With consistent planning and operation of water management systems, irrigation and drainage can be sustained in humid areas with minimal environmental impacts, while enhancing the Nation’s agricultural productivity. The profitability of irrigation and drainage in humid areas depends on seasonal rainfall, adequate economic returns from crops, and irrigation and drainage expenses. To boost profitability and reduce risks, we need better methods for determining when and how much to irrigate. And we need new ways to design and operate drainage systems. Managing surface and subsurface drainage systems to control contamination of surface runoff and shallow groundwater, as well as the depth of the water table, evolved first in humid areas and later in arid areas. In humid areas, controlled drainage has reduced nitrate in subsurface drainage discharge. Many questions remain about the best drainage practices for improving crop production and the quality of runoff and subsurface drainage discharge in humid, semiarid, and arid areas. We need different drainage systems to ensure efficient, environmentally sound crop production in all of these areas.