This region of Oregon is blessed with a number of rivers that provide an outlet for water based sports enthusiasts. The mighty Willamette River offers plenty of entry points from along its shore that are not too violent for beginner kayakers or for more gentle activities like river floats.
A number of sporting organizations and private companies will drop you off and pick you up for a charge, and I'd recommend exercising this option. Otherwise someone in your own party will have to miss the fun, then chaffeur the others back home. If you do set out on your own, you'll want to first investigate the current river information to determine which segments are safe to travel.