Looking at the size, the colour of the bill, and the brownish light coloured wings and body, it seems to fit best with a first-year Western gull looking at my Peterson's guide 4th Edition page 183.
The photo is a bit washed out, but I would expect western gull to be darker... that being said, there are many GWGUxWEGU around, so it becomes a constant ID challenge... I am no gull expect though.