U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


To reach the tidal bench marks from the intersection of U.S. Highway 1 and 17th
Street in Vero Beach, go east on 17th Street for 1.13 km (0.7 mi) to the
intersection of Indian River Boulevard, turn left on Indian River Boulevard and
go north for about 60.96 m (200.0 ft) to the main entrance road to the Vero
Beach Municipal power plant on the right.  To reach the tide gage turn right on
the min entrance road and go east for 0.40 km (0.25 mi) to the boat ramp, now by
boat go SE about 0.48 km (0.3 mi).  The Tide gage is attached to the SW end of
the west bridge fender.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1972
                         DESIGNATION:          872 2125 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         5411
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AF6802
SETTING CLASSIFICATION:  Retaining wall                        OPUS PID#: AF6802
LATITUDE:   27° 38.0' N (  27.63250)          LONGITUDE:  80° 22.6' W ( -80.37611)


The bench mark is a disk set flush in the top of the north retaining wall of the
water intake structure about 0.61 m (2.0 ft) above the level of the ground,
59.34 m (194.7 ft) SW of a fire hydrant, 52.21 m (171.3 ft) SE of another fire
hydrant, 26.94 m (88.4 ft) south of the approximate centerline of the power
plant main entrance road, 24.84 m (81.5 ft) SSW of tidal mark NO 2 1972 and 0.15
m (0.5 ft) north of the south face of the water intake structures north
retaining wall.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  NO 2 1972
                         DESIGNATION:          872 2125 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         5412
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AF6801
SETTING CLASSIFICATION:  Large concrete seawall                OPUS PID#: AF6801
LATITUDE:   27° 38.0' N (  27.63250)          LONGITUDE:  80° 22.6' W ( -80.37611)


The bench mark is a disk set flush in the top of the NW corner of the concrete
seawall of the oil barge basin and about level with the entrance road, 51.66 m
(169.5 ft) east of a fire hydrant, 34.50 m (113.2 ft) WSW of another fire
hydrant, 24.84 m (81.5 ft) NNE of tidal mark NO 1 1972, 3.11 m (10.2 ft) south
of the approximate centerline of the power plants main entrance road and 1.34 m
(4.4 ft) SW of a 0.30 m (1.0 ft) wide x 0.58 m (1.9 ft) tall bollard.



                         BENCH MARK STAMPING:  2125 C 1980
                         DESIGNATION:          872 2125 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         5415
AGENCY:                  Florida Department of Natural Resources
                         (FLDNR)                               IDB PID#:  AF6933
SETTING CLASSIFICATION:  Guardrail                             OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63194)          LONGITUDE:  80° 22.5' W ( -80.37583)


The bench mark is a disk set flush in the top of the south guardrail of the 17th
Street Bridge 0.91 m (3.0 ft) above the level of the road, 76.2 m (250.0 ft)
east of bench mark 2125 D 1995, 13.96 m (45.8 ft) SSW of the first street light
on the west side of the eastbound lanes of 17th Street, 7.13 m (23.4 ft) south
of the approximate centerline of 17th Street (eastbound 2 lanes) and 0.34 m (1.1
ft) east of the SW end of the 17th Street Bridge.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 D 1995
                         DESIGNATION:          872 2125 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17747
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Bridge memorial monument              OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63194)          LONGITUDE:  80° 22.7' W ( -80.37861)


The bench mark is a disk set in the top of the SW corner of the base of the 17th
Street Bridge concrete memorial about 0.30 m (1.0 ft) above the level of 17th
Street, 29.32 m (96.2 ft) east of the approximate centerline of Indian River
Boulevard, 12.56 m (41.2 ft) south of the approximate centerline of 17th Street,
12.13 m (39.8 ft) NE of a fire hydrant, 4.66 m (15.3 ft) west of an 2.44 m (8.0
ft) tall chain link fence, 1.52 m (5.0 ft) east of a concrete power pole, and
0.18 m (0.6 ft) north of a carsonite witness post.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 E 1995
                         DESIGNATION:          872 2125 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17748
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: DM4024
LATITUDE:   27° 38.0' N (  27.63250)          LONGITUDE:  80° 22.7' W ( -80.37889)


The bench mark is a stainless steel rod located 26.00 m (85.3 ft) east of the
approximate centerline of Indian River Boulevard, 13.62 m (44.7 ft) SE of a
concrete power pole, 11.34 m (37.2 ft) SE of an electrical manhole cover, 8.02 m
(26.3 ft) north of the approximate centerline of the power plant main entrance
road, 1.89 m (6.2 ft) NE of a wooden power pole number 209A, 1.52 m (5.0 ft)
west of a 2.44 m (8.0 ft) tall chain link fence, and 0.30 m (1.0 ft) west of a
carsonite witness post.  The bench mark is a stainless steel rod driven to
refusal at a depth of 23.77 m (78.0 ft) with a NGS logo cap recessed 0.06 m (0.2
ft) below the level of the ground and below the level of Indian River Boulevard,
the datum point being accessed through a 5-inch NGS logo cap and recessed 0.09 m
(0.3 ft) below the level of the NGS logo cap.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 F 1995
                         DESIGNATION:          872 2125 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17749
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   27° 38.0' N (  27.63389)          LONGITUDE:  80° 22.5' W ( -80.37528)


