U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
To reach the tidal bench marks from the intersection of U.S. Highway 1 (Broad
Street) and Main Street, proceed south on Main Street for 1.0 km (0.6 mi) to a
fork in the road at Margin Street and Beach Street, continue right on Margin
Street and proceed80 m (250 ft) south to number 4 Margin Street. The bench
marks are located along the east side of the Pawcatuck River between 4 Margin
Drive and the Canal Street railroad overpass north of downtown Westerly. The
tide gauge is located on the south side of the pier at 4 Margin Street.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: A 18 1965
DESIGNATION: A 18
MONUMENTATION: Bench Mark disk VM#: 21485
AGENCY: US Coast & Geodetic Survey IDB PID#: LW0745
SETTING CLASSIFICATION: Retaining wall OPUS PID#: LW0745
LATITUDE: 41° 22.6' N ( 41.37750) LONGITUDE: 71° 49.9' W ( -71.83144)
The primary bench mark is a disk set on top of a concrete retaining wall for the
U.S. highway 1 bridge over the Pawcatuck river, 38.45 m (126.1 ft) NNE of the S
end of a 0.84 m (2.8 ft) tall retaining wall bordering a parking lot and the
river, 23.61 m (77.5 ft) NNW of the third decorative lamppost S of the westerly
bridge, 17.32 m (56.8 ft) WNW of the W curb edge of main street, 15.69 m (51.5
ft) SW of the end of the SE bridge parapet, 9.93 m (32.6 ft) WSW of the S of
three flag poles, 6.83 m (22.4 ft) WSW of the SW corner of the Korean war
memorial wall and about 3.40 m (11.2 ft) above the retaining wall footing in the
river.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 1 1917 4.656 FT
DESIGNATION: 845 5189 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 2215
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW0747
SETTING CLASSIFICATION: Stone walkway OPUS PID:
LATITUDE: 41° 22.2' N ( 41.36939) LONGITUDE: 71° 49.9' W ( -71.83203)
The bench mark is a disk set in a 1.10 m (3.6 ft) by 0.90 m (3.0 ft) stone
sidewalk slab leading to the pier, 27.23 m (89.3 ft) WSW of a utility pole
numbered 26, 25.00 m (82.0 ft) N of the high point of the S most granite
driveway entrance monolith, 4.48 m (14.7 ft) ESE of the river side edge of a
stone retaining wall bordering the Pawcatuck River, 3.54 m (11.6 ft) NW of the
curb edge of margin drive, 0.36 m (1.2 ft) WSW of the NE corner of the bottom of
the steps and about 1.60 m (5.2 ft) lower than the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM B 1 1961
DESIGNATION: B 1
MONUMENTATION: Bench Mark disk VM#: 2217
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW0746
SETTING CLASSIFICATION: Stone retaining wall OPUS PID:
LATITUDE: 41° 22.2' N ( 41.36983) LONGITUDE: 71° 49.9' W ( -71.83167)
The bench mark is a disk set in a 0.40 m (1.3 ft) by 2.73 m (9.0 ft) by 0.20 m
(0.7 ft) capstone to a retaining wall along the E bank of the Pawcatuck River on
the property of 2 margin street, 23.54 m (77.2 ft) W of the top bolt of a fire
hydrant, 19.53 m (64.1 ft) WSW of a utility pole numbered 25, 19.36 m (63.5 ft)
NNW of a concrete monument S of a driveway for 2 margin street, 11.82 m (38.8
ft) NW of the center line of margin road and about 1.40 m (4.6 ft) above the
river bottom.
BENCH MARK STAMPING: 5189 A 2015
DESIGNATION: 845 5189 A
MONUMENTATION: Tidal Station disk VM#: 21486
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Catch basin with wing wall OPUS PID:
LATITUDE: 41° 22.5' N ( 41.37500) LONGITUDE: 71° 49.9' W ( -71.83214)
The bench mark is a disk set in a catch basin with a wing wall at the boat
launch ramp, 15.87 m (52.1 ft) E of the SW most piling in the river, 15.62 m
(51.2 ft) SW of the S post of a fishing area sign, 7.70 m (25.3 ft) N of the S
edge of the catch basin, 4.34 m (14.2 ft) SSE of the SW corner of a square storm
drain, 0.55 m (1.8 ft) SE of the face of the NE most piling with a hand rail and
0.18 m (0.6 ft) E of the drain strip in the catch basin.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: G 18 1965
DESIGNATION: G 18
MONUMENTATION: Bench Mark disk VM#: 21487
AGENCY: US Coast & Geodetic Survey IDB PID#: LW0750
SETTING CLASSIFICATION: Railroad bridge abutment OPUS PID:
LATITUDE: 41° 22.8' N ( 41.38075) LONGITUDE: 71° 49.8' W ( -71.83067)
The bench mark is a disk set vertically in the wing wall of a rail road overpass
spanning canal street, 26.51 m (87.0 ft) SE of a power pole W of the underpass
numbered 44, 11.55 m (37.9 ft) SSW of the top of the stairs (slant distance),
10.65 m (34.9 ft) NW of a 0.35 m (1.1 ft) by 0.17 m (0.6 ft) plaque in memory of
Anthony J Perrone, 8.16 m (26.8 ft) NW of a utility pole E of the underpass
numbered 45, 8.13 m (26.7 ft) NE of the centerline of canal street, 0.45 m (1.5
ft) NE of the S end of the bridge wing wall, and set vertically in the SE face
of the wing wall about 0.90 m (3.0 ft) higher than the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
T I D A L D A T U M S
Tidal datums at WESTERLY, PAWCATUCK RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: May 2015 - August 2015
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8461490 NEW LONDON, THAMES RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.973
MEAN HIGH WATER MHW = 0.883
North American Vertical Datum NAVD88 = 0.572
MEAN SEA LEVEL MSL = 0.474
MEAN TIDE LEVEL MTL = 0.472
MEAN LOW WATER MLW = 0.061
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
A 18 1965 4.127 3.244
NO 1 1917 4.656 FT 1.684 0.801
BM B 1 1961 1.504 0.621
5189 A 2015 1.534 0.651
G 18 1965 6.600 5.717
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8455189 PUBLICATION DATE: 06/20/2016
Name: WESTERLY, PAWCATUCK RIVER
RI
NOAA Chart: 13214 Latitude: 41° 22.9' N ( 41.38170)
USGS Quad: WATCH HILL Longitude: 71° 49.9' W ( -71.83170)
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.