3195-Yasu River Dam/Yasugawa Dam

Location: 338, Okawara-aza, Tsuchiyama-cho, Koka-shi, Shiga
Date of interview: Monday, 12/06/2010

View of the top edge from the left bank

Normally, to get to this dam from my area, one would go from the Higashimeihan Yokkaichi Interchange through Komono Town and then go along the Suzuka Skyline to the dam. So we approached the dam from the Shin-Meishin Koga-Tsuchiyama Interchange.

Also, since I visited the site without a thorough preliminary study, I decided to look at it from the top level instead of from downstream.

And as you can see, the top edge is off-limits.

Yasu River Weir Completion Monument and Yasu River Dam Repair Completion Monument

The Yasu River Dam is a gravity-type concrete dam for irrigation only. The cities of Koka, Konan, Ritto, Moriyama, and Yasu downstream were breadbasket areas, but water shortages occurred frequently and water conflicts broke out frequently. In order to secure stable water for agriculture, this dam was started in 1939 as a prefectural project of Shiga Prefecture, which was also a long-cherished wish of farmers.

However, due to the intensification of the Pacific War in 1944, the project was suspended with the completion of temporary dam closure and temporary drainage tunnel construction.

In the chaotic postwar period, the situation was so dire that many people died of starvation. To overcome this situation, the then Ministry of Agriculture and Forestry launched the National Agricultural Water Utilization Project, and the National Yasu River Agricultural Water Utilization Project was put into effect in 1947.

The project was transferred from Shiga Prefecture to the Ministry of Agriculture and Forestry, construction resumed, and in 1951, the Yasu River Dam, a long-held dream of the farmers, was completed.

View of water intake facilities from the left bank

However, 50 years have passed since its construction, and the dam has become decrepit, so it has been repaired by raising the embankment and reconstructing the flood discharge. Therefore, the dam introduced here is the Yasu River Dam after the renovation work was completed. Although I like the old, smoked silver dam, a fully renovated modern concrete dam is not so bad either.

The water intake system is a spindle-type perforated sliding gate. Nevertheless, the water level was very low on this day, and we were happy to have a full view of it, lol.

View of the embankment on the lake side from the left bank

Crestgate is a trendy free overflow system.

Looking downstream from the left bank

It seems that the downstream side of the river is also well maintained, but when I visited the downstream side later, I found that it was fenced off and I could not enter. However, I was told a few years later that the fence was only for protection against animal damage and that the door could be opened and closed freely to enter. And after my second visit.... Well, it's ok, I can go there anytime because it's so close! I am suppressing my feelings.

View of the dam lake from the left bank

As you can see, the water level is this low.

Yasu River Dam Management Station

Now, we have come to the downstream. It looks like it could have appeared in the magazine "Shinkenchiku" (New Architecture). I have seen the control center of many dams, and I personally think it is the coolest.

View of the levee from downstream

I took this shot thinking that this was the best place to see downstream due to the aforementioned fence. I wanted to get closer to the levee. Maybe I will go back in the fall.

View of the left bank conduit wall from downstream

The control center is cool, but of course the dike is cool too. The more you look at this ledge wall in combination with the footings, the cooler it looks.

View of footing on left bank from downstream

It feels like it has been meticulously designed in every detail. Like the design of the administrative offices, I really like the overall sense of design.

View of the flood discharge from downstream

Personally, I prefer mechanical gates to these gateless types, but this is also a trend of the times. The historic Yasu River Dam has been reborn in this way, and I hope it will continue to do its best for the nation's 100-year plan.

The discharge on May 5, 2012

We were able to see the dam releasing water on May 5, 2012, when we revisited. The dam log is a brief summary of that time, so please refer to this page if you like. ⇒ The dam log is available here. Saw the discharge of the Yasu River Dam and the overflow of the Aodogi Dam | damlog :: damlog

Yasu River Dam specifications (specifications in parentheses are specifications before renovation, etc.)

Other facilities/observations