Data are presented here on the hydraulic conductivity of subsoils of major soils from the Lajas Valley Irrigation Drainage Project. The data reveal that subsoil hydraulic conductivity is very slow in all cases. In some cases favorable features are the gently sloping topography at the upper Valley and the fact that topsoils generally conduct water rather well. Careful soil-management and cropping programs should take account of these facts, recognizing the limitations involved.