NOAA Office for Coastal Management (OCM) Lake Level Data: -6 Feet to +6 Feet Water Level Change

These data were created as part of the National Oceanic and Atmospheric Administration Office for Coastal Management's efforts to create an online

mapping viewer depicting potential water level increase and decrease in the coastal areas of the Great Lakes. The lakes included are: Erie, Huron, Michigan,

Ontario, St. Clair, and Superior. The purpose of the mapping viewer is to provide coastal managers and scientists with a preliminary look at lake level

change and potential coastal impacts. The viewer is a screening-level tool that uses nationally consistent data sets and analyses to help users examine

multiple scenarios and prioritize actions. The Lake Level Viewer may be accessed at https://coast.noaa.gov/llv.

These data consist of 13 water extent polygons and 13 water depth rasters (3 m resolution, depth values in meters) that show the potential water level when

the water level is decreased from 0 feet to -6 feet (resulting in potential land exposure) and when water level is increased from 0 to +6 feet (resulting

in potential flooding). These data are based on the each lake's long term average water level over the period of record (1913-2008). More information on

the long term average water level can be found at https://www.glerl.noaa.gov//pubs/fulltext/2013/20130021.pdf,

https://www.glerl.noaa.gov//pubs/fulltext/2013/20130022.pdf, and the Great Lakes Water Level Dashboard (https://www.glerl.noaa.gov/data/dashboard/GLWLD.html).

The process used to produce the data can be described as a bathtub approach. The process uses two source data sets to derive the final water extent polygons

and water depth rasters for each iteration of water level decrease or increase: the Digital Elevation Model (DEM) of the area and each lake's long term

average water level over the period of record (1918-2017) at the time of data set creation. Data can be downloaded at https://coast.noaa.gov/llv.

The model used to produce these data does not account for erosion, subsidence, or any future construction. Water levels are as they would appear during calm

conditions (excludes wind-driven effects). As with all remotely sensed data, all features should be verified with a site visit. The data are provided as is,

without warranty to their performance, merchantable state, or fitness for any particular purpose. The entire risk associated with the results and

performance of these data is assumed by the user. This data should be used strictly as a planning reference and not for navigation, permitting, or other

legal purposes.

The purpose of these data is to provide the user with information that can help communicate potential lake level change impacts as a result of either

water level decrease or increase. These data can be incorporated with the user's own data in order to make customized lake level impacts analyses.

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Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: NAD 1983 Great Lakes and St Lawrence Albers

Albers_Conical_Equal_Area:

Standard_Parallel: 42.122774

Standard_Parallel: 49.01518

Longitude_of_Central_Meridian: -83.248627

Latitude_of_Projection_Origin: 45.568977

False_Easting: 1000000.0

False_Northing: 1000000.0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.000000003398570314061545

Ordinate_Resolution: 0.000000003398570314061545

Planar_Distance_Units: meter

Geodetic_Model:

Horizontal_Datum_Name: D North American 1983

Ellipsoid_Name: GRS 1980

Semi-major_Axis: 6378137.0

Denominator_of_Flattening_Ratio: 298.257222101

These data illustrate the scale of potential water level decrease and increase, not the exact location, and do not account for erosion, subsidence,

or future construction. Water level is shown as it would appear based on each lake's long term average water level over the period of record (excludes wind

driven effects) with one foot increments of water level decrease or increase. These data should be used only as a screening-level tool for management

decisions. As with all remotely sensed data, all features should be verified with a site visit. The data set is provided as is, without warranty to its

performance, merchantable state, or fitness for any particular purpose. The entire risk associated with the results and performance of this data set is

assumed by the user. This data set should be used strictly as a planning reference and not for navigation, permitting, or other legal purposes. Any

conclusions drawn from the analysis of this information are not the responsibility of the Office for Coastal Management (OCM) or its partners.

This data may be downloaded at https://coast.noaa.gov/llv;

None

These data illustrate the scale of potential water level decrease and increase, not the exact location, and do not account for erosion, subsidence,

or future construction. Water level is shown as it would appear based on each lake's long term average water level over the period of record (1918-2003)

(excludes wind driven effects) with one foot increments of water level decrease or increase. These data should be used only as a screening-level tool for

management decisions. As with all remotely sensed data, all features should be verified with a site visit. The data set is provided as is, without warranty

to its performance, merchantable state, or fitness for any particular purpose. The entire risk associated with the results and performance of this data set

is assumed by the user. This dataset should be used strictly as a planning reference and not for navigation, permitting, or other legal purposes.

These data are complete. Data supplied are from the most current elevation data available at the time of creation. Gaps may exist, but these are due

to a lack of available elevation data at the time of data set creation.

Standard methods for determining water level decrease and increase were used. The vertical accuracy of these data is dependent on the source elevation

data.