U.S. DEPARTMENT OF COMMERCE
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Datums Page Page 1 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
To reach the bench marks from the intersection of US Route 1 Bypass and State
Route 129 in Damariscotta, proceed SW on State Route 129 for 5.3 km (3.3 mi) to
Clarks Cove Road, turn right and continue west on Clarks Cove Road for 1.9 km
(1.2 mi) to the Darling Marine Center, University of Maine. The bench marks are
located in the vicinity of the Mitchell Flowing Seawater Laboratory. The tide
gage was located on the Center boat dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6731 A 1976
DESIGNATION: 841 6731 A
MONUMENTATION: Tidal Station disk VM#: 16115
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete cap logs OPUS PID#: BBBG27
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The primary bench mark is a disk set in the top center of the southern of two
concrete cap logs leading to the Ira C. Darling Boat House and Pump Station,
7.07m (23.2 ft) west of the east end of the cap log, 2.83 m (9.3 ft) south of
the center of the road leading to the pier, and 0.40 m (1.3 ft) east of the west
end of the cap log.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6731 B 1976
DESIGNATION: 841 6731 B
MONUMENTATION: Tidal Station disk VM#: 16116
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite rock outcrop OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set in a granite rock outcrop south of the road leading
to the pier, 14.63 m (48.0 ft) SE of the SE corner of the southern concrete cap
log, and 10.00 m (32.8 ft) south of the road leading to the Ira C. Darling Boat
Dock and pump house.
BENCH MARK STAMPING: 6731 C 1976
DESIGNATION: 841 6731 C
MONUMENTATION: Tidal Station disk VM#: 16117
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete cap logs OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set in the northern of two concrete cap logs leading to
the Ira C. Darling Boat Dock and pump house, 6.83 m (22.4 ft) west of the east
end of the cap log, 2.83 m (9.3 ft) north of the center line of the road leading
to the pier, and 0.61 m (2.0 ft) east of the west end of the cap log.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6731 D 1976
DESIGNATION: 841 6731 D
MONUMENTATION: Tidal Station disk VM#: 16118
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Building foundation OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set in the building foundation of the Aquacultural
Laboratory at the Ira C. Darling Center, located in the entrance way for the big
loading door on the west side of the building, 13.90 m (45.6 ft) south of the NW
corner of the Laboratory, and 4.42 m (14.5 ft) north of the SW corner of the
Laboratory.
BENCH MARK STAMPING: 6731 F 1979
DESIGNATION: 841 6731 F
MONUMENTATION: Tidal Station disk VM#: 16120
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set flush in bedrock about 137 m (450 ft) south of the
pier at the ruins of the old pier, 14.33 m (47.0 ft) north of a 15-inch diameter
apple tree, 12.50 m (41.0 ft) west of the centerline of a gravel road leading
south, and 6.77 m (22.2 ft) east of the most easterly concrete pier ruins.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6731 G 1979
DESIGNATION: 841 6731 G
MONUMENTATION: Tidal Station disk VM#: 16121
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set flush in a 3 m x 7.6 m (10 ft x 25 ft) section of
bedrock north of the boat ramp, 31 m (102 ft) west of the entrance door to the
marine lab, and 15.85 m (52 ft) north of the north edge of the boat ramp.
BENCH MARK STAMPING: 6731 H 1979
DESIGNATION: 841 6731 H
MONUMENTATION: Tidal Station disk VM#: 16122
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set flush in bedrock north of the pier, 39.9 m (131.0
ft) west of the centerline of the road leading north, 39 m (128 ft) NNW of the
NW corner of the Marine Lab, and 19.51 m (64 ft) SW of the most westerly of
three 4-inch PVC pipe air vents.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6731 J 1979
DESIGNATION: 841 6731 J
MONUMENTATION: Tidal Station disk VM#: 16123
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set flush in a 2 m x 2 m (6 ft x 8 ft) boulder NE of
the Marine Lab, 59 m (192 ft) NE of the NE corner of the metal pump house, 40 m
(130 ft) east of the most easterly of three 4-inch PVC air vents, and 23 m (74
ft) east of the centerline of a gravel road leading north.
BENCH MARK STAMPING: 6731 K 1979
DESIGNATION: 841 6731 K
MONUMENTATION: Tidal Station disk VM#: 16124
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 43° 56.0' N ( 43.93330) LONGITUDE: 69° 34.8' W ( -69.58000)
The bench mark is a disk set flush in a 9 m x 9 m (30 ft x 30 ft) section of
bedrock at the end of the gravel road leading north, 37 m (122 ft) north of the
centerline of the gravel turn around, 13 m (43 ft) NW of the treeline, and 2 m
(7 ft) south of the high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
T I D A L D A T U M S
Tidal datums at WALPOLE, DAMARISCOTTA RIVER based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: January 1979 - December 1979
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8418150 PORTLAND, CASCO BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (01/28/1979) = 4.075
MEAN HIGHER HIGH WATER MHHW = 3.094
MEAN HIGH WATER MHW = 2.960
MEAN SEA LEVEL MSL = 1.540
MEAN TIDE LEVEL MTL = 1.535
MEAN LOW WATER MLW = 0.110
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/31/1978) = -0.658
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6731 A 1976 5.455 2.495
6731 B 1976 4.000 1.040
6731 C 1976 5.461 2.501
6731 D 1976 7.253 4.293
6731 F 1979 3.940 0.980
6731 G 1979 3.771 0.811
6731 H 1979 3.710 0.750
6731 J 1979 10.699 7.739
6731 K 1979 3.860 0.900
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8416731 PUBLICATION DATE: 05/07/2003
Name: WALPOLE, DAMARISCOTTA RIVER
ME
NOAA Chart: 13293 Latitude: 43° 56.0' N ( 43.93330)
USGS Quad: BRISTOL Longitude: 69° 34.8' W ( -69.58000)
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.