2. Description of Study Area 
2.1 Physical Characteristics of the Estuary 
Yaquina Estuary is a small, drowned, river valley estuary located along the central 
Oregon coast (latitude = 44.62°N, longitude = 124.02° W) of the United States (Figure 2.1) with 
an estuarine surface area of 19 km and a watershed area of 650 km (Figure 2.2; Lee et al., 
2006). Approximately 48% of the estuarine area is intertidal. This estuary experiences mixed 
semidiurnal tides and is mesotidal with a mean tidal range of approximately 1.9 m and a tidal 
prism volume of 2.4 x 10 m (Shirzad et al., 1988). Yaquina Estuary has jetties that extend into 
the Pacific to the 10-m depth contour. Due to the small volume of the estuary (25 x 10 m at 
Mean Lower Low Water (MLLW)) and the strong tidal forcing, there is close coupling between 
the estuary and the coastal ocean. Approximately 70% of the volume of the estuary is exchanged 
with the coastal ocean during each tidal cycle (Karentz and Mclntire, 1977). 
(Zone 1) and “riverine dominated” (Zone 2) segments (Lee et al., 2006) based on the 
relative proportion of oceanic-derived nutrients versus terrestrially-derived nutrients. 
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