Gauge Description:

300 cfs is what most paddlers might call a minimum. If you were really jonesing for a Flint run, you could bounce down at 200 cfs.

The linked USGS gage appears to be a new phenomenon. (Note: many of these new gages are the direct result of American Whitewater's close alliance with the USGS, through its officers and advocates and through the StreamKeeper Project. You are a member...aren't you?)

There is a hand-painted gauge on the Eagle Street bridge in Phelps (see description below). Consider the creek runnable when there is enough water to run Old Mill Falls in downtown Phelps (about 3.5 feet or higher on the gauge).
Class III- @ 3.0 at the bridge (~2.3', 170 cfs USGS)
Class III @ 4.0 at the bridge (~3.2', 450 cfs USGS)
Class IV- @ 4.5 (~3.8', 1100 cfs USGS)
Class IV @ 5.0 at the bridge (~4.2', 1800 cfs USGS)
Class IV+ @ 5.5