Utilization of Ground-Water Storage in Stream System Development

The first developers of irrigation on the stream systems in western United States utilized such surface discharges as were available. In streams fed by melting snow these discharges might be fairly large until late in the growing season, but in streams where snowfall at the headwaters was small, or where the runoff season began early, the dependable surface flow was small in the latter part of the growing season. In this circumstance and where climate and geology were favorable, recourse was had at about the turn of the century to wells and pumps to utilize ground water for supplementary irrigation; but in locations where runoff was larger and in more favorable regimen, utilization of ground water was long delayed unless artesian flows could be developed. However (especially in the 1930's which in western United States was a decade of drought generally), pressure of need forced the use of ground water by individuals even in those areas favored by fairly stable surface flow in the irrigation season and by large surface reservoir capacity. Use of pumped water for irrigation is expanding rapidly in some of these areas and in others that formerly had available only such natural discharge as occurred in the flood season of early summer.