Nantahala

Showing the full flow at the Hewitt gauge is actually useful. When this section of river runs, the powerplant is almost always generating. Subtract the ~650 cfs the powerplant generates and you have an idea of the flow in the Upper Nanty and Cascades.

Given that you need at least 250 cfs to paddle the Upper (even that is bony), look for the Hewitt gauge to have 900 cfs for elf and 1,000 cfs for a healthy minimum.