Idaho History: Arrowrock Dam near Boise was a colossal achievement

Just 100 years ago the tallest dam in the world was nearing completion right here in Idaho. Arrowrock Dam had been envisioned first by engineer Arthur De Wint Foote as an ambitious private irrigation project that would bring many thousands of acres of Boise Valley sagebrush land under cultivation. The soil was rich and the valley was blessed with more than 200 days of sunshine a year. All that was needed to make the valley “bloom like the rose” was a reliable source of water throughout the growing season. Foote’s project failed for lack of adequate funding, despite the talent and determination of its great engineer.

Arthur Foote’s wife, writer and illustrator Mary Hallock Foote, was undoubtedly more famous than her husband in the years they lived in the stone house he built for her at the bend of the river below today’s Lucky Peak Dam, (another site for a future dam that he had envisioned). Her stories and pictures were published regularly in leading national magazines of the day. The Footes were the subject of Wallace Stegner’s novel “Angle of Repose,” which won the 1972 Pulitzer Prize for literature.

In 1915, Arrowrock Dam was the most ambitious project ever undertaken by the U.S. Reclamation Service, involving the capture and storage of the water from a drainage area of 2,200 square miles of Idaho mountains. The concrete arch dam, at the confluence of the main Boise River and its south fork, is about 20 miles east of the capital city. The big dam is 350 feet high and 1,150 feet long.

Before construction could begin, the Reclamation Service needed to build a railroad to transport the enormous tonnage of material needed to build the dam and housing and other facilities for the men that would build it and their families. Since Barber Lumber Co. owned the right-of-way to the dam site, an agreement had to be reached as to who owned the railroad after it was built. The agreement reached was unprecedented: the government leased the track from the lumber company but ran the Arrowrock & Boise Railroad with its own equipment, making it the first publicly owned railroad line in the country. Work began on the railroad on Aug. 22, 1910.

With the railroad’s completion in November 1911, scenic weekend excursions to Arrowrock became popular with Boise Valley residents. Most were surprised at the amenities they found at the little construction town. There was an electrical system supplied by a generating plant that had been installed at Diversion Dam at the head of the New York Canal in 1912, and there were water and sewer systems, a hospital, mess hall, post office, a school, YMCA, dance hall and a hotel. Residents numbered about 1,400 people, including 200 families.

Common laborers were paid $2.40 a day, from which was deducted 75 cents for meals and $1.25 a month for a bed in a bunkhouse, or $4 for a private room. Another $1 a month was deducted to support the hospital. Numerous injuries and 12 accidental deaths occurred during the building of Arrowrock Dam.

Equipment used in construction of the dam included a 70-ton Atlantic steam shovel that had been used in building Deer Flat reservoir, two “dinkey” excavators and several dump cars, one Buick and seven Ford trucks, and many teams of work horses. The cement mixers produced more than 2,000 barrels of concrete per day and ran night and day.

Arrowrock Dam, now listed in the National Register of Historic Places, was dedicated on Oct. 4, 1915. The Boise & Arrowrock Railroad was decommissioned on Aug. 11, 1916.

Arthur Hart writes this column on Idaho history for the Idaho Statesman each Sunday. Email histnart@gmail.com.

This story was originally published April 12, 2015 at 12:00 AM.