U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8450954 PUBLICATION DATE: 06/28/2004
Name: NANNAQUAKET
RI
NOAA Chart: 13221 Latitude: 41° 37.1' N ( 41.61830)
USGS Quad: TIVERTON Longitude: 71° 12.2' W ( -71.20330)
To reach the tidal bench marks proceed from the junction of State Route 138 and
State Route 24 near Tiverton, proceed south on State Route 138 to State Route
77, then proceed south on State Route 77 to Nannaquaket Road, then turn right
and proceed south on Nannaquaket Road and cross the bridge to the St. James
Convent. The bench marks are between the convent and the shore. The tide gage
and staff were located on the concrete jetty located on the north shore of the
Convent Sisters of the Holly Union.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0954 A 1977
DESIGNATION: 845 0954 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 2133
AGENCY: National Ocean Survey (NOS) IDB PID#: LW5608
SETTING CLASSIFICATION: Concrete jetty OPUS PID:
LATITUDE: 41° 37.1' N ( 41.61830) LONGITUDE: 71° 12.7' W ( -71.21170)
The primary bench mark is a disk set flush in the east end of a concrete jetty
on the westernmost position of the convent grounds, 76 m (250 ft) NW (300
magnetic) of the flag pole, and 37 m (120 ft) NNW (330 magnetic) of the
concrete base of the wooden stairs leading from the convent cabana to the beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8450954 PUBLICATION DATE: 06/28/2004
Name: NANNAQUAKET
RI
NOAA Chart: 13221 Latitude: 41° 37.1' N ( 41.61830)
USGS Quad: TIVERTON Longitude: 71° 12.2' W ( -71.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0954 B 1977
DESIGNATION: 845 0954 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 2134
AGENCY: National Ocean Survey (NOS) IDB PID#: LW5609
SETTING CLASSIFICATION: Concrete base for stairs OPUS PID:
LATITUDE: 41° 37.1' N ( 41.61830) LONGITUDE: 71° 12.7' W ( -71.21170)
The bench mark is a disk set flush in the concrete base of the wooden stairs
leading from the cabana to the beach, 49 m (160 ft) west (270 magnetic) of the
flag pole, and 37 m (120 ft) SSE (150 magnetic) of the concrete jetty.
BENCH MARK STAMPING: 0954 C 1977
DESIGNATION: 845 0954 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 2135
AGENCY: National Ocean Survey (NOS) IDB PID#: LW5610
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 41° 37.1' N ( 41.61830) LONGITUDE: 71° 12.7' W ( -71.21170)
The bench mark is a disk set flush in a concrete step to the cabana shore room,
61 m (200 ft) SE (140 magnetic) of the east end of the concrete jetty, 23 m (75
ft) east (90 magnetic) of the concrete base of the wooden stairs leading from
the cabana to the beach and 17 m (55 ft) SW (239 magnetic) of the flag pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8450954 PUBLICATION DATE: 06/28/2004
Name: NANNAQUAKET
RI
NOAA Chart: 13221 Latitude: 41° 37.1' N ( 41.61830)
USGS Quad: TIVERTON Longitude: 71° 12.2' W ( -71.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0954 D 1977
DESIGNATION: 845 0954 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 2136
AGENCY: National Ocean Survey (NOS) IDB PID#: LW5520
SETTING CLASSIFICATION: Concrete base OPUS PID:
LATITUDE: 41° 37.1' N ( 41.61830) LONGITUDE: 71° 12.7' W ( -71.21170)
The bench mark is a disk set flush in the concrete base of the bar-b-que
platform, 19 m (62 ft) SW (215 magnetic) of the NW corner of the convent, 18 m
(59 ft) NW (330 magnetic) of the northwesternmost concrete clothes line pole,
and 16 m (52 ft) SE (110 magnetic) of the flag pole.
BENCH MARK STAMPING: 0954 E 1977
DESIGNATION: 845 0954 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 2137
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 37.1' N ( 41.61830) LONGITUDE: 71° 12.7' W ( -71.21170)
The bench mark is a disk set flush in a concrete pad located at the SW corner of
the convent, 26 m (84 ft) east (95 magnetic) of the flag pole and 16 m (54 ft)
north of the northernmost concrete clothes line pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8450954 PUBLICATION DATE: 06/28/2004
Name: NANNAQUAKET
RI
NOAA Chart: 13221 Latitude: 41° 37.1' N ( 41.61830)
USGS Quad: TIVERTON Longitude: 71° 12.2' W ( -71.20330)
T I D A L D A T U M S
Tidal datums at NANNAQUAKET based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: October 1977 - October 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8452660 NEWPORT, NARRAGANSETT BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.200
MEAN HIGH WATER MHW = 1.115
MEAN TIDE LEVEL MTL = 0.581
MEAN SEA LEVEL MSL = 0.539
MEAN LOW WATER MLW = 0.047
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0954 A 1977 2.475 1.360
0954 B 1977 2.306 1.191
0954 C 1977 6.038 4.923
0954 D 1977 8.196 7.081
0954 E 1977 8.788 7.673
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8450954 PUBLICATION DATE: 06/28/2004
Name: NANNAQUAKET
RI
NOAA Chart: 13221 Latitude: 41° 37.1' N ( 41.61830)
USGS Quad: TIVERTON Longitude: 71° 12.2' W ( -71.20330)
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.