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Contact EPA Pacific Southwest Water Division

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

EMAP Western Pilot

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Western EMAP


The EPA Environmental Monitoring and Assessment Program (EMAP) is a multi-year effort to assess landscape conditions relating to aquatic resources across a 12-state area of the western United States. Landscape conditions are assessed on areas ranging in size from small watersheds (a few hectares) to entire basins (several million hectares). The landscape assessments were conducted jointly by the EPA Office of Research and Development and EPA Regions 8, 9 and 10. Initial efforts in EPA Region 9 focused on subregional areas in coastal northern and southern California to allow integration with the intensive survey monitoring conducted by coastal and surface waters components of EMAP. The assessments are designed to help environmental managers target those areas where aquatic resource conditions appear most vulnerable to decline based on watershed-scale, landscape conditions.

Landscape indicators

The landscape assessment approach involved the analysis of spatial patterns in biophysical features (e.g., soils, topography, climate, vegetation, land use, drainage pathways) and quantification of associations between those patterns and indicators of aquatic resource condition. Landscape indicators are measures, indices or models describing the condition of an ecosystem or one of its critical components, and may reflect biological, chemical or physical attributes of ecological condition. Examples include extent of riparian zones, upland erosion potential, population distribution, total impervious area, and nutrient loading potential. Landscape indicators were generated in a geographic information system (GIS) from satellite imagery and other spatial data sources. Multiple watershed studies were conducted in the intensive study areas (i.e., northern and southern California) to establish linkages between landscape pattern and aquatic resource condition. Understanding these linkages will allow the evaluation of the degree to which landscape condition and other stressors contribute to observed aquatic conditions across broad spatial scales. Watersheds where aquatic resources appear most vulnerable to decline can be targeted for future protection or additional research by land management agencies.


The Western EMAP landscape assessment was implemented in a phased approach. Phase I (1999-2000) involved the assembly of aquatic and landscape data, landscape indicator development and calculation, and aquatic resource-landscape indicator quantification in eight geographic areas. During Phase II (2001-2002), aquatic resource-landscape indicator relationships were quantified in additional geographic areas. Areas will be chosen that are expected to differ from the first eight study areas in their response to landscape pattern. During Phase III (2002-2003), landscape indicators will be quantified across the entire western U.S., and the potential risks to aquatic resources will be analyzed.


Further information

Daniel Heggem (heggem.daniel@epa.gov)
(702) 798-2278

General information on the U.S. EPA landscape assessment.

Landscape Ecology Study Area

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