A federal judge had ordered the lookout removed after an environmental group sued.
U.S. Sens. Patty Murray and Maria Cantwell, as well as Reps. Suzan DelBene and Rick Larsen say the legislation is good news for an area reeling from the March 22 mudslide that killed at least 37 people in Oso.
The lookout is popular with hikers, tourists and locals in the area and has been seen as a driver of recreation and tourism.
The legislation preserves the lookout and prevents the U.S. Forest Service from removing it unless it is deemed unsafe for visitors.
It's one of only a few surviving fire lookouts in the West.