I'm pretty sure its not the biggest producer in Oregon, it could possibly be just SW Oregon. Baker county production far exceeds every other county in production.
From 1902- 1965 here are the top producing counties in order-
Baker- 1,258,979 ounces
Grant- 349,604 ounces
Josephine- 250,530 ounces
Jackson- 204,022 ounces
Lane- 34,624 ounces
Malheur- 31,827 ounces
All other- 56,192 ounces
I'd have to look up each individual mine to find out who the biggest producer was, which could take some time.
I know that Wolf Creek, Coyote Creek and Graves creek all have good gold in them, in spots.