U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9414818 PUBLICATION DATE: 03/09/2004 Name: ANGEL ISLAND, EAST GARRISON, S.F. BAY CA NOAA Chart: 18649 Latitude: 37° 51.8' N ( 37.86330) USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.2' W (-122.42000) To reach the tidal bench marks from San Francisco, proceed north by boat (or alternately, from Sausalito, proceed east by boat) to Quarry Point on the south side of the Island at Fort McDowell, then proceed east to the east barracks on the base. The bench marks are located on Fort Dowell. The tide gage was located on an old wooden dock at Old East Garrison of Fort McDowell at Point Blunt and the staff was 6 m (20 ft) west of the south corner of the dock. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 4818 F 1980 DESIGNATION: 941 4818 F TIDAL MONUMENTATION: Tidal Station disk VM#: 8430 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Cement at base of pier OPUS PID#: BBCN58 LATITUDE: 37° 51.6' N ( 37.86000) LONGITUDE: 122° 26.6' W (-122.44300) The primary bench mark is a disk set flush in cement at the base of the U.S. Coast Guard pier located on Point Blunt, Angel Island, on the south side of the foot of the pier, 3 m (11 ft) north of a short telephone pole with a power box attatched, and 0.46 m (1.5 ft) west of the southern pier sill.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9414818 PUBLICATION DATE: 03/09/2004 Name: ANGEL ISLAND, EAST GARRISON, S.F. BAY CA NOAA Chart: 18649 Latitude: 37° 51.8' N ( 37.86330) USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.2' W (-122.42000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4818 G 1980 DESIGNATION: 941 4818 G TIDAL MONUMENTATION: Tidal Station disk VM#: 15715 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Sand stone ledge OPUS PID: LATITUDE: 37° 51.6' N ( 37.86000) LONGITUDE: 122° 26.6' W (-122.44300) The bench mark is a disk set flush with the surface of a grey sandstone ledge, 91 m (300 ft) north of bench mark 4818 F 1980, 54.86 m (180 ft) south of bench mark 4818 H 1980, 1 m (3 ft) east of the edge of a cliff, 0.3 m (1 ft) above the approximate mean high water line. Note: There is a prominent rock ledge due east of the mark which is exposed at approximate mean high water line. BENCH MARK STAMPING: 4818 H 1980 DESIGNATION: 941 4818 H TIDAL MONUMENTATION: Tidal Station disk VM#: 15716 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Sandstone bedrock OPUS PID: LATITUDE: 37° 51.6' N ( 37.86000) LONGITUDE: 122° 26.6' W (-122.44300) The bench mark is a disk set in a grey sandstone bedrock 1 m (2 ft) above the mean high water level, 137 m (450 ft) NNW of the end of the Coast Guard Pier, 122 m (400 ft) SSW of bench mark 4818 I 1980, 61 m (200 ft) north of bench mark 4818 G 1980, 27.43 m (90 ft) NW of a 4 m (12 ft) x 4 m (12 ft) ledge of rocks, and 1 m (2 ft) above the approximate mean high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9414818 PUBLICATION DATE: 03/09/2004 Name: ANGEL ISLAND, EAST GARRISON, S.F. BAY CA NOAA Chart: 18649 Latitude: 37° 51.8' N ( 37.86330) USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.2' W (-122.42000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4818 I 1980 DESIGNATION: 941 4818 I TIDAL MONUMENTATION: Tidal Station disk VM#: 15717 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 37° 51.6' N ( 37.86000) LONGITUDE: 122° 26.6' W (-122.44300) The bench mark is a disk set in the western portion of a 4 m (12 ft) x 2 m (6 ft) boulder at approximate mean high water line located on the first prominent point of land north of the Coast Guard pier at Pt. Blunt, 91 m (300 ft) SSE of bench mark 4818 J 1980, 122 m (400 ft) NNE of bench mark 4818 H 1980, and 6.80 m (22.3 ft) SW of a white "KEEP OUT-Do Not Enter Beyond This Point-USCG Station Pt. Blunt" sign set in concrete in a large boulder. BENCH MARK STAMPING: 4818 J 1980 DESIGNATION: 941 4818 J TIDAL MONUMENTATION: Tidal Station disk VM#: 15718 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Sand stone