In the century and a half since Idaho water was first used to water crops, irrigation has changed the landscape of the Eastern Snake River Plain. Water in its many forms shapes Idaho 's economy, culture, politics, and society. In recent years it has come to dominate the state's legal landscape as well.

It's not surprising that much of Idaho's concern relating to the INL centers around the Eastern Snake River Plain Aquifer. If activities at the lab were to result in irreparable harm to the aquifer, it could be a devastating blow to Idaho's economy and way of life.

The history of the aquifer is inexorably tied to the history of irrigation. A prime example is the difference between the Magic Valley being a semi-arid desert with farms along the river, and the extraordinarily productive agricultural area it is today. Because irrigation is the primary agent of change to the Eastern Snake River Plain Aquifer, the history of irrigation on the Eastern Snake River Plain provides vital insight into the factors that shape Idaho 's concern over operations at the Idaho National Laboratory.

In 1890, the newly-admitted state of Idaho feared that all the land that could be developed for agriculture was already under the plow. Many miles of canals were already being used to take the natural flow of Idaho's waterways to fields. But serious and expensive efforts were needed to store and transfer the huge volumes of water that flowed down the Snake and other rivers throughout the year to the many acres of rich volcanic soils that were beyond the reach of canals or could be supplied with just the low river flows during southern Idaho's dry summers. It was feared that without these great efforts, Idaho 's growth would run out of momentum. It could not have been imagined that just ten years later, total irrigated acres across the State topped 550,000, more than double that at the time of Idaho 's statehood.

Development of the arid Snake River Plain was encouraged by the Carey Act (1894) and other federal legislation that provided government land at bargain prices to those that could bring that land under irrigation and into production. Private investment provided the capital to buy the lands and build canals. Among the first projects were canals near American Falls , and Milner Dam and associated canals near Burley and Rupert. Familiar landmarks such as Milner Dam, Perrine Bridge , Buhl, and Kimberly remind us of those that helped to finance these early projects. Still, the limiting factor for further development was how to store the melting snows and high spring flows for irrigation in the hot, dry Idaho summers.

Even with the help of wealthy investors, it became clear that the astronomical cost of building dams required more assistance from the federal government. The 1902 Newlands Reclamation Act allowed the Federal Government to finance the work of constructing dams and irrigation works beyond the ability of private investment. From this grew the Minidoka Project that eventually resulted in the Minidoka, American Falls, Palisades, Jackson Lake , and other major dams of the Upper Snake River Valley , as well as dams on other southeast Idaho streams. In addition to storing water for irrigation, these dams helped to tame the floods that often came with spring's melting snow.

Irrigation on the Eastern Snake River Plain was underway by 1880, on lands immediately adjacent to the Snake River and other eastern Idaho streams. By 1899-1900, about 330,000 acres were under irrigation. From 1903 through 1938 Mindoka, Jackson Lake , Milner, American Falls, Henrys Lake , Island Park , and Grassy Lake Dams were constructed. Acres irrigated increased to about 1.54 million in 1929, and 1.7 million acres by 1945.

From 1945 to 1959, acres irrigated increased to 1.83 million acres. Although ground water had been used for irrigation since the 1920s in some areas on the Eastern Snake River Plain, the development of powerful and efficient electric pumps allowed significant ground water usage, with 400,000 acres irrigated from this "new" source. Surface water irrigation accounted for 1.43 million acres.

By 1966, acres irrigated by ground water grew to 640,000, and by surface water, to 1.56 million acres, for a total of 2.20 million acres. Irrigated acres totaled 2.27 million in 1979. The source for irrigation water for some lands switched from surface water to ground water, with surface water the source for irrigation of 1.23 million acres, and ground water the source for 930,000 acres. Both surface and ground water resources were used to irrigate 110,000 acres.

A century of irrigation on the Eastern Snake River Plain Aquifer

Flooding fields with water is a relatively inefficient means of providing water to crops. The amount of water applied to the fields and furrows prior to more modern irrigation methods was sometimes as much as seven times what the crop could use. All that extra water, as much as 12 feet of water applied during the course of an irrigation season, recharged the aquifer. This "waste" became water stored for later use, just like water stored behind a dam.