Shohoji River Tanukizawa No. 3 Stone Dam

Shobojigawa Tanukisawa Dam No. 3

The tallest of the three Tanukisawa dams, No. 3 finishes its crest with pentagonal stones, a place where the mason's choices in splitting and setting rock remain visible.

In 1913 a great flood tore through the Shobojigawa valley. In response, Yamagata Prefecture spent the years from 1922 to 1927 building masonry check dams through the ravines above Shimo-Oginoto in Tendo City. The stream drains through the Kuratsugawa into the Mogami River.

Roughly thirty-five metres below Dam No. 2. Its crest is laid with pentagonal stones, a detail that catches the eye. One of a tight sequence set along a steep-gradient stream to steady the bed as a whole.

Why It Matters

The system divides among three side-ravines, north, Tanuki and south, each carrying its own line of stone dams, with wire-gabion works to blunt the force of the water. The reliance on many small and medium dams rather than a single giant reflects the sabo engineering of the day.

The stones are coursed diagonally, the tanizumi bond, and mortared between, the nerizumi finish, so the body holds together under pressure. Like the other dams here it is built mainly of rhyolitic welded tuff. The downstream face carries a 3-bu batter.

Intact groups of stone check dams from the 1920s are not common. The 2005 listing set the whole undertaking, a community's long reckoning with landslide and flood, in the frame of cultural heritage.

Seeing It Today

Reaching the dam means walking mountain paths, best avoided after rain or during snowmelt when the stream runs high. Seen from nearby, each block of rhyolitic welded tuff, split and set by hand, still carries the mark of the mason who placed it.

The dam measures 11 metres along its crest and stands 3.2 metres high. It belongs to the Tanukisawa branch and was completed in 1923.