U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
To reach the tidal bench marks from the intersection of State Highway 360 and
County Road 624 south of Calao, proceed 9.8 km (6.1 miles) north on County Road
624 to the Lewisetta Marina and General Store. The bench marks are located in
the vicinity of the marina and store and the tide gage is located on the fuel
pier.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: R 462 1971
DESIGNATION: R 462
MONUMENTATION: Bench Mark disk VM#: 493
AGENCY: National Geodetic Survey (NGS) IDB PID#: GV0156
SETTING CLASSIFICATION: Metal rod on base plate encased in 4
inch Orangeburg pipe OPUS PID#: GV0156
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.8' W ( -76.46330)
The primary bench mark is a disk located 52.2 m (171.3 ft) SE of the east corner
of the Lewisetta General Store, 37.8 m (124.0 ft) south of the centerline of a
gravel road, 16.67 m (54.7 ft) SW of the SW corner of a two story white house,
from the SW corner of a 12 x 12 wooden shed, and NNW of a fiberglass witness
post. The bench mark is set 0.3 m (1 ft) below grade, crimped to the top of a
1.2 m (4 ft) section of copper clad rod attached to a metal base plate, and
encased in a 4 inch Orangeburg pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2 1959
DESIGNATION: 863 5750 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 494
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: GV0157
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.8' W ( -76.46330)
The bench mark is a disk set in a concrete monument on the south side of the
Aluminum Boat and Storage Shed at the Lewisetta Marina, 33.68 m (110.5 ft) north
of the west corner of the boat rental building, 32.98 m (108.2 ft) NW of the
west corner of the Lewisetta General Store, 9.81 m (32.2 ft) west of the south
corner of the storage shed, and 9.63 m (31.6 ft) SE of the south corner of a
concrete block pump house. Bench Mark Is Set in a Concrete Monument on the
South Side of the Aluminum Boat and Storage Shed at the Lewisetta Marina, 33.68
M (110.50 Ft) North of the West Corner of the Boat Rental Building, 32.98 M
(108.20 Ft) Nw of the West Corner of the Lewisetta General Store, 9.81 M (32.18
Ft) West of the South Corner of the Storage Shed, and 9.63 M (31.59 Ft) Se of
the South Corner of a Concrete Block Pump House.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: Q 462 1971
DESIGNATION: Q 462
MONUMENTATION: Bench Mark disk VM#: 495
AGENCY: National Geodetic Survey (NGS) IDB PID#: GV0155
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.8' W ( -76.46330)
The bench mark is a disk set in a concrete post located on the east side of a
two story metal building, 37.64 m (123.5 ft) NW of the centerline of County Road
624, 14.39 m (47.2 ft) SE of the NE corner of the building, 10.76 m (35.3 ft)
ENE of the SE corner of the building, and 0.03 m (0.1 ft) below grade.
BENCH MARK STAMPING: NO 5 1973
DESIGNATION: 863 5750 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 496
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.8' W ( -76.46330)
The bench mark is a disk set in the bottom concrete step of the boat rental
building located in the vicinity of the fuel pier at the Lewisetta Marina, 20.60
m (67.6 ft) SW of the SW face of the Lewisetta General Store, 13.38 m (43.9 ft)
WNW of the steel sign post for the gas pumps, 5.91 m (19.4 ft) north of the
shore end of the fuel pier, 2.10 m (6.9 ft) ESE of the WNW corner of the bottom
step of the boat rental building, and 0.03 m (0.1 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5750 H 1978
DESIGNATION: 863 5750 H
MONUMENTATION: Tidal Station disk VM#: 499
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.8' W ( -76.46330)
The bench mark is a disk located at the east corner of the Aluminum Boat and
Storage Shed at the Lewisetta Marina, 30.17 m (99.0 ft) south of the east corner
of a wooden boat shed, 26.36 m (86.5 ft) NW of the NW corner of the Lewisetta
General Store, and 0.37 m (1.2 ft) NE of the east corner of the storage shed.
The bench mark is crimped to the top of a stainless steel rod driven 14.6 m (48
ft) to refusal, and encased in a PVC pipe with concrete kickblock.
