The following information obtained from UNAVCO's online DOI system:
(https://www.unavco.org/data/doi/search/search.html)

PBO GPS Network - P444-RossLakeDmWA2006 P.S.
Start: 09-Mar-2006
End: 05-Apr-2021
UNAVCO Community, 2006, PBO GPS Network - P444-RossLakeDmWA2006 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5TM783S