Executive Summary 
An assessment of the condition of the intertidal, soft sediment habitat of the 
states of Washington, Oregon, and California was successfully conducted during the 
summer of 2002. The assessment survey was conducted under the EPA National 
Coastal Assessment Program (NCA), in partnership with Washington Department of 
Ecology, Oregon Department of Environmental Quality, and the Southern California 
Coastal Water Research Project (SCCWRP), with additional contributions from 
personnel of Moss Landing Marine Laboratories and the San Francisco Estuary 
Institute. 
A major impetus for conducting the intertidal assessment is the fact that on the 
West Coast, the large tidal amplitude experienced over much of the region means that a 
large proportion of total estuarine area is intertidal. Methods and indicators for 
assessment of condition in the NCA program were primarily developed for sampling of 
subtidal habitats within estuaries of the Atlantic and Gulf coasts. The western regional 
component of the NCA therefore needed to develop a variety of modified methods and 
additional indicators to be able to assess condition in the extensive estuarine intertidal 
zones prevalent in West Coast estuaries. Additional emphasis was placed on site 
characterization metrics that included the occurrence of macroalgal beds/mats, 
submerged aquatic vegetation (SAV) or emergent vegetation, the presence of 
burrowing shrimp, the occurrence of marine debris, and obvious evidence of disruptive 
anthropogenic activities (e.g., dredging or landfill activity). Measurements of sediment 
nutrients (total N, total P) were added as potential indicators of site eutrophication 
where water column samples could not be taken. Where plants (seagrass, marsh 
plants, macroalgae) were encountered, percent cover and biomass estimates to lowest 
feasible taxonomic level were obtained. For rooted plants, maximum plant height was 
measured. Categorization of shoreline land use adjacent to sample sites was included 
as a potential indicator of land use stressors on the intertidal sites. 
Data were successfully collected from a total of 217 out of 223 targeted sites in 
the intertidal zone of the three west coast states, with the exception of the estuarine 
zone of the Columbia River, which had been extensively sampled in previous NCA 
assessments. The definition of intertidal zone for the west-wide sampling included all 
intertidal area except that classified by the National Wetlands Inventory as hard 
substrate, high marsh, diked, or artificial substrate. The study utilized a stratified 
random sampling design, with sampling effort partitioned among states (Washington - 
68, Oregon - 65, California - 90), and among regions within a state. Washington sites 
were divided among Puget Sound (25), Willapa Bay (30), and the remaining estuaries 
(13). Oregon sites were divided between Coos Bay (30) and the remaining estuaries 
(35). The California sites were divided among pilot study areas in Southern California 
(30), San Francisco Bay (30), and the remaining estuaries (30). 
The San Francisco Bay pilot study differed from the remainder of the study by 
dividing sampling effort approximately equally between three habitat types, tide flats, 
low marsh, and high marsh (excluded elsewhere). For both the San Francisco and 
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