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Datums Page Page 1 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1892 D 1980
DESIGNATION: 857 1892 D
MONUMENTATION: Tidal Station disk VM#: 13432
AGENCY: National Ocean Survey (NOS) IDB PID#: AC6854
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 38° 34.4' N ( 38.57330) LONGITUDE: 76° 4.2' W ( -76.07000)
The primary bench mark is a disk located along the east side of Hayward Street,
31.46 m (103.2 ft) west of the south corner of the Governors Hall, 28.99 m (95.1
ft) SE of the bulkhead face, 4.33 m (14.2 ft) WNW of the west corner of a storm
drain, and 0.55 m (1.8 ft) NE of power pole numbered 33471-00805 with white
witness post. The bench mark is set 9.1 cm (0.3 ft) below ground, crimped to the
top of a stainless steel rod driven 11 m (36 ft) to refusal, and encased in a 4
inch PVC pipe with concrete kickblock. Note: Sleeve depth does not meet the
specifications of a class a rod mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1892 A 1980
DESIGNATION: 857 1892 A
MONUMENTATION: Tidal Station disk VM#: 13429
AGENCY: National Ocean Survey (NOS) IDB PID#: AC6857
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 38° 35.1' N ( 38.58500) LONGITUDE: 76° 3.8' W ( -76.06330)
The bench mark is a disk located at the NW corner of the intersection of
Maryland Avenue and Hayward Street, 9.24 m (30.3 ft) NW of the centerline of
Hayward Street, 7.80 m (25.6 ft) NE of the centerline of Maryland Avenue, and
0.49 m (1.6 ft) north of power pole numbered 33432/00725. The bench mark is
crimped to the top of a galvanized steel rod driven 9.8 m (32 ft) to refusal,
and encased in a 4 inch PVC pipe with concrete kickblock. Note: Sleeve depth
does not meet the specifications of a class a rod mark.
BENCH MARK STAMPING: 1892 B 1980
DESIGNATION: 857 1892 B
MONUMENTATION: Tidal Station disk VM#: 13430
AGENCY: National Ocean Survey (NOS) IDB PID#: AC6856
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 38° 34.3' N ( 38.57170) LONGITUDE: 76° 4.2' W ( -76.07000)
The bench mark is a disk located at the NE corner of the intersection of Byrn
Street and Hayward Street, 10.91 m (35.8 ft) NE of the centerline of Byrn
Street, 6.55 m (21.5 ft) SE of the centerline of Hayward Street, and 0.4 m (1.3
ft) west of a light pole numbered 33453/00763. The bench mark is set 9.1 cm (0.3
ft) below ground, crimped to the top of a stainless steel rod driven 11 m (36
ft) to refusal, and encased in a 4 inch PVC pipe with concrete kickblock.
Note: Sleeve depth does not meet the specifications of a class a rod mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1892 C 1980
DESIGNATION: 857 1892 C
MONUMENTATION: Tidal Station disk VM#: 13431
AGENCY: National Ocean Survey (NOS) IDB PID#: AC6855
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID#: AC6855
LATITUDE: 38° 34.3' N ( 38.57170) LONGITUDE: 76° 4.2' W ( -76.07000)
The bench mark is a disk located along the east side of Hayward Street, 23.07 m
(75.7 ft) south of the SW corner of the brick office building, 6.71 m (22.0 ft)
SE of the centerline of Hayward Street, and 0.43 m (1.4 ft) SE of power pole
numbered 33459/00777. The bench mark is crimped to the top of an unspecified
rod driven 7.3 m (24 ft) to refusal, and encased in a 4 inch PVC pipe with
concrete kickblock. Note: Sleeve depth does not meet the specifications of a
class a rod mark.
BENCH MARK STAMPING: 1892 F 1980
DESIGNATION: 857 1892 F
MONUMENTATION: Tidal Station disk VM#: 13434
AGENCY: National Ocean Survey (NOS) IDB PID#: DL8742
SETTING CLASSIFICATION: Concrete loading dock OPUS PID:
LATITUDE: 38° 34.4' N ( 38.57330) LONGITUDE: 76° 4.1' W ( -76.06830)
The bench mark is a disk set in the concrete loading dock on the east corner of
the Governors Hall, 5.79 m (19.0 ft) NW of three cables for a canvas canopy,
4.21 m (13.8 ft) SE of the NE corner of the hall, 0.3 m (1 ft) SW of the NE
corner of a concrete platform, and 1.13 m (3.7 ft) above ground.
