Nutrient Management Plans require you to designate a buffer around all water features, wells and sinkholes. Creating a setback allows you to put a buffer area around a feature. By default, the set back distance is 150 feet (this can be changed to meet your requirements).
To apply a setback around a feature, you need to save the feature after it is created or select a preexisting feature. Accept or change the default distance (150 feet), click "Create Setback" tab and the yellow setback will automatically be created following the contours of the feature.
Text will appear at the bottom of the feature information window to notify you that the setback was successfully created.