The Takahashi River is a first-class river that flows through western Okayama Prefecture.
In Kurashiki City, it is a water source that supports daily life and industry, used mainly for tap water, agricultural water, and industrial water.
The author, born in 1979 and raised in Kurashiki, has no memory of river flooding or similar events over the past 40 years or so.
For that reason, perhaps other Kurashiki City residents also think of the Takahashi River as a calm river.
However, did you know that until about 100 years ago, it repeatedly flooded and caused hardship for many people?
It was once divided into the West Takahashi River and East Takahashi River, and the present-day areas of Kurashiki, Mizushima, Funao, and Tamashima were created by reclaiming the land between them. These reclaimed lands were vulnerable to flood damage.
According to the “History of Kibi County,” 36 floods were recorded over the 170 years from 1664 to 1834.
In other words, flooding occurred once every five years.
Residents therefore petitioned almost every year from around 1883, and in 1911, work began on river improvements under the direct control of the Ministry of Home Affairs at the time.
This was a “national project” that spanned 14 years, from 1911 to 1925.
This article introduces the history of the Takahashi River East-West Irrigation Water Intake and Distribution Facilities, as well as the work of the Takahashigawa Tozai Yosui Association, which has managed water intake and distribution since the facilities were built.
The information presented is as of the article’s publication in January 2022. Please note that it may differ from current information.
What are the Takahashi River East-West Irrigation Water Intake and Distribution Facilities?
The Takahashi River East-West Irrigation Water Intake and Distribution Facilities are agricultural water facilities developed alongside the major Takahashi River improvement project, which began in 1911.
The major Takahashi River improvement project was truly a monumental undertaking that took 14 years to complete, and consisted mainly of the following work:
- Blocking off the East Takahashi River at Sakazu and joining it to the West Takahashi River downstream (the East Takahashi River was discontinued)
- Widening the entire river channel to improve water flow
- Deepening the riverbed and building strong embankments, among other work
Since then, flood damage has fallen dramatically to just a few cases, and the situation remains so today.
At Sakazu, where the East Takahashi River was blocked off, 11 separate intake sluice gates that had stood on both banks of the Takahashi River were consolidated into a single intake sluice gate and distribution facilities.
These are the Takahashi River East-West Irrigation Water Intake and Distribution Facilities.
The East-West Irrigation Water facilities are not for drinking water (tap water), but are intended to distribute agricultural water. They consist mainly of the following facilities:
- Kasai Weir
- Intake Sluice Gate
- Distribution Basin
- South Distribution Sluice Gate
- North Distribution Sluice Gate
With a history of nearly 100 years, the East-West Irrigation Water facilities have also been selected as one of Japan’s Top 100 Irrigation Canals (February 2006).
Some of the facilities have been designated as Modernization Industrial Heritage and Important Cultural Properties (structures), and are also constituent cultural properties of Japan Heritage. Although some people may think of them as historical cultural heritage, they still exist and remain in use today.
| Name | Recognition/designation date | Facilities covered |
|---|---|---|
| Civil Engineering Heritage | November 2003 | ・Intake Sluice Gate ・South Distribution Sluice Gate ・North Distribution Sluice Gate |
| Modernization Heritage | March 2005 | ・Takahashigawa Tozai Yosui Association Office ・Intake Sluice Gate ・South Distribution Sluice Gate ・North Distribution Sluice Gate |
| Japan’s Top 100 Irrigation Canals | February 2006 | ・Takahashi River East-West Irrigation Water |
| Modernization Industrial Heritage | February 2009 | ・Sakazu Sluice Gate of the Takahashi River East-West Irrigation Water ・Takahashigawa Tozai Yosui Association Office |
| National Important Cultural Property (structure) | July 2016 | ・Takahashi River East-West Irrigation Water Intake and Distribution Facilities |
| Japan Heritage Constituent Cultural Property | April 2017 | ・Takahashi River East-West Irrigation Water Intake and Distribution Facilities |
Kasai Weir
A weir is a structure that blocks the river’s flow to divert water through the single consolidated intake sluice gate.