BENCH MARK STAMPING: BALTO MARYLAND
DESIGNATION: 19 BALTO
ALIAS:
MONUMENTATION: Survey disk VM#: 13435
AGENCY: US Geological Survey (USGS) IDB PID#: HV0236
SETTING CLASSIFICATION: Granite foundation OPUS PID:
LATITUDE: 38° 34.3' N ( 38.57170) LONGITUDE: 76° 4.6' W ( -76.07670)
The bench mark is a disk set vertically in the NW face of the granite foundation
for the Dorchester County Courthouse, at the intersection of High Street and
Spring Street, 35.4 m (116 ft) NE of the centerline of Spring Street, 29 m (95
ft) SE of the centerline of High Street, 0.21 m (0.7 ft) NE of the west corner
of the building, and 1 m (3 ft) above High Street.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: CAM 1980
DESIGNATION: CAM 1980
MONUMENTATION: Triangulation Station disk VM#: 13823
AGENCY: US Army Corps of Engineers (USE) IDB PID#: DL8743
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 38° 34.2' N ( 38.57000) LONGITUDE: 76° 4.4' W ( -76.07330)
The bench mark is a disk set in the concrete sidewalk on the SW corner of the
Cambridge Creek Bridge on Maryland Avenue, 44.10 m (144.7 ft) west from the
centerline of the opening of the draw bridge, 34.11 m (111.9 ft) west of the
west edge of the bridge span, 15.42 m (50.6 ft) east of the bridge stoplight at
the west end of the bridge, 4.83 m (15.8 ft) SSW from the centerline of the
bridge road, and 0.73 m (2.4 ft) north of the concrete railing.
BENCH MARK STAMPING: 1892 G 2012
DESIGNATION: 857 1892 G
MONUMENTATION: Tidal Station disk VM#: 20464
AGENCY: CO-OPS IDB PID:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 38° 34.3' N ( 38.57228) LONGITUDE: 76° 4.1' W ( -76.06789)
The bench mark is a brass disc set in a concrete pad located 26.13 M (85.7 FT)
southeast of power line pole #33509 on the north side of Hayward St, 20.2 M
(66.3 FT) east of a red fire hydrant located on Hayward St, 7.1 M (23.3 FT)
northwest of the south corner of a 7.3 M (24 FT) x 7.0 M (23 FT) concrete pad
used for 2 medical oxygen tanks and is 11 inches (28 cm) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: S 61 1942
DESIGNATION: S 61
MONUMENTATION: Bench Mark disk VM#: 22856
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: HV0002
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 38° 34.1' N ( 38.56889) LONGITUDE: 76° 3.8' W ( -76.06319)
The mark is a brass disk set in a concrete abutment of the U.S. 50 bridge over
the Choptank River, 12.8 m (42 ft) ENE of the SE corner of a placard on bricks
located on the west side of the Frederick C. Malkus, Jr. Bridge, 8.38 m (27.5
ft) SW of a galvanized steel double chain link gate standing approximately 2.7 m
(9 ft), 5.00 m (16.4 ft) west of the centerline of a paved road leading to the
Bill Burton Fishing Pier.
BENCH MARK STAMPING: 1892 H 2018
DESIGNATION: 857 1892 H
MONUMENTATION: Bench Mark disk VM#: 22857
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 38° 34.3' N ( 38.57242) LONGITUDE: 76° 3.7' W ( -76.06175)
The bench mark is a brass disk set flush in concrete located 7.0 m (23.0 ft) NNW
of the SSE face of the Bill Burton Fishing Pier curb, 1.20 m (3.9 ft) SSE of the
NNW of the curb, 0.61 m (2.0 ft) east of the east corner of the wind mast base
plate located next to the NOAA tide enclosure, and 0.23 m (0.8 ft) above the
road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
T I D A L D A T U M S
Tidal datums at CAMBRIDGE, CHOPTANK 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 (09/19/2003) = 1.884
MEAN HIGHER HIGH WATER MHHW = 0.622
MEAN HIGH WATER MHW = 0.558
North American Vertical Datum NAVD88 = 0.337
MEAN TIDE LEVEL MTL = 0.310
MEAN SEA LEVEL MSL = 0.309
MEAN LOW WATER MLW = 0.063
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/17/1982) = -0.878
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1892 D 1980 2.594 2.036
1892 A 1980 4.184 3.626
1892 B 1980 4.527 3.969
1892 C 1980 3.913 3.355
1892 F 1980 3.910 3.352
BALTO MARYLAND 6.106 5.548
CAM 1980 3.549 2.991
1892 G 2012 3.992 3.434
S 61 1942 4.214 3.656
1892 H 2018 4.187 3.629
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8571892 PUBLICATION DATE: 02/26/2020
Name: CAMBRIDGE, CHOPTANK RIVER
MD
NOAA Chart: 12266 Latitude: 38° 34.5' N ( 38.57417)
USGS Quad: CAMBRIDGE Longitude: 76° 4.3' W ( -76.07222)
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.
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Station Location
Published bench mark
Unpublished bench mark