The Tohickon Creek internet gage is located near Pipersville, several miles upstream from the Stover Park Gage, the one most used and most useful to paddlers. The Stover Park Gage is painted on the center pier of the wooden bridge at the park.
The rough equivalence is:
200 cfs is about 1/2 foot on the park gage, and is the minimum flow to just get down.
400 cfs gives one foot, a fine play level.
600 cfs is the standard fall release, 1.6 foot on the park gauge
1400 cfs gives around 2.5 foot on the park gage. At this level and above, all of the major drops are class 4, and the holes become very sticky, some are dangerous.
1800 cfs is about 3 foot on the park gauge, the toughest level
3000 cfs is just over 4 foot, the current is very fast, but the big holes are beginning to wash out.
Note that this a rough equivalence, and that other conditions such as inflow rate below the gage and ice conditions can change the level. Nothing beats on-site inspection and paddling experience!