outcrop OPUS PID: LATITUDE: 37° 51.6' N ( 37.86000) LONGITUDE: 122° 26.6' W (-122.44300) The bench mark is a disk set flush in a sandstone rock surface, 91 m (300 ft) NNW of bench mark 4818 I 1980, 2 m (5 ft) east of a prominent rock cliff, 1 m (3 ft) east of the range line formed by bench mark 4818 I 1980 and the Echo span of the Oakland-Bay Bridge (the Echo span is the span just to the west of Yerba Buena Island), and 1 m (3 ft) above the approximate mean high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9414818 PUBLICATION DATE: 03/09/2004 Name: ANGEL ISLAND, EAST GARRISON, S.F. BAY CA NOAA Chart: 18649 Latitude: 37° 51.8' N ( 37.86330) USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.2' W (-122.42000) T I D A L D A T U M S Tidal datums at ANGEL ISLAND, EAST GARRISON, S.F. BAY based on: LENGTH OF SERIES: 7 MONTHS TIME PERIOD: May 1980 - November 1980 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 1.799 MEAN HIGH WATER MHW = 1.616 MEAN TIDE LEVEL MTL = 0.981 MEAN SEA LEVEL MSL = 0.972 MEAN LOW WATER MLW = 0.346 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 4818 F 1980 3.445 1.829 4818 G 1980 2.111 0.495 4818 H 1980 2.342 0.726 4818 I 1980 1.793 0.177 4818 J 1980 2.434 0.818
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9414818 PUBLICATION DATE: 03/09/2004 Name: ANGEL ISLAND, EAST GARRISON, S.F. BAY CA NOAA Chart: 18649 Latitude: 37° 51.8' N ( 37.86330) USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.2' W (-122.42000) D E F I N I T I O N S Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal Datum Epoch. It pertains to local mean sea level and should not be confused with the fixed datums of North American Vertical Datum of 1988 (NAVD88). NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum constraint adjustment of Canadian/Mexican/United States leveling observations. Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as the single initial constraint. NAVD88 replaces NGVD29 as the national standard geodetic reference for heights. Bench mark elevations relative to NAVD88 are available from NGS through the World Wide Web at National Geodetic Survey. NGVD29 is a fixed datum adopted as a national standard geodetic reference for heights but is now considered superseded. NGVD29 is sometimes referred to as Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological Survey Topographic Quads. NGVD29 was originally derived from a general adjustment of the first-order leveling networks of the U.S. and Canada after holding mean sea level observed at 26 long term tide stations as fixed. Numerous local and wide-spread adjustments have been made since establishment in 1929. Bench mark elevations relative to NGVD29 are available from the National Geodetic Survey (NGS) data base via the World Wide Web at National Geodetic Survey. NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to local MSL and other tidal datums may not be consistent from one location to another. The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique identifiers for bench marks in the tidal and geodetic databases, respectively. Each bench mark in either database has a single, unique VM# and/or PID# assigned. Where both VM# and PID# are indicated, both tidal and geodetic elevations are available for the bench mark listed. The NGS's Integrated Data Base (IDB PID) provides geodetic datum based on traditionally leveled and bluebooked ties to the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/. The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/. The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred to MLLW only when two or more of the bench marks listed have NAVD88 elevations. The NAVD88 elevation relationship shown in the table is derived from an average of several bench mark elevations relative to tide station datum. As a result of this averaging, NAVD88 bench mark elevations computed indirectly from the tidal datums elevation table may differ slightly from NAVD88 elevations listed for each bench mark in the NGS database.