Spillway

The spillway at Shimizusawa Thermal Power Plant carries the cooling water discharge from the plant back to the Yubari River below. The spillway is a concrete-lined channel running down the slope from the plant's outlet pipe to the river edge, the channel sized for the working flow rate of the plant in full operation. The concrete is the original 1926-era pour, weathered along the working surface where the water flowed for sixty-four years. Moss and small vegetation have grown along the edges of the channel where it sat dry between operating cycles. The outlet pipe at the upper end of the spillway is steel, painted dark, rusted at the joints.

Cooling water at Shimizusawa was drawn from the Yubari River through the pump house upstream, passed through the plant's condensers, and discharged back to the river through the spillway. After operations ceased in 1990 the cooling-water demand stopped. The spillway sat dry. The channel and the outlet pipe remain in place; the vegetation has had three decades to fill in the spaces between the concrete walls.