U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9415623 PUBLICATION DATE: 02/05/2004
Name: NAPA, NAPA RIVER
CA
NOAA Chart: 18654 Latitude: 38° 17.9' N ( 38.29830)
USGS Quad: NAPA Longitude: 122° 16.8' W (-122.28000)
To reach the tidal bench marks from the intersection of State Routes 12, 29 and
221, proceed north on State Route 221 (Napa Vallejo Highway) for 4.5 km (2.8 mi)
until it becomes Route 121 (Soscol Avenue), then proceed north on Soscol Avenue
for 2.5 km (1.6 mi) to Third Street, then turn left and proceed west on Third
Street for about 100 m (328 ft) to the bridge over Napa River. The bench marks
are along the bridge and to the west of Napa River. The tide gage and staff
were on the seawall at the west side of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5 1937
DESIGNATION: 941 5623 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 8702
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: JT9307
SETTING CLASSIFICATION: Granite basement wall OPUS PID:
LATITUDE: 38° 17.8' N ( 38.29670) LONGITUDE: 122° 17.2' W (-122.28700)
The primary bench mark is a disk set in the top of the granite basement wall at
the east corner of post office at the intersection of Second and Randolph
Streets, 3.75 m (12.3 ft) NE of center of building entrance, 0.34 m (1.1 ft)
east of east corner of building, and 7 m (23 ft) above sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9415623 PUBLICATION DATE: 02/05/2004
Name: NAPA, NAPA RIVER
CA
NOAA Chart: 18654 Latitude: 38° 17.9' N ( 38.29830)
USGS Quad: NAPA Longitude: 122° 16.8' W (-122.28000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1937
DESIGNATION: TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 8700
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: JT0428
SETTING CLASSIFICATION: Concrete retaining wall OPUS PID:
LATITUDE: 38° 17.9' N ( 38.29830) LONGITUDE: 122° 17.0' W (-122.28300)
The bench mark is a disk set in top of concrete retaining wall on west bank of
Napa River, 61 m (201 ft) NE of center of intersection of Fourth and Main
Streets, 12.65 m (41.5 ft) SE of east corner of Krafts Machine Shop, 6.71 m
(22.0 ft) SE of center of flight of steps leading to wharf, and 0.30 m (1 ft)
north of south end of the wall.
BENCH MARK STAMPING: 20
DESIGNATION: 20 USGS
MONUMENTATION: Survey disk VM#: 8703
AGENCY: US Geological Survey (USGS) IDB PID#: JT0430
SETTING CLASSIFICATION: Building wall OPUS PID:
LATITUDE: 38° 17.9' N ( 38.29830) LONGITUDE: 122° 17.1' W (-122.28500)
The bench mark is a disk set vertically in NE concrete wall of the Napa County
Courthouse at Second and Brown Streets, 7.62 m (25.0 ft) NW of center of north
entrance to courthouse, 0.91 m (3.0 ft) SE of north corner of building, and 1.07
m (3.5 ft) above sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9415623 PUBLICATION DATE: 02/05/2004
Name: NAPA, NAPA RIVER
CA
NOAA Chart: 18654 Latitude: 38° 17.9' N ( 38.29830)
USGS Quad: NAPA Longitude: 122° 16.8' W (-122.28000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NA 2
DESIGNATION: NA 2
MONUMENTATION: Survey disk VM#: 8704
AGENCY: US Army Corps of Engineers (USE) IDB PID#: JT0426
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 38° 17.9' N ( 38.29830) LONGITUDE: 122° 17.1' W (-122.28500)
The bench mark is a disk set in the top of the south curb of the south sidewalk
near the intersection of Main and Third Streets, near the east end of the
Francis Bridge, 7.16 m (23.5 ft) south of centerline of Third Street, 3.26 m
(10.7 ft) north of eastern most lamp post set atop the southern rail, 1.22 m
(4.0 ft) north of south guardrail of bridge, and 0.1 m (0.4 ft) south of curb
edge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9415623 PUBLICATION DATE: 02/05/2004
Name: NAPA, NAPA RIVER
CA
NOAA Chart: 18654 Latitude: 38° 17.9' N ( 38.29830)
USGS Quad: NAPA Longitude: 122° 16.8' W (-122.28000)
T I D A L D A T U M S
Tidal datums at NAPA, NAPA RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: March 1979 - June 1979
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 = 2.091
MEAN HIGH WATER MHW = 1.946
MEAN SEA LEVEL MSL = 1.165
MEAN TIDE LEVEL MTL = 1.130
MEAN LOW WATER MLW = 0.314
North American Vertical Datum NAVD88 = 0.079
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5 1937 7.583 5.637
NO 3 1937 5.582 3.636
20 7.171 5.225
NA 2 6.487 4.541
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9415623 PUBLICATION DATE: 02/05/2004
Name: NAPA, NAPA RIVER
CA
NOAA Chart: 18654 Latitude: 38° 17.9' N ( 38.29830)
USGS Quad: NAPA Longitude: 122° 16.8' W (-122.28000)
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.