The bench mark is a stainless steel rod located 170.69 m (560.0 ft) NE of tidal
mark NO 2 1972, about 91.44 m (300.0 ft) NE of the NW corner of the cooling
tower, about 84.43 m (277.0 ft) NE of the NE corner of the cooling tower, about
63.70 m (209.0 ft) NE of a fire hydrant, 4.72 m (15.5 ft) west of the west bank
of the Indian River and 0.91 m (3.0 ft) SW of the NE corner of a 2.44 m (8.0 ft)
tall chain link fence.  The bench mark is a stainless steel rod driven to
refusal at a depth of 21.64 m (71.0 ft) with a NOS logo cap flush with the
ground, the datum point being accessed through a 5-inch logo cap and recessed
0.09 m (0.3 ft) below the level of the NOS logo cap.



                         BENCH MARK STAMPING:  2125 G 1995
                         DESIGNATION:          872 2125 G TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17750
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.5' W ( -80.37472)


The bench mark is a disk set in the top of the NE corner of the most northern
piling base of the 3rd piling, starting from the west side of the bridge,
projecting about 0.61 m (2.0 ft) above the level of the Indian River, 56.08 m
(184.0 ft) west of bench mark 2125 H 1995, 3.44 m (11.3 ft) east of the NW
corner of the piling base, 2.01 m (6.6 ft) north of the SE corner of the piling
base, 0.94 m (3.1 ft) NE of the NE piling face and 0.82 m (2.7 ft) SW of the NE
corner of the piling base.  NOTE:  Access to the mark is by boat.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 H 1995
                         DESIGNATION:          872 2125 H TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17751
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.5' W ( -80.37417)


The bench mark is a disk set in the top of the NE corner of the most northern
piling base of the 5th piling, starting from the west side of the bridge,
projecting about 0.61 m (2.0 ft) above the level of the Indian River, 56.08 m
(184.0 ft) west of bench mark 2125 J 1995, 3.08 m (10.1 ft) east of the NW
corner of the piling base, 2.71 m (8.9 ft) north of the SE corner of the piling
base, 1.10 m (3.6 ft) NE of the NE piling face and 0.98 m (3.2 ft) SW of the NE
corner of the piling base.  NOTE: Access to the mark is by boat.  



                         BENCH MARK STAMPING:  2125 J 1995
                         DESIGNATION:          872 2125 J TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17752
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.4' W ( -80.37361)


The bench mark is a disk set in the top of the NE corner of the most northern
piling base of the 7th piling, starting from the west side of the bridge,
projecting about 0.61 m (2.0 ft) above the level of the Indian River, 56.08 m
(184.0 ft) west of bench mark 2125 K 1995, 3.35 m (11.0 ft) north of the SE
corner of the piling base, 2.77 m (9.1 ft) SE of the NW corner of the piling
base, 1.01 m (3.3 ft) NE of the NE piling face, and 0.88 m (2.9 ft) SW of the NE
corner of the piling base.  NOTE: Access to mark is by boat.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 K 1995
                         DESIGNATION:          872 2125 K TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17753
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.4' W ( -80.37306)


The primary bench mark is a disk set in the top of the NE corner of the most
northern piling base of the 9th piling, starting from the west side of the
bridge, projecting about 0.61 m (2.0 ft) above the level of the Indian River
56.08 m (184.0 ft) west of bench mark 2125 L 1995, 3.38 m (11.1 ft) east of the
NW corner of the piling base, 2.74 m (9.0 ft) north of the SE corner of the
piling base, 0.98 m (3.2 ft) NE of the NE piling face, and 0.91 m (3.0 ft) SW of
the NE corner of the piling base.  NOTE:  Access to the mark is by boat.



