This was copy/pasted from an e-mail on Thursday 2 December 2021 from Snohomish County Parks and Recreation:
Due to a sinkhole, a section of the Centennial Trail north of the Machias trailhead will be closed until further notice with no detour while it is being repaired. Coordinates: 47°59'09.9"N 122°02'41.7"W
Location of closure on Google Maps.