U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
TO REACH THE NOS GAUGING STATION AT POINT IROQUOIS, CHIPPEWA COUNTY, MICHIGAN,
FROM THE POST OFFICE IN BRIMLEY, ON SR 221 ( W LAKESHORE DR), PROCEED NW ON SR
221 FOR 11.67 KM (7.25 MI) TO THE POINT IROQUOIS LIGHT HOUSE, THE NOS GAUGE
HOUSE WHICH IS IN THE NE AREA OF LIGHTHOUSE PROPERTY NEAR THE SHORE LINE.
G R E A T L A K E S B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: A 293 1983
DESIGNATION: A 293
MONUMENTATION: Flange-encased Rod VM#: 13353
AGENCY: National Geodetic Survey IDB PID#: RJ0586
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 46° 29.0' N ( 46.48400) LONGITUDE: 84° 37.9' W ( -84.63236)
The bench mark is a flange-encased rod 58.52 m (192 ft) NNE of the corner of the
asphalt road, 22.09 m (72.5 ft) South of the South face of the lighthouse
building, 21.6 m (71 ft) WNW of the SE corner of the rock wall, 21.4m (70.2 ft)
SE of the SW corner of the rock wall, 3.72 meters (12.2 ft) SSE of the South
face of the rock wall and 2.83m (9.3 ft) South of the flag pole, encased in a
5-inch pvc pipe and concrete kickblock with aluminum acces cover flush with the
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
G R E A T L A K E S B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 909 9004 IROQUOIS LH
MONUMENTATION: Bolt VM#: 13354
AGENCY: IDB PID#: RJ0270
SETTING CLASSIFICATION: Coping stone foundation/bedrock OPUS PID:
LATITUDE: 46° 29.1' N ( 46.48439) LONGITUDE: 84° 37.9' W ( -84.63222)
The bench mark is a bolt set in the North face of the old lighthouse tower,
13.2 m (43.3 ft) East of the East face of the West rock wall around the
lighthouse, 8.5 m (27.9 ft) South of the South face of the North rock wall, 4.1
m (13.5 ft) West of the centerline of the stairs leading to the tower, being the
center of punch mark in end of brass bolt leaded vertically into the coping
stone, 1.11 m (3.6 ft above the ground.
BENCH MARK STAMPING:
DESIGNATION: 909 9004 UTILITY
MONUMENTATION: Metal Rod VM#: 13355
AGENCY: National Geodetic Survey IDB PID#: RJ0274
SETTING CLASSIFICATION: Copper-clad steel rod w/o sleeve OPUS PID:
LATITUDE: 46° 29.1' N ( 46.48444) LONGITUDE: 84° 37.9' W ( -84.63119)
The bench mark is a metal rod set 117.3 m (384.8 ft) NE of the Old Lighthouse,
27.3 m (89.6 ft) West of the SW corner of the NOS gauge house, 21.6 m (70.9 ft)
SW of utility pole number BR1/148N, 6.8 m (22.3 ft) NW of a 1 inch diameter iron
imbedded in a 2X21/2 foot boulder, 5.6 m (18.4 ft) SE of South edge of sidewalk,
flush with the ground, being highest point on top of 5/8-inch diameter copper
coated steel rod, 3.4m (11.2 ft) long, encased in a 5-inch pvc pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
G R E A T L A K E S B E N C H M A R K S
BENCH MARK STAMPING: LOOK 1971
DESIGNATION: 909 9004 LOOK
MONUMENTATION: Survey disk VM#: 13356
AGENCY: Army Corp of Engineers IDB PID#: RJ0273
SETTING CLASSIFICATION: Foundation OPUS PID:
LATITUDE: 46° 29.1' N ( 46.48425) LONGITUDE: 84° 37.9' W ( -84.63200)
The bench mark is a disk set in the East face at the NE corner of old lighthouse
dewelling, 106.7 m (350.1 ft) North of SR 221, 6.6 m (21.7 ft) West of the West
face of the East rock wall around the lighthouse, 1.83 m (6 ft) North of the
centerline of the steps leading up to the private entrance, 0.15 m (0.49 ft)
South of NEcorner of building, 0.91 m (3 ft) above the ground surface, being
horizontal line of cross on bronze disc set vertically into the concrete block
foundation.
BENCH MARK STAMPING:
DESIGNATION: 909 9004 IROQUOIS 1
MONUMENTATION: See descriptive text VM#: 13358
AGENCY: IDB PID#: RJ0272
SETTING CLASSIFICATION: Stone Post OPUS PID:
LATITUDE: 46° 29.0' N ( 46.48392) LONGITUDE: 84° 37.9' W ( -84.63214)
The bech mark is the highest point on top of a brass plug set into top of a
horizontal stone post set South of the lighthouse dwelling under the NW corner
of the second cobblestone post from the East end of the East-West cobblestone
wall, 26.5 m (89.9 ft) SE of the SW corner of the dwelling, 23.3 m (76.4 ft)
South of the SE corner of dwelling, 16.8 m (55 ft) East of the flagpole, 0.67 m
(2.20 ft) below the ground surface.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
G R E A T L A K E S B E N C H M A R K S
BENCH MARK STAMPING: HOUSE 1965 USLS
DESIGNATION: 909 9004 HOUSE
MONUMENTATION: Bench Mark disk VM#: 13359
AGENCY: US Army Corps of Engineers IDB PID#: RJ0275
SETTING CLASSIFICATION: Foundation OPUS PID:
LATITUDE: 46° 29.1' N ( 46.48453) LONGITUDE: 84° 37.9' W ( -84.63089)
The bench mark is a disk set on the NOAA/NOS water level gauge house
foundationlocated in the NE area of the property, near the shore line, 50.3 m
(165 ft) NE of the lighthouse, 0.34 m (1.12 ft) NW of the South corner, 0.15 m
(0.49 ft) SW of S face of gauge house, and 0.12 m (0.39 ft ) NE of the South
edge of the foundation.
BENCH MARK STAMPING:
DESIGNATION: 909 9004 OLD BM
MONUMENTATION: Chiseled Square VM#: 13361
AGENCY: IDB PID#: RJ0271
SETTING CLASSIFICATION: Stone Foundation OPUS PID:
LATITUDE: 46° 29.1' S ( -46.48433) LONGITUDE: 84° 37.9' W ( -84.63239)
The bench mark is a chiseled square set on the top of the lighthouse foundation
on the North face of the tower, 11.6 m (38.1 ft) East of the East cobble wall,
9.1 m (29.9 ft) South of the North cobble wall, 5.8 m (19.0 ft) West of the
centerline of the steps leading into the lighthouse, 1.1 m (3.6 ft) above the
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
G R E A T L A K E S B E N C H M A R K S
BENCH MARK STAMPING: BIP+145 1988
DESIGNATION: BRANDT 2 BIP+145
MONUMENTATION: Triangulation Station disk VM#: 19392
AGENCY: Army Corp of Engineers IDB PID#: RJ1258
SETTING CLASSIFICATION: Metal rod driven into the ground OPUS PID:
LATITUDE: 46° 29.1' N ( 46.48469) LONGITUDE: 84° 37.8' W ( -84.63081)
The mark is a disk set into a 15 cm (6 in) casing below grade attached to an
aluminum rod driven 4.3 m (14 ft) into the ground, located 15 m (50 ft) from the
water's edge, 13.9 meters (45.5 ft) NW from a NOAA gauge building and 11.9
meters (39 ft) NE from a light pole.
Foot Notes:
Above marks are published for informational purposes only. Long term stability
has not been reviewed prior to publication.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
D E F I N I T I O N S
The International Great Lakes Datum (IGLD) is the vertical height reference
datum used in the Great Lakes/St. Lawrence River System for engineering,
charting, channel dredging, navigation safety, power generation, and water
resource management. It is a coordinated datum between the United States and
Canada that ensures both countries are using the same reference for projects
in the Great Lakes basin. The datum origin, or zero, is defined as Mean Sea
Level at Pointe-au-Pere /Rimouski, Quebec, Canada at the mouth of the
St. Lawrence River. IGLD requires updating approximately every 25-30 years
to account for varying changes in the land surface elevations following the
retreat of the glaciers during the last ice age, referred to as Glacial
Isostatic Adjustment (GIA). The current IGLD 1985 was implemented in 1992.
IGLD 1985 uses dynamic heights as the vertical reference standard and lakes
station water level elevations are adjusted to provide a level geopotential
plane for lake level reference.
Dynamic height is the potential difference along the plumbline between the
vertical datum and a point of interest divided by a constant value of
gravity. In Canada and USA, the constant value of gravity is the
"normal gravity" on the ellipsoid at latitude 45° (9.806199 ms-2). Dynamic
heights have no geometric meaning. They are mainly used for the management
of water in large lakes, rivers and channels. The surface of a lake has a
constant dynamic height if undisturbed by currents, winds, atmospheric
pressure, etc.
The Hydraulic Corrector (HC) is the difference in the long term water level
mean between Subordinate and Master station. The difference (HC) is
subtracted algebraically at the subordinate gauge referencing the same
elevation as the master station. Thus all water levels on a given lake can
be referenced to the same lakes LWD/Chart Datum reference elevation.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9099004 PUBLICATION DATE: 08/11/2017
Name: POINT IROQUOIS, LAKE SUPERIOR
MI
NOAA Chart: 14962 Latitude: 46° 29.1' N ( 46.48450)
USGS Quad: Longitude: 84° 37.9' W ( -84.63089)
D E F I N I T I O N S
A Master Stations is the control point for determining water level
elevations on a particular lake of the Great Lakes. Since water surfaces
of the Great Lakes are considered to be at geopotential equal, all Mean
Water Level (MWL) values for stations on a particular lake should have the
same dynamic height. Therefore, all subordinate water level station MWL
values are adjusted to match the dynamic water level elevation of the Master
Station through the use of a hydraulic corrector. In the establishment of
International Great Lakes Datum (1985) the connecting waterways station
dynamic elevations were calculated through the use of a linear regression
while constraining the end points of the regression with the dynamic
elevations of the corresponding master station above and below the
connecting channel.
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 toNAVD88 are available from NGS through the World Wide
Web at National Geodetic Survey.
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/.