Netarts Bay
Netarts Bay is an