U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
To reach the bench marks from the intersection of State Highways 213 and 291 in
Chestertown, proceed west on Route 291 for 0.8 km (0.5 mi) to Highway 20, turn
right and continue west on Highway 20 for 11.3 km (7.0 mi) to Highway 21. Turn
right and proceed west on Highway 21 for 5.3 km (3.3 mi) to the Tolchester
Marina. The bench marks are located between Route 21 and the entrance channel to
the marina. The tide gage is located on the north bulkhead along the entrance
channel.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3364 B 1983
DESIGNATION: 857 3364 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 3160
AGENCY: National Ocean Survey (NOS) IDB PID#: AJ8034
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: AJ8034
LATITUDE: 39° 12.9' N ( 39.21475) LONGITUDE: 76° 14.6' W ( -76.24339)
The primary bench mark is a disk located on the east side of the tennis courts,
21.76 m (71.4 ft) SSW of the NE end post of a wood fence post, 18.59 m (61.0
ft) south of the East corner of the chain link fence around the tennis courts,
4.54 m (14.9 ft) SE of the SE side fence for the tennis courts, 1.01m (3.31 ft)
NW of the wood fence and 0.12m (0.39 ft) SE of a fiberglass witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3364 C 1983
DESIGNATION: 857 3364 C
MONUMENTATION: Tidal Station disk VM#: 3161
AGENCY: National Ocean Survey (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 39° 12.9' N ( 39.21475) LONGITUDE: 76° 14.5' W ( -76.24208)
The bench mark is a disk located on an earthen dam on the north side of Route 21
across from the entrance to the Tolchester Marina, 31.82 m (104.4 ft) SE of the
SE corner fence post for a hurricane fence by the pond on the north side of
Route 21, 24.60 m (80.7 ft) north of the eastern gate post at the entrance to
the marina, 22.19 m (72.8 ft) NNE of the western gate post, 13.35 m (43.8 ft) NE
of the centerline of Route 21, 5.76 m (18.9 ft) south of the waters edge of the
SE corner of the pond, and 0.09 m (0.30 ft) south of an orange fiberglass
witness post. The bench mark is set 0.12 m (0.4 ft) below ground, crimped to
the top a stainless steel rod driven 16.5 m (54 ft) to refusal, and encased in a
4-inch PVC pipe with a protective cap.
BENCH MARK STAMPING: 3364 D 2003
DESIGNATION: 857 3364 D
MONUMENTATION: Tidal Station disk VM#: 16991
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Foundation of boat storage OPUS PID:
LATITUDE: 39° 12.8' N ( 39.21347) LONGITUDE: 76° 14.5' W ( -76.24142)
The bench mark is a disk set in the foundation of a large corrugated steel
workshop/boat storage building on the east side of the Tolchester marina, 37.52
m (123.1 ft) east of the SE corner of the Tolchester marina office/restaurant,
15.33 m (50.3 ft) north of the south corner of the corrugated steel building,
15.31 m (50.2 ft) south of the north corner of the corrugated steel building,
and 0.27 m (0.9 ft) west of the west face of the corrugated steel building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3364 E 2015
DESIGNATION: 857 3364 E
MONUMENTATION: Flange-encased Rod VM#: 21638
AGENCY: National Ocean Survey (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBDW47
LATITUDE: 39° 12.9' N ( 39.21456) LONGITUDE: 76° 14.4' W ( -76.24061)
The bench mark is a flanged encased stainless steel deep rod with NOS logo cap
and concrete kick block located on the south side of Tolchester Beach road
across from the driveway for the residence at 21096 Tolchester Beach road, 22.4
m (73.5 ft) east of the green electrical box number 135, 7.4 m (24.4 ft) south
of the center line of Tolchester Beach road, and 0.9 m (2.9 ft) north of the
orange NOAA survey witness post attached to the green fence for the marina,
driven 33.2 m (108.9 ft) to refusal, and is recessed 8 cm (3 inches) below
grade.
BENCH MARK STAMPING: 3364 F 2016
DESIGNATION: 857 3364 F
MONUMENTATION: Flange-encased Rod VM#: 21961
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 39° 12.9' N ( 39.21458) LONGITUDE: 76° 14.3' W ( -76.23783)
The bench mark is a rod driven 10.7 m into the ground that is surrounded by a
sleeve. The bench mark is located on the south side of Tolchester Beach Road ,
98.1 m (321.8 ft) east of the center of the intersection between Tolchester
Beach Road and Park Drive, 16.9 m (55.4 ft) south of the telephone pole 'KOP
FI-4 07', and 1.1 m (3.5 ft) north of the orange NOAA survey witness post
attached to the chain link fence for the marina.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1-TC-02 2009
DESIGNATION: 1-TC-02
MONUMENTATION: Bench Mark disk VM#: 21962
AGENCY: US Army Corps of Engineers IDB PID:
SETTING CLASSIFICATION: Concrete monument OPUS PID#: BBBQ08
LATITUDE: 39° 12.9' N ( 39.21450) LONGITUDE: 76° 14.3' W ( -76.23903)
The bench mark is a disk set in a concrete pipe embedded in the ground located
6.40 m (21.0 ft) west from the western most gate post of a chain link fence,
5.63 m (18.5 ft) south of centerline of Tolchester Beach Road, and 2.59 m (8.5
ft) north of an orange witness post attached to a chain link fence.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
T I D A L D A T U M S
Tidal datums at TOLCHESTER BEACH, CHESAPEAKE BAY based on:
LENGTH OF SERIES: 24 Years
TIME PERIOD: September 1994 - September 2019
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8574680 BALTIMORE, FORT MCHENRY, PATAPSCO RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/19/2003) = 2.412
MEAN HIGHER HIGH WATER MHHW = 0.529
MEAN HIGH WATER MHW = 0.434
North American Vertical Datum NAVD88 = 0.297
MEAN SEA LEVEL MSL = 0.255
MEAN TIDE LEVEL MTL = 0.249
MEAN LOW WATER MLW = 0.065
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (03/03/2018) = -1.062
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3364 B 1983 1.947 1.513
3364 C 1983 3.246 2.812
3364 D 2003 2.628 2.194
3364 E 2015 8.536 8.102
3364 F 2016 8.709 8.275
1-TC-02 2009 9.156 8.722
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8573364 PUBLICATION DATE: 12/03/2020
Name: TOLCHESTER BEACH, CHESAPEAKE BAY
MD
NOAA Chart: 12278 Latitude: 39° 12.8' N ( 39.21344)
USGS Quad: ROCK HALL Longitude: 76° 14.7' W ( -76.24453)
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.