U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9415477 PUBLICATION DATE: 03/14/2006 Name: SAND POINT, TOMALES BAY CA NOAA Chart: 18643 Latitude: 38° 13.9' N ( 38.23170) USGS Quad: TOMALES Longitude: 122° 58.1' W (-122.96800) To reach the tidal bench marks from Dillon Beach, proceed SW 0.32 km (0.2 mi) along the beach road known as Cliff Street from Lawsons Store in Dillons Beach. The tide gage is located on the south end of the beach. The bench marks are located near the pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 5477 A 1993 DESIGNATION: 941 5477 A MONUMENTATION: Tidal Station disk VM#: 15723 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete fuel bunker OPUS PID: LATITUDE: 38° 13.9' N ( 38.23170) LONGITUDE: 122° 58.1' W (-122.96800) The primary bench mark is a disk set in the top of the SW corner of a concrete fuel bunker located on the west side of the inshore end of the pier, 16.76 m (55.0 ft) south (180 magnetic) from the SE corner of Lawsons Landing boathouse, 8.23 m (27.0 ft) west (270 magnetic) from the centerline of the pier, and 1.83 m (6.0 ft) above grade.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9415477 PUBLICATION DATE: 03/14/2006 Name: SAND POINT, TOMALES BAY CA NOAA Chart: 18643 Latitude: 38° 13.9' N ( 38.23170) USGS Quad: TOMALES Longitude: 122° 58.1' W (-122.96800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 5477 B 1993 DESIGNATION: 941 5477 B MONUMENTATION: Tidal Station disk VM#: 15724 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Unspecified deep rod OPUS PID#: BBCN52 LATITUDE: 38° 13.9' N ( 38.23170) LONGITUDE: 122° 58.1' W (-122.96800) The bench mark is a disk located on the east side of the main road 0.16 km (0.10 mi) north of the end of the pier, 34.44 m (113.0 ft) NE (060 magnetic) from the center of the y-intersection of the main, paved, and graveled road, 8.53 m (28.0 ft) east (090 magnetic) from the south corner of a public restroom, and 1.83 m (6.0 ft) SW (230 magnetic) from power pole #4067. The bench mark is set flush with the ground, crimped to the top of a deep rod, hand driven 6.1 m (20 ft) to refusal, and set in the top of a 0.91 m (3.0 ft) section of a 4-inch ABS pipe filled with concrete. BENCH MARK STAMPING: 5477 C 1993 DESIGNATION: 941 5477 C MONUMENTATION: Tidal Station disk VM#: 15725 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Unspecified deep rod OPUS PID: LATITUDE: 38° 13.9' N ( 38.23170) LONGITUDE: 122° 58.1' W (-122.96800) The bench mark is a disk located on the west side of the main road 0.32 km (0.20 mi) north of the end of the pier, 24 m (79 ft) SW (220 magnetic) from power pole #4065, 10.67 m (35.0 ft) NE (025 magnetic) from a metal power box standing 1.52 m (5.0 ft) high, and 8.84 m (29.0 ft) from the NE corner of a public restroom. The bench mark extends 0.15 m (0.5 ft) above ground, crimped to the top of a deep rod, hand driven 6.7 m (22 ft) to refusal, and set in the top of a 0.61 m (2.0 ft) section of a 4-inch ABS pipe filled with concrete.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9415477 PUBLICATION DATE: 03/14/2006 Name: SAND POINT, TOMALES BAY CA NOAA Chart: 18643 Latitude: 38° 13.9' N ( 38.23170) USGS Quad: TOMALES Longitude: 122° 58.1' W (-122.96800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 5477 D 1993 DESIGNATION: 941 5477 D MONUMENTATION: Tidal Station disk VM#: 15726 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Unspecified deep rod OPUS PID: LATITUDE: 38° 13.9' N ( 38.23170) LONGITUDE: 122° 58.1' W (-122.96800) The bench mark is a disk located on the west side of the main road 0.32 km (0.20 mi) north of the end of the pier, 24 m (79 ft) SW (220 magnetic) from power pole #4065, 10.67 m (35.0 ft) NE (025 magnetic) from a metal power box standing 1.52 m (5.0 ft) high, and 8.84 m (29.0 ft) from the NE corner of a public restroom. The bench mark extends 0.09 m (0.3 ft) above ground level, crimped to the top of a deep rod, hand driven 7 m (23 ft) to refusal, and set in the top of a 0.76 m (2.5 ft) section of a 4-inch ABS pipe filled with concrete. BENCH MARK STAMPING: NO 2 1957 DESIGNATION: 941 5477 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 15728 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete filled 4-inch tile OPUS PID: LATITUDE: 38° 13.9' N ( 38.23170) LONGITUDE: 122° 58.1' W (-122.96800) The bench mark is a disk set in top of a concrete filled 4-inch tile located in the same general vicinity as bench mark NO 1 1957, 89 m (292 ft) NW of the inshore end of the dock and in range with the inshore end of the dock and Hog Island just below the top at a small sand dune and projecting 0.30 m (1 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9415477 PUBLICATION DATE: 03/14/2006 Name: SAND POINT, TOMALES BAY CA NOAA Chart: 18643 Latitude: 38° 13.9' N ( 38.23170) USGS Quad: TOMALES Longitude: 122° 58.1' W (-122.96800) T I D A L D A T U M S Tidal datums at SAND POINT, TOMALES BAY based on: LENGTH OF SERIES: 4 MONTHS TIME PERIOD: October 1993 - January 1994 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9415020 POINT REYES, DRAKES BAY Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 1.573 MEAN HIGH WATER MHW = 1.355 MEAN TIDE LEVEL MTL = 0.827 MEAN SEA LEVEL MSL = 0.802 MEAN LOW WATER MLW = 0.298 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 5477 A 1993 3.591 2.236 5477 B 1993 3.130 1.775 5477 C 1993 3.189 1.834 5477 D 1993 2.813 1.458 NO 2 1957 4.253 2.898
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9415477 PUBLICATION DATE: 03/14/2006 Name: SAND POINT, TOMALES BAY CA NOAA Chart: 18643 Latitude: 38° 13.9' N ( 38.23170) USGS Quad: TOMALES Longitude: 122° 58.1' W (-122.96800) 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.