U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
To reach the tidal bench marks from the U.S. Post Office in Wiscasset on U.S.
Highway 1 (Main Street) at Fort Hill Street, travel SE on Highway 1 for 0.1 km
(0.1 mi) to Water Street, turn right on Water Street and proceed 0.3 km (0.2 mi)
south on Water Street to its termination at the entrance to the Wiscasset town
harbor parking lot. The bench marks are located from the east end of the Highway
1 Bridge over the Sheepscot River to a bedrock outcrop located in tidal flats to
the west of the harbor. The tide gauge and staff are located on a concrete pier
in the harbor.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6921 A 2015
DESIGNATION: 841 6921 A
MONUMENTATION: DB VM#: 21452
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: In rock outcrop OPUS PID#: BBDV82
LATITUDE: 43° 60.0' N ( 43.99992) LONGITUDE: 69° 40.0' W ( -69.66681)
The primary bench mark is a disk set in a 2.3 m (7.5 ft) by 3.9 m (12.8 ft)
bedrock outcrop projecting above high water near the center of the lagoon W of
the town harbor and N of a small rail road bridge over the inlet of the lagoon,
57.74 m (189.4 ft) WSW of the SE corner of the house at number 12 Fore street,
54.12 m (177.6 ft) SSW of a power pole 701 W of house at 12 Fore street, 50.76 m
(166.5 ft) SW of the SW corner of the house at number 12 fore street and 8.63 m
(28.3 ft) ENE of a 2.5 inch (6 cm) aluminum cap projecting above the bedrock
about 1.0 ft (0.3 m) and 0.55 m (1.8 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6921 B 2015
DESIGNATION: 841 6921 B
MONUMENTATION: DB VM#: 21453
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Retaining walls OPUS PID:
LATITUDE: 43° 60.0' N ( 43.99944) LONGITUDE: 69° 39.9' W ( -69.66525)
The bench mark is set in the S end of the town concrete pier abutment, 37.25 m
(122.2 ft) SSW of light pole numbered 198129 E of tracks and SW of the
harbormaster building, 30.90 m (101.4 ft) SE of the E rail of tracks at center
line of water street, 28.50 m (93.5 ft) SW of flag pole near boardwalk between
docks E of the harbormasters office, 6.91 m (22.7 ft) WNW of light pole number 9
on S side of the pier at ramp to commercial floating dock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H 17 1933
DESIGNATION: H 17
MONUMENTATION: DB VM#: 21454
AGENCY: US Coast & Geodetic Survey IDB PID#: PE1285
SETTING CLASSIFICATION: Massive structures (other than those
listed below) OPUS PID:
LATITUDE: 44° 0.0' N ( 44.00028) LONGITUDE: 69° 39.9' W ( -69.66547)
The bench mark is set vertically in the S side of the SE corner of the old 1870
customhouse which is now a privately owned building at 14 water street, 18.23 m
(59.8 ft) WNW of the 0.80 m (2.6 ft) tall fence post at the SE corner, 16.15 m
(53.0 ft) NW of a fire hydrant on the N side of Fore street W of intersection
with water street, 15.65 m (51.3 ft) ESE of the SW corner of the customhouse,
6.80 m (22.3 ft) E of the E column of the entrance on S side of building and
1.24 m (4.1 ft) above grade.
BENCH MARK STAMPING: 2262-W 1984
DESIGNATION: 2262W
MONUMENTATION: DB VM#: 21455
AGENCY: Maine Department of Transportation IDB PID#:
SETTING CLASSIFICATION: Abutments and piers of large bridges OPUS PID:
LATITUDE: 44° 0.1' N ( 44.00189) LONGITUDE: 69° 39.7' W ( -69.66247)
The bench mark is a disk slightly recessed in the S side of the W bridge
abutment near the center of the sidewalk, 11.19 m (36.7 ft) SE of manhole cover
just N of the centerline of Route 1 W of the abutment, 9.84 m (32.3 ft) ESE of
an 18 inch utility access cover in sidewalk W of abutment, 6.49 m (21.3 ft) SSW
of the centerline of Route 1 at the W most expansion joint, 4.22 m (13.8 ft) W
of bridge drain on S sidewalk E of the abutment, and 2.78 m (9.1 ft) E of the NE
corner of Donald Davey bridge memorial plaque.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2262-E 1984
DESIGNATION: 2262E
MONUMENTATION: DB VM#: 21456
AGENCY: Maine Department of Transportation IDB PID#:
SETTING CLASSIFICATION: Abutments and piers of large bridges OPUS PID:
LATITUDE: 43° 60.0' N ( 43.99989) LONGITUDE: 69° 39.1' W ( -69.65244)
The bench mark is set slightly recessed into the S end of the E bridge abutment
near the center of the sidewalk, 58.34 m (191.4 ft) ESE of sign on S side of
bridge reading Sheepscot harbor resort, 37.55 m (123.2 ft) WNW of a power pole
on S side of highway just W of Eddy road, 13.51 m (44.3 ft) W of drain in gutter
on S side of highway, 10.80 m (35.4 ft) WSW of sewer manhole cover at centerline
of highway E of abutment, 6.34 m (20.8 ft) SSW of the centerline of highway at
bridge expansion joint.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
T I D A L D A T U M S
Tidal datums at WISCASSET, SHEEPSCOT RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: May 2015 - August 2015
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 = 3.119
MEAN HIGH WATER MHW = 2.989
MEAN TIDE LEVEL MTL = 1.544
MEAN SEA LEVEL MSL = 1.541
MEAN LOW WATER MLW = 0.099
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6921 A 2015 3.849 0.860
6921 B 2015 3.904 0.915
H 17 1933 10.456 7.467
2262-W 1984 7.460 4.471
2262-E 1984 7.354 4.365
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8416921 PUBLICATION DATE: 02/10/2016
Name: WISCASSET, SHEEPSCOT RIVER
ME
NOAA Chart: 13293 Latitude: 44° 0.0' N ( 44.00000)
USGS Quad: Westport & Wiscasset Longitude: 69° 40.0' W ( -69.66670)
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.