U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
To reach the tidal bench marks from the Post Office in Sun City, proceed south
on old U.S. Highway 41 for 80.47 m (264.0 ft) to Lavender Road, go west on
Lavender Road for 0.64 km (0.4 mi) to the end of the pavement, continue west on
the graded dirt road for 1.13 km (0.7 mi) to a point where the road curves north
to the Hillsborough Community College Environmental Studies Center chain link
fence and locked gate, go through the gate and proceed 243.84 m (800.0 ft) to
the Environmental Studies Center buildings. The bench marks are along the dirt
road and wooden boardwalk to the pier behind the Environmental Studies Center.
The tide gauge and staff were at the end of the T-shaped pier on the left.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6425 H 1990
DESIGNATION: 872 6425 H TIDAL
MONUMENTATION: Tidal Station disk VM#: 11312
AGENCY: National Ocean Service (NOS) IDB PID#: AG9399
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: AG9399
LATITUDE: 27° 40.6' N ( 27.67670) LONGITUDE: 82° 29.8' W ( -82.49670)
The primary bench mark is a disk located between the dirt drive and the chain
link fence, 220.68 m (724.0 ft) north of the entrance gate to the Environmental
Studies Center, 97.54 m (320.0 ft) north of bench mark 6425 J 1990, 12.50 m
(41.0 ft) south of a telephone pole, 1.89 m (6.2 ft) west of the chain link
fence, and 1.89 m (6.2 ft) west of a witness post. The bench mark is crimped to
the top of a stainless steel rod driven 13.72 m (45.0 ft).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6425 G 1990
DESIGNATION: 872 6425 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 6439
AGENCY: National Ocean Service (NOS) IDB PID#: AG9398
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 40.6' N ( 27.67670) LONGITUDE: 82° 29.8' W ( -82.49670)
The bench mark is a disk located behind the Environmental Studies Center near
the point where the wooden boardwalk begins, 26.54 m (87.3 ft) north of the SW
corner of the chain link fence surrounding the lab buildings, 2.50 m (8.2 ft)
north of the north edge of the wooden boardwalk, and 0.40 m (1.3 ft) south of a
witness post. The mark is crimped to the top of a stainless steel rod driven
10.97 m (36.0 ft).
BENCH MARK STAMPING: 6425 F 1990
DESIGNATION: 872 6425 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 6443
AGENCY: National Ocean Service (NOS) IDB PID#: AG9397
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 40.6' N ( 27.67670) LONGITUDE: 82° 29.8' W ( -82.49670)
The bench mark is a disk located behind the Environmental Studies Center, 203.61
m (668.0 ft) westerly along the wooded boardwalk from the fence and gate, 97.20
m (318.9 ft) SE of the westerly end of the boardwalk, and 0.40 m (1.3 ft) south
of the south edge of the wooden boardwalk, and 0.40 m (1.3 ft) east of a witness
post. The mark is crimped to the top of a stainless steel rod driven 9.75 m
(32.0 ft).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6425 J 1990
DESIGNATION: 872 6425 J TIDAL
MONUMENTATION: Tidal Station disk VM#: 6444
AGENCY: National Ocean Service (NOS) IDB PID#: AG9400
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: AG9400
LATITUDE: 27° 40.6' N ( 27.67670) LONGITUDE: 82° 29.8' W ( -82.49670)
The bench mark is a disk located between the dirt drive and the chain link fence
at the Environmental Studies Center, 121.16 m (397.5 ft) north of the entrance
gate, 118.05 m (397.3 ft) north of bench mark 6425 K 1990, 69.19 m (227.0 ft)
south of 872 6425 F, 8.90 m (29.2 ft) east of a two trunked oak tree, 1.80 m
(5.9 ft) west of the chain link fence, and 1.80 m (5.9 ft) west of a witness
post. The mark is crimped to the top of a stainless steel rod driven 12.80 m
(42.0 ft).
BENCH MARK STAMPING: 6425 K 1990
DESIGNATION: 872 6425 K TIDAL
MONUMENTATION: Tidal Station disk VM#: 6445
AGENCY: National Ocean Service (NOS) IDB PID#: AG9396
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 40.6' N ( 27.67670) LONGITUDE: 82° 29.8' W ( -82.49670)
The bench mark is a disk located at the locked entrance gate to the
Environmental Studies Center, 27.61 m (90.6 ft) north of a power pole numbered
4000, 17.89 m (58.7 ft) north of the approximate center of the dim dirt road on
the inside of the curve in the road, 5.00 m (16.4 ft) east of the locked chain
link gate, and 1.19 m (3.9 ft) south of the chain link fence and a witness post.
