Thorp Mill, located west of Ellensburg in the tiny town of Thorp, utilized Yakima River water brought to the area via canal. A horizontal water wheel powered both the gristmill and a nearby sawmill. An ice pond and log pond were located nearby. The ice pond was used for recreational skating, and from it ice was harvested to chill the train cars that carried local fresh produce to market.
Kittitas Valley farmers brought their wheat crops to the Thorp Mill in wagons, and the grain was ground into flour, bran, or feed for livestock. Initially the grain was processed between huge stone burrs that had been brought laboriously via wagon from The Dalles. In 1895 the arrival of the Northern Pacific Railroad enabled importation and installation of more efficient steel roller burrs. The railroad also provided local farmers with an easy means to sell their flour throughout the Puget Sound region.
In 1906, the energy from the water wheel was utilized to power a steam generator, which furnished electricity for laundering clothing two mornings each week, and for lighting homes for a few hours each evening. Thorp was one of the first towns in Washington to get electricity.
Thorp Mill continued active operation through 1946. On November 23, 1977, it was listed in the National Register of Historic Places.