A colony on a ditch
Everything about early Scottsdale ran through one structure most of its settlers never saw. The Arizona Canal, dug in 1883–85, took its water from a wooden diversion dam on the Salt River a few miles above where Granite Reef Dam stands today — fourteen feet of timber crib and rock fill that turned the river’s flow into the ditch that reached the benchland north of Phoenix. Winfield Scott’s 640 acres sat on that ditch. His citrus, his figs, the alfalfa and barley of the families he was recruiting: all of it depended on a dam that had been built to work in an ordinary year.
February 1891 was not an ordinary year. Warm rain fell on heavy snowpack in the Salt and Verde watersheds, and the river came down the canyon at a scale no one in the Valley had a number for. Early on the morning of February 18 the Salt was a foot and a half over the Arizona Dam. Hours later it was five feet over. By the morning of the 19th the water was running some eighteen feet deep across the spot where the dam had been, and the dam was simply gone — carried downstream in pieces. Below Phoenix the river spread three miles wide, took out the railroad bridge at Tempe, and put the south side of the territorial capital under water. When the crest finally receded, the river rose again on the 24th, this time to an estimated 300,000 cubic feet per second — the largest flow ever recorded on the Salt, before or since.
What the settlement learned
The immediate consequence for the Scott colony was a dry canal in the middle of the growing season, until the dam could be rebuilt. The larger consequence took a decade to work out. The valley’s farmers had already known that the river could fail them by running low; 1891 demonstrated that it could also fail them by running high, and that the private canal companies had neither the capital nor the engineering to build anything the Salt could not destroy. The only durable answer was storage — a dam in the mountains that would hold the floods and release them in the dry months — and no local investor could afford one.
That argument, made over and over through the drought years that began in 1898, is what sent the Salt River Valley to Washington. It produced the Reclamation Act of 1902, the farmers’ pledge of their own land as collateral in 1903, and Roosevelt Dam in 1911. The 1891 flood is where the case begins. The rest of the year is at 1891, and the founding decade runs through the 1890s chapter.