U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 04/06/1992
Station ID: 8774513 SUPERCEDED DATE: 04/21/2003
Name: COPANO BAY STATE FISHING PIER, ARANSAS BAY
TEXAS
NOAA Chart: 11313 Latitude: 28° 7.1' N
USGS Quad: ROCKPORT Longitude: 97° 1.3' W
To reach the tidal bench marks from the south side of Copano Bay Bridge on State
Highway 35, proceed south on State Highway 35 for 0.2 mile (0.3 km), turn west
onto the access road and go north for 0.2 mile (0.3 km) to the foot of old
Copano Bay Bridge (now Copano Bay State Fishing Pier). The bench marks are along
the access road. The tide gauge and staff were on the east side of the pier,
about 0.2 mile (0.3 km) from the south foot of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4513 C 1989
MONUMENTATION: Survey Disk VM#: 10577
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The primary bench mark is 149 feet (45 m) north of the third power pole south of
the boat ramp, 62 feet (19 m) WNW of the centerline of the access road, and 56
feet (17 m) SW of the second power pole south of the boat ramp. The bench mark
is crimped to a stainless steel road driven 64 feet (20 m) to substantial
resistance.
BENCH MARK STAMPING: 4513 A 1989
MONUMENTATION: Survey Disk VM#: 10578
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Bulkhead
The bench mark is on the NW corner of a bulkhead at a boat ramp, 185 feet (56 m)
SW of the SW corner of the Copano State Fishing Pier building, 167 feet (51 m)
WNW of the centerline of the access road, and 46 feet (14 m) WNW of the east end
of the ramp bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 04/06/1992
Station ID: 8774513 SUPERCEDED DATE: 04/21/2003
Name: COPANO BAY STATE FISHING PIER, ARANSAS BAY
TEXAS
NOAA Chart: 11313 Latitude: 28° 7.1' N
USGS Quad: ROCKPORT Longitude: 97° 1.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4513 B 1989
MONUMENTATION: Survey Disk VM#: 10579
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is on the NE corner of a Southwestern Bell Telephone fiber optic
cable junction box, 252.5 feet (77.0 m) SSW of the SE corner of the Copano Bay
State Fishing Pier building, 34 feet (10 m) WNW of the centerline of the access
road, and 19 feet SSW of the first power pole south of the boat ramp.
BENCH MARK STAMPING: 4513 D 1989
MONUMENTATION: Survey Disk VM#: 10580
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 112 feet (34 m) north of the fourth power pole south of the
boat ramp, 92 feet (28 m) SW of the third power pole south of boat ramp, and 61
feet (19 m) WNW of the centerline of the access road. The bench mark is crimped
to a stainless steel rod driven 60 feet (18 m) to substantial resistance.
BENCH MARK STAMPING: USGS GAGING STATION
MONUMENTATION: Survey Disk VM#: 10581
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is at the south foot of Copano Bay Bridge, on the west side of
Texas Highway 35, 122 feet (37 m) SE of the SE corner of the Copano Bay State
Fishing Pier building, 87 feet (27 m) east of the centerline of the west
access road, and 6.5 feet (5.0 m) west of the centerline of the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 04/06/1992
Station ID: 8774513 SUPERCEDED DATE: 04/21/2003
Name: COPANO BAY STATE FISHING PIER, ARANSAS BAY
TEXAS
NOAA Chart: 11313 Latitude: 28° 7.1' N
USGS Quad: ROCKPORT Longitude: 97° 1.3' W
T I D A L D A T U M S
Tidal datums at COPANO BAY STATE FISHING PIER, ARANSAS BAY based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: DECEMBER 1989-APRIL 1990
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8774770 ROCKPORT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (04/26/1990) = 1.77
MEAN HIGHER HIGH WATER MHHW = 0.40
MEAN HIGH WATER MHW = 0.38
MEAN TIDE LEVEL MTL = 0.19
MEAN LOW WATER MLW = 0.00
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (12/23/1989) = -1.63
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
4513 C 1989 3.80 3.42
4513 A 1989 3.08 2.70
4513 B 1989 6.61 6.23
4513 D 1989 4.10 3.72
USGS GAGING STATION 20.45 20.07
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 04/06/1992
Station ID: 8774513 SUPERCEDED DATE: 04/21/2003
Name: COPANO BAY STATE FISHING PIER, ARANSAS BAY
TEXAS
NOAA Chart: 11313 Latitude: 28° 7.1' N
USGS Quad: ROCKPORT Longitude: 97° 1.3' 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.