A photograph from Scientific American dated February 5, 1898, documents the initial phase of New Croton Dam construction—redirecting the Croton River's natural flow to create the excavation site for the dam's foundation.

The project commenced on September 20, 1892, with river diversion work. Engineers blasted a channel measuring 125 feet wide and approximately a quarter-mile long through solid rock on the valley's north side. A masonry barrier 25 feet high was constructed alongside this channel, with earthen dams positioned at each end. The temporary dam depicted measured roughly 1,600 feet in length.

The foundation excavation required removing "approximately 1,821,400 cubic yards of earth and 400,250 cubic yards of rock." The river diversion and foundation excavation consumed four years, making this photograph roughly eighteen months into the process.

The image shows suspension bridges spanning the diversion channel in the foreground, providing engineers access between the main office building on the north bank and the work site. A small-gauge railroad bridge (tramway) appears in the background, transporting materials from quarries located along Crompond Road in Cortlandt and Croton Avenue north of Route 129. Railcars are visible queued behind the diversion wall beneath the bridge.