The energy grade line (EGL) at the upstream side of a structure is computed based on the characteristics of the structure and its upstream pipes. The reported EGL is generally reported as the lowest EGL of all non- plunging upstream pipes, based on normalized flow values. If there are no non-plunging pipes upstream, the structure's upstream EGL is taken as the higher of the structure's downstream EGL and upstream hydraulic grade line (HGL).

In situations where the structure's upstream EGL is lower than its downstream EGL or upstream HGL, the highest value governs. This rare condition may indicate that the presumed headloss in the structure is not significant enough to produce the expected energy loss. The modeler may accept this as a minor limitation of the hydraulic theory, or may choose to use different structure headloss methods or values.

The reported upstream velocity and velocity head for the structure are based on the difference between the structure's upstream EGL and HGL.