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

                                                                                
Station ID: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


TO REACH THE NOS GAUGING STATION, IN DETOUR VILLAGE, CHIPPEWA COUNTY, MICHIGAN,
FROM THE INTERSECTION OF M 134 (ONTARIO ST) AND ELIZABETH ST. PROCEED EAST ON
ELIZABETH STREET FOR 0.18 MILES TO THE CINDERBLOCK AND BRICK NOS GAUGE HOUSE.


                    G R E A T  L A K E S   B E N C H   M A R K S
                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


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


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

MONUMENTATION:           Flange-encased Rod                    VM#:        13074
AGENCY:                  National Geodetic Survey              IDB PID#:  QJ0086
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   45° 59.5' N (  45.99214)          LONGITUDE:  83° 54.0' W ( -83.89936)


The bench mark is a flange encased rod on the South side of Elizabeth St in the
East lawn of the Central Savings Bank located at the junction of Elizabeth
Street and Huron Street, 20.72 m (67.98 ft) South of the center of Elizabeth
Street, 12.80 m (41.99 ft) West of the center of Huron Street, 7.46 m (24.48 ft)
NW of a power line pole with three transformers, 7.16 m (23.49 ft) NE of the SE
corner of the bank building, 4.17 m (13.68 ft) SE of the NE corner, and 3.41 m
(11.19 ft) East of the East face. Mark protected by a PVC sleeve and alum access
lid.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          907 5099 HARRY

MONUMENTATION:           Bench Mark disk                       VM#:        13075
AGENCY:                  US Engineers                          IDB PID#:  QJ0088
SETTING CLASSIFICATION:  Concrete foundation                   OPUS PID:        
LATITUDE:   45° 59.6' N (  45.99253)          LONGITUDE:  83° 53.9' W ( -83.89831)


The bench mark is a disk at the East end of Elizabeth Street, being an unstamped
disk cemented in the top of the concrete foundation and at the SW corner of the
NOS water level gauge station building, 12.7 m (41.7 ft) North of the center of
the approach ramp to the Drummond Island ferry, 0.57 m (1.87 ft) South of the
South edge of the door at the West entrance to the water level gauge station,
and 0.15 meters (0.49 ft) WNW of the SW corner of the gauge station building.

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

                                                                                
Station ID: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


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


                         BENCH MARK STAMPING:  5099 F 1993
                         DESIGNATION:          907 5099 F

MONUMENTATION:           Bench Mark disk                       VM#:        13076
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  AC6043
SETTING CLASSIFICATION:  Concrete support of ferry ramp        OPUS PID:        
LATITUDE:   45° 59.5' N (  45.99236)          LONGITUDE:  83° 53.9' W ( -83.89831)


The bench mark is a disk in the South concrete support of the North ferry
landing ramp, 16.2 m (53.1 ft) South of the South face of the NOS water level
gauge house, 13.2 m (43.3 ft) North of the centerline of the South ferry landing
ramp, 3.2 m (10.5 ft) West of the East end of the concrete support, set 1.1 m
(3.6 ft) above the road surface.



                         BENCH MARK STAMPING:  BANK
                         DESIGNATION:          907 5080 BANK

MONUMENTATION:           Metal Rod                             VM#:        13077
AGENCY:                  National Geodetic Survey              IDB PID#:  QJ0087
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   45° 59.5' N (  45.99203)          LONGITUDE:  83° 54.0' W ( -83.89967)


The bench mark is a copper-clad steel rod on the South side of Elizabeth St, at
the SE corner of the Central Savings Bank located at the junction of Elizabeth
Street and Huron Street, 19.05 m (62.50 ft) SW of power line pole number DT
2198, 14.32 m (46.98 ft) West of the center of Huron Street, 12.45 m (40.85 ft)
South of the NE corner of the bank and in line with the East side of building,
0.67 m (2.20 ft) East of the East face and in line with the South face of the
bank building, 0.66 m (2.17 ft) East of the SE corner of the bank and in line
with the South side of bldg, being the high point on top of a 5/8-inch diameter
copper clad steel rod 3.05 m (10.01 ft) long, encased in a 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: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


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


                         BENCH MARK STAMPING:  SM 34 1934 MCK
                         DESIGNATION:          907 5099 SM 34

MONUMENTATION:           Bench Mark disk                       VM#:        13079
AGENCY:                  US Lakes Survey                       IDB PID#:  QJ0052
SETTING CLASSIFICATION:  Building                              OPUS PID:        
LATITUDE:   45° 59.5' N (  45.99189)          LONGITUDE:  83° 54.1' W ( -83.90228)


The bench mark is a disk at the Saint Stephens Episcopal Church located on the W
side of Ontario Street between Elizabeth Street and St. Mary's Street, set
vertically in the West face and at the SW corner of the stone wall building,
0.24 m (0.79 ft) North of the SW corner, 1.22 m (4.00 ft) above the ground.

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

                                                                                
Station ID: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


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


                         BENCH MARK STAMPING:  DETOUR MARINA 1997
                         DESIGNATION:          DETOUR MARINA

MONUMENTATION:           Horizontal Station disk               VM#:        18304
AGENCY:                  National Geodetic Survey              IDB PID#:  AH9228
SETTING CLASSIFICATION:  Drill hole in a rock ledge            OPUS PID:        
LATITUDE:   45° 59.9' N (  45.99897)          LONGITUDE:  83° 54.0' W ( -83.90053)


The bench mark is a disk set in a drill hole in a 1x1-foot area of exposed
bedrock, North of the harbor marina office, South of a weather station and
between the water's edge and a sidewalk, 28.7 m (94.2 ft) NNE of the marina
office building's North corner, 20.1 m (65.9 ft) South of the SW corner of a
chain-link fence around a weather tower/station, 13.5 m (44.3 ft) North of the
North 1 of 2 barbecue grill pedestals, 6.1m  (20.0 ft) West of a witness post
near the water's edge, 3.5 m (11.5 ft) East of a sidewalk.





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: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


                             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: 9075099                         PUBLICATION DATE:  08/11/2017
Name:       DE TOUR VILLAGE, LAKE HURON                       
            MI
NOAA Chart: 14881                           Latitude:   45° 59.5' N (  45.99250)
USGS Quad:                                  Longitude:  83° 53.9' W ( -83.89820)


                             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/.