Waterfall Bridge (1925) was the fifth of 17 bridges constructed along 57 miles of carriage road on Mount Desert Island between 1917 and 1940. The bridge carries Jordan-Sargent Mountain Road over Upper Hadlock Brook at a 40-foot high waterfall. Along with Hemlock Bridge, located just one-tenth of a mile apart, it was one of two bridges required from Brown Mountain Highway around the west side of Sargent Mountain.

Measuring 120-feet long and 31-feet at its highest point, the masonry arch bridge is constructed of random-coursed ashlar granite over reinforced concrete, and is literally built into the stone around it. The bridge is skewed and curved to fit the topography, and although the stonework differs, its parapet walls curve with the road and end in spiraled end posts.

The semi-circular arch, 26-feet wide, has a ring of 30 quarry-faced radiating voussoirs, and is flanked by two round buttress-like towers which form lookouts at the parapet level. From these lookouts, there is a view of the waterfall on the upstream side, and a vista (now obscured by overgrown trees) across the Hadlock Ponds to the ocean beyond. The curve of the bridge and the semi-circular arch result in a skewed barrel which is also faced with stone as it is visible in approaching the bridge. Flattened-arch parapet walls have large projecting granite capstones and terminate in scrolled endings or “curtails."

Costs exceeded estimates by nearly 25 percent, and Waterfall Bridge was completed in 1925 for $44,103.81.