U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 08/22/2000
Station ID: 8554399 SUPERCEDED DATE: 04/21/2003
Name: MAHON RIVER ENTRANCE, DELAWARE BAY
DELAWARE
NOAA Chart: 12304 Latitude: 39° 11.1' N
USGS Quad: LITTLE CREEK Longitude: 75° 24.0' W
To reach the tidal bench marks from the Little Creek Post Office at the
intersection of State Route 9 and Road 89 in Little Creek, proceed east on Road
89 for 4.8 km (3.0 mi) to a wooden pier extending into Delaware Bay near the
Mahon River entrance. The bench marks are along Road 89. The tide gage and
staff were on the Delaware Storage and Pipeline Companies wooden fuel pier near
the Mahon River entrance.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING:
DESIGNATION: 855 4399 F
MONUMENTATION: Metal Rod VM#: 15886
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve
The primary bench mark is a metal rod located near the fuel pier, 34.45 m
(113.0) WNW of the west end of the Delaware Storage and Pipeline Companies fuel
pier, 1.15 m (3.8 ft) west of power pole no. BA-30T-90, which is the first power
pole south of the fuel pier, and 0.91 m (3.0 ft) east of a witness post. The
datum point is the top of a stainless steel rod driven 18.2 m (60 ft) to
refusal, and encased in a 0.91 m (3.0 ft) sleeve and 6-inch PVC pipe with no
logo cap.
BENCH MARK STAMPING: 4399 C 1983
DESIGNATION: 855 4399 C
MONUMENTATION: Tidal Station disk VM#: 2993
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a disk located SE of the Port Mahon boat launching area, 7.77
m (25.5 ft) east of the centerline of Road 89, 6.92 m (22.7 ft) NE of a utility
pole, and 0.30 m (1.0 ft) west of a witness post. The bench mark is crimped to
a stainless steel rod driven 16.5 m (54 ft) to refusal, and encased in a 5-inch
PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 08/22/2000
Station ID: 8554399 SUPERCEDED DATE: 04/21/2003
Name: MAHON RIVER ENTRANCE, DELAWARE BAY
DELAWARE
NOAA Chart: 12304 Latitude: 39° 11.1' N
USGS Quad: LITTLE CREEK Longitude: 75° 24.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4399 E 1999
DESIGNATION: 855 4399 E
MONUMENTATION: Tidal Station disk VM#: 15887
AGENCY: National Ocean Service (NOS) PID#: AS5705
SETTING CLASSIFICATION: Concrete and steel bulkhead
The bench mark is a disk set flush in the concrete and steel bulkhead near the
fuel pier, 8.56 m (28.1 ft) NE of the west end of the Delaware Storage and
Pipeline Companies fuel pier, 1.71 m (5.6 ft ) south of the north face of the
bulkhead, and 1.49 m (4.9 ft) west of the east face of the bulkhead.
BENCH MARK STAMPING:
DESIGNATION: 855 4399 COE
MONUMENTATION: Survey disk VM#: 15888
AGENCY: US Army Corps of Engineers (USCOE) PID:
SETTING CLASSIFICATION: Clay tile pipe and concrete
The bench mark is a disk set in concrete in the center of a clay pipe, just
south of the Port Mahon boat launching area, 31.82 m (104.4 ft) WNW of a power
pole with transformer No. 1122, 20.61m (67.6 ft) north of the NE corner of the
bait and tackle shop, and 0.76 m (2.5 ft) south of a witness post.
BENCH MARK STAMPING:
DESIGNATION: 855 4399 COE 2
MONUMENTATION: Survey disk VM#: 16237
AGENCY: US Army Corps of Engineers (USCOE) PID:
SETTING CLASSIFICATION: Pavement
The bench mark is a disk set in concrete pavement near the parking lot of the
Port Mahon River boat ramp, 30.00 m (98.4 ft) SW of the east corner of the dirt
parking lot, 11 m (36 ft) NE of the centerline of the Route 89, and 10.81 m
(35.5 ft) north of a utility pole No 107.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 08/22/2000
Station ID: 8554399 SUPERCEDED DATE: 04/21/2003
Name: MAHON RIVER ENTRANCE, DELAWARE BAY
DELAWARE
NOAA Chart: 12304 Latitude: 39° 11.1' N
USGS Quad: LITTLE CREEK Longitude: 75° 24.0' W
T I D A L D A T U M S
Tidal datums at MAHON RIVER ENTRANCE, DELAWARE BAY based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: July 1999 - October 1999
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8557380 LEWES, FT. MILES
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.886
MEAN HIGH WATER MHW = 1.746
MEAN SEA LEVEL MSL = 0.925
MEAN TIDE LEVEL MTL = 0.913
MEAN LOW WATER MLW = 0.079
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
855 4399 F 2.589 0.843
4399 C 1983 1.799 0.053
4399 E 1999 3.047 1.301
855 4399 COE 2.230 0.484
855 4399 COE 2 2.240 0.494
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 08/22/2000
Station ID: 8554399 SUPERCEDED DATE: 04/21/2003
Name: MAHON RIVER ENTRANCE, DELAWARE BAY
DELAWARE
NOAA Chart: 12304 Latitude: 39° 11.1' N
USGS Quad: LITTLE CREEK Longitude: 75° 24.0' W
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 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.