The mark is crimped to the top of a stainless steel rod driven 12.19 m (40.0
ft).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: Q 256 1965
DESIGNATION: Q 256
MONUMENTATION: Bench Mark disk VM#: 19667
AGENCY: National Geodetic Survey (NGS) IDB PID#: AG6188
SETTING CLASSIFICATION: Round concrete monument OPUS PID:
LATITUDE: 27° 40.3' N ( 27.67086) LONGITUDE: 82° 29.2' W ( -82.48606)
The bench mark is a disk set in the top of a round concrete monument, 0.24 m
(0.8 ft) east of a green Carson Industries Electric Box 0.30 m by 0.61 m (1.0 ft
by 2.0 ft), projecting 0.09 m (0.3 ft) above the level of the ground and about
level with U.S. Hwy 41 southbound lanes, 79.25 m (260.0 ft) NE of the NW head
wall of a pipe culvert under the south-bound lane of the highway, 63.09 m (207.0
ft) NE of the extended centerline of a road leading SE, 16.76 m (55.0 ft)
northeast of the center line of the dim sand road, 14.94 m (49.0 ft) NW of the
centerline of U.S. Hwy 41 southbound lanes, 10.97 m (36.0 ft) east of the
approximate centerline of the east drive of 6601, 4.72 m (15.5 ft) SSW of south
leg of an ORIENT ROAD NEXT SIGNAL sign, 2.44 m (8.0 ft) west of the NW corner of
the parking lot of 6801, 1.68 m (5.5 ft) north of a wooden Power Pole #168584
(#24274, #31226) and 0.37 m (1.2 ft) WSW of a metal witness post. NOTE: A
magnet was imbedded in the ground on the south side of the monument.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H.C.S.D. GULF AZ MK 1985
DESIGNATION: GULF A AZ MK
MONUMENTATION: Bench Mark disk VM#: 19668
AGENCY: H.C.S.D. IDB PID#: AG8859
SETTING CLASSIFICATION: Round concrete monument OPUS PID:
LATITUDE: 27° 40.5' N ( 27.67450) LONGITUDE: 82° 28.8' W ( -82.47969)
The bench mark is a disk set in the top of a round concrete monument flush with
the ground and about 0.61 m (2.0 ft) below the level of U.S. Hwy 41 northbound
lanes, 20.12 m (66.0 ft) SE of the centerline of U.S. Hwy 41 northbound lanes,
11.43 m (37.5 ft) SW of a 30-inch (76.2 cm) pine tree with a 12-inch (30.48 cm)
palm tree next to it, 8.78 m (28.8 ft) WNW of the western-most sign post
supporting a billboard, 3.35 m (11.0 ft) SW of the approximate centerline of a
driveway, 3.05 m (10.0 ft) west of a power pole, 2.90 m (9.5 ft) west of wooden
Power Pole #168862, and 2.83 m (9.3 ft) west of a FL-057 metal witness post.
NOTE 1: There is no underground mark; station is a county traverse station.
NOTE 2: A magnet was imbedded in the ground on the south side of the monument.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
T I D A L D A T U M S
Tidal datums at COCKROACH BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: August 1990 - August 1990
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8726520 ST. PETERSBURG, TAMPA BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.508
MEAN HIGH WATER MHW = 0.426
North American Vertical Datum NAVD88 = 0.317
MEAN TIDE LEVEL MTL = 0.240
MEAN SEA LEVEL MSL = 0.234
MEAN LOW WATER MLW = 0.054
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6425 H 1990 1.595 1.169
6425 G 1990 0.967 0.541
6425 F 1990 0.614 0.188
6425 J 1990 1.444 1.018
6425 K 1990 1.467 1.041
Q 256 1965 6.730 6.304
H.C.S.D. GULF AZ MK 1985 7.392 6.966
Foot Notes:
Geodetic heights of the bench marks meet all NOAA/NOS/NGS quality control
standards for Second Order, Class 1 leveling. It is advised that a confirmation
set of levels be established for bench marks H.C.S.D. GULF AZ MK 1985 and Q 256
1965 to verify height differences before using tidal bench mark elevation
information.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8726425 PUBLICATION DATE: 03/16/2011
Name: COCKROACH BAY
FL
NOAA Chart: 11415 Latitude: 27° 40.7' N ( 27.67830)
USGS Quad: Ruskin Longitude: 82° 30.2' W ( -82.50330)
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.