Have you had it out in a LAKE yet? Don't know your rowing experience, but if you are new to rowing DB's, take it out in a lake for a few hours and get used to turning, stopping, etc. Especially the 180 and 360 moves...as those are what you use to get un-stuck off of boulders, etc.

(best bet is not hit them to start with,,,but it is inevitable that sooner or later we all hit one.)
Can't help you on the southern rivers...but if your up by the Skagit I can show you the way down one of the drifts up here..
Mike