structures stand nearby: the former office, now Suidoyama Memorial Hall, the junction well at the southwest corner, and a measuring room of just four square metres. The pump room at Imafuku makes five, all registered on the same day.
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Q&A
- Can visitors see the Midoricho Distribution Plant Reservoir?
- The reservoir is buried and turfed over, so there is nothing to enter, and Ashikaga City lists the plant as normally closed to visitors because it remains in service. The two small structures on the lawn have been visible on special-viewing days announced by the city.
- How large is the Midoricho Distribution Plant Reservoir and how much water does it hold?
- It covers 1,606.73 square metres, roughly 60 by 27 metres, and is divided into three basins holding 1,700 cubic metres each, 5,100 in total, at a depth of 3.6 metres. As first built in 1930 it held about 3,340 cubic metres.
- When was the Midoricho Distribution Plant Reservoir built and registered?
- It was completed in December 1930 and began distributing water in April 1931. Registration as a national Tangible Cultural Property took effect on 2 March 2006, gazetted on 23 March, under register number 09-0134.
- What are the two small buildings on top of the Midoricho reservoir?
- They are the water-level gauge house and the maintenance and inspection entrance, placed almost symmetrically on the east side. Both are hexagonal in plan with pilasters at the corners and a jointed parapet above the cornice, in the Secession-influenced manner used across the plant.
- How does water reach Ashikaga households from the Midoricho reservoir?
- Groundwater collected at the Imafuku Purification Plant is pumped up to this hilltop tank, then flows out to the city by gravity, using the height difference rather than further pumping. The system has worked this way since 1931.
Basic Information
| Name | Midoricho Distribution Plant Reservoir (緑町配水場配水池) |
|---|---|
| Location | 1-3780 Midoricho, Ashikaga City, Tochigi Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), register number 09-0134 |
| Year Designated | Registered 2 March 2006, gazetted 23 March 2006 |
| Quantity | 1 unit |
| Dimensions | Reinforced concrete, area 1,606.73 m² (about 60 × 27 m), with water-level gauge house and maintenance and inspection entrance; completed December 1930, extended mid-1950s |
| Owner | Ashikaga City waterworks utility |
| Public Access | Normally closed; opened occasionally by the city |
References
- Agency for Cultural Affairs — National Cultural Properties Database, Midoricho Haisuijo Haisuichi
- https://kunishitei.bunka.go.jp/heritage/detail/101/00005239
- Ashikaga City — Registered Tangible Cultural Properties among the city's waterworks facilities
- https://www.city.ashikaga.tochigi.jp/urban/000070/000943/p003271.html
- Ashikaga City — Midoricho Distribution Plant: memorial hall, reservoir, junction well and measuring room
- https://www.city.ashikaga.tochigi.jp/education/000029/000169/000627/p000937.html
- Ashikaga City — Outline of waterworks facilities
- https://www.city.ashikaga.tochigi.jp/living/000021/000142/000585/p003291.html
Last verified: 2026.08.05