第一大川橋梁, bridge in Japan

The Daiichi Okawa Bridge was a single-track railway bridge on the former JNR Aizu Line, spanning the Aga River (Okawa) on the boundary between Aizu-Wakamatsu and Shimogo, Fukushima Prefecture. Completed in 1932, it consisted of eleven through-plate-girder spans and climbed toward Yuno on a 25‰ gradient. Its girders were removed in 1980 when the line was rerouted for the Okawa Dam; the abutments now lie submerged in Wakaso Lake, crossed overhead by the Okawa Lake Surface Bridge.

Completed in 1932 during the extension of the JNR Aizu Line between Kami-Yosoi (now Ashinomaki-Onsen) and Yuno (now Yunokami-Onsen) stations, the bridge carried the single-track line over the Agagawa River between Kuwabara and Yuno. It was removed in 1980 when the line was rerouted around the new Okawa Dam reservoir, submerging the old alignment.

The bridge itself is gone: its abutments lie under Lake Wakago, and the Lake Wakago surface bridge of Fukushima Prefectural Route 214 now crosses above them. The old line climbed toward Yunoami at a 25‰ gradient, not 25%. The relocated Kuwabara and Yunoami stations serve the current Aizu Railway line.

The old line left Kuwabara Station on a climb, crossed this bridge over the Agagawa, then entered the First Konumazaki Tunnel, now also submerged. The stretch from Kuwabara to Yunokami was called the most beautiful on the Aizu Line, and this bridge, with the Second Okawa Bridge, drew railway fans and photographers.