In the early 1900s in the arid West, C. W. McConaughy recognized the discontinuity between high river flows in the spring and low flows in the middle of summer, when farmers needed water most. McConaughy, a grain merchant and mayor of Holdrege, Nebraska, developed the idea of supplemental irrigation.

A series of bathtubs dot Wyoming’s North Platte River, filling and releasing water for summer irrigation, power generation, and recreation. During western expansion, it became necessary to control the river, building dams and reservoirs that helped to regulate flow between seasons and wet and dry years.