I agree with Dunlin, but are you sure with a juvenile (1cy)? Although hard to judge on this blurred picture, wing-coverts and scapulars seems long, different shaped and worn. In a 1 cy, they should be more even in shape, smaller and rounded and with a pale fringe (can they be allready completly worn of by early september?).
Looks more like a worn adult to me.
But I must admit, when just looking at head and belly, this looks ok for 1 cy , so another possibility is a poor 1 cy bird with some kind of worn and bleached and "dirted" wings, so they look larger and different shaped . Are there other pictures of this Dunlin?
I'm positive about the age. There are a number of scapulars already moulted (visibly greyer, more uniform and longer), giving it a variegated look in such a blurred picture. The type of dark belly spotting is unique to juvs, the adults never have that dot pattern that reaches the breast is that way: the black belly patch is composed of much broader black tips (normally black to the tips, with no white edges by post-breeding moult), etc. The unmoulted old feathers (the browner ones) are not worn breeding plumage remnants but evenly margined juv. feathers.