Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

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                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 9410971                         PUBLICATION DATE:  12/08/2011
Name:       PRISONERS HARBOR, SANTA CRUZ IS.                  
            CA
NOAA Chart: 18727                           Latitude:   34°  1.2' N (  34.02000)
USGS Quad:  SANTA CRUZ ISLAND               Longitude: 119° 41.0' W (-119.68300)


To reach the tidal bench marks proceed 32.2 km (20.0 mi) due south of Santa
Barbara by boat across Santa Barbara Channel to Prisoners Harbor located on
north central coast of the Island in the Pacific Ocean.  Then proceed along dirt
road (running east-west from dry canyon wash to boat ramp just past wooden
pier), parallel to sand and gravel beach along harbor shoreline.  The bench
marks are located in the vicinity.  The tide gauge and staff were located on the
NE end of the Prisoners Harbor Pier.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  1 1934

MONUMENTATION:           Tidal Station disk                    VM#:         8016
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  EW5798
SETTING CLASSIFICATION:  Concrete post                         OPUS PID:        
LATITUDE:   34°  1.2' N (  34.02000)          LONGITUDE: 119° 41.0' W (-119.68300)


The primary bench mark is a disk set in a concrete post 10.76 m (35.3 ft) SW of
SE corner of wooden pier, 62.64 m (205.5 ft) west of the west corner of a fence
around an abandoned 2-story concrete ranch house, 5.18 m (17.0 ft) west of the
centerline of a dirt road (from wharf passed warehouse to farm houses), 1.68 m
(5.5 ft) SE of north corner of warehouse, and 0.30 m (1.0 ft) east of the east
wall of a double gabled red brick warehouse.



                         BENCH MARK STAMPING:  4 1946

MONUMENTATION:           Tidal Station disk                    VM#:         8017
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  EW5800
SETTING CLASSIFICATION:  Cemented in Drill Hole                OPUS PID:        
LATITUDE:   34°  1.2' N (  34.02000)          LONGITUDE: 119° 41.0' W (-119.68300)


The bench mark is a disk set in top of a long sloping sandstrone outcrop, 224.03
m (735.0 ft) west of the SW corner of wooden pier, 160 m (525 ft) west of SW
corner of US Navy Steel floating pier, 10.36 m (34.0 ft) NW of the NW corner of
long graveled beach, and 2.44 m (8.0 ft) east of the east face of a steep bluff.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 9410971                         PUBLICATION DATE:  12/08/2011
Name:       PRISONERS HARBOR, SANTA CRUZ IS.                  
            CA
NOAA Chart: 18727                           Latitude:   34°  1.2' N (  34.02000)
USGS Quad:  SANTA CRUZ ISLAND               Longitude: 119° 41.0' W (-119.68300)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0971 A 1977

MONUMENTATION:           Tidal Station disk                    VM#:         8018
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   34°  1.2' N (  34.02000)          LONGITUDE: 119° 41.0' W (-119.68300)


The bench mark is a disk located in line of four pine trees, 31.00 m (101.7 ft)
SW of the SW corner of wooden pier, 29.99 m (98.4 ft) SE of an excavated boat
ramp centerline, 14.33 m (47.0 ft) north of steep bluff, 3 m (10 ft) SW and 2.90
m (9.5 ft) NW of middle two of four pine trees.  The site is marked by rock
cairn.  The bench mark is set 0.09 m (0.3 ft) below ground level, fastened to a
galvanized steel rod driven 3 m (10 ft) to bedrock refusal.   



                         BENCH MARK STAMPING:  0971 B 1977

MONUMENTATION:           Tidal Station disk                    VM#:         8019
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   34°  1.2' N (  34.02000)          LONGITUDE: 119° 41.0' W (-119.68300)


The bench mark is a disk located 91.99 m (301.8 ft) west of south end of wooden
pier, 44.99 m (147.6 ft) west of centerline of excavated boat ramp, 9.75 m (32.0
ft) north of steep bluff, 8 m (26.0 ft) south of ground and rocky beach
coastline, and 1.22 m (4.0 ft) south of a large pine tree.  The bench mark is
set 0.09 m (0.3 ft) below ground level, fastened to a galvanized steel rod
driven 7 m (23 ft) to bedrock refusal.   

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 9410971                         PUBLICATION DATE:  12/08/2011
Name:       PRISONERS HARBOR, SANTA CRUZ IS.                  
            CA
NOAA Chart: 18727                           Latitude:   34°  1.2' N (  34.02000)
USGS Quad:  SANTA CRUZ ISLAND               Longitude: 119° 41.0' W (-119.68300)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0971 C 1977

MONUMENTATION:           Tidal Station disk                    VM#:         8020
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   34°  1.2' N (  34.02000)          LONGITUDE: 119° 41.0' W (-119.68300)


The bench mark is a disk located 22 m (72 ft) ESE of SE corner of wooden pier,
58.00 m (190.3 ft) ESE of main gate across road leading from pier area, 11 m (36
ft) south of intersection of road to Navy facility and road to ranch, and 3.66 m
(12.0 ft) NW of west end of gate across road to ranch house and entrance to
canyon.  The bench mark is set 0.09 m (0.3 ft) below ground level, fastened to a
galvanized steel rod driven 10 m (33 ft) to bedrock refusal.   

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 9410971                         PUBLICATION DATE:  12/08/2011
Name:       PRISONERS HARBOR, SANTA CRUZ IS.                  
            CA
NOAA Chart: 18727                           Latitude:   34°  1.2' N (  34.02000)
USGS Quad:  SANTA CRUZ ISLAND               Longitude: 119° 41.0' W (-119.68300)


                            T I D A L   D A T U M S 


Tidal datums at PRISONERS HARBOR, SANTA CRUZ IS. based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           April 1978 - July 1978
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9411340 SANTA BARBARA, PACIFIC OCEAN


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  1.600
     MEAN HIGH WATER                            MHW    =  1.368
     MEAN TIDE LEVEL                            MTL    =  0.829
     MEAN SEA LEVEL                             MSL    =  0.822
     MEAN LOW WATER                             MLW    =  0.290
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     1 1934                                      3.521    2.153
     4 1946                                      2.586    1.218
     0971 A 1977                                 3.759    2.391
     0971 B 1977                                 3.614    2.246
     0971 C 1977                                 4.801    3.433

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 9410971                         PUBLICATION DATE:  12/08/2011
Name:       PRISONERS HARBOR, SANTA CRUZ IS.                  
            CA
NOAA Chart: 18727                           Latitude:   34°  1.2' N (  34.02000)
USGS Quad:  SANTA CRUZ ISLAND               Longitude: 119° 41.0' W (-119.68300)


                             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.