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

                                                                                
Station ID: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


TO REACH THE NOS GAUGING STATION, IN COOK COUNTY, CHICAGO, ILLINOIS, (FIRST
CHECK IN AT GUARD STATION FOR LAKE SIDE MARKETING). TO REACH LAKE SIDE
MARKETING, FROM INTERSECTION OF 87TH AND BURLEY (3432) AVE. TURN NORTH ON BURLEY
ST AND GO TO 86TH ST. TURN EAST AND GO TO END (SOUTH GREEN BAY AVE AND E 86TH
ST). GUARD WILL HELP YOU. TO GO STRAIGHT TO STATION, FROM INTERSECTION OF (3432)
LAKE SHORE DR.(HWY N41)AND 87TH ST. PROCEED EAST ON 87TH, GATE TO STATION IS
(N41 44' 24.9",W087 32' 18.9"), IS FIRST DIRT RD (APPOX 40 YARDS), ON RIGHT
(WITH AN ARMY CORP OF ENGINEERS SIGN ON FENCE). THEN FOLLOW GRAVEL ROAD WEST
(RIGHT) APPROXIMATELY 0.4 KM (0.25 MI) TO SECONDARY GATE (OR FIRST RIGHT),
PROCEED SOUTH (RIGHT) ALONG SECONDARY GRAVEL ROAD APPROXIMATELY 0.2 KM (0.12 MI)
TO GAUGE SITE.


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


                 PRIMARY BENCH MARK STAMPING:  COM 1958
                         DESIGNATION:          908 7044 COM

MONUMENTATION:           Metal Rod                             VM#:        13199
AGENCY:                  National Geodetic Survey              IDB PID#:  ME2189
SETTING CLASSIFICATION:  Metal rod driven into the ground      OPUS PID:        
LATITUDE:   41° 43.8' N (  41.73011)          LONGITUDE:  87° 32.3' W ( -87.53881)


The bench mark is a metal rod 116.3m (381.6 ft) East of the extended center of
the avenue, 11.2m (36.7 ft) South of the extended center of the street, 4.70m
(15.42 ft) SW of the center of a driveway, 4.27m (14.01 ft) NNE of a telephone
pole, 3.10m (10.17 ft) SE of the North corner of the foundation of a razed
building, and 0.70m (2.30 ft) NE of the foundation.  Note - the datum point is
the top of a 1-inch metal rod that is recessed 0.3 m (1.0 ft) below the ground
surface.

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

                                                                                
Station ID: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


                    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 7044 REP

MONUMENTATION:           Bolt                                  VM#:        13200
AGENCY:                                                        IDB PID#:  ME2190
SETTING CLASSIFICATION:  Tower base                            OPUS PID:        
LATITUDE:   41° 43.8' N (  41.72981)          LONGITUDE:  87° 32.3' W ( -87.53889)


The bench mark is a bolt 97.5m (319.9 ft) East of the extended center of the
avenue, 45.4m (148.9 ft) South of the extended center of the street, 21.7m (71.2
ft) NNW of the center of a paved road parallel to the Calumet River, 10.5m (34.4
ft) WSW of the SW edge of a foundation of a razed building, 1.2m (3.9 ft) NW of
the tower leg, 0.4m (1.3 ft) SE of the NW corner of the concrete footing for the
NE leg of a high line tower, being a 3/8 inch bolt set in the concrete footing.

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

                                                                                
Station ID: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


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


                         BENCH MARK STAMPING:  M 274 1973
                         DESIGNATION:          M 274

MONUMENTATION:           Vertical Control disk                 VM#:        13201
AGENCY:                  National Geodetic Survey              IDB PID#:  ME1966
SETTING CLASSIFICATION:  Retaining wall - bulkhead             OPUS PID:        
LATITUDE:   41° 43.8' N (  41.72992)          LONGITUDE:  87° 32.3' W ( -87.53797)


The bench mark is a disk 172.0m (564.3 ft) East of the extended center of the
avenue, 67.9m (222.8 ft) South of the extended center of the street, 9.9m (32.5
ft) NE of the NE side of a Corp of Engineers boat ramp, 1.9m (6.2 ft) SW of the
SW end of a concrete retaining wall bulkhead along a US Steel Corp slip, 1.6m
(5.2 ft) South of the most southerly mooring post and set in the top of concrete
retaining wall.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          908 7044 BOLT

MONUMENTATION:           Bolt                                  VM#:        13203
AGENCY:                                                        IDB PID#:  AC8298
SETTING CLASSIFICATION:  Concrete gauge house floor            OPUS PID:        
LATITUDE:   41° 43.8' N (  41.72986)          LONGITUDE:  87° 32.3' W ( -87.53839)


The bench mark is a bolt just inside East side of doorway of NOS gauging
station, 1.74m (5.71 ft) North of the South interior wall of the gauge house,
0.79m (2.59 ft) East of the West edge of the door frame, 0.27m (0.89 ft) West of
the East interior wall of the gauge house, being highest point of hexagon bolt
set into concrete floor of gauge house.

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

                                                                                
Station ID: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


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


                         BENCH MARK STAMPING:  7044 H 1995
                         DESIGNATION:          908 7044 H

MONUMENTATION:           Bench Mark disk                       VM#:        18321
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  AE9231
SETTING CLASSIFICATION:  Stainless steel rod w/o sleeve        OPUS PID:        
LATITUDE:   41° 43.8' N (  41.72983)          LONGITUDE:  87° 32.3' W ( -87.53844)


The bench mark is a disk 34.7m (113.8 ft) South of the SW corner of the U.S.
Army Engineers District Field Building (with four bay doors), 9.2m (30.2 ft)
West of the SW corner of steel bulkhead, 1.3m (4.3 ft) South of the NW corner of
the NOS gauge house, being stainless steel rod driven 12.2m (40.0 ft) to
refusal, encased in 5" PVC sleeve with concrete kick-block with aluminum access
cover with witness post.



                         BENCH MARK STAMPING:  7044 J 2002
                         DESIGNATION:          908 7044 J

MONUMENTATION:           Survey disk                           VM#:        18322
AGENCY:                  National Ocean Service                IDB PID#:        
SETTING CLASSIFICATION:  Concrete pad                          OPUS PID:        
LATITUDE:   41° 43.8' N (  41.72989)          LONGITUDE:  87° 32.3' W ( -87.53822)


The bench mark is a disk 15.30m (50.20 ft) East from East corner of the NE face
of the gage house, 6.64m (21.78 ft) SW of the South face of the boat launch,
5.50m (18.04 ft) West of the 2nd yellow bollard from the North along the face of
the bulkhead that lies East of the gauge house, set in Rohn tower concrete
foundation, being a brass survey disk set into a 5ft by 5ft concrete pad that is
6ft deep, which has a Rohn tower secured into it and aluminum stand with Henasee
box.





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: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


                             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: 9087044                         PUBLICATION DATE:  08/11/2017
Name:       CALUMET HARBOR, LAKE MICHIGAN                     
            IL
NOAA Chart: 14929                           Latitude:   41° 43.8' N (  41.72972)
USGS Quad:                                  Longitude:  87° 32.3' W ( -87.53833)


                             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/.