U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


TO REACH THE NOS GAUGE HOUSE, IN ST CLAIR SHORES, MACOMB COUNTY, MICHIGAN, FROM
THE INTERSECTION OF BLOSSOM HEATH AND JEFFERSON AVE, PROCEED EAST ON BLOSSOM
HEATH FOR APPROX 0.25 MILE (0.40 KM) TO THE FIRST USCG GATE ON UNMARKED SERVICE
DRIVE LEADING TO THE USCG STATION, THEN CONTINUE TO PROCEED EAST ON SERVICE
DRIVE FOR APPROX 0.30 MILE (0.48 KM) TO THE 2ND USCG GATE, AT U.S. COAST GUARD
STATION, NOAA GAUGE HOUSE ON NW CORNER OF USCG PROPERTY.


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


                 PRIMARY BENCH MARK STAMPING:  FOOD
                         DESIGNATION:          903 4052 FOOD

MONUMENTATION:           Pipe Cap                              VM#:        12968
AGENCY:                  National Geodetic Survey              IDB PID#:  NE0165
SETTING CLASSIFICATION:  Galvanized steel pipe in sleeve       OPUS PID:        
LATITUDE:   42° 28.4' N (  42.47383)          LONGITUDE:  82° 52.9' W ( -82.88219)


The bench mark is a disk on the S side of drive inside fenced in area at the
Saint Clair Recreation Center bath house building, set in the lawn on the E side
of the building and in line with the N face, 22.6 m (74.1 ft) SE of a fire
hydrant, 15.3 m (50.2 ft) NE of the SE corner of recreation building, 5.1 m
(16.7 ft) SE of a 4-inch metal post supporting the NE corner of roof, 5.0 m
(16.4 ft) E of the NE corner of the building, 1.9 m (6.2 ft) E of the E edge of
the sidewalk, 0.46 m (1.51 ft) below ground surface. The mark is a stainless
steel plug on top of a 3/8-inch diameter galvanized steel pipe encased in a
1-inch diameter steel pipe which in encased by a 6-inch concrete pipe 0.3 meter
(1.0 ft) below the ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          903 4052 TOWER

MONUMENTATION:           Chiseled Cross                        VM#:        12970
AGENCY:                                                        IDB PID#:  NE0167
SETTING CLASSIFICATION:  Concrete footing                      OPUS PID:        
LATITUDE:   42° 28.4' N (  42.47267)          LONGITUDE:  82° 52.8' W ( -82.87950)


The bench mark is a chiseled cross in a bolt 15.9 m (52.2 ft) SW of the NW
corner of the garage, 10.5 m (34.4 ft) W of the SW corner of the garage, 7.8 m
(25.6 ft) SE of the NW face of the bulkhead, 0.07 m (0.23 ft) above the ground,
being the top of an 5/8-inch diameter bolt marked with an X set into the 18-inch
diameter concrete footing bolting down the W leg of the radio antenna of the
USCG station.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          903 4052 POLE

MONUMENTATION:           Metal Rod                             VM#:        12971
AGENCY:                  National Geodetic Survey              IDB PID#:  NE0164
SETTING CLASSIFICATION:  Copper-clad steel rod w/o sleeve      OPUS PID:        
LATITUDE:   42° 28.4' N (  42.47386)          LONGITUDE:  82° 52.9' W ( -82.88156)


The bench mark is a copper-clad steel rod approximately in front of dwelling at
22715 Revere, between fence and utility pole, 49.7 m (163.1 ft) NE of NE corner
of the St. Clair Shores recreation building, 2.7 m (8.9 ft) N of centerline of
road leading to Coast Guard station, 0.27 m (0.89 ft) N of utility pole, just
below the ground surface, being highest point on top of a 5/8-inch copper-coated
steel rod, 2.13 m (6.99 ft) long. Mark is protected by a standard 5" PVC sleeve
with aluminum access lid.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


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


                         BENCH MARK STAMPING:  N 235 1980
                         DESIGNATION:          N 235

MONUMENTATION:           Flange-encased Rod                    VM#:        12972
AGENCY:                  National Geodetic Survey              IDB PID#:  NE0898
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   42° 28.4' N (  42.47367)          LONGITUDE:  82° 52.9' W ( -82.88231)


The mark is a stainless steel rod on the S side of drive inside the fenced in
area at the Saint Clair Recreation Center bath house building, set in the lawn
on the E side of the building, 9.5 m (31.2 ft) SE of the SE corner of the
building, 1.6 m (5.2 ft) SE of the most S 4-inch overhang support post and in
line with the S face of the building, 1.3 m (4.3 ft) N of the N edge of a
concrete sidewalk on the S side of the building, 1.3 m (4.3 ft) E of the E edge
of a concrete sidewalk on the E side of the building. Mark is protected by a
standard 5" PVC sleeve with aluminum access lid.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


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


                         BENCH MARK STAMPING:  H 235 1980
                         DESIGNATION:          H 235

MONUMENTATION:           Flange-encased Rod                    VM#:        12973
AGENCY:                  National Geodetic Survey              IDB PID#:  NE0896
SETTING CLASSIFICATION:  Stainless steel rod w/o sleeve        OPUS PID:        
LATITUDE:   42° 28.1' N (  42.46814)          LONGITUDE:  82° 53.3' W ( -82.88764)


The bench mark is a stainless steel rod located at the junction of Jefferson Ave
and Ridgeway St, 19.1 m (62.7 ft) SW of the center of Jefferson Avenue, 14.3 m
(46.9 ft) NNW of the NW corner of the office building, 9.0 m (29.5 ft) S of the
S curb of Ridgeway St, 4.5 m (14.8 ft) W of the SW of two round supports for the
bank sign, 0.95 m (3.12 ft) N of the N curb of the entrance to the office
building, protected by PVC sleeve with alum access lid and witness post.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


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


                         BENCH MARK STAMPING:  J 235 1980
                         DESIGNATION:          J 235

MONUMENTATION:           Flange-encased Rod                    VM#:        12974
AGENCY:                  National Geodetic Survey              IDB PID#:  NE0897
SETTING CLASSIFICATION:  Stainless steel rod w/o sleeve        OPUS PID:        
LATITUDE:   42° 28.5' N (  42.47469)          LONGITUDE:  82° 53.3' W ( -82.88914)


The mark is a stainless steel rod set in the median on the E side of Jefferson
Ave, 7.7 m (25.3 ft) E of the E curb of Jefferson Avenue at the W end of the
median, 3.5 m (11.5 ft) E of the E edge of a sidewalk, 2.8 m (9.4 ft) N of the S
curb of the medium, 2.6 m (8.5 ft) S of the N curb of the median, 2.2 m (7.4 ft)
W of W face of a street lamp pole, 0.9 ft (27.4 cm) W from witness post. Mark
protected by a standard 5" PVC sleeve with aluminum access lid.





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: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


                             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: 9034052                         PUBLICATION DATE:  08/11/2017
Name:       ST. CLAIR SHORES, LAKE ST. CLAIR                  
            MI
NOAA Chart: 14852                           Latitude:   42° 28.4' N (  42.47322)
USGS Quad:                                  Longitude:  82° 52.8' W ( -82.87925)


                             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/.