The loss estimate came from Fire Chief Jasper Umphrey who said he believed the fire was set off by a malfunction in the building's oil furnace.
The structure and its contents, including some equipment, were owned by Herbert Jordan of Washburn. Umphrey said that the potatoes were insured, but that the building and it's equipment were not.
The fire was discovered by people living next door to the potato house, Umphrey said, noting that the fire apparently burned for some time before being noticed.
Umphrey said the fire reached the area where electricity was fed into the building and ignited by the wires, "really lighting up the sky up" and awakening neighbors.
Firemen cut off the electricity upon their arrival.
Washburn Fire Department responded with three trucks and 16 men.
Firemen were at the locale until around 5 a.m.