The substrate type varied widely and included salt marsh, oysters, and sand and 
mud flats (Fig. 3.1.2.). Percentage of area within the West Coast intertidal region 
sampled was statistically estimated for 9 habitat categories. The dominant types of 
estuarine intertidal habitat varied among the three states. Unvegetated tide flats, 
classified either as sand or mud flats, were the dominant habitat types for all three 
states, for San Francisco Bay, and for the west as a whole (Fig. 3.1.2.). Higher 
percentages of mud flats were recorded in California and San Francisco Bay versus 
Washington and Oregon, which possessed higher percentages of sand flats. Shellfish 
beds (oysters), gravel bottom, and intertidal seagrasses were recorded only in 
Washington and Oregon. The non-native marsh grass Spartina alterniflora was 
recorded in Washington in Willapa Bay, where efforts to eradicate the species are 
currently underway. 
Bank 
I I Gravel 
V////A High marsh 
l l Marsh 
SAV 
Tidal flat-Spartina 
I I Shellfish 
Z///A Tidal flat-mud 
k yyn Tidal flat-sand 
Figure 3.1.2. Percentage area of habitat types for the 2002 West Coast Intertidal 
Assessment. Values for California do not include San Francisco Bay. 
14 
