=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Unalaska            820/021 RLR(1970) is 9.0m below BM7
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 24-Nov-2011
Using information from the NOAA website the RLR diagram has been revised. Primary benchmark remains NO 7 1956 3.597m above gauge datum.