Built across the Takahashi River on both banks, with the river’s midstream island, Mt. Myoken, between them, Kasai Weir regulates the water level of the Takahashi River and enables smooth intake into the distribution basin.
It has now been renovated into a hydraulically operated tilting gate that can be controlled remotely, but it is aging, and reconstruction is planned.
The name “Kasai Weir” was given in honor of Shinichi Kasai, the Okayama Prefectural Governor at the time the East-West Irrigation Water facilities were completed in 1925.
Intake Sluice Gate
The Intake Sluice Gate is the facility that channels water from the Takahashi River, held back by Kasai Weir, into the distribution basin.
It is on the left bank of the Takahashi River, just upstream from Kasai Weir.
Distribution Basin
Water from the Takahashi River brought in through the Intake Sluice Gate first flows into the distribution basin.
The banks are lined with cherry trees, making this a popular spot for hanami in spring and a place where residents can relax while jogging or walking at other times.
However, the distribution basin is more than just a reservoir: it temporarily stores water for distribution to irrigation channels and also serves as a settling basin for sand and gravel.
South Distribution Sluice Gate
From left: Seigan Irrigation Canal, Seibu Irrigation Canal, Nanbu Irrigation Canal, Bizenbi Irrigation Canal, Kurashiki Irrigation Canal
The sluice gate located south of the distribution basin is the South Distribution Sluice Gate.
Even if the name “Takahashi River East-West Irrigation Water Intake and Distribution Facilities” doesn’t ring a bell, you may recognize this structure.
There are 15 sluice gates in total, each 1.2 meters high and 1.18 to 1.75 meters wide.
Their arch-like shape is striking, but they serve the important function of distributing water to five of the six irrigation canals: Kurashiki, Bizenbi, Nanbu, Seibu, and Seigan.
North Distribution Sluice Gate
The sluice gate on the north side of the reservoir is the North Water Distribution Sluice Gate.
It supplies water to the Yatsugago Irrigation Canal, and just ahead is “Mizube no Cafe Miyake Shoten Sakazu.”
The Takahashigawa Tozai Yosui Association was established to ensure fair distribution of irrigation water
The East-West Irrigation System, which is still operating today, is run using this system.
Since then, not only flood damage but also droughts have fallen to just a few cases, and the area has become a comfortable place to live, allowing the Kurashiki region to prosper.
However, we must not forget that the prosperity of the Kurashiki region was due not only to its excellent facilities, but also to the fact that a system covering everything from water intake to distribution was created at the same time.
More than 100 years ago, agriculture was the main industry. Water posed not only the threat of flooding but also the pressing problem of “disputes over irrigation water.”
If large amounts of water are taken upstream, water shortages occur downstream. This was a matter of life and death, especially for farmers in the East Takahashi River basin, whose river had been blocked off.
To resolve these problems and ensure fair distribution of irrigation water, the Takahashigawa Tozai Yosui Association was established in 1916.
Under the Takahashigawa Tozai Yosui Association, the 11 separate water intake sluice gates on both banks of the Takahashi River were consolidated into one system, allowing water to be distributed fairly from the reservoir.
All the sluice gates are the same height. By changing their widths and numbers, water was distributed as before.
| Water Distribution Sluice Gate | Irrigation Canal | Number of Sluice Gates |
|---|---|---|
| South Water Distribution Sluice Gate | Kurashiki Irrigation Canal | 2 |
| 〃 | Bizenhi Irrigation Canal | 2 |
| 〃 | Southern Irrigation Canal | 5 |
| 〃 | Western Irrigation Canal | 3 |
| 〃 | West Bank Irrigation Canal | 3 |
| North Water Distribution Sluice Gate | Yatsugago Irrigation Canal | 6 |
※Quoted from “Takahashigawa Tozai Yosui Association: 100 Years of History”
The Takahashigawa Tozai Yosui Association Office retains its Taisho-era appearance
The Takahashigawa Tozai Yosui Association Office is still located close to the East-West Irrigation System.
