Popular hiking spot Saddle Rock, from the trailhead to the top, will be closed for more than a month and a half beginning Sept. 16.
During the closure mining waste rocks will be removed from the area.
The closure will likely continue through the end of November.
Dry Gulch will remain open, as will the trail near the Wenatchee Racquet and Athletic Club.
The area is a former mining site now owned by the city of Wenatchee.
There are piles of waste rocks that have shown elevated arsenic levels, according to the city.
This will be the first phase of the cleanup, with the next phase expected next summer.