Spatial Data in WATERS
- Spatial Reference Systems used in WATERS
- Measurements in WATERS datasets
- Raster Grids in WATERS
- Adding Custom Coordinate Reference System
EPA Office of Water geospatial and tabular data are hosted in a variety of formats including enterprise relational databases, web mapping servers and file-based storage.
Spatial Reference Systems used in WATERS
The majority of Office of Water spatial data is stored in the federal standard geodetic NAD83 coordinate system having the following parameters:
Angular Unit: Degree (0.01745329251994328)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: North_American_Datum_1983
Spheroid: Geodetic Reference System of 1980
Semimajor Axis: 6378137.000000000000000000
Semiminor Axis: 6356752.314140356100000000
Inverse Flattening: 298.257222101
This spatial reference system is defined in the EPSG Geodetic Parameter Dataset Exitwith the numeric id of 4269. Depending on the geographic information system several synonyms and equivalencies are utilized:
- Oracle Spatial Exit
Oracle Spatial defines geospatial information as its native MDSYS.SDO_GEOMETRY object. Each object has an SDO_SRID attribute value indicating the spatial reference system used. When storing NAD83 geodetic information in Oracle, WATERS uses SDO_SRID 8265 which is described by Oracle Corporation as "Longitude / Latitude (NAD 83)".
- ESRI ArcGIS Exit
ArcGIS describes geospatial information using named coordinate systems. When storing NAD83 geodetic information in ESRI products, WATERS uses the stock "NAD 1983" coordinate system. In older version of ESRI software this may be displayed as "GCS_North_American_1983".
- Safe Software FME Exit
FME describes geospatial information using named coordinate systems. When storing or transforming NAD83 geodetic information using FME, WATERS uses the stock "LL-83: NAD83 Latitude/Longitude, Degrees" coordinate system identifier.
- PostGIS Spatial and Geographic Objects for PostgreSQL Exit
PostGIS defines geospatial information using numeric spatial reference identifiers. When storing or transforming NAD83 geodetic information using PostGIS, WATERS uses SRID 4269.
- Other Geographic Information Systems
Most other GIS software and mapping servers reference NAD83 geodetic coordinate system as either EPSG SRID 4269 or via urn-notation as "urn:ogc:def:crs:OGC::CRS83".
Measurements in WATERS datasets
While features are stored as NAD83 geodetic data, when length and area are calculated EPA Office of Water follows the common approach of measuring geometries in an Albers Equal-Area Conic projection having the following parameters:
- Continental United States:
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: -96.0
Standard_Parallel_1: 29.5
Standard_Parallel_2: 45.5
Latitude_Of_Origin: 23.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 5070
- Oracle: 5070
- ESRI: "NAD_1983_Contiguous_USA_Albers"
- FME: None, custom SRS required
- PostGIS: 5070
- Hawaii:
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: -157.0
Standard_Parallel_1: 8.0
Standard_Parallel_2: 18.0
Latitude_Of_Origin: 3.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: None
- Oracle: None, custom SRS required
- ESRI: None, custom SRS required
- FME: None, custom SRS required
- PostGIS: None, Custom SRS required
- Alaska:
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: -154.0
Standard_Parallel_1: 55.0
Standard_Parallel_2: 65.0
Latitude_Of_Origin: 50.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 3338
- Oracle: 3338
- ESRI: "NAD_1983_Alaska_Albers"
- FME: None, custom SRS required
- PostGIS: 3338
- Puerto Rico/US Virgin Islands:
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: -66.0
Standard_Parallel_1: 8.0
Standard_Parallel_2: 18.0
Latitude_Of_Origin: 3.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: None
- Oracle: None, custom SRS required
- ESRI: None, custom SRS required
- FME: None, custom SRS required
- PostGIS: None, custom SRS required
- Pacific Trust Territories:
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: 145.0
Standard_Parallel_1: 8.0
Standard_Parallel_2: 18.0
Latitude_Of_Origin: 3.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: None
- Oracle: None, custom SRS required
- ESRI: None, custom SRS required
- FME: None, custom SRS required
- PostGIS: None, custom SRS required
Raster Grids in WATERS
WATERS hosts select raster grids produced by NHDPlus. These resources utilize specification projections for different parts of the nation.
