The widespread occurrence and rapid growth of saline seeps on or adjacent to cultivated drylands has become one of the most serious conservation problems in the Great Plains region of North America. Dryland salinity, hardly recognized 35 years ago, has now taken approximately 0.8 million ha out of crop production. Equally serious as the loss of arable land is the local and potential regional deterioration of surface and shallow groundwater resources which, in many areas, are the primary sources of potable water. Significant concentrations of trace metals, particularly selenium, as well as high nutrient levels, have been found in many ground and surface water samples. A number of livestock, wildlife, and fish kills have been noted and are believed to be directly related to the saline seep problem. The best solution to the problem is to utilize precipitation where it falls, before it moves beneath the root zone. A number of conservation practices have been identified, but three of the most successful control practices are: a) growing deep-rooted perennial crops; b) switching to flexible, intensive cropping systems; and c) draining selected upland, freshwater potholes. On one research site where these practices were applied during the past 10 years, significant results include: lowering the water table an average of 2.5 m; a decrease in salinity of groundwater by approximately 25%; a 75% reduction in soil salinity in the seep area, from the surface to 0.6 m; and a decrease in the salt-affected area from 12 ha to less than 0.4 ha.