The fairgrounds does have camping on the east side of the fairgrounds near the race track. If you go to the website you can make reservations. It is not camping in the traditional sense it's basicly a grass field, I can't remember if any of the spots have hookups.
You can camp at the fair grounds
https://wa-evergreenstatefairgrounds2.civicplus.com/142/RV-Park
As Dan said. The fair grounds portion is all for regular parking. You'd need to call ahead of time to check for campers parking to the event.
flowing lake in between monroe and Snohomish
None that i can think of.
There is no camping nearby
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