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

                                                                                
Station ID: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


TO REACH THE NOS GAUGING STATION IN ST LOUIS COUNTY, DULUTH, MN, FROM THE
INTERSECTION OF LAKE AVE AND 9TH ST, PROCEED WEST ON 9TH ST FOR 0.05 MILE (0.08
KM) TO THE THE CORPS OF ENGINEERS PROPERTY AT 901 MINNESOTA AVENUE, THE GAUGE IS
LOCATED INSIDE A GLASS WINDOW ROOM LOCATED INSIDE THE COE VELLEL YARD MAIN
WAREHOUSE, THE GAUGE ENCLOSURE IS AGAINST THE NORTH WAREHOUSE WALL, WEST OF THE
ENTRANCE DOOR TO PARKING LOT.


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


                 PRIMARY BENCH MARK STAMPING:  9064 F 1990
                         DESIGNATION:          909 9064 F

MONUMENTATION:           Bench Mark disk                       VM#:        13388
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  AE8288
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   46° 46.6' N (  46.77586)          LONGITUDE:  92°  5.5' W ( -92.09225)


The bench mark is a disk 20.3m (66.6 ft) SW of centerline of Minnesota Avenue,
6.5m (21.3 ft) North of NW corner of Corps of Engineers warehouse, 3.9m (12.8
ft) SE of SE corner of steps leading into COE dwelling, 18.3 cm below ground,
being highest point on standard survey disc crimped to a stainless steel rod
44.0 feet (13.4 m) long driven to refusal and encased in concrete kick block and
5" PVC pipe with aluminum cap.



                         BENCH MARK STAMPING:  451 A
                         DESIGNATION:          451 A

MONUMENTATION:           Triangulation Station disk            VM#:        13386
AGENCY:                  Army Corps of Engineers               IDB PID#:  AE8287
SETTING CLASSIFICATION:  Large concrete bulkhead               OPUS PID:        
LATITUDE:   46° 46.5' N (  46.77544)          LONGITUDE:  92°  5.5' W ( -92.09225)


The bench mark is a disk 24.4m (80.1 ft) South of flag pole, 10.1m (33.1 ft) WSW
of NW corner of warehouse building, 0.9m (3.0 ft) from SE corner of inner end of
boat slip, being highest point over center of bronze disc set in the concrete.

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

                                                                                
Station ID: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


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


                         BENCH MARK STAMPING:  BM 60
                         DESIGNATION:          909 9064 60

MONUMENTATION:           Bench Mark disk                       VM#:        13387
AGENCY:                  US Engineers                          IDB PID#:  RN1078
SETTING CLASSIFICATION:  Building                              OPUS PID:        
LATITUDE:   46° 46.5' N (  46.77533)          LONGITUDE:  92°  5.5' W ( -92.09206)


The bench mark is a disk 12.10m (39.70 ft) SE of the NW corner of the warehouse,
10.58m (34.71 ft) SW of the SE corner of the office building, 10.15m (33.30 ft)
North of the North face door entrance of the warehouse that flammable material
is stored, 27.4cm above concrete pavement.  Note - mark is a punch mark in the
center of a bronze disk.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          909 9064 56

MONUMENTATION:           Bolt                                  VM#:        13389
AGENCY:                  US Engineers                          IDB PID#:  RN1076
SETTING CLASSIFICATION:  Wall                                  OPUS PID:        
LATITUDE:   46° 46.7' N (  46.77825)          LONGITUDE:  92°  5.5' W ( -92.09214)


The bench mark is a bolt 13.7m (44.9 ft) SW of a 4 light lamp post erected to
light bridge, 3.60m (11.81 ft) NE of the NE side of a concrete end post at the
SW end of the wall, 0.79m (2.59 ft) West of West corner of the house, note -
mark is the top of a 1-inch bolt in top of the wall.

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

                                                                                
Station ID: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          909 9064 57

MONUMENTATION:           Bolt                                  VM#:        13390
AGENCY:                  US Engineers                          IDB PID#:  RN1075
SETTING CLASSIFICATION:                                        OPUS PID:        
LATITUDE:   46° 46.7' N (  46.77811)          LONGITUDE:  92°  5.6' W ( -92.09261)


The bench mark is a bolt 19.15m (62.83 ft) North of the centerline of the
driveway to the South Pier Inn, 12.30m (40.35 ft) East of the West side of the
door entrance to the inn, 0.30m (0.98 ft) West of a concrete end post at the
start of the stone wall, 0.86m (2.82 ft) above the ground on the park side of
the stone wall.  Note - mark is the top of a 1-inch brass bolt in top of the
wall.



                         BENCH MARK STAMPING:  451
                         DESIGNATION:          451

MONUMENTATION:           Triangulation Station disk            VM#:        13391
AGENCY:                  Army Corps of Engineers               IDB PID#:  RN1464
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   46° 46.5' N (  46.77494)          LONGITUDE:  92°  5.6' W ( -92.09386)


The bench mark is a disk 23.2m (76.1 ft) North of the South edge of COE pier,
0.88m (2.89 ft) SSW of the NNE corner and 0.87m (2.85 ft) ENE of the NNW corner
of dock.

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

                                                                                
Station ID: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


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


                         BENCH MARK STAMPING:  602 1988
                         DESIGNATION:          602

MONUMENTATION:           Tidal Station disk                    VM#:        13392
AGENCY:                  Army Corps of Engineers               IDB PID#:  AE8289
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   46° 46.5' N (  46.77472)          LONGITUDE:  92°  5.6' W ( -92.09372)


The bench mark is a disk 23.2m (76.1 ft) South of the North face of concrete
bulkhead, 0.90m (2.95 ft) North of South face of COE concrete bulkhead, 0.90m
(2.95 ft) East of the West face of COE concrete bulkhead and 0.65m (2.13 ft) NW
of the last cleat on the North side of COE concrete bulkhead.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          909 9064 NO STAMPING

MONUMENTATION:           Triangulation Station disk            VM#:        21247
AGENCY:                  Army Corps of Engineers               IDB PID#:        
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   46° 46.5' N (  46.77511)          LONGITUDE:  92°  5.6' W ( -92.09261)


The bench mark is a disk 11.16m (36.6 ft) SW of SW corner of main warehouse
building, 8.63m (28.3 ft) West of point at which concrete bulkhead meets steel
bulkhead, 6.74m (22.1 ft) South of welding shop building, 5.35m (17.6 ft) West
of fourth bollard running in East-West line, 0.51m (1.7 ft) North of edge of
concrete bulkhead, flush with the ground, being the high point of a brass US
Corps of Engineers bench mark disk with no stamping.





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: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


                             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: 9099064                         PUBLICATION DATE:  08/11/2017
Name:       DULUTH, LAKE SUPERIOR                             
            MN
NOAA Chart: 14975                           Latitude:   46° 46.5' N (  46.77575)
USGS Quad:                                  Longitude:  92°  5.5' W ( -92.09203)


                             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/.