Information Resources and Technology Management


You are invited to read the definitions of terms used in this data standard.

Ecosystem Unit Number
One- and/or two-digit numbers that represent the ecosystem unit boundaries of the United States, which are drawn primarily along watershed boundaries. The Service originally chose the U.S. Geological Survey's Hydrologic Unit Map as the foundation for delineating ecosystem unit boundaries on a national scale. Since that time, boundaries in some of the regions have been moved to the closest county boundaries to simplify management responsibilities. The current unit boundaries reflect this combination.  
Character Field (to allow leading zeros in this data field when required)
NN, where each N represents a number from 0 through 9. 
Recommended Field Name ECONUM
The official values to be used for this data element are described in the reference and available for download in the Source section. 
An electronic copy of the official values to be used for this data element is available here in ASCII (.txt) format. An electronic copy of the file is also available here in MS Word format. These values represent the official ecosystem unit names used by the Service as of December 26, 2008. The source files include Region numbers to identify the ecosystem units associated with each Region of the Service.
Historical Data For information on past versions of this standard, contact the Chief Data Officer

Part 052, FW 1,  Ecosystem Approach to Fish and Wildlife Conservation.

Part 052, FW 1, Exhibit 1, Watershed Based Units, is a PDF of the FWS ecosystem boundaries, names, and numbers as of April 19, 1996.  NOTE:  Two ecosystems have been renamed to coincide with FWS ecoregion names in the Southeast (Region 4):  30 - Northeast Gulf Watersheds (formerly Florida Panhandle Watersheds); and 32 - North Florida (formerly Peninsular Florida). 

Part 270, FW 6, Data Management and Standards has been superceded by Part 274, FW 2, Establishing Service Data Standards.

Ecosystem Approach to Fish and Wildlife Conservation: An Assessment by Ohio State University - an evaluation of the above document and results.

Use Instructions
As of the approval date, this data element will be used in any new automated system, data set, database, or information application, including new Geographic Information System (GIS) data and applications. This data element will also be used in any major modifications to existing systems or versions of these data-related items that use numbers to identify the Service's ecosystem unit boundaries. The Ecosystem Unit Boundaries data standard references the spatial component of the ecosystem unit boundary information, using the same names and coding scheme as this data element. The ecosystem unit boundaries can be downloaded from this site as geographic information system (GIS) coverages or graphic files.

Service staff are strongly encouraged to utilize this data element in existing systems, data sets, databases, and information applications. Where existing systems and data-related items are not in compliance, they should be modified to achieve compatibility and implement this data standard.

The ecosystem unit number should normally be used in conjunction with the ecosystem unit name. The Service data standard for Ecosystem Unit Name can be viewed at this site. It references the official names used by the Service to identify the ecosystem unit boundaries of the United States. The numeric designation of "00" (Not Applicable) should be assigned to Service organizations that do not have an ecosystem association, such as the Washington Office and Regional Directorate and Regional administration offices.

Ecosystem unit numbers and ecosystem unit names will be handled as separate data fields in any new or modified automated system, and will not be combined in a single data field.

Approval Date
March 21, 2000
Validation Date
September 16, 2013
Data Steward Kurt Snider, Cartographer, Cookeville Ecological Services Field Office, FWS Region 4.


Last updated: May 9, 2019