Idaho usually has adequate surface water supplies, but those water supplies are cyclic. Some years, there is too much and other years not enough. Idaho has experienced a number of water shortages. The earliest well-documented shortages occurred in the 1920s and 1930s during the Dust Bowl era. These historic records are still used today as a benchmark in evaluating potential problems.
Idaho has not been without problems since then. During the early 1960s, several areas in the state experienced water shortages. In 1977, the worst single year on record, a severe water shortage occurred throughout Idaho and the West. In 1987, the water supply ranged from 10 to 50 percent below normal over many areas of the state. The impacts were kept to a minimum because of a good reservoir carry-over supply from 1986 and judicious use of water.
In 1988, even though the overall supply was better (at around 70 percent of normal), the impact was greater because of poor carry-over reservoir storage and dry soil conditions. Conditions in 1991 and 1992 mirrored conditions in 1987 and 1988. Overall, conditions between 1987 and 1993 in the southwestern part of Idaho have displaced the Dust Bowl period of the 1930s as the most severe period of drought on record.
As a result of the 1977 drought, state, federal, and local agencies directed considerable effort toward drought planning and assistance. Valuable information was collected, many water supply problems were addressed, and drought response procedures were developed. An important item not completed in 1977, was the production of a "Drought Plan." In 1990, a plan was designed to fill that need. The Idaho Water Supply Committee was developed as one action element of that plan.