                         BENCH MARK STAMPING:  2125 L 1995
                         DESIGNATION:          872 2125 L TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17754
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.4' W ( -80.37250)


The bench mark is a disk set in the top of the NE corner of the most northern
piling base of the 11th piling, starting from the west side of the bridge,
projecting about 0.61 m (2.0 ft) above the level of the Indian River, 56.08 m
(184.0 ft) west of bench mark 2125 m 1995, 3.47 m (11.4 ft) east of the NW
corner of the piling base, 2.74 m (9.0 ft) north of the SE corner of the piling
base, 1.13 m (3.7 ft) NE of the NE piling face, and 0.82 m (2.7 ft) SW of the NE
corner of the piling base.  NOTE: Access to the mark is by boat.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  2125 M 1995
                         DESIGNATION:          872 2125 M TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17755
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bridge piling base                    OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63222)          LONGITUDE:  80° 22.3' W ( -80.37194)


The bench mark is a disk set in the top of the NE corner of the most northern
piling base of the 13th piling, starting from the west side of the bridge,
projecting about 0.61 m (2.0 ft) above the level of the Indian River 56.08 m
(184.0 ft) east of bench mark 2125 L 1995, about 28.65 m (94.0 ft) SW of
872-2125 aqua trak (tidal gage), 3.35 m (11.0 ft) east of the NW corner of the
piling base, 2.74 m (9.0 ft) north of the SW corner of the piling base, 1.07 m
(3.5 ft) SW of the NE corner of the piling base and 1.01 m (3.3 ft) NE of the NE
piling face.  NOTE: Access to the mark is by boat.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  9 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  IND. R. 1 1979 CLB
                         DESIGNATION:          IND R 1 FLDNR

MONUMENTATION:           Bench Mark disk                       VM#:        19495
AGENCY:                  FL Department of Natural Resources
                         (FLDNR)                               IDB PID#:  AF6800
SETTING CLASSIFICATION:  Concrete post                         OPUS PID:        
LATITUDE:   27° 37.9' N (  27.63194)          LONGITUDE:  80° 23.1' W ( -80.38556)


The bench mark is a disk located 5.85 m (19.2 ft) south of 17th Street eastbound
lane centerline, 16.31 m (53.5 ft) west of the 6th Avenue centerline, 2.93 m
(9.6 ft) west of a concrete traffic light pole (CVB-50954), 7.47 m (24.5 ft) WNW
of a steel power pole, and 2.13 m (7.0 ft) N from a witness post.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 10 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


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


                         BENCH MARK STAMPING:  W 200 1960
                         DESIGNATION:          W 200

MONUMENTATION:           Bench Mark disk                       VM#:        19496
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AF3371
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   27° 38.5' N (  27.64222)          LONGITUDE:  80° 23.3' W ( -80.38889)


The bench mark is 8.38 m (27.5 ft) north of the north curb line of Royal Palm
Boulevard, 10.97 m (36.0 ft) east of the center line of the junction of Royal
Palm Boulevard and 8th Avenue, 3.35 m (11.0 ft) NNW of the first palm tree east
of the junction, 0.61 m (2.0 ft) NE of the extended center line of the west
drive leading to the Royal Palm court, 0.61 m (2.0 ft) west of a steel witness
post, about 0.30 m (1.0 ft) below the level of the Boulevard, about level with
the graded road, and set in top of a concrete post projecting 5-inches.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 11 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


                            T I D A L   D A T U M S 


Tidal datums at VERO BEACH, INDIAN RIVER based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           April 1999 - June 1999
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720220 MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     North American Vertical Datum              NAVD88 =  0.409
     MEAN HIGHER HIGH WATER                     MHHW   =  0.272
     MEAN HIGH WATER                            MHW    =  0.247
     MEAN TIDE LEVEL                            MTL    =  0.133
     MEAN SEA LEVEL                             MSL    =  0.131
     MEAN LOW WATER                             MLW    =  0.019
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1972                                   2.408    2.161
     NO 2 1972                                   2.090    1.843
     2125 C 1980                                 4.722    4.475
     2125 D 1995                                 2.233    1.986
     2125 E 1995                                 1.639    1.392
     2125 F 1995                                 1.303    1.056
     2125 G 1995                                 0.999    0.752
     2125 H 1995                                 0.964    0.717
     2125 J 1995                                 0.961    0.714
     2125 K 1995                                 0.966    0.719
     2125 L 1995                                 0.938    0.691
     2125 M 1995                                 0.920    0.673
     IND. R. 1 1979 CLB                          1.853    1.606
     W 200 1960                                  2.056    1.809


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 12 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


Foot Notes:

Geodetic heights of the bench marks meet all NOAA/NOS/NGS quality control
standards for Second Order, Class 1 leveling.  It is advised that a confirmation
set of levels be established for bench marks 2125 C 1980, 2125 D 1995, 2125 E
1995, 2125 F 1995, 2125 G 1995, 2125 H 1995, 2125 J 1995, IND. R.1 1979 CLB, and
W 200 1960 to verify height differences before using tidal bench mark elevation
information.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 13 of 13

                                                                                
Station ID: 8722125                         PUBLICATION DATE:  05/08/2012
Name:       VERO BEACH, INDIAN RIVER                          
            FL
NOAA Chart: 11474                           Latitude:   27° 37.9' N (  27.63170)
USGS Quad:  VERO BEACH                      Longitude:  80° 22.3' W ( -80.37170)


                             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.