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Project: Environmental Monitoring and Assessment (EMAP) 2002 Western Pilot 

Background and Objectives

The EMAP Western Pilot was a six-year research effort led by EPA’s Office of Research and Development to advance the science of monitoring ecosystem health and to demonstrate the applicability of EMAP assessment tools. The overall objective was to develop and demonstrate the tools needed to measure the ecological condition of aquatic resources in the western US. The program had several components, one of which was an assessment of estuarine condition through an integrated comprehensive coastal monitoring program along the West Coast (including Alaska and Hawaii). It was intended to demonstrate the value of survey-based monitoring by applying these techniques to answer questions of regional and state interest.

In 2002 (the fourth year of the EMAP Western Pilot), EMAP conducted an assessment of estuarine subtidal and intertidal mudflat and emergent macrophyte (marsh) habitats in California, Washington, and Oregon, with an intensification of assessment effort in the California regions of San Francisco Bay and southern California. These activities advance EMAP’s goal of expanding its program into wetlands, and provide continuity with data management and quality assurance procedures established in the previous years. The specific objectives of the program were to:

1) Provide a statewide estimate of intertidal wetland condition for a core indicator set.
2) Intensify the assessment effort in Southern California and the San Francisco (SF) Bay area.
3) Develop and apply additional indicators appropriate for wetland intertidal habitat.


This study was conducted in 2002.


The base sampling design in California allowed for a statewide assessment of intertidal wetland condition as well as independent assessments of southern California and San Francisco Bay. To achieve this, 30 sample points were randomly allocated along the Central and North Coast, and 30 were allocated to each of the two intensification regions. Assessment efforts were intensified in southern California and the San Francisco Bay area in order to serve the information needs of local, well-established coastal zone management units in those regions. These two units were the Southern California Wetland Recovery Project and the San Francisco Bay Area Wetlands Regional Monitoring Program (WRMP), which were both formed via a cooperative agreement among local, state, and federal agencies involved in wetland conservation, restoration, and management in their respective regions. In the intensification areas, some modifications of the traditional EMAP sampling design were made to accommodate local management interests.

According to EMAP standard practices, 30 1-m2 core sample plots were randomly selected from the total population of possible plots in each intensification project area. The 1-m2 plot and a short line transect adjacent to the plot comprised a core station. A variety of standard measures (core indicators) were assessed within the selected plots and along adjacent transects using EMAP protocols (Table 1). An additional suite of intensification indicators was used to assess the stressors and/or condition of the watersheds, tidal marsh habitat patches, and tidal drainage systems to which the selected 1-m2 plots belonged. Since the core stations were randomly selected, the associated drainage systems, patches, and watersheds were also randomly selected. This nested approach allowed for statistical assessment of intertidal conditions at three spatial scales: core stations, drainage systems that contain the core stations, and habitat patches that contain the drainage systems. The nested approach also facilitated an assessment of watershed-level stressors that act on these scales.

Illustration of the nested sampling design to sample core indicators in a 1-m2 plot within a marsh drainage system, drainage systems within a habitat patch, and habitat patches within a local watershed.
Table 1. List of core and intensification indicators used in the EMAP 2002 pilot in estuarine intertidal wetlands.


EMAP findings had significant meaning in the context of coastal zone planning and restoration. This project enabled examination of patterns in intertidal habitat fragmentation using regional rule sets to define alternative patch types, barriers between patches, and inter-patch distance. Results indicated that as watersheds fill with people, the number of intertidal stressors increases and the integrity of the plant community decreases, regardless of salinity regime.

Small patches of habitat represent an important component of these inter-tidal ecosystems. Since Euro-American contact, though, the intertidal ecosystem has become more fragmented for most endemic wildlife species of highest concern to managers. The EMAP study found that this fragmentation is due to a decreased number of patches and increased patch isolation, rather than a change in the relative abundance of large patches.

Some of the indicators and sampling approaches tested in the EMAP Pilot were applied in other segments of the larger estuarine Integrated Wetlands Regional Assessment Program (IWRAP). For example, the probabilistic sampling method piloted in the EMAP study, was recommended as a means of sampling for a number of the estuarine indicators used in IWRAP.


This project was conducted in collaboration with the San Francisco Estuary Institute, Moss Landing Marine Laboratory, University of San Francisco, San Francisco State University, and US EPA Office of Research and Development Newport Laboratory (Oregon).

For more information on EMAP 2002 Estuarine Wetland Assessment, contact Martha Sutula at (714) 755-3222.
This page was last updated on: 6/30/2014