Nagawado Dam, Hydroelectric dam in Nagano Prefecture, Japan.

Nagawado Dam is a 155-metre dome-shaped concrete arch dam on the Azusa River in Matsumoto, Nagano Prefecture, completed in 1969. Its crest carries National Route 158, and the reservoir behind it, Lake Azusa, holds 123 million cubic metres, the largest volume of any dam reservoir in the Shinano River system. The dam's downstream face curves outward from the base, so rain does not reach it and the concrete stays white.

Construction began in 1961 and finished in 1969 during Japan's rapid post-war infrastructure expansion. This project was one of many energy facilities built to support the nation's growing industrial and urban development.

The name Nagawado comes from the hamlet at the junction of the Azusa and Nagawa rivers. When TEPCO announced it would call the dam Azumi, residents of the former Nagawa village protested, and the company kept the local name. The reservoir is called Lake Azusa; the dam's crest carries National Route 158, and the Nagawa-Kiso prefectural road starts here.

National Route 158 runs across the dam crest and is open to traffic, linking Matsumoto with Takayama and giving access to Kamikochi and Norikura. The crest is also the start of Nagano Prefectural Route 26. The former TEPCO visitor center, Azusa Tepco-kan, closed in 2011.

The dam's arched crest carries National Route 158, and its dome shape leans downstream so the lower face stays dry and the concrete remains white. The reservoir, Lake Azusa, holds 123 million cubic metres, the largest volume of any dam reservoir in the Shinano River system.