Sorry, this is not a Western Sandpiper. Any WESA in April would have at least some bright reddish in the face and scaps, and the structure lacks the front-heavy look of Western, plus the bill is on the shorter end for that species.
Honestly this looks ok for Semipalmated. However, I don't mean to be rude, but I'd recommend focusing on field observation in this case, as peep ID from a single fairly low-quality photo is difficult.