Please note: In many cases, the station position in our database is accurate
to only one minute. Thus, the tide gauge may not appear to be on the coast.
Portland (Maine) 960/181 RLR(1964) is 11.4m below BM31
Documentation added 2011-08-17
Using NOAA data the RLR diagram has been re-drawn. The Primary benchmark BM 31 8.406m above gauge datum remains the same but has now been given the full name ELEV 14.501 FT TIDAL 31 as appears on the NOAA website.