Drainage area: ~49.3 sq.mi.

Drainage area at CTH.G is about 41.7 square miles (as calculated by USGS StreamStats 4.0 Beta software).
At CTH.J it has increased to 48.7 square miles.
At 97th Street (our recommended put-in) it is 49.3 square miles.
At our take-out it is 58.6 sq.mi. (an increase of 20% from our listed put-in).

Our reference gauge (Prairie at Merrill) has drainage of 184 square  miles, so ...

flow on this run *could* be 0.2266 times (or a bit under 1/4th) that gauge reading.