鳥居忠政と治水工事の城郭改修,The Yamagata Goseki (Five Weirs) and the Livelihood of its People

Torii Tadamasa and Castle Renovation Through Flood Control Works

Torii Tadamasa, lord of Yamagata Domain from 1622 to 1628, is said to have constructed the Yamagata Goseki. In earlier times, the Mamigasaki River flowed near the area of present-day Bunshokan and frequently caused flooding, at times even reaching Yamagata Castle. To protect the castle town, Tadamasa carried out large-scale flood control works to redirect the river farther away from the urban center.

At the same time, canals were constructed to distribute water where it was needed for daily life and agriculture. These waterways became known as the Yamagata Goseki. Branching off from the Mamigasaki River, the goseki are: Sasazeki, Gotenzeki, Hakkagozeki, Miyamachizeki, and Sotsukizeki. Although no official documents from the time of construction remain, historical records state that after five consecutive days of heavy rain and flooding in 1623, Torii Tadamasa undertook river diversion works on the Mamigasaki River and established the goseki to secure water for household and agricultural use.