U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 5
Station ID: 8419317 PUBLICATION DATE: 12/12/2018
Name: WELLS, WEBHANNET RIVER
ME
NOAA Chart: 13286 Latitude: 43° 19.2' N ( 43.32000)
USGS Quad: WELLS Longitude: 70° 33.8' W ( -70.56331)
To reach the bench marks from the intersection of US Route 1 and State Route 9
in Wells, proceed north on Route 1 for 46m (150 ft) to Lower Landing Road and
proceed east for 1.6 km (1.0 mi) to the Wells Town Dock. The bench marks are
along Lower Landing Road, Route 9, and Route 1. The tide gage is located on the
town pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: PUMP 1987
DESIGNATION: 841 9317 PUMP
MONUMENTATION: Survey disk VM#: 15919
AGENCY: US Army Corps of Engineers (USE) IDB PID:
SETTING CLASSIFICATION: Concrete pad OPUS PID#: BBCF81
LATITUDE: 43° 19.3' N ( 43.32100) LONGITUDE: 70° 33.9' W ( -70.56539)
The primary bench mark is a disk set in the east corner of a concrete pad at the
entrance to the pump station next to Lords Harbor Restaurant, 72 m (236 ft)
north of the centerline of Lower Landing Road, 12.88 m (42.3 ft) north of a
utility pole numbered DC-C7, and 5.46 m (17.9 ft) NE of the center of the
circular concrete pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8419317 PUBLICATION DATE: 12/12/2018
Name: WELLS, WEBHANNET RIVER
ME
NOAA Chart: 13286 Latitude: 43° 19.2' N ( 43.32000)
USGS Quad: WELLS Longitude: 70° 33.8' W ( -70.56331)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9317 A 1999
DESIGNATION: 841 9317 A
MONUMENTATION: Tidal Station disk VM#: 15920
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete skidway OPUS PID#: BBCC03
LATITUDE: 43° 19.2' N ( 43.32011) LONGITUDE: 70° 33.9' W ( -70.56486)
The bench mark is a disk set in the concrete skidway at Webhannet River
Boatyard, 13.44 M (44.1 ft) east of the NE corner of the Webhannet River
Boatyard building, 5.72 m (18.8 ft) south of the SE corner of the Webhannet
River Boat Supply Shop, and 0.29 m (0.1 ft) SE of the NW edge of the concrete
skidway at the boatyard.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8419317 PUBLICATION DATE: 12/12/2018
Name: WELLS, WEBHANNET RIVER
ME
NOAA Chart: 13286 Latitude: 43° 19.2' N ( 43.32000)
USGS Quad: WELLS Longitude: 70° 33.8' W ( -70.56331)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: LORD 1975
DESIGNATION: LORD
MONUMENTATION: Survey disk VM#: 15922
AGENCY: Maine Department of Transportation
(MEDT) IDB PID#: OC2106
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 43° 19.2' N ( 43.31969) LONGITUDE: 70° 34.3' W ( -70.57201)
The bench mark is a disk set in a concrete post located 0.8 km (0.5 mi) ESE
along Lower Landing Road from its intersection with U.S. Highway 1, 11.80 m
(38.7 ft) west of power pole numbered 20, 11.40 m (37.4 ft) north of a cable
pole, 11 m (35 ft) SSW of the Lower Landing Road centerline, and 1 m (3 ft)
below the road.
BENCH MARK STAMPING: 9317 C 2008
DESIGNATION: 841 9317 C
MONUMENTATION: Tidal Station disk VM#: 18994
AGENCY: National Ocean Survey/Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete Slab Leading to Pier OPUS PID:
LATITUDE: 43° 19.2' N ( 43.32017) LONGITUDE: 70° 33.8' W ( -70.56375)
The bench mark is a disk set in a concrete slab located 8.52 m (28.0 ft) east
from the NE corner of the new Harbor Master's building, 6.21 m (20.4 ft) south
from the SE corner of a small wood frame building for oyster hatchery, and 0.75
m (2.5 ft) SW of the NE corner of a concrete slab next to the pier entrance or
onshore end of a wooden pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8419317 PUBLICATION DATE: 12/12/2018
Name: WELLS, WEBHANNET RIVER
ME
NOAA Chart: 13286 Latitude: 43° 19.2' N ( 43.32000)
USGS Quad: WELLS Longitude: 70° 33.8' W ( -70.56331)
T I D A L D A T U M S
Tidal datums at WELLS, WEBHANNET RIVER based on:
LENGTH OF SERIES: 9 YEARS
TIME PERIOD: 12/05-11/08, 12/09-11/10, 7/11-6/16
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 (01/04/2018) = 4.068
MEAN HIGHER HIGH WATER MHHW = 2.913
MEAN HIGH WATER MHW = 2.782
North American Vertical Datum NAVD88 = 1.566
MEAN SEA LEVEL MSL = 1.454
MEAN TIDE LEVEL MTL = 1.443
MEAN LOW WATER MLW = 0.104
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/20/2015) = -0.935
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
PUMP 1987 5.498 2.716
9317 A 1999 5.122 2.340
LORD 1975 3.959 1.177
9317 C 2008 4.666 1.884
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8419317 PUBLICATION DATE: 12/12/2018
Name: WELLS, WEBHANNET RIVER
ME
NOAA Chart: 13286 Latitude: 43° 19.2' N ( 43.32000)
USGS Quad: WELLS Longitude: 70° 33.8' W ( -70.56331)
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.