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Contact EPA Pacific Southwest Water Division

Pacific Southwest, Region 9

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

Western Environmental Monitoring and Assessment Program

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Western EMAP

The EPA created the Environmental Monitoring and Assessment Program (EMAP) to develop tools necessary to monitor and assess the status and trends of national ecological resources. The primary goal of the EMAP Western Pilot Study is to generate state and regional scale assessments of the condition of ecological resources in the western United States, and to identify stressors associated with the degradation of these resources. In 1999, EMAP is embarked on a multi-year effort to demonstrate the application of core monitoring and assessment tools across a large geographical area of the western United States. The EMAP Western Pilot will encompass the states of EPA Regions 8, 9 and 10 (i.e., Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, Wyoming).


EMAP Western Pilot Study assessment efforts include three core components:

A probability-based sampling approach will be used to monitor the ecological condition of coastal and surface waters. The landscapes component will make use of remotely sensed imagery and utilize a census approach. All three components will produce regional-scale assessments of ecological condition. The coastal watersheds in Northern and Southern California are two special focus areas in Region 9 that have been selected for more intensive monitoring and assessment.

Coastal Waters - The overall objective of the coastal portion of the EMAP Western Pilot Study is to assess the ecological condition of estuarine and offshore waters of the Pacific Coast States (including Alaska and Hawaii). This will be accomplished by monitoring water column quality, sediment chemistry and toxicity, and benthic invertebrate and fish community structure. In Region 9, we are coordinating our efforts with the States of California, Hawaii, Guam and American Samoa. The results of the coastal EMAP are a major component of the National Coastal Condition Assessments reports.

Surface Waters - Perennial rivers and streams are monitored for indicators of pollutant exposure and habitat condition. These indicators include aquatic macroinvertebrate, fish and periphyton assemblages, water quality, physical habitat structure and riparian condition. In Region 9, we are coordinating our efforts with the States of Arizona, California, Nevada, and affected tribes. The results from these studies will be a component of the National Wadeable Streams Assessment.

Landscapes - Landscape conditions will be assessed using a variety of indicators generated in a Geographic Information System (GIS) from spatial data derived from satellite imagery and other data sources. Results of the assessment should help environmental managers target those areas where aquatic resource conditions appear most vulnerable to impairment based on watershed-scale, landscape conditions. We anticipate collaboration with U.S. Geological Survey, U.S. Forest Service, Natural Resources Conservation Service and Bureau of Land Management.

Further information

Janet Hashimoto (hashimoto.janet@epa.gov)
(415) 972-3452

Separate fact sheets are available that provide more specific information on the Western EMAP components.


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