If you live in Kurashiki City, have you ever noticed this retro building near Sakazu Park, a familiar cherry-blossom viewing spot?
The association office is a two-story wooden building, and as of January 2022, four staff members work there.
Here is a brief look inside the building.
The interior features exposed timber framing, wainscoting, and plastered partition walls
※They are no longer in use (the switch on the left in the photo is used)
Staff working at the association office
From left: gatekeeper Kunibe, office clerk Nakahara, chief Okamoto, deputy administrator Kono
As of January 2022, the following four people work there full-time.
- Deputy administrator
- Chief
- Office clerk
- Gatekeeper
Incidentally, the administrator is Kurashiki City Mayor Kaori Ito.
The administrator at the time of the association’s establishment was designated as the Governor of Okayama Prefecture under its regulations. However, following a revision to the regulations in 1964, the administrator has been elected by the association council from among the mayors of the municipalities in the association, and the Mayor of Kurashiki City has been elected ever since.
In addition to maintaining and managing the sluice gates and reservoirs, the association regulates the amount of water taken in and distributed. (Most of the equipment has now been electrified and can reportedly be operated from the control room on the premises.)
The watchman lives in the staff quarters next to the office, allowing them to respond immediately in an emergency.
Since its completion in 1925, the Takahashigawa Tozai Yosui Association has maintained and managed the east and west irrigation canals for nearly 100 years. We spoke with staff about their work and what they would like local residents to know.
Interview with Takahashi River Tozai Yosui Association staff Kono Hiroshi and Okamoto Yumiko
We asked Kono Hiroshi, deputy administrator of the Takahashigawa Tozai Yosui Association, and Okamoto Yumiko, a chief, about the association and their work.
Why they came to work for the Takahashigawa Tozai Yosui Association
First, when did you start working here?
Kono
We both started in April this year (2021). We were appointed after retiring from Kurashiki City Office.
The Takahashigawa Tozai Yosui Association is classified as a “partial-affairs association.” The association’s administrator is the Mayor of Kurashiki City, and the Mayor of Hayashima Town serves as an adviser.
A partial-affairs association is an administrative body established by multiple local governments (such as cities, towns, villages, and special wards) to jointly provide some administrative services.
What kind of work does the Takahashigawa Tozai Yosui Association do?
What specific work does the Takahashigawa Tozai Yosui Association do?
Kono
The watchman handles most of the raising and lowering of the Kasai Weir’s tilting gates and the management of the sluice gates. In particular, the Kasai Weir has not been electrified, and its operating procedure is complicated.
However, since we are sometimes away, everyone, including me, is trained to open and close the sluice gates.
What has changed and what has stayed the same since it was completed in 1925?
Kono
The way it is operated has changed.
One sluice gate for each irrigation canal has been electrified, so it can now be operated from the control room on the premises.
It is faced with stone over reinforced concrete, so I don’t think its appearance has changed.
When do you open and close the sluice gates?
Kono
Basically, we act on the administrator’s instructions, but often we open and close them at the direction of the Farmland and Waterway Division, which receives instructions from the mayor.
The instructions are not issued because it is raining or has rained; they are usually given three or four days in advance based on the weather forecast and other information.
As a result, we often end up taking action unnecessarily, but we do this from a disaster-prevention perspective.
Is it something like emptying the canals to prepare for heavy rain?
When it was completed, the purpose was to supply water for agriculture. Is disaster prevention now the more important role?
Kono
No, that’s not the case.
The purpose of the east and west irrigation canals is simply to take in and convey water for agriculture.
What kind of work do you do during normal times?
Kono
The amount of water distributed is set for each period, so we adjust the sluice gates accordingly.
Also, when there is construction or cleaning work somewhere, we receive instructions for each canal, such as “lower the water level to XX centimeters,” and respond accordingly.
