Yakima Valley State Representative Ina P. Williams introduced legislation to create the Irrigation Experiment Station on March 13, 1917. The station was to be operated by the College of Agriculture of the State College of Washington. In early 1919, the station was established in Benton County, north of the Sunnyside Canal near Prosser, Washington.

In its first year IES employed 115 men and women, almost all of whom were day laborers. The first superintendent was Roy P. Bean, an animal scientist working in Dairy and Animal Husbandry, who was appointed on May 1, 1919. Irrigation water reached the fields on May 24, 1919, and potatoes, corn, and millet soon began growing as the station's first crops. In 1923 IES added two straw-loft poultry houses with a capacity for 250 hens each. The swine herd was started during 1921 with the purchase of five Duroc-Jersey sows. Cattle came to the station in 1922 when IES bought seven Holstein heifers. In 1924 twenty Lincoln-Merino ewes were purchased from two Prosser citizens.

The experiment station went on to produce large crops and herds in order to fully research the needs of agriculturalists in the state. Its goals included giving attention first to the production of crops under irrigation; second, to the principles and practices involved in the proper use of irrigation water; third, to the disposal of pasture and home grown feed by pasturing dairy cattle and hogs and by feeding sheep, beef cattle and poultry; fourth, to horticultural problems with special reference to tree fruits and potatoes." (Director's Statement, 33rd Annual Report, Washington Agricultural Experiment Station, pp. 5-6.)

On July 11, 1929, Roy Bean was killed by a dairy bull. He had been connected with the station since its establishment and under his supervision two-hundred acres of typical sagebrush land was developed into a well-planned experiment station, rendering effective service to irrigation agriculture," stated the IES Annual Report for that year. Harold P. Singleton succeeded Bean as Superintendent of IES.

The Washington State legislature halved IES's appropriation during the depression and reduced its staff. Some of the livestock had to be sold and salaries and wages were reduced by twenty percent. Although many thought the station faced closure, Governor Clarence D. Martin assigned it an additional $8000 from his emergency fund. Economic conditions improved starting in 1935 and as they did IES added more staff, faculty, and programs. C. Emil Nelson started work in the new plant pathology section, specifically with plant diseases. In 1942 J.D. Menzies became the first designated Plant Pathologist.

In 1937 the station began to produce hybrid corn seed for sale to farmers. Doing so had required the addition of new facilities for drying, shelling, and storage. Eventually the corn seed program supplied corn for all the farmers in the Yakima Valley.

Along with the Washington Agricultural Experiment Station at Pullman and the Washington State Penitentiary at Walla Walla, IES began experimenting with vegetable crop varieties, fertilizer use, and management practices. The project, led by Walter Clore, lasted eight years. AES supplied guard salaries, the penitentiary supervised laborers and guards, and IES supervised field operations and record keeping.

From 1939 to 1945 the station also conducted research on processing adaptability studies of fruits and vegetables. In 1940 this research included work involving processing by freezing. In 1951 the whole processing laboratory transferred from Pullman to Prosser, along with its staff, Dr. A.M. Neubert and George Carter. The program moved again in 1965 to the Western Washington Research and Extension Center.

After the war the Bureau of Reclamation began operating pre-development farm units in the Columbia Basin for crop trials, later were called "Development Farms." The U.S.D.A. and IES worked with the Bureau of Reclamation on these units, concentrating mainly upon horticulture for small fruits and vegetables; they later also researched erosion control and irrigation. Both H.P. Singleton and J.D. Menzies worked as directors of these units.

A greenhouse facility, long sought after for research purposes, was finally added in 1946 and is still in use today at the Prosser station. In 1945 the Poultry Disease Committee suggested that the station establish a diagnostic laboratory to research diseases in poultry. Three years later a laboratory was functioning, but only lasted until 1952 when no veterinarians could be found to fill the researcher position.

Staff increases were common well into the sixties at every level and unit. Programs were also added, including programs in hops research; Aides Programs; fruit breeding; fruit fly control; outlying testing; irrigation engineering; virus diseases; breeding, diseases, and cultural practices with process peas; cherry fruit fly control; and, potato breeding. The results of such programs were regularly shown to area and state farmers at Feeders Days, Field Days, and Special Exhibits Days at Prosser Station.

The Interregional Research Project (IR-2), following years of planning, began operation on July 1, 1955. The project aimed to "assemble desirable clones of deciduous fruit trees, verify their virus freedom, maintain these clones in an isolated repository and distribute propagating materials to scientists or regulatory officials for research or for release to industry." The group would also conduct research and thermotherapy. Funds were provided by the U.S.D.A. and the Prosser station was the national headquarters. Begun on August 1, 1955, the unit soon became the national leader in research on detection and behavior of viral diseases among fruit trees.

Forage seed research produced three new projects, as well: Environmental Effects on the Genetic Stability of Forage Crops Seeds; Cultural and Management Practices in Forage Legume Seed Production with Alfalfa and Red Clover; and, Physiology of Seed Production in Forage Legumes with Alfalfa and Red Clover.

Still other new programs at the station were the Nematology Program and the Potato Disease Program, unique in that it was the only such project wherein the growers provided all the funding for the employment of faculty and non-faculty personnel. The station also did research in green beans and pears.

Dean L.L. Madsen, of the WSU College of Agriculture, C.A. Svinth, Director of Washington Agricultural Extension Service, and Mark T. Buchanan, Director of Washington Agricultural Experiment Station, determined in 1960 that the Irrigation Extension Service Center for Irrigation should be based in Prosser, too.

By 1988 the Superintendent of the station was Lindsey Faulkner. The main research areas continued to be Irrigation, Horticulture, and Plant Pathology.