Pseudocyphellaria rainierensis, or the old-growth specklebelly lichen, is considered an important indicator of temperate rain forests of high conservation value in the Pacific Northwest bioregion of North America. Concerns about continued habitat destruction and recent population losses due to wildfires prompted us to investigate the status of P. rainierensis. We gathered all available records of the species for Washington State and conducted an extensive assessment of occurrences. We revisited 31 of the 143 known occurrences and did not recover P. rainierensis at 13 occurrences, suggesting a decline of at least 9% and at most 41% across the state. An additional analysis of Forest Inventory and Analysis (FIA) data revealed the presence of P. rainierensis in eight of 664 forest plots surveyed over a 20-year period. During field surveys, we discovered four new occurrences, and a review of records from the community science database iNaturalist identified eight new occurrences. Our findings underscore the critical need to regularly monitor old-growth dependent lichen populations and plan for strategic surveys to identify potential new locations where these species may occur. Our study offers a model for successful monitoring of rare species through public-private partnerships and engagement with community science efforts. Using these methods, forest managers and policy makers can utilize the best available scientific information to make informed conservation decisions. Keywords: Conservation, old-growth forests, phytogeography, Pacific Northwest, rare species.