Is there a minimum rainfall event depth or intensity you would consider ideal to generate a good system response?

Think of the minimum Rainfall Threshold as a default value to automatically identify rainfall events, not as an ideal value. As a rule-of-thumb, we often do not evaluate a rainfall event for I/I if the rainfall total is less than 0.5 inches. However, there is not a particular rainfall total that is universally accepted as a significant wet weather event in the context of I/I. Rather, it is the response of the sewer system to a given rainfall amount that determines if a rainfall event is significant or not. This amount can vary from one sewer system to another and can even vary within different parts of the same sewer system.