Delta is rather unusual among the primarily agricultural towns in the state, since it was founded in the twentieth century and owed virtually nothing regarding its establishment to direction from the general hierarchy of the Church of Jesus Christ of Latter-day Saints.

The previously settled West Millard farming area was already becoming prosperous from alfalfa seed production when Frederick R. Lyman and others of his Oak City family began investigating the possibility of diverting Sevier River water upstream from the relatively new Gunnison Bend Reservoir, which was used for cultivating lands at Oasis, Deseret, Hinckley, and Abraham. After farmers from those communities claimed winter runoff water and commenced building a larger Sevier Bridge Reservoir in southeastern Juab County, Lyman persuaded his fellow members of the Millard LDS Stake presidency, Orvil Thompson and Alonzo A. Hinckley, to call attorney James A. Melville to determine the feasibility of forming a new irrigation company in connection with this reservoir project. The Mellville Irrigation Company was organized for that purpose on 24 March 1906. Twenty-nine of the thirty-four original incorporators were residents of Millard County.