U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8725269 PUBLICATION DATE: 11/13/2003
Name: IMPERIAL RIVER ENTRANCE
FL
NOAA Chart: 11426 Latitude: 26° 20.2' N ( 26.33670)
USGS Quad: BONITA SPRINGS Longitude: 81° 49.8' W ( -81.83000)
To reach the tidal bench marks from the intersection of U.S. Highway 41 (South
Tamiami Trail) and Bonita Beach Road (County Road C864), proceed west on Bonita
Beach Road SW for 2.3 km (1.4 mi) to the intersection with Imperial Shores
Boulevard, then turn right and proceed north on Imperial Shores Boulevard for
0.6 km (0.4 mi) to Tarpon Avenue, then turn left and proceed west to the end of
Tarpon Avenue and Riverwood Drive, a dirt road leading to the Riverwood Estates.
The bench marks are along the roads leading to the Riverwood Estates. The tide
station was on the pier on the Imperial River at the end of Riverwood Drive.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5269 D 1978
DESIGNATION: 872 5269 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 7863
AGENCY: National Ocean Survey (NOS) IDB PID#: AD7878
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 20.1' N ( 26.33500) LONGITUDE: 81° 49.7' W ( -81.82830)
The primary bench mark is a disk located NW of the intersection of Imperial
Shores Boulevard with Tarpon Avenue, 88 m (289 ft) ENE of bench mark 5269 C
1978, 18.44 m (60.5 ft) SE of a cream colored stucco dwelling with Box No. 644,
12.80 m (42.0 ft) north of the centerline of Tarpon Avenue. and 0.24 m (0.8 ft)
south of a cable TV pole. The bench mark is crimped to the top of a 5/8 inch
copper-coated steel rod driven 9.8 m (32.0 ft) to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8725269 PUBLICATION DATE: 11/13/2003
Name: IMPERIAL RIVER ENTRANCE
FL
NOAA Chart: 11426 Latitude: 26° 20.2' N ( 26.33670)
USGS Quad: BONITA SPRINGS Longitude: 81° 49.8' W ( -81.83000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5269 A 1978
DESIGNATION: 872 5269 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 7860
AGENCY: National Ocean Survey (NOS) IDB PID#: AD7876
SETTING CLASSIFICATION: Concrete post OPUS PID:
LATITUDE: 26° 20.2' N ( 26.33670) LONGITUDE: 81° 49.8' W ( -81.83000)
The bench mark is a disk on the property of the Riverwood Estates, 23.77 m (78.0
ft) east of the small dock, 13.35 m (43.8 ft) west of a large pine, 5 m (16 ft)
south of the riverss edge, 3.47 m (11.4 ft) south of a small single pine and
0.24 m (0.8 ft) south of a witness post, set into the top of a 0.91 m (3.0 ft)
concrete post, at ground level.
BENCH MARK STAMPING: 5269 B 1978
DESIGNATION: 872 5269 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 7861
AGENCY: National Ocean Survey (NOS) IDB PID#: AD7877
SETTING CLASSIFICATION: Concrete post OPUS PID:
LATITUDE: 26° 20.1' N ( 26.33500) LONGITUDE: 81° 49.8' W ( -81.83000)
The bench mark is a disk set into the top of a 0.91m (3.0 ft) concrete post at
the NE corner of the Tarpon Avenue dirt road and the drive leading to Riverwood
Estates, 153.33 m (503.0 ft) south of bench mark 5269 A 1978, 16.15 m (53.0 ft)
north of the centerline of Tarpon Avenue, 10 m (33 ft) east of the centerline of
the entrance drive, 2.99 m (9.8 ft) SE of the Riverwood Estates sign, 0.70 m
(2.3 ft) south of a chainlink fence, 0.61 m (2.0 ft) south of a witness post,
and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8725269 PUBLICATION DATE: 11/13/2003
Name: IMPERIAL RIVER ENTRANCE
FL
NOAA Chart: 11426 Latitude: 26° 20.2' N ( 26.33670)
USGS Quad: BONITA SPRINGS Longitude: 81° 49.8' W ( -81.83000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5269 C 1978
DESIGNATION: 872 5269 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 7862
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete post OPUS PID:
LATITUDE: 26° 19.9' N ( 26.33170) LONGITUDE: 81° 50.3' W ( -81.83830)
The bench mark is a disk set in the top of a 0.91 m (3.0 ft) concrete post south
of Tarpon Avenue and at the beginning of the Tarpon Avenue dirt road which ends
at Riverwood Estates among a cluster of Palms, 102.72 m (337.0 ft) east of bench
mark 5269 B 1978, 21 m (69.0 ft) north of the north face of a concrete block
dwelling, 12.19 m (40.0 ft) west of the centerline of the driveway leading to
the dwelling and 8.23 m (27.0 ft) south of the centerline of Tarpon Avenue, and
0.12 m (0.4 ft) below the ground surface.
BENCH MARK STAMPING: 5269 E 1978
DESIGNATION: 872 5269 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 7864
AGENCY: National Ocean Survey (NOS) IDB PID#: AD7879
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 20.1' N ( 26.33500) LONGITUDE: 81° 49.6' W ( -81.82670)
The bench mark is a disk located at the SW corner of the intersection of
Imperial Shores Boulevard and Tarpon Avenue, 93 m (305 ft) SE of Bench Mark 5269
D 1978, 20.88 m (68.5 ft) NNE of the NE corner of a white block house, 15.24 m
(50.0 ft) south of the centerline of Tarpon Avenue, 11 m (36 ft) west of
Imperial Shores Boulevard and 0.46 m (1.5 ft) NE of utility pole No. 36 EM-91.
The bench mark is crimped to the top of a 5/8 inch diameter copper-coated steel
rod driven 7.9 m (26 ft) to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8725269 PUBLICATION DATE: 11/13/2003
Name: IMPERIAL RIVER ENTRANCE
FL
NOAA Chart: 11426 Latitude: 26° 20.2' N ( 26.33670)
USGS Quad: BONITA SPRINGS Longitude: 81° 49.8' W ( -81.83000)
T I D A L D A T U M S
Tidal datums at IMPERIAL RIVER ENTRANCE based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: April 1978 - August 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8725110 NAPLES, GULF OF MEXICO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.280
MEAN HIGH WATER MHW = 0.221
North American Vertical Datum NAVD88 = 0.210
MEAN SEA LEVEL MSL = 0.129
MEAN TIDE LEVEL MTL = 0.127
MEAN LOW WATER MLW = 0.032
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5269 D 1978 0.800 0.579
5269 A 1978 0.930 0.709
5269 B 1978 0.982 0.761
5269 C 1978 0.689 0.468
5269 E 1978 1.284 1.063
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8725269 PUBLICATION DATE: 11/13/2003
Name: IMPERIAL RIVER ENTRANCE
FL
NOAA Chart: 11426 Latitude: 26° 20.2' N ( 26.33670)
USGS Quad: BONITA SPRINGS Longitude: 81° 49.8' W ( -81.83000)
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.