Hey Frank, nice find! I agree with Gadwall x Mallard.
This hybrid combo, aka Brewer’s Duck, is variable but yours looks good to me. Clearly Gadwall-like but the bi-colored face and rufous-tinged breast plus the overall structure (longer bill and longer body with more pointed back end) seem to favor x Mallard. It matches nicely with the Gadwall x Mallard illustration ‘d’ in the photo attachment, from ‘Waterfowl of North America, Europe, & Asia’ by Sebastian Reeber. There is an eBird entry option for this combo FYI, and there are currently less than 20 records in the database for Oregon all-time.
-Alex
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