- Continental United States (same projection as used for measurement):
Projection: Albers Equal Area
Datum: NAD 1983
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: -96.0
Standard_Parallel_1: 29.5
Standard_Parallel_2: 45.5
Latitude_Of_Origin: 23.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 5070
- Oracle: 5070
- ESRI: "NAD_1983_Contiguous_USA_Albers"
- FME: None, custom SRS required
- PostGIS: 5070
- Hawaii:
Projection: Transverse Mercator
Datum: NAD 1983
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: -159.0
Scale_Factor: 0.9996
Latitude_Of_Origin: 0.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 26904
- Oracle: 26904
- ESRI: "NAD_1983_UTM_Zone_4N"
- FME: "EPSG:26904"
- PostGIS: 26904
- Puerto Rico/US Virgin Islands:
Projection: Lambert Conformal Conic
Datum: NAD 1983
False_Easting: 200000.0
False_Northing: 200000.0
Central_Meridian: -66.43333333333334
Standard_Parallel_1: 18.03333333333334
Standard_Parallel_2: 18.43333333333333
Latitude_Of_Origin: 17.83333333333333
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 32161
- Oracle: 32161
- ESRI: "NAD_1983_StatePlane_Puerto_Rico_Virgin_Islands_FIPS_5200"
- FME: "EPSG:32161"
- PostGIS: 32161
- Territory of American Samoa:
Projection: Transverse Mercator
Datum: WGS 1984
False_Easting: 500000.0
False_Northing: 10000000.0
Central_Meridian: -171.0
Latitude_Of_Origin: 0.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 32702
- Oracle: 32702
- ESRI: "WGS_1984_UTM_Zone_2S"
- FME: "EPSG:32702"
- PostGIS: 32702
- Territory of Guam and Commonwealth of the Northern Mariana Islands:
Projection: Transverse Mercator
Datum: WGS 1984
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: -147.0
Latitude_Of_Origin: 0.0
Linear Unit: Meter (1.0)
Geographic Information System SRS Information:- EPSG: 32655
- Oracle: 32655
- ESRI: "WGS_1984_UTM_Zone_55N"
- FME: "EPSG:32655"
- PostGIS: 32655
Adding Custom Coordinate Reference Systems
Support for these Albers Equal-Area Conic projections in commercial and open source GIS software is limited as these projections have only slowly been registered with the EPSG Geodetic Parameter Dataset Exit. Below are instructions for adding these projections to your GIS.
- Oracle Spatial
Oracle users will need to add custom coordinate references to their installation of Oracle Spatial (MDSYS). This action will require administrative privileges on the Oracle database instance. Executing the script adds three custom projections, three custom transformation operations, and three operation parameters for each custom transformation to your Oracle Spatial coordinate system tables. We assume that SRIDs 1002002 through 1002005 are free and custom operation ids 1002002 through 1002005 are free. If you have preexisting custom or Oracle installed projections and/or operations in that range you will need to adjust these ids accordingly.
At the end you will have three new custom projection SRIDs available:
- 1002002 - NAD83 Hawaii Albers Equal Area USGS
- 1002004 - NAD83 Puerto Rico/Virgin Islands Albers Equal Area USGS
- 1002005 - NAD83 Pacific Trust Albers Equal Area USGS
- ESRI ArcGIS
ESRI ArcGIS as of version 10.6 only provides stock coordinate reference systems for the continental United States and Alaska. In order to work with geospatial data in other US exclaves, users will need to add custom projections. The easiest way to do so is to copy the well known text definition below into a text file and save with the extension ".prj". Then within ArcCatalog simply import the file into your list of custom projections.
NAD83 Hawaii Albers Equal Area USGS.prj
NAD83 Puerto Rico Virgin Islands Albers Equal Area USGS.prj
NAD83 Pacific Trust Albers Equal Area USGS.prj
- Safe Software FME
FME as of version 2013 does not provide definitions for these projections. Users may add the projections to FME by editing their MyCoordSysDefs.fme file as detailed here Exit. Inserting the following text and restarting FME will allow users to work with all five projections.
- PostGIS Spatial and Geographic Objects for PostgreSQL
PostGIS as of version 2.5.1 does not provide definitions for all projections. Users will need to add three entries to their public.spatial_ref_sys table. We assume that SRIDs 990002 through 990005 are free. If you have preexisting custom projections in that range you will need to adjust these ids accordingly. At the end you will have three new SRIDs available:
- 990002 - NAD83 Hawaii Albers Equal Area USGS
- 990004 - NAD83 Puerto Rico/Virgin Islands Albers Equal Area USGS
- 990005 - NAD83 Pacific Trust Albers Equal Area USGS