U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


To reach the tidal bench marks from the intersection of U.S. Highway 50 and
Maryland Avenue, proceed NW on Maryland Avenue for about 0.6 km (0.4 mi) to
Hayward Street and turn right.  The bench marks are located in the park and
along Maryland Street.  Station is located on the Sailwinds Park property in the
back on a small wooden pier.


                         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  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 4 1942
                         DESIGNATION:          857 1892 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:        13428
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  HV0238
SETTING CLASSIFICATION:  Flagpole base                         OPUS PID#: HV0238
LATITUDE:   38° 34.5' N (  38.57500)          LONGITUDE:  76°  4.3' W ( -76.07170)


The bench mark is a disk set in the west side of a 2.13 m (7.0 ft) diameter
concrete flagpole foundation located 0.5 km (0.3 mi) NE along High Street from
the Dorchester County Courthouse, 12.41 m (40.7 ft) NW of the NW curb of the
drive on the SE side of the circle drive at the end of High Street, 11.80 m
(38.7 ft) SE of the SE curb of the drive on the NW side of the circle drive,
8.05 m (26.4 ft) NE of the NE edge of a walkway on the NE side of a pool of
water, 0.3 m (1 ft) west of the flagpole, and 0.3 m (1 ft) above the drive.



                         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.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         T I D A L   B E N C H   M A R K S


                         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.



                         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.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  1892 E 1980
                         DESIGNATION:          857 1892 E

MONUMENTATION:           Tidal Station disk                    VM#:        13433
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DL8741
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   38° 34.4' N (  38.57330)          LONGITUDE:  76°  4.0' W ( -76.06670)


The bench mark is a disk set in a concrete seawall SW of the wooden pier, 12.13
m (39.8 ft) east of the NW end of the pier, 11.98 m (39.3 ft) west of the east
end of the sea wall,  6.37 m (20.9 ft) NE of a fire hydrant, and 0.61 m (2.0 ft)
SW of a chain link fence.



                         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  5 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:   
                         DESIGNATION:          BM USE
                         ALIAS:                NO STAMPING 1

MONUMENTATION:           Triangulation Station disk            VM#:        13436
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  HV0239
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID#: HV0239
LATITUDE:   38° 34.5' N (  38.57500)          LONGITUDE:  76°  4.3' W ( -76.07170)


The bench mark is a disk set in a concrete monument located 0.5 km (0.3 mi) NE
along High Street from the Dorchester County Courthouse, 13.4 m (44 ft) south of
a flagpole, 8.08 m (26.5 ft) SE of the extended centerline of High Street, 4.27
m (14.0 ft) NW of the NW curb of the drive on the SE side of the circle at the
end of High Street, and 1.58 m (5.2 ft) east of the east edge of a walkway
around a pool of water.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         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.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  W 127 1941
                         DESIGNATION:          W 127

MONUMENTATION:           Magnetic station disk                 VM#:        13824
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  HV0237
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID#: HV0237
LATITUDE:   38° 34.5' N (  38.57500)          LONGITUDE:  76°  4.4' W ( -76.07330)


The bench mark is a disk set in a concrete monument, located in a park along the
NE side of Water Street between Water Street and the boat docks, 73.55 m (241.3
ft) NW of the NW curb of High Street, 37.80 m (124.0 ft) NE of the centerline of
Water Street, 24.69 m (81.0 ft) SW of the SW side of the boat docks, 20.79 m
(68.2 ft) north of the north corner of a World War II Monument, and about 0.3 m
(1 ft) above Water Street.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                            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
     NO 4 1942                                   1.534    0.976
     1892 A 1980                                 4.186    3.628
     1892 B 1980                                 4.527    3.969
     1892 C 1980                                 3.913    3.355
     1892 E 1980                                 2.667    2.109
     1892 F 1980                                 3.908    3.350
     BALTO MARYLAND                              6.105    5.547
     BM USE                                      1.465    0.907
     CAM 1980                                    3.549    2.991
     W 127 1941                                  1.394    0.836


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  9 of  9

                                                                                
Station ID: 8571892                         PUBLICATION DATE:  10/06/2011
Name:       CAMBRIDGE, CHOPTANK RIVER                         
            MD
NOAA Chart: 12266                           Latitude:   38° 34.4' N (  38.57330)
USGS Quad:  CAMBRIDGE                       Longitude:  76°  4.1' W ( -76.06830)


                             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.