Best tip I can offer for Umatilla, especially on the river, is be prepared for the occasional goose. You may get a small flock, and you can call in a lone honker, if you can blow a goose call and have a few goose decoys in the water.
And of course, if a goose does come by, let em get real close if you are shooting #3 or smaller shot.
Don't count of geese of course, but it's a nice bonus you can get out there.
Other thing about hunting the river is know your retriever's limits. If you have a dog, be confident you can call him back in. Easy for a dog to swim a mile into the river chasing a cripple (current isn't strong, but wind can whip up big waves). Or bring a kayak or canoe to retrieve the swimmers.