U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8730561 PUBLICATION DATE: 11/22/2021
Name: ARNICA BAY MILL POINT
AL
NOAA Chart: 11378 Latitude: 30° 18.6' N ( 30.31022)
USGS Quad: ORANGE BEACH Longitude: 87° 31.2' W ( -87.51928)
To reach the station from the intersection of Alabama Coastal Connection,
Highway 161 and Canal Rd, Highway 180 in Orange Beach, Alabama, proceed East on
Canal Rd for 5.44 Km (3.4 miles) tum left on Bay La Launch Ave, and proceed
North for 0.8 Km ( 0.5 miles) The station is located on the NW corner of the
Westernmost dock inside the Bear Point Harbor.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0561 B 2020
DESIGNATION: 873 0561 B
MONUMENTATION: Flange-encased Rod VM#: 23787
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBHH90
LATITUDE: 30° 18.6' N ( 30.30919) LONGITUDE: 87° 31.5' W ( -87.52578)
The primary bench mark is a stainless steel rod located 86.70m (284.4 ft) SW of
utility light pole #369-681, 42.20m (138.5 ft) NW of light pole #313, 29.30m
(96.1 ft) SE of electrical equipment box #3009272, 8.30m (27.2 ft) North of
utility pole #312-1211, 6.70m (22.0 ft) North of buried cable marked #A 10-1,
and 4.60m (15.1 ft) South of centerline of Bay La Launch Ave. The datum point is
the top of a stainless steel rod driven 15.2m (49.9 ft) to refusal and encased
in a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8730561 PUBLICATION DATE: 11/22/2021
Name: ARNICA BAY MILL POINT
AL
NOAA Chart: 11378 Latitude: 30° 18.6' N ( 30.31022)
USGS Quad: ORANGE BEACH Longitude: 87° 31.2' W ( -87.51928)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0561 A 2020
DESIGNATION: 873 0561 A
MONUMENTATION: Tidal Station disk VM#: 23788
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stormdrain concrete OPUS PID:
LATITUDE: 30° 18.6' N ( 30.31008) LONGITUDE: 87° 31.5' W ( -87.52497)
The bench mark is a disk set in a concrete foundation for a storm drain located
47.20m (154.9 ft) SW of wooden utility pole #443, 15.20m (49.9 ft) SW of wooden
utility pole #444, 14.50m (47.6 ft) East of fire department plug #FOO-01355,
12.30m (40.4 ft) South of access gate to Bear Point boat launch, 7.00m (23.0 ft)
North of centerline of Bayshore Drive North, and 3.40m (11.2 ft) East of
centerline of Bear Point Boat Launch Access Road.
BENCH MARK STAMPING: 0561 C 2020
DESIGNATION: 873 0561 C
MONUMENTATION: Flange-encased Rod VM#: 23789
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBHN32
LATITUDE: 30° 18.5' N ( 30.30792) LONGITUDE: 87° 31.6' W ( -87.52611)
The bench mark is a stainless steel rod located 36.80m (120.7 ft) SE of utility
pole #241, 32.90m (107.9 ft) West of utility pole #181, 24.40m (80.1 ft) North
of utility pole #244, 9.30m (30.5 ft) NE of electrical pole #240, and 7.10m
(23.3 ft) NW of centerline of Low Road. The datum point is a stainless steel rod
driven 24.4m (80.1 ft) to refusal and encased in a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8730561 PUBLICATION DATE: 11/22/2021
Name: ARNICA BAY MILL POINT
AL
NOAA Chart: 11378 Latitude: 30° 18.6' N ( 30.31022)
USGS Quad: ORANGE BEACH Longitude: 87° 31.2' W ( -87.51928)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0561 D 2020
DESIGNATION: 873 0561 D
MONUMENTATION: Flange-encased Rod VM#: 23790
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 30° 18.5' N ( 30.30789) LONGITUDE: 87° 31.5' W ( -87.52539)
The bench mark is a stainless steel rod located 44.40m (145.7 ft) SW of utility
pole #362, 41.90m (137.5 ft) East of utility light pole #306, 34.50m (113.2 ft)
West of utility light pole #385, 21.40m (70.2 ft) SW of buried cable marker
#A9R1, and 4.10m (13.5 ft) South of centerline of Low Drive. The datum point is
the top of a stainless steel rod driven 18.9m (62.0 ft) to refusal and encased
in a concrete kickblock.
BENCH MARK STAMPING: 0561 E 2020
DESIGNATION: 873 0561 E
MONUMENTATION: Flange-encased Rod VM#: 23791
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBHH91
LATITUDE: 30° 18.5' N ( 30.30789) LONGITUDE: 87° 31.5' W ( -87.52444)
The bench mark is a stainless steel rod located 47.00m (154.2 ft) East of
utility light pole #358/1214, 40.20m (131.9 ft) SW of utility light pole #429,
17.70m (58.1 ft) SW of buried cable marker #89R2, and 4.10m (13.5 ft) South of
centerline of Low Road. The datum point is the top of a stainless steel rod
driven 17.7m (58.1 ft) to refusal and encased in a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8730561 PUBLICATION DATE: 11/22/2021
Name: ARNICA BAY MILL POINT
AL
NOAA Chart: 11378 Latitude: 30° 18.6' N ( 30.31022)
USGS Quad: ORANGE BEACH Longitude: 87° 31.2' W ( -87.51928)
T I D A L D A T U M S
Tidal datums at ARNICA BAY MILL POINT based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 2021 - July 2021
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8729840 PENSACOLA, PENSACOLA BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.242
MEAN HIGH WATER MHW = 0.235
MEAN TIDE LEVEL MTL = 0.120
MEAN SEA LEVEL MSL = 0.117
North American Vertical Datum NAVD88 = 0.020
MEAN LOW WATER MLW = 0.004
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0561 B 2020 1.000 0.765
0561 A 2020 1.293 1.058
0561 C 2020 0.838 0.603
0561 D 2020 0.943 0.708
0561 E 2020 1.173 0.938
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8730561 PUBLICATION DATE: 11/22/2021
Name: ARNICA BAY MILL POINT
AL
NOAA Chart: 11378 Latitude: 30° 18.6' N ( 30.31022)
USGS Quad: ORANGE BEACH Longitude: 87° 31.2' W ( -87.51928)
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.