BENCH MARK STAMPING: 5750 J 1979
DESIGNATION: 863 5750 J TIDAL
MONUMENTATION: Tidal Station disk VM#: 500
AGENCY: National Ocean Survey (NOS) IDB PID#: AJ4589
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: AJ4589
LATITUDE: 38° 60.0' N ( 38.99950) LONGITUDE: 76° 27.9' W ( -76.46422)
The bench mark is a disk located on the east side of County Road 624 at the
Lewisetta Chapel, 16.09 m (52.8 ft) NW of the north corner of the Chapel, 5.21 m
(17.1 ft) east of the centerline of County Road 624, and 0.49 m (1.6 ft) west of
a utility pole. The bench mark is crimped to the top of a stainless steel rod
driven 11.0 m (36 ft) to refusal, and encased in a 4 inch PVC pipe with concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5750 K 1980
DESIGNATION: 863 5750 K
MONUMENTATION: Tidal Station disk VM#: 501
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.9' W ( -76.46500)
The bench mark is a disk located in the Y junction of County Road 624 and a dirt
road near the concrete boat ramp at the Lewisetta Marina, 25.51 m (83.7 ft) ENE
of the NE end of the ramp, 7.35 m (24.1 ft) NW of the centerline of County Road
624, 4.23 m (13.9 ft) NNE of the centerline of the south part of the dirt road,
and 4.11 m (13.5 ft) south of the centerline of the north part of the dirt road.
The bench mark is crimped to the top of a galvanized steel rod driven 14.6 m
(48 ft) to refusal, and encased in a PVC pipe with concrete kickblock.
BENCH MARK STAMPING: 5750 M 1986
DESIGNATION: 863 5750 M
MONUMENTATION: Tidal Station disk VM#: 1624
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 38° 59.9' N ( 38.99830) LONGITUDE: 76° 27.9' W ( -76.46500)
The bench mark is a disk located along the west side of County Road 624 in the
vicinity of the Lewisetta Marina, 27.74 m (91.0 ft) south of a gravel road
leading to a tan house, 7.01 m (23.0 ft) west of the centerline of County Road
624, 3.41 m (11.2 ft) east of TTCO power pole #136 branded 7-25, and 0.30 m (1.0
ft) east of a NOAA witness post. The bench mark is set 0.06 m (0.2 ft) below
ground, crimped to the top of a stainless steel rod driven 11.0 m (36 ft) to
refusal, and encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1959
DESIGNATION: 863 5750 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 13557
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 37° 59.8' N ( 37.99670) LONGITUDE: 76° 27.9' W ( -76.46500)
The bench mark is a disk set in a concrete monument on top of a small mound
located at the 'Y' junction of a dirt road near the ramp at the Lewisetta
Marina, 25.51 m (83.7 ft) ENE of the NE end of the concrete boat ramp, 7.32 m
(24.0 ft) NW of the centerline of County Road 624, 4.21 m (13.8 ft) NNE of the
centerline of the south part of the dirt driveway, and 0.61 m (2.0 ft) east of
bench mark 5750 K 1980.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
T I D A L D A T U M S
Tidal datums at LEWISETTA, POTOMAC RIVER based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: January 1983 - December 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/01/2006) = 1.721
MEAN HIGHER HIGH WATER MHHW = 0.458
MEAN HIGH WATER MHW = 0.415
North American Vertical Datum NAVD88 = 0.253
MEAN SEA LEVEL MSL = 0.230
MEAN TIDE LEVEL MTL = 0.226
MEAN LOW WATER MLW = 0.036
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/05/1975) = -0.869
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
R 462 1971 1.420 1.004
NO 2 1959 1.278 0.863
Q 462 1971 1.219 0.803
NO 5 1973 1.471 1.055
5750 H 1978 1.193 0.777
5750 J 1979 1.346 0.931
5750 K 1980 1.567 1.152
5750 M 1986 1.297 0.882
NO 3 1959 1.542 1.127
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 9
Station ID: 8635750 PUBLICATION DATE: 10/12/2011
Name: LEWISETTA, POTOMAC RIVER
VA
NOAA Chart: 12233 Latitude: 37° 59.8' N ( 37.99611)
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W ( -76.46444)
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.