U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8724448 PUBLICATION DATE: 02/05/2004
Name: WALTZ KEY
FLORIDA
NOAA Chart: 11445 Latitude: 24° 38.8' N
USGS Quad: SNIPE KEYS Longitude: 81° 39.2' W
To reach the tidal bench marks from the west end of the bridge between Big
Coppitt Key and Saddlebunch Keys, proceed by boat NW for 2.7 km (1.7 statute
mi), then north for 2.9 km (1.8 statute mi) to Waltz Key. The bench marks are
located in the middle of the key. The tide gage and staff were located on the
west side of the key.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: WALL KEY 2 NO 1 1934
DESIGNATION: WALL KEY 2 RM 1
ALIAS: 1
MONUMENTATION: Reference Mark disk VM#: 9618
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: AE4419
SETTING CLASSIFICATION: Concrete monument
The primary bench mark is a disk set in a concrete monument on a pile, 90 m (295
ft) north of the southern tip of the key, 12.92 m (42.4 ft) SSE of bench mark
WALL KEY 2 1934, 0.43 m (1.4 ft) north of a witness post, and 0.30 m (1.0 ft)
above the ground.
BENCH MARK STAMPING: WALL KEY 2 1934
DESIGNATION: WALL KEY 2
ALIAS: 2
MONUMENTATION: Triangulation Station disk VM#: 9617
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: AA1118
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in a concrete monument on a pile, 95 m (311 ft)
north of the south end of the key, 25 m (81 ft) west of a witness sign nailed to
a tree at the waters edge, 1.71 m (5.6 ft) SSE of an old witness sign nailed to
a tree, 0.15 m (0.5 ft) east of a new witness post, and 0.30 m (1.0 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8724448 PUBLICATION DATE: 02/05/2004
Name: WALTZ KEY
FLORIDA
NOAA Chart: 11445 Latitude: 24° 38.8' N
USGS Quad: SNIPE KEYS Longitude: 81° 39.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: WALL KEY 2 NO 2 1934
DESIGNATION: WALL KEY 2 RM 2
ALIAS: 3
MONUMENTATION: Reference Mark disk VM#: 9619
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: AE4420
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in a concrete monument on a pile, about 100 m (330
ft) north of the southern tip of the key, 23.16 m (76.0 ft) NNW of bench mark
WALL KEY 2 NO 1 1934, 16.15 m (53.0 ft) NW of bench mark WALL KEY 2 1934, 0.18 m
(0.6 ft) east of a witness post, and 0.30 m (1.0 ft) above ground level.
BENCH MARK STAMPING: 4448 D 1984
DESIGNATION: 872 4448 D
MONUMENTATION: Tidal Station disk VM#: 9620
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a disk located 84 m (275 ft) north of the south end of the
key, 14.48 m (47.5 ft) SSE of bench mark WALL KEY 2 1934, 12.34 m (40.5 ft) SW
of bench mark 4448 E 1984, and 0.30 m (1.0 ft) ESE of a witness post. The bench
mark is 0.24 m (0.8 ft) above ground level, crimped to the top of a stainless
steel rod driven 6.1 m (20 ft) to refusal, encased in a PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8724448 PUBLICATION DATE: 02/05/2004
Name: WALTZ KEY
FLORIDA
NOAA Chart: 11445 Latitude: 24° 38.8' N
USGS Quad: SNIPE KEYS Longitude: 81° 39.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4448 E 1984
DESIGNATION: 872 4448 E
MONUMENTATION: Tidal Station disk VM#: 9621
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a disk located 14 m (45 ft) ESE of bench mark WALL KEY 2 1934,
13 m (43 ft) WSW of a witness sign nailed to a tree at the outer mangrove edge,
and 0.37 m (1.2 ft) ESE of a witness post. The bench mark is set 0.24 m (0.8
ft) above ground level, crimped to the top of a stainless steel rod driven 6.1 m
(20 ft) to refusal, encased in a PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8724448 PUBLICATION DATE: 02/05/2004
Name: WALTZ KEY
FLORIDA
NOAA Chart: 11445 Latitude: 24° 38.8' N
USGS Quad: SNIPE KEYS Longitude: 81° 39.2' W
T I D A L D A T U M S
Tidal datums at WALTZ KEY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: January 1975 - January 1975
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER (MHHW) = 0.560
MEAN HIGH WATER (MHW) = 0.473
MEAN SEA LEVEL (MSL) = 0.273
MEAN TIDE LEVEL (MTL) = 0.269
MEAN LOW WATER (MLW) = 0.065
MEAN LOWER LOW WATER (MLLW) = 0.000
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
WALL KEY 2 NO 1 1934 0.598 0.125
WALL KEY 2 1934 0.595 0.122
WALL KEY 2 NO 2 1934 0.699 0.226
4448 D 1984 0.673 0.200
4448 E 1984 0.712 0.239
Foot Notes:
Bench marks 4448 D 1984 and 4448 E 1984 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8724448 PUBLICATION DATE: 02/05/2004
Name: WALTZ KEY
FLORIDA
NOAA Chart: 11445 Latitude: 24° 38.8' N
USGS Quad: SNIPE KEYS Longitude: 81° 39.2' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.