Okamoto
In summer, we also remove algae from the distribution reservoirs. All the staff do this together for about two days each week.
It’s quite strenuous work.
Kono
That’s why this job requires stamina and motivation (laughs).
Photo courtesy of the Takahashigawa Tozai Yosui Association
Do you also clean the bottoms of the reservoirs regularly?
Okamoto
We periodically dredge the bottoms of the distribution reservoirs to remove sediment and other material, but we haven’t done so recently.
The last time was in 2002, so it was 20 years ago.
According to the records, only part of the reservoir was dredged then. The last time it was done in its entirety was in 1984, nearly 40 years ago.
What they would like to do in the future and the challenges they face
You mentioned that you only took up your posts this fiscal year. Is there anything you would like to do in the future, or any challenges you face?
Okamoto
I’d like to display materials on the history of the east and west irrigation canals and the Takahashi River in a room on the first floor. I hope this will give local children a chance to learn about how the town they live in came to be, and help them feel a stronger attachment to and affinity for their community.
Kono
Nearly 100 years have passed since its completion, and the structure is deteriorating. However, because it is an Important Cultural Property, repairs cannot be carried out easily.
In many cases, repairs would require removing the stone facing to fix the reinforced-concrete structure inside.
After repairs, the “original stones” must be put back, which is costly. What’s more, it is almost impossible to obtain the “original stones.”
I think we need to consider how to carry out future repairs while continuing to maintain the structure.
What they want Kurashiki City residents to know
Finally, is there anything you would like Kurashiki City residents to know?
Okamoto
The Takahashigawa Tozai Yosui Association’s main role is maintaining and managing the irrigation facilities, so we rarely warn people for doing things at Sakazu Park.
However, the one thing we do warn people about is jumping into the distribution reservoirs.
It’s dangerous for children, of course, but adults should be careful too.
That’s because many people think the distribution reservoirs are very deep, but in fact, an adult can stand with their feet on the bottom (about 150 centimeters deep).
So if you jump in, you could hit the bottom. The current is also fast near the sluice gates, and you could get trapped in them, making it extremely dangerous.
Kono
Please value water.
Valuing water also means keeping rivers and ponds clean.
We maintain and manage the east and west irrigation canals, so people don’t need to give them any special thought in their daily lives.
However, recently, a bed was dumped in one of the distribution reservoirs.
Please take good care of this remarkable water-use system, built about 100 years ago, so that it can continue to be used for as long as possible.
The system is located within Sakazu Park, a place where Kurashiki City residents can relax, and we want people to enjoy their time here.
From the Writer
I’m embarrassed to admit that I thought the water-distribution facilities, such as the sluice gates, were no longer in use, even though they were still there. I also didn’t know that people still worked in the Takahashigawa Tozai Yosui Association office building.
Okayama is known as the “Land of Sunshine,” a region with few natural disasters, but the foundation for this was the water-use system called the east and west irrigation canals, built nearly 100 years ago, which played a major role.
It may be difficult to think about systems that were already in place before we were born.
However, the calm river and the water we take for granted were made possible by the wisdom of those who came before us, and the system is still in use today, maintained and managed by people.
I felt that as many people as possible should know this.
- A 100-Year History of the Takahashigawa Tozai Yosui Association
- Commemorative Book for the 100th Anniversary of the Takahashigawa Tozai Yosui Association
Articles about Kurashiki City’s Japan Heritage
Takahashigawa Tozai Yosui Association Information
| Organization Name | Takahashigawa Tozai Yosui Association |
|---|---|
| Industry | Repair and management of water distribution sluice gates and reservoirs, and operation of necessary water intake and distribution |
| Representative | Administrator: Kaori Ito (Mayor of Kurashiki City) |
| Year Established | 1916 (1916) |
| Address | 2826 Sakazu, Kurashiki City, Okayama Prefecture |
| Contact | 086-422-0219 |
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