So here's an idea that should help you out; maybe not right now, but for future hunts.
GO out hunting when conditions are as you like them (water level wise).
Then, log onto ifish.net and click on "River Levels".
Then select NOAA and click on the nearest spot along the Columbia to where you hunt (probably Vancouver).
Look at the river level WHEN you were out there (you'll have to do this within 1 day of the time you hunted) and remember or write this level down. That's you Baseline.
Then, at any later time, either after extreme weather periods or whenever and check to see what the river's level will be when you want to go hunting.