U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8635150 PUBLICATION DATE: 04/21/2003
Name: COLONIAL BEACH, POTOMAC RIVER
VA
NOAA Chart: 12286 Latitude: 38° 15.1' N ( 38.25170)
USGS Quad: COLONIAL BEACH NORTH Longitude: 76° 57.6' W ( -76.96000)
To reach the tidal bench marks from the intersection of State Highway 205 and
Colonial Avenue in Colonial Beach, proceed east on Colonial Avenue for 1.0 km
(0.6 mi) to Washington Avenue, then south on Washington Avenue for 0.5 km (0.3
mi) to Hawthorn Street, and then east on Hawthorn Street to the Colonial Beach
Municipal Pier. The bench marks are around town in the vicinity of the pier. The
tide gage and staff are at the east end of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5150 E 2000
DESIGNATION: 863 5150 E
MONUMENTATION: Flange-encased Rod VM#: 16169
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 38° 15.1' N ( 38.25170) LONGITUDE: 76° 57.7' W ( -76.96170)
The primary bench mark is located near the intersection of Taylor Street and
Dennison Street, 41.46 M (136.0 ft) east of the centerline of Taylor Street,
4.92 M (16.1 ft) north of the extended centerline of Dennison Street, 3.63 m
(11.9 ft) west of the centerline of the concrete boardwalk running along the
beach, and 1.10 m (3.6 ft) south of the south edge of a 8.60 m(28.2 ft) X 7.32m
(24.0 ft) concrete pad. The datum point is 0.07 m (0.2 ft) below ground, being
the top of a stainless steel rod driven 12.60 m (41.3 ft) to refusal, in a
sleeve extending to a depth of 0.6 m (2 ft), and encased in a 5 inch NOS logo
cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8635150 PUBLICATION DATE: 04/21/2003
Name: COLONIAL BEACH, POTOMAC RIVER
VA
NOAA Chart: 12286 Latitude: 38° 15.1' N ( 38.25170)
USGS Quad: COLONIAL BEACH NORTH Longitude: 76° 57.6' W ( -76.96000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 1 1972
DESIGNATION: 863 5150 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 489
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: HV8242
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 38° 15.0' N ( 38.25000) LONGITUDE: 76° 57.6' W ( -76.96000)
The bench mark is a disk set in the NE corner of a 4.6 m x 5.5 m (15 ft x 18 ft)
concrete pad located at the east end of Hawthorn Street, 11.89 m (39.0 ft) NW of
the NW end of Colonial Beach Municipal Pier, 11.83 m (38.8 ft) north of the
centerline of Hawthorn Street, 8.17 m (26.8 ft) WNW of power pole numbered WA
51, and 5.49 m (18.0 ft) east of the edge of the Francis Karn boardwalk.
BENCH MARK STAMPING: 5150 A 1978
DESIGNATION: 863 5150 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 491
AGENCY: National Ocean Survey (NOS) IDB PID#: HV8245
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 38° 15.0' N ( 38.25000) LONGITUDE: 76° 57.7' W ( -76.96194)
The bench mark is a disk located at the NE corner of the Colonial Beach School
Board office building at 16 Irving Avenue, 11.1 m (36.4 ft) west of the center
of the avenue, 3.7 m (12.1 ft) SSW of the NE corner of the building, 2.1 m (6.9
ft) north of the center of the main entrance, 1.1 m (3.6 ft) ESE of the east
face of the building, and 0.45 m (1.5 ft) NNE of a stoop. The bench mark is 0.1
m (0.3 ft) above ground, crimped to a stainless steel rod driven 7.3 m (24 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 3 of 5
Station ID: 8635150 PUBLICATION DATE: 04/21/2003
Name: COLONIAL BEACH, POTOMAC RIVER
VA
NOAA Chart: 12286 Latitude: 38° 15.1' N ( 38.25170)
USGS Quad: COLONIAL BEACH NORTH Longitude: 76° 57.6' W ( -76.96000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5150 C 1979
DESIGNATION: 863 5150 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 492
AGENCY: National Ocean Survey (NOS) IDB PID#: HV8248
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 38° 15.1' N ( 38.25170) LONGITUDE: 76° 57.7' W ( -76.96170)
The bench mark is a disk set in the NE corner of a concrete pad at the east
entrance to Potomac River Fisheries Commission on 222 Taylor Street, 17.80 m
(58.4 ft) south of the centerline of Wilder Street, 8.50 m (27.9 ft) south of
the NE corner of the Potomac River Fisheries Commission, 5.70 m (18.7 ft) west
of the centerline of Taylor Street, 1.75 m (5.7 ft) north of the center entrance
into the building, and 0.10 m (0.3 ft) above the street.
BENCH MARK STAMPING: LEARY 1954
DESIGNATION: LEARY KB AZ MK
ALIAS:
MONUMENTATION: Azimuth Mark disk VM#: 13444
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: HV8244
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 38° 15.0' N ( 38.25000) LONGITUDE: 76° 57.7' W ( -76.96170)
The bench mark is a disk set in the concrete sidewalk on the north side of
boundary street in the vicinity of the war memorial, 30.60 m (100.4 ft) west of
the centerline of Beach Terrace, 21.52 m (70.6 ft) NW of the NW corner of the
war memorial curbing, 14.02 m (46.0 ft) east of the centerline of Irving Street,
4.94 m (16.2 ft) north of the centerline of Boundary Street, and 0.61 m (2.0 ft)
south of a chain link fence.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8635150 PUBLICATION DATE: 04/21/2003
Name: COLONIAL BEACH, POTOMAC RIVER
VA
NOAA Chart: 12286 Latitude: 38° 15.1' N ( 38.25170)
USGS Quad: COLONIAL BEACH NORTH Longitude: 76° 57.6' W ( -76.96000)
T I D A L D A T U M S
Tidal datums at COLONIAL BEACH, 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 (09/06/1996) = 1.586
MEAN HIGHER HIGH WATER MHHW = 0.591
MEAN HIGH WATER MHW = 0.541
North American Vertical Datum NAVD88 = 0.301
MEAN SEA LEVEL MSL = 0.293
MEAN TIDE LEVEL MTL = 0.292
MEAN LOW WATER MLW = 0.043
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/04/1975) = -1.192
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5150 E 2000 1.924 1.383
NO 1 1972 2.516 1.976
5150 A 1978 3.792 3.251
5150 C 1979 2.514 1.973
LEARY 1954 3.709 3.168
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8635150 PUBLICATION DATE: 04/21/2003
Name: COLONIAL BEACH, POTOMAC RIVER
VA
NOAA Chart: 12286 Latitude: 38° 15.1' N ( 38.25170)
USGS Quad: COLONIAL BEACH NORTH Longitude: 76° 57.6' W ( -76.96000)
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.