Description of Minidoka County

  • Area: 762 square miles
  • Business Hours: 8:30 a.m. until 5 p.m.

  • County Seat: Rupert
  • Population: 20,174


Minidoka County is located in the fertile Snake River Plain of Southern Idaho approximately 160 miles east of Boise, 160 miles northwest of Salt Lake City, Utah and 90 miles west of Pocatello. The county contains approximately 480,000 acres, of which 42% is in production agriculture. The county has a unique topography and elevation. Its southern portion, which runs along the Snake River, was originally part of the riverbed. Its northern portion runs over a somewhat higher table and is called the North side project. Its extreme northern and eastern boundaries consist of lava flows with large and small areas of arable land. Although the surface structure is varied, there is only 180 feet difference in elevation from the lowest point at the southwest corner, 4180 feet and its highest point in the northeast corner, 4360 feet.


Water stored in reservoirs created by dams on the Snake River provides the means of irrigation for the diversified farming on the original Minidoka Project. Water was first delivered to the Minidoka Project in 1907 with the completion of Minidoka Dam. The old project consists of 72,221 acres. Deep wells provide the water for the new Governmental Homestead Project consisting of 89,000 acres. Additional acres have been developed by private enterprise since the first Veteran Homestead drawing in 1953. Today there is approximately 160,000 acres of rich sagebrush land under irrigation by pumping.


The climate of Minidoka County corresponds in general, with that of the semi-arid valleys of Southern Idaho. The annual precipitation is 9.48 inches coming primarily in the form of snow during the months of November through February. However, it did increase to 13.7 inches in 1968 and an unprecedented low of 3.38 as of September 1969. The mean temperature for Rupert is 62.2 degrees maximum, with highs of 105 degrees Fahrenheit recorded and minus 35 degrees Fahrenheit for the low.


The average date of killing frosts in the spring is May 17th and the first frost in the fall is September 21. We did experience scattered frost damage on July 4 and 5th in 1986. The average frost-free days are 127 days.


Interstate Highway 84 traverses Minidoka County from east to west for approximately 15 miles. In addition to the Interstate system there are 72 additional miles of State maintained highways in the county. Minidoka County Highway District maintains 608 miles of road in the county and also cooperates with the cities in the county on highway maintenance. The District's goal was to hard surface all roads on the North side, but this objective has changed with an increased energy cost and the current economic situation in the state and county. They currently have 310 miles of highways that qualify for Federal Highway funds. 60% percent of the District budget is derived from gasoline taxes.

Rural Highways

The rural highway marking system is unique and is much copied by other rural counties in southern Idaho. The system makes it extremely easy for emergency and service personnel to locate rural families in the county.


The mainline of the Union Pacific railroad crosses the northern side of the county from east to west. A spur line comes off the mainline at Minidoka, running past Acequia, Rupert, Burley, Paul terminating in Twin Falls. While rail passenger service is available on Amtrak only with a stop in Shoshone, the railroad serves a valuable function in the transportation of agricultural produce from the area.

Air Transportation

Air transportation is limited to size of the facilities. The Burley airport, located on the eastern edge of the city of Burley and is not large enough to serve commercial air transportation. However, there is an active private and charter service from the Burley airport.