head north about a mlie or so from the kelso bridge green steel one (For those who don't know there is a newly constructed Concrete 1 just below it).
Look for carnival market on west side and park at the rivers edge below on east side of hwy..flat landing above the river(pull out) with large mud puddles but I believe you can put a wheelchair for watching pretty safely there while you dip.
Saturday and sunday will be hectic, and dippers every 5ft so parking will be very very crowded!!
Remember the cowlitz is open 7 days a week for dippers from the hrs of 6a.m. to 10p.m.