William Frederick Seltz was born on September 12, 1875, in Wacona, Minnesota, one of eight children. William graduated from the University of Minnesota's agricultural school. After graduation he moved to Washburn, North Dakota.

In January 1910, he incorporated the Missoula Orchards Company, along with William L. Nuessle, John Wittmayer, and others of North Dakota, and Albert Besancon and T.T. Black of Missoula. The company was established to deal in real estate, to acquire and develop water rights, to build irrigation systems, and to raise fruit, produce, and livestock. The company bought the old O'Keefe ranch at the base of Evaro Hill west of Missoula; Seltz moved to Montana to manage the property. During the 1920s the company became a major shipper of Macintosh apples to New York City. The farm also raised wheat and hogs. Due to poor weather conditions and the general depression in the early 1930s, the company fell onto economic hard times. Faced with the foreclosure of its mortgage and possible bankruptcy, the company accepted a take-over offer by the New World Life Insurance Company and voluntarily dissolved the corporation in March 1934.

William Seltz retained a small portion of the farm and continued to raise wheat and livestock there until 1947, when he sold the farm and moved to Missoula.

Seltz married Iva Esther Kuney and helped raise her three sons Lawrence, Charles, and Joseph. William F. Seltz died June 2, 1951.