Arakawa Third Dam

What the Arakawa Third Dam Is

The Arakawa Third Dam (荒川第三堰堤, Arakawa Dai-san Entei) is a gravity-type concrete sabo dam built in 1940 on the Arakawa River at Sawaoriba, Tsuchiyu Onsen-cho, in Fukushima City, Fukushima Prefecture, and registered as a Registered Tangible Cultural Property (structure) of Japan on March 7, 2008. It is 47 meters long and 15 meters high, and Fukushima City lists the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) as the owner.

One of the 15 registered Arakawa River Sabo Dams, it stands about 1,200 meters upstream of the Arakawa Eighth Dam and is the farthest upstream of the registered dams on the main river. Its registration number is 07-0092.

The Tallest Prewar Dam on the Arakawa

The Agency for Cultural Affairs identifies the Arakawa Third Dam as the tallest of the dams built on the Arakawa before the war. National sabo work started in 1936, produced the Arakawa First Dam in 1937 and the Arakawa Second Dam in 1938, and reached this third dam in 1940. Its two predecessors are 10 meters and 13 meters high. The Third reaches 15.

Height grows with distance upstream because the valley closes in. The Arakawa cuts down from the Azuma range through deeply eroded hills, and near its upper end the banks pinch together. A dam that cannot be built wide generally has to be built tall to hold back the same load of sediment.

A Shape Set by the Gorge

The Agency notes that the Arakawa Third Dam sits in a narrow gorge carved by vertical erosion, the process by which a river keeps cutting its bed downward until the walls stand steep on either side, and that the shape of the dam body expresses those conditions well.

The numbers make the point. The Third Dam is 47 meters long and 15 meters high, so its length is only about three times its height. Downstream, the Arakawa Fifth Dam is 150 meters long and 12 meters high, a ratio of more than 12 to 1. One is a tall slot of masonry, the other a long low wall. Both are faced in stone.

The address of the Arakawa Third Dam is given as Sawaoriba in the Agency's database and as Oriba in Fukushima City's list of cultural properties. This article follows the Agency's spelling.

Seeing the Arakawa Third Dam

The Arakawa Third Dam is a working sabo structure. Viewing is free from the surrounding ground; walking on the dam or entering the riverbed is not allowed.

What you come for is the upright dam body filling the width of the gorge. Its short, tall proportions show how closely the structure was fitted to the width of the gorge. If you have walked up past the lower dams, the Third reads as the end point of a sequence in which each dam grows narrower and taller as the valley tightens.

Because it is the farthest upstream of the registered main-river dams, reaching it on foot from Tsuchiyu Onsen means a mountain walk, and Fukushima Prefecture warns that some of these sites require a round trip of two hours or more or a light hike. Do not enter the gorge after rain. Directions to the area are on the Arakawa River Sabo Dams page.