Many photos on eBird (eg https://macaulaylibrary.org/asset/280938991;
https://macaulaylibrary.org/asset/280426461;
https://macaulaylibrary.org/asset/279601681;
https://macaulaylibrary.org/asset/279592351;
https://macaulaylibrary.org/asset/279283571) show that the bird clearly has
white secondaries, a key character for White-winged Scoter and one not
present in Surf Scoter. Additionally, the shape and structure of the bill
and head, distribution of the white on the face, and other features all
point towards White-winged Scoter.

Matt Brady
Baton Rouge