a Values shown are the control setting (depth below average surface elevation) and should not be considered the actual water table depth in the field, which will be lower except during drainage periods.
b Most adjustments are related to trafficability and must take into account weather conditions and soil water status at the time:
– in an unusually dry season, control can be 3 to 6 inches higher;
– in an unusually wet season, control should be 3 to 6 inches lower;
– in coarse-textured soils, trafficability can be provided with the water table approximately 6 inches higher.