U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
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
PRIMARY BENCH MARK STAMPING: R 462 1971
DESIGNATION: R 462
MONUMENTATION: Bench Mark disk VM#: 493
AGENCY: National Geodetic Survey (NGS) PID#: GV0156
SETTING CLASSIFICATION: Metal rod on base plate encased in 4 inch Orangeburg
pipe
The primary bench mark is a disk located 52.2 m (171.4 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 one story white house,
5.48 m (18.0 ft) NW of the high water line of the Coan River, 2.59 m (8.5 ft)
WNW of a 0.41 m (1.3 ft) diameter cottonwood tree, and 0.21 m (0.7 ft) SE of a
fiberglass witness post. The bench mark is 0.30 m (1.0 ft) below grade, crimped
to 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.
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) PID#: GV0157
SETTING CLASSIFICATION: Concrete monument
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.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
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) PID#: GV0155
SETTING CLASSIFICATION: Concrete monument
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) PID:
SETTING CLASSIFICATION: Concrete step
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 3 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5750 G 1978
DESIGNATION: 863 5750 G
MONUMENTATION: Tidal Station disk VM#: 498
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a disk located along the west side of State Road 6211 in the
vicinity of the Lewisetta Marina, 40.69 m (133.5 ft) east of the NE corner of
the two story metal boat repair building, 22.89 m (75.1 ft) SE of the SE corner
of a white one story house, 5.79 m (19.0 ft) west of the centerline of State
Road 6211, and 0.61 m (2.0 ft) west of a birch tree. The bench mark is 0.40 m
(1.3 ft) below ground, crimped to a stainless steel rod driven 14.6 m (48 ft) to
refusal, and encased in a 5 inch PVC pipe with concrete kickblock.
BENCH MARK STAMPING: 5750 H 1978
DESIGNATION: 863 5750 H
MONUMENTATION: Tidal Station disk VM#: 499
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
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 a stainless steel rod driven 14.6 m (48 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 4 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5750 J 1979
DESIGNATION: 863 5750 J
MONUMENTATION: Tidal Station disk VM#: 500
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
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 a stainless steel rod driven 11.0 m
(36 ft) to refusal, and encased in a 4 inch PVC pipe with concrete kickblock.
BENCH MARK STAMPING: 5750 K 1980
DESIGNATION: 863 5750 K
MONUMENTATION: Tidal Station disk VM#: 501
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Galvanized steel rod
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 a galvanized steel rod driven 14.6 m (48 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 5 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5750 M 1986
DESIGNATION: 863 5750 M
MONUMENTATION: Tidal Station disk VM#: 1624
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
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 0.06 m (0.2 ft) below ground,
crimped to a stainless steel rod driven 11.0 m (36 ft) to refusal, and encased
in a PVC pipe with concrete kickblock.
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) PID:
SETTING CLASSIFICATION: Concrete monument
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 6 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
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 (02/05/1998) = 1.170
MEAN HIGHER HIGH WATER (MHHW) = 0.458
MEAN HIGH WATER (MHW) = 0.415
NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 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
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
R 462 1971 1.420 1.004
NO 2 1959 1.289 0.874
Q 462 1971 1.216 0.801
NO 5 1973 1.474 1.059
5750 G 1978 1.046 0.631
5750 H 1978 1.192 0.776
5750 J 1979 1.341 0.925
5750 K 1980 1.564 1.149
5750 M 1986 1.293 0.877
NO 3 1959 1.543 1.127
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8635750 PUBLICATION DATE: 04/21/2003
Name: LEWISETTA, POTOMAC RIVER
VIRGINIA
NOAA Chart: 12233 Latitude: 37° 59.7' N
USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W
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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.