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

                                                                                
Station ID: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


TO REACH THE NOS GAUGING STATION, IN THE VILLAGE OF GULLIVER, SCHOOLCRAFT
COUNTY, MICHIGAN, FROM THE INTERSECTION OF US HWY 2 AND ROUTE 432 (PORT INLAND
RD), PROCEED SOUTH ON 432 (PORT INLAND RD) INTO THE PLANT PROPERTY FOR APPROX
13.44 KM (8.35 MI) TO THE NOS GAUGE HOUSE ON THE PROPERTY OF SPECIALTY MINERALS,
INC., (OLD PORT INLAND LIME AND STONE CO.), AT THE NORTHWEST CORNER OF THE
HARBOR, AT THE NORTH END OF A BOAT SLIP.


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


                 PRIMARY BENCH MARK STAMPING:  7096 F 1979
                         DESIGNATION:          908 7096 F

MONUMENTATION:           Survey disk                           VM#:        13238
AGENCY:                  National Ocean Survey                 IDB PID#:  AC8316
SETTING CLASSIFICATION:  Flag pole base                        OPUS PID:        
LATITUDE:   45° 58.3' N (  45.97142)          LONGITUDE:  85° 52.3' W ( -85.87247)


The bench mark is a disk on the East side of the road in front of Specialty
Minerals Inc. office building, (Old Port Inland Lime and Stone Co.) In the flag
pole base, 4.9 m (16.1 ft) West of the inner face of West curb, 1.54 m (5.05 ft)
South of the South edge of a sidewalk, 0.25 m (0.82 ft) SE of the East face of
the flag pole, 0.17 m (0.56 ft) NW of the SE corner of the concrete foundation.

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

                                                                                
Station ID: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


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


                         BENCH MARK STAMPING:  7096 G 1981
                         DESIGNATION:          908 7096 G

MONUMENTATION:           Survey disk                           VM#:        13239
AGENCY:                  National Ocean Survey                 IDB PID#:  AC8317
SETTING CLASSIFICATION:  72FT X 35FT CONCRETE PLATFORM         OPUS PID:        
LATITUDE:   45° 58.2' N (  45.97047)          LONGITUDE:  85° 52.4' W ( -85.87392)


The bench mark is a disk on the property of Specialty Minerals, Inc., (Old Port
Inland Lime and Stone Co.), located at the West side and near the SW corner of
the oil house (building no.  9) , on a 72ft x 35ft concrete storage platform,
10.65 m (34.94 ft) North of the South corner of the building, 0.8 m (2.6 ft)
North of the steps leading to building, 0.15 m (0.49 ft) West of the East face
of the building, with witness post.

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

                                                                                
Station ID: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


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


                         BENCH MARK STAMPING:  7096 J 1998
                         DESIGNATION:          908 7096 J

MONUMENTATION:           Flange-encased Rod                    VM#:        18314
AGENCY:                  National Geodetic Survey              IDB PID#:  DJ5177
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   45° 58.3' N (  45.97247)          LONGITUDE:  85° 52.3' W ( -85.87247)


The benchmark is a stainless steel rod 47.75 m (156.66 ft) South of first power
pole North of the closest entrance to gravel yard area behind admin bldg
(referred to as Gate 3), power pole is unnumbered but the face of pole is marked
with stainless steel washer and nail, 26.27 m (86.19 ft) North of centerline of
the closest entrance drive to the gravel yard area behind the admin bldg
(referred to as Gate 3), 19.35 m (63.48 ft) South of the first telephone pole
North of the Gate 3 entrance, 9.00m  (29.53 ft) West of centerline of Port
Inland Road 432, 3.35 m (10.99 ft) North from (road ends) pole, 2.55 m (8.37 ft)
East from water's edge of ditch line, set in PVC sleeve with aluminum access lid
and witness post.



                         BENCH MARK STAMPING:  7096 H RESET 2001
                         DESIGNATION:          908 7096 H RESET 2001

MONUMENTATION:           Bench Mark disk                       VM#:        18315
AGENCY:                  National Ocean Service                IDB PID#:        
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   45° 58.1' N (  45.96839)          LONGITUDE:  85° 52.3' W ( -85.87203)


The bench mark is a disk on the property of Specialty Minerals, Inc., (Old Port
Inland Lime and Stone Co.), 167.6 m (549.9 ft) South of the NW corner of the
harbor, 13.4 m (44.0 ft) East of the most North leg of a conveyor station, 4.2 m
(13.8 ft) North of the North rail leading to the conveyor station, 1.0 m (3.3
ft) West of the bulkhead face, set flush in top of concrete bulkhead.

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

                                                                                
Station ID: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


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


                         BENCH MARK STAMPING:  7096 K 2004
                         DESIGNATION:          908 7096 K

MONUMENTATION:           Flange-encased Rod                    VM#:        18316
AGENCY:                  National Geodetic Survey              IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   45° 58.5' N (  45.97439)          LONGITUDE:  85° 52.3' W ( -85.87219)


The bench mark is a stainless steel rod 8.60 m (28.22 ft) East of the centerline
of 432 (Port Inland Rd), then 5.39 m (17.68 ft) East of the East edge of Port
Inland Rd, 3.40 m (11.15 ft) South of the face of a power pole MC-1195, NPSK-S,
WQO, marked with a nail and S/S washer on the South side of pole, 0.20 m (0.66
ft) West of a witness post protected with a PVC sleeve, stamped alum access lid
and witness post.



                         BENCH MARK STAMPING:  908 7096 L 2006
                         DESIGNATION:          908 7096 L

MONUMENTATION:           Bench Mark disk                       VM#:        18317
AGENCY:                  National Ocean Service                IDB PID#:        
SETTING CLASSIFICATION:  Tower foundation                      OPUS PID:        
LATITUDE:   45° 58.1' N (  45.96828)          LONGITUDE:  85° 52.1' W ( -85.86886)


The bench mark is a disk on the property of O-N Minerals Inc., (Old Port Inland
Lime and Stone Co.) at the SE corner of the harbor, near the SE end of spit of
land, set in the top of the NOAA MET tower foundation, 1.67 m (5.47 ft) NE of
the SW corner of the met tower foundation, 1.15 m (3.77 ft) NW of the NE corner
of the met tower foundation, 0.25 m (0.81 ft) South of the North corner of the
met tower foundation.

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

                                                                                
Station ID: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          908 7096 CAP

MONUMENTATION:           Not specified (see descriptive text)  VM#:        18318
AGENCY:                                                        IDB PID#:        
SETTING CLASSIFICATION:  Steel bulkhead cap                    OPUS PID:        
LATITUDE:   45° 58.2' N (  45.96989)          LONGITUDE:  85° 52.3' W ( -85.87139)


The bench mark is on the property of Specialty Minerals, Inc., (Old Port Inland
Lime and Stone Co.), at the NW corner of the harbor, at the North end of boat
slip area, 5.7m (18.70 ft) West of the West edge of first East bollard from
gauge house, 3.09m (10.14 ft) Est of the East gauge house wall, 0.69m (2.26 ft)
East of the East side of bollard, 0.04m (0.12 ft) South of the North edge of the
steel bulkhead cap, being the high point on steel bulkhead cap created with a
grinder.





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: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


                             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: 9087096                         PUBLICATION DATE:  08/11/2017
Name:       PORT INLAND, LAKE MICHIGAN                        
            MI
NOAA Chart: 14911                           Latitude:   45° 58.2' N (  45.96989)
USGS Quad:                                  Longitude:  85° 52.3' W ( -85.87150)


                             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/.