U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8733839 PUBLICATION DATE: 03/22/2011
Name: MEAHER STATE PARK, DUCKER BAY
AL
NOAA Chart: 11376 Latitude: 30° 40.0' N ( 30.66717)
USGS Quad: BRIDGEHEAD Longitude: 87° 56.2' W ( -87.93644)
To reach the tide station from the intersection of highway 98 and highway 31 in
Spanish Fort, proceed west on highway 98 for 2.4 km (1.5 mi) to the entrance of
Meaher State Park. Enter the park and follow the road to the fishing pier. The
tide station is at the southeast end of the pier "T", on the north side. The
bench marks are within a one mile radius of the station.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3839 A 2010
DESIGNATION: 873 3839 A
MONUMENTATION: Flange-encased Rod VM#: 19772
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: concrete kick block OPUS PID#: BBCD51
LATITUDE: 30° 40.1' N ( 30.66827) LONGITUDE: 87° 56.2' W ( -87.93622)
The bench mark is located at Meaher State Park, in line with the centerline of
the park fishing pier, about 3 m (9.8 ft) north of the north edge of the
asphault road just north of the pier. The mark is a stainless steel rod with
flange, driven 13.07 m (42.9 ft) to refusal, and encased in a concrete kick
block. The mark is 50.05 m (164.2 ft) south of the SW corner of a picnic
pavilion, 41.00 m (134.5 ft) west of the NW corner of the restrooms, 26.7 m
(87.6 ft) east of the NW corner of the road passing the pier, 14.35 m (47.1 ft)
north of a witness post adjacent to the NE edge of the pier entrance, and 14.01
m (46.0 ft) north of the centerline of the north end of the pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8733839 PUBLICATION DATE: 03/22/2011
Name: MEAHER STATE PARK, DUCKER BAY
AL
NOAA Chart: 11376 Latitude: 30° 40.0' N ( 30.66717)
USGS Quad: BRIDGEHEAD Longitude: 87° 56.2' W ( -87.93644)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3839 B 2010
DESIGNATION: 873 3839 B
MONUMENTATION: Bench Mark disk VM#: 19773
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: concrete median OPUS PID:
LATITUDE: 30° 40.2' N ( 30.66967) LONGITUDE: 87° 56.1' W ( -87.93522)
The bench mark is a brass disk set flush in the concrete median of highway 98,
just outside and east of the entrance to Meaher State Park. The bench mark is
located 60.1 m (197.2 ft) ENE of a communication call box at the entrance gate
of Meaher State Park, 29.02 m (95.2 ft) south of a high-powered electrical
transmission pole, and 16.92 m (55.5 ft) east of the west end of the conrete
median.
BENCH MARK STAMPING: K 512 18.987
DESIGNATION: 873 3839 K 512
MONUMENTATION: Vertical Control disk VM#: 19774
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: bridge abutment OPUS PID:
LATITUDE: 30° 40.1' N ( 30.66831) LONGITUDE: 87° 55.7' W ( -87.92758)
The bench mark is a disc, set in the SW bridge abutment of the Blakely River
Bridge. The bench mark is located 82.67 m (271.2 ft) ESE of a sign for the
Blakely River, 27.3 m (89.6 ft) SSW of bench mark J 406 RESET, 19.85 m (65.1 ft)
SE of the west end of the concrete median at the west end of the bridge, 7.1 m
(23.3 ft) south of the centerline of highway 98, and 1.8 m (5.9 ft) north of the
south end of the SW bridge abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8733839 PUBLICATION DATE: 03/22/2011
Name: MEAHER STATE PARK, DUCKER BAY
AL
NOAA Chart: 11376 Latitude: 30° 40.0' N ( 30.66717)
USGS Quad: BRIDGEHEAD Longitude: 87° 56.2' W ( -87.93644)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: U 406 RESET 1978
DESIGNATION: 873 3839 U 406 RESET
MONUMENTATION: Vertical Control disk VM#: 19775
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: bridge abutment OPUS PID:
LATITUDE: 30° 40.1' N ( 30.66856) LONGITUDE: 87° 55.7' W ( -87.92756)
The bench mark is a disc, set flush in the NW bridge abutment of the Blakeley
River Bridge. The bench mark is located 72.35 m (237.4 ft) east of phone pole
number 36816, 19.86 m (65.1 ft) NE of the west end of the concrete median, and
1.88 m (6.2 ft) south of the north end of the northwest bridge abutment.
BENCH MARK STAMPING: J 512 16.60
DESIGNATION: 873 3839 J 512
MONUMENTATION: Vertical Control disk VM#: 19776
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: bridge abutment OPUS PID:
LATITUDE: 30° 40.1' N ( 30.66761) LONGITUDE: 87° 55.4' W ( -87.92333)
The bench mark is a disc set in the SE abutment of the Blakeley River Bridge.
The bench mark is located 21.88 m (71.9 ft) west of sign for highway 90 east,
18.95 m (62.2 ft) SW of the east end of the concrete median, 3.04 m (10.0 ft)
WNW of a chain link fence corner, and 1.85 m (6.1 ft) north of the south edge of
the SW bridge abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8733839 PUBLICATION DATE: 03/22/2011
Name: MEAHER STATE PARK, DUCKER BAY
AL
NOAA Chart: 11376 Latitude: 30° 40.0' N ( 30.66717)
USGS Quad: BRIDGEHEAD Longitude: 87° 56.2' W ( -87.93644)
T I D A L D A T U M S
Tidal datums at MEAHER STATE PARK, DUCKER BAY based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: December 2010 - January 2011
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8735180 DAUPHIN ISLAND, MOBILE BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.469
MEAN HIGH WATER MHW = 0.468
MEAN TIDE LEVEL MTL = 0.242
MEAN SEA LEVEL MSL = 0.241
MEAN LOW WATER MLW = 0.016
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3839 A 2010 0.976 0.508
3839 B 2010 2.304 1.836
K 512 18.987 5.907 5.439
U 406 RESET 1978 5.988 5.520
J 512 16.60 5.192 4.724
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8733839 PUBLICATION DATE: 03/22/2011
Name: MEAHER STATE PARK, DUCKER BAY
AL
NOAA Chart: 11376 Latitude: 30° 40.0' N ( 30.66717)
USGS Quad: BRIDGEHEAD Longitude: 87° 56.2' W ( -87.93644)
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.