The color of a gate has nothing to do with if it's open to public access or not.
Yes this is true, The dnr land that I hunt on just swapped out there blue gate's for yellow one's.

Lets see, Pope marks most of its gate entrance's with a sign. Mainke dose not put up any signs but they mark there gates with M1,M2,M3... ect. Almost all of the timber land on the kitsap peninsula is either Pope,Mainke or dnr. The dnr land is normally marked because of the discover pass stuff, if it isn't marked they will have dnr stickers on the tree's with right of way boundaries.