Ground water in the Raft River Basin, Idaho, with special reference to irrigation use, 1956-60

In the Raft River basin in south-central Idaho, ground-water withdrawals
for irrigation have more than doubled since 1955, when data were compiled
for a comprehensive report on the area. The present report summerizes data
on the ground-water use and changes in the water regimen during the intervening
5 years. Water levels have declined 10 to 20 feet in the areas of heaviest pumping
and 3 to 5 feet throughout the remainder of the area. These water-level declines
are related to increased ground-water pumpage and below-normal precipitation
in the basin. The total pumpage during the 1960 irrigation season is estimated
to be about 127,000 acre-feet, of which about half was consumed by crops or
evaporated. The remainder returned to the aquifer.

Irrigation development is acting to reduce the amount of underflow out of the
basin. The water table can be lowered considerably more before underflow from
the basin would be reduced substantially.