U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8723688 PUBLICATION DATE: 05/28/2004
Name: ROCK HARBOR INSIDE
FL
NOAA Chart: 11463 Latitude: 25° 4.9' N ( 25.08170)
USGS Quad: ROCK HARBOR Longitude: 80° 26.7' W ( -80.44500)
To reach the tidal bench marks from the intersection of U.S. Highway 1 and Ocean
Bay Drive in Key Largo, proceed south on Ocean Bay Drive for 1.1 km (0.7 mi)
over a canal to a dirt road, then turn right onto the dirt road and proceed west
for 0.40 km (0.25 mi) to the end of the road. The bench marks are in the fill
area at the end of the dirt road. The tide gage and staff were west of bench
mark TIDAL BM 1A.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: TIDAL BM 1A
DESIGNATION: 872 3688 TIDAL1 A ERBA
MONUMENTATION: Tidal Station disk VM#: 5964
AGENCY: ER Brownell and Associates IDB PID#: AC3349
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 26.7' W ( -80.44500)
The primary bench mark is a disk set in the top of a concrete monument at the
edge of the canal, 40.66 m (133.4 ft) south of the extended centerline of the
dirt road, 21 m (70 ft) north of the south end of the canal, 2.29 m (7.5 ft)
east of the east edge of the canal, and level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 8723688 PUBLICATION DATE: 05/28/2004
Name: ROCK HARBOR INSIDE
FL
NOAA Chart: 11463 Latitude: 25° 4.9' N ( 25.08170)
USGS Quad: ROCK HARBOR Longitude: 80° 26.7' W ( -80.44500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL BM 2A
DESIGNATION: 872 3688 TIDAL 2 A ERBA
MONUMENTATION: Tidal Station disk VM#: 5965
AGENCY: ER Brownell and Associates IDB PID#: AC3348
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 26.8' W ( -80.44670)
The bench mark is a disk set in the top of a concrete monument at the south edge
of the fill, 62 m (205 ft) south of the extended centerline of the dirt road,
17.19 m (56.4 ft) SE of bench mark TIDAL BM 1A, 2 m (6 ft) north of the south
edge of the fill, and level with the ground.
BENCH MARK STAMPING: TIDAL BM 3X
DESIGNATION: 872 3688 TIDAL 3 X ERBA
MONUMENTATION: Tidal Station disk VM#: 5966
AGENCY: ER Brownell and Associates IDB PID#: AC3350
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 26.7' W ( -80.44500)
The bench mark is a disk set in the top of a concrete monument at the east edge
of the canal, 37.61 m (123.4 ft) north of bench mark TIDAL BM 1A, 3 m (10 ft)
south of the extended centerline of the dirt road, 2 m (8 ft) east of the east
edge of the canal, and level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 8723688 PUBLICATION DATE: 05/28/2004
Name: ROCK HARBOR INSIDE
FL
NOAA Chart: 11463 Latitude: 25° 4.9' N ( 25.08170)
USGS Quad: ROCK HARBOR Longitude: 80° 26.7' W ( -80.44500)
T I D A L D A T U M S
Tidal datums at ROCK HARBOR INSIDE based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: February 1975 - March 1975
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.762
MEAN HIGH WATER MHW = 0.714
North American Vertical Datum NAVD88 = 0.680
MEAN SEA LEVEL MSL = 0.395
MEAN TIDE LEVEL MTL = 0.392
MEAN LOW WATER MLW = 0.070
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
TIDAL BM 1A 1.151 0.437
TIDAL BM 2A 1.110 0.396
TIDAL BM 3X 1.126 0.412
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8723688 PUBLICATION DATE: 05/28/2004
Name: ROCK HARBOR INSIDE
FL
NOAA Chart: 11463 Latitude: 25° 4.9' N ( 25.08170)
USGS Quad: ROCK HARBOR Longitude: 80° 26.7' W ( -80.44500)
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.