I see no stretch. It is quite correctly tagged as a [ford][1].
"A ford is a small part of a highway where a waterway runs over it." Yes, a few hundred meters is still a small part, IMHO. IMHO.
"How to Map: use the way-method for larger streams with mapped riverbanks" Yes. There's depth, there's surface, there's tracktype.tracktype. Looking good :)
[1]: http://wiki.openstreetmap.org/wiki/Ford
I see no stretch. "A ford is a small part of a highway where a waterway runs over it." Yes, a few hundred meters is still a small part, IMHO. "How to Map: use the way-method for larger streams with mapped riverbanks" Yes. There's depth, there's surface, there's tracktype.