Some ephemeral features and some persistent features. For the full
gallery in its geotagged glory check out:

http://picasaweb.google.com/drjerque/BigSandyRiverAndBurroCreek#

Bottom line: Big Sandy had a decent, but not extraordinary flood above
the confluence with Burro Creek. Burro Creek had a notable flood that
buried vegetation along the edge of the channel with sediment and
nearly lapped onto a late Plesitocene terrace. Burro Creek is a
notorious flood machine that drains a very rugged part of west-central
Arizona.

I blew it by not visiting the Big Sandy/Burro Creek confluence.