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Science behind the Status and Trends of Wetlands 2004 to 2009 Report to Congress

2009 Report cover pageThe U.S. Fish and Wildlife Service (USFWS) is the principal Federal agency that provides information to the public on the extent and status of the Nation’s wetlands. The Wetland Status and Trends study has had a history of success in providing scientific information to resource managers and decision makers about wetlands resource trends in the conterminous U.S. The USFWS has used a scientific probability sample of the surface area of the conterminous U.S. to produce wetland status and change estimates, producing a series of five national reports on wetland trends covering the past 60 years. Because the national wetlands status and trends report contains scientific information with findings or conclusions representing the official position of one or more agencies of the federal government, the information contained in the report is considered to be a “highly influential scientific assessment.” 

Monitoring Wetland Trends in the Conterminous United States

The Wetlands Status and Trends study was developed specifically for monitoring the Nation's wetland area using a single, consistent definition and study protocol. The USFWS has specialized knowledge of wetland habitats, classification, ecological change processes and has used that capability to conduct a series of wetland monitoring studies that document spatial changes on the landscape. Wetlands status and trends information is widely distributed and used extensively by industry, all levels of government, university researchers, educators and the general public. Three hundred and seventy private businesses, 94 state government agencies, 29 Federal agencies and the Congress are actively using the wetlands information contained in recent status and trends reports or data summaries. Due to the technical complexities and the ramifications of the resultant report, the USFWS has established technical panels to continually review scientific configuration, data collection and protocol issues1. A formal expert subject matter peer review process is also used to scrutinize the report findings and conclusions.

Employing the Latest Technologies for Change Detection and Spatial Analysis

Technological advances in the acquisition of remotely sensed imagery and computerized mapping techniques often provide the ability to capture detailed information about Earth objects. Various commercial satellite imaging platforms with improved spatial resolution and sensors have made detailed imagery more readily available and applicable to wetlands identification, classification, and monitoring work.


The comparison of historical and recent imagery to determine change increases our understanding of natural and human-induced processes at work on the landscape. Highly skilled image analysts rely primarily on observable physical or spectral characteristics evident on high altitude imagery, in conjunction with collateral data and field verification work, to make decisions regarding wetland extent and classification.

The integration of Geographic Information Systems (GIS) and remote sensing for ecological monitoring has become even more important as technologies have improved and ecological assessments address more challenging issues. The use of such technologies as part of this study provided tremendous advantages for producing higher quality natural resource information including wetland location, extent and type.

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The Status and Trends of Wetlands in the Conterminous United States Report is produced every 10 years by the U.S. Fish and Wildlife Service with the cooperation of other principle Federal agencies.  This year’s report is available at:


Contact Information

U.S. Fish and Wildlife Service, National Standards and Support Team, 505 Science Drive, Madison, WI 53711-1061. Phone: (608) 238-9333



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