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Datums Page Page 1 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
To reach the tidal bench marks from the intersection of Main Street and Jellison
Point Road in Stockton Springs, proceed south on Jellison Point Road for 4.0 km
(2.5 mi) to the entrance to Fort Point State Park, then turn left into the park
and follow the entrance road to the first dirt road on the left which leads to a
parking area. The bench marks are in the vicinity of the parking area, and
along the beach near the pier. The tide gage was located at the NE end of the
State Park pier.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 30 1948
DESIGNATION: TIDAL 30 STA 30
MONUMENTATION: Tidal Station disk VM#: 13997
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: PE0381
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 44° 28.0' N ( 44.46670) LONGITUDE: 68° 48.6' W ( -68.81000)
The primary bench mark is a disk set on top of a 2.4 m x1.5 m (8.0 ft x1.5 ft)
boulder projecting 1.2 m (4.0 ft) above the level of the ground, about 0.3 km
(0.2 mi) along a trail from the lighthouse at Fort Point on Cape Jellison, 110 m
(360 ft) SE along the waters edge from the end of the trail leading from the
lighthouse to the beach, and near the grass line of a 6.1 m (20.0 ft) bluff.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: TIDAL 3 STA 30
ALIAS: NO 3 (1908)
MONUMENTATION: Drill Hole VM#: 13998
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: PE0382
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 44° 28.1' N ( 44.46830) LONGITUDE: 68° 48.6' W ( -68.81000)
The bench mark is a drill hole on the top of a 3 m x 2 m (10 ft x 8 ft) boulder
projecting 2.1 m (7 ft) above the level of the beach and surrounded by water at
high tide, about 274 m (900 ft) NW along the waters' edge from the end of the
trail leading to the lighthouse, 165 m (540 ft) NW of bench mark NO 30 1948,
59.4 m (195.0 ft) SE of the inshore end of an old wharf, and 22.9 m (75.0 ft) NW
of the north bank of Cape Jellison.
BENCH MARK STAMPING: NO. 2 1948
DESIGNATION: 841 4721 NO 2
MONUMENTATION: Tidal Station disk VM#: 13999
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: PE0383
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 44° 28.2' N ( 44.47000) LONGITUDE: 68° 48.8' W ( -68.81330)
The bench mark is a disk set in top of a 3 m x 3m x 2 m (10 ft x 10 ft x 8 ft)
boulder just off the south shoreline, 18.17 m (59.6 ft) SSW of the north corner
of the third pier cribbing, 9.06 m (29.7 ft) west of the north corner of the
second pier cribbing, and 8.55 m (28.0 ft) south of the north corner of the
first cribbing, and approximately 2 m (6 ft) above the beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4721 A 1998
DESIGNATION: 841 4721 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 14000
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Pier foundation OPUS PID#: BBBF06
LATITUDE: 44° 28.3' N ( 44.47170) LONGITUDE: 68° 48.7' W ( -68.81170)
The bench mark is a disk set in the NW end of the concrete foundation for the
State Park pier, 57.40 m (188.3 ft) SSW of the NNE end of State Park pier, 3.41
m (11.2 ft) WNW of the ESE corner of the pier foundation, and 0.34 m (1.1 ft)
east of the west edge of the concrete foundation.
BENCH MARK STAMPING: 4721 B 1998
DESIGNATION: 841 4721 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 14001
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 44° 28.4' N ( 44.47330) LONGITUDE: 68° 48.7' W ( -68.81170)
The bench mark is a disk set in a boulder west of and uphill from the State Park
pier, 24.46 m (80.2 ft) south of the north corner of the parking area, 21.21 m
(69.6 ft) SSE of the west corner of the parking area, and 19.25 m (63.2 ft) ENE
of the northern granite block marking the trail leading to the State Park pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
T I D A L D A T U M S
Tidal datums at FORT POINT, PENOBSCOT RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 1999 - July 1999
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8418150 PORTLAND, CASCO BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 3.397
MEAN HIGH WATER MHW = 3.276
MEAN SEA LEVEL MSL = 1.710
MEAN TIDE LEVEL MTL = 1.693
MEAN LOW WATER MLW = 0.110
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 30 1948 4.175 0.899
TIDAL 3 STA 30 3.442 0.166
NO. 2 1948 3.448 0.172
4721 A 1998 6.243 2.967
4721 B 1998 13.560 10.284
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8414721 PUBLICATION DATE: 04/01/2004
Name: FORT POINT, PENOBSCOT RIVER
ME
NOAA Chart: 13309 Latitude: 44° 28.3' N ( 44.47170)
USGS Quad: CASTINE Longitude: 68° 48.8' W ( -68.81330)
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.