Jim
An important factor is the wind in the gorge nearly always is blowing
east to west and it happens to be with the water current too. Not
uncommon for the winds to be blowing there in excess of 50 knots. If I
recall, the max winds recorded there are well in excess of 100 mph!
I landed seaplanes a number of times on rivers, mainly the Mississippi
which in many ways reminds me of the Columbia. I've lived on the shores
of both and often thought of the way I'd make an emergency landing to
the water. Includes rivers, lakes, and ocean. Since each situation is
so different its nearly impossible to say it should be done one way or
other.