U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


TO REACH THE NOS GAUGE HOUSE, IN SAULT STE MARIE, CHIPPEWA COUNTY, MICHIGAN,
FROM THE INTERSECTION OF ASHMUN ST AND PORTAGE AVE, PROCEED SOUTH ON PORTAGE FOR
0.2 MILES (0.3 KM) TO THE INTERSECTION WITH BRADY ST, THEN PROCEED NORTH ON
BRADY ST FOR 0.07 MILES (0.11KM) TO THE INTERSECTION WITH WATER ST, THEN PROCEED
EAST ON WATER STREET FOR 0.25 MILES (0.40 KM) TO THE INTERSECTION WITH LEGION
DR, THEN PROCEED NORTH ON LEGION DR FOR 0.10 MILES (0.16 KM) TO THE CORPS OF
ENGINEERS BOATYARD ON THE NORTH SIDE OF LEGION DR, THE GAUGING STATION IS
LOCATED INSIDE THE CAGED AREA OF THE NORTHWEST CORNER OF THE COE BOATHOUSE.


                    G R E A T  L A K E S   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  C 293 1983
                         DESIGNATION:          C 293

MONUMENTATION:           Flange-encased Rod                    VM#:        13171
AGENCY:                  National Geodetic Survey              IDB PID#:  RJ0613
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   46° 30.0' N (  46.50075)          LONGITUDE:  84° 20.6' W ( -84.34297)


The bench mark is a flange-encased rod 29.57 meters (97.01 ft) ENE of the SE
corner of the concrete foundation of the General Lewis Cass rock monument, 27.0
meters (88.6 ft) NNE of the North curb of Water Street, 4.7 meters (15.4 ft) NNW
of the NE corner of the Saint Mary's fall monument, 4.6 meters (15.1 ft) NNE of
the NW corner of monument, being a deep rod set in a 5 inch sleeve level with
grade.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


                    G R E A T  L A K E S   B E N C H   M A R K S


                         BENCH MARK STAMPING:   
                         DESIGNATION:          907 6060 BOATHOUSE

MONUMENTATION:           See descriptive text                  VM#:        13172
AGENCY:                                                        IDB PID#:  RJ0009
SETTING CLASSIFICATION:  WALL                                  OPUS PID:        
LATITUDE:   46° 30.0' N (  46.50081)          LONGITUDE:  84° 20.4' W ( -84.34036)


The bench mark is a high point on a one inch brass plate at the end of an iron
arm, located inside and near center of a 0.31m (1.02 ft) diameter iron well with
metal cover, 4.6m (15.1 ft) NE of the NW corner of monument, 1.5 meters (4.9 ft)
South of North wall of building, and 0.37 meters (1.21 ft) East of West wall of
monument.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          907 6060 BOATHOUSE W

MONUMENTATION:           Chiseled Square                       VM#:        13173
AGENCY:                                                        IDB PID#:  RJ0010
SETTING CLASSIFICATION:  WATER TABLE                           OPUS PID:        
LATITUDE:   46° 30.0' N (  46.50081)          LONGITUDE:  84° 20.4' W ( -84.34036)


The bench mark is a 1-inch chiseled square cut in top of the SW corner of the
concrete water table, near the North side of a double door which leads to water
level gauge inside boathouse, 4.22m (13.85 ft) NE of a flagpole, 3.1m (10.2 ft)
South of NW corner of boathouse, 1.2m (3.9 ft) North of the center of double
doors (West entrance to boathouse).

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


                    G R E A T  L A K E S   B E N C H   M A R K S


                         BENCH MARK STAMPING:   
                         DESIGNATION:          907 6060 WAREHOUSE N

MONUMENTATION:           Bolt                                  VM#:        13176
AGENCY:                                                        IDB PID#:  RJ0013
SETTING CLASSIFICATION:  CONCRETE SILL                         OPUS PID:        
LATITUDE:   46° 30.1' N (  46.50203)          LONGITUDE:  84° 20.7' W ( -84.34442)


The bench mark is a bolt below the locks, on the canal side (channel side) of
the U.S. Corps of Engineers warehouse building on the east side of the middle
entrance to building, 3.02 m (9.91 ft) east of the west side of concrete
entrance, 0.37 m (1.21 ft) south of a steel post on west side of entranceway,
10.67 cm west of the east side of concrete entrance, a brass bolt set in
concrete door sill at the NE corner of sill.



                         BENCH MARK STAMPING:  PT
                         DESIGNATION:          907 6060  PT

MONUMENTATION:           Survey disk                           VM#:        13177
AGENCY:                  US Engineers                          IDB PID#:  RJ0014
SETTING CLASSIFICATION:  Approach seawall to lock              OPUS PID:        
LATITUDE:   46° 30.1' N (  46.50219)          LONGITUDE:  84° 20.7' W ( -84.34478)


The bench mark is is a survey disk below the locks, on South seawall of approach
to the Mac Arthur Lock, on an extended line and North of the West face of the
U.S. Corps of Engineers warehouse building, 11.00m (36.09 ft) WNW of the last
entrance way on the North face of the warehouse, near the NW corner, 8.80m
(28.87 ft) North of the NW corner of the COE warehouse, 0.58m (1.90 ft) South of
North edge of seawall.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


                    G R E A T  L A K E S   B E N C H   M A R K S


                         BENCH MARK STAMPING:  PC
                         DESIGNATION:          907 6060 PC

MONUMENTATION:           Survey disk                           VM#:        13178
AGENCY:                  US Engineers                          IDB PID#:  RJ0015
SETTING CLASSIFICATION:  Approach seawall to lock              OPUS PID:        
LATITUDE:   46° 30.1' N (  46.50233)          LONGITUDE:  84° 20.8' W ( -84.34736)


The bench mark is is a survey disk just below the Soo Lock, set in top of the S
seawall of approach to Mac Arthur Lock, and about 97.6m (320.2 ft) East of
extended line of East face of U.S. Corps of Engineers administration building,
31.7m (104.0 ft) NE of light pole 216, 7.88m (25.85 ft) North of the security
fence, 0.6m (2.0 ft) South of North edge of seawall.



                         BENCH MARK STAMPING:  10
                         DESIGNATION:          10

MONUMENTATION:           Survey disk                           VM#:        18416
AGENCY:                                                        IDB PID#:  AE8000
SETTING CLASSIFICATION:  CONCRETE BULKHEAD                     OPUS PID:        
LATITUDE:   46° 30.1' N (  46.50178)          LONGITUDE:  84° 20.5' W ( -84.34206)


The bench mark is a survey disk set flush in the concrete bulkhead at the East
end of the locks, 18.48 m (60.63 ft) NW of the boat basin's NW inside corner,
7.29 m (23.92 ft) NNE of the NE corner of a concrete building, 1.07 m (3.51 ft)
South of the face of the bulkhead.





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  5 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


                             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  6 of  6

                                                                                
Station ID: 9076060                         PUBLICATION DATE:  08/11/2017
Name:       U.S. SLIP, ST. MARYS RIVER                        
            MI
NOAA Chart: 14884                           Latitude:   46° 30.0' N (  46.50080)
USGS Quad:                                  Longitude:  84° 20.4' W ( -84.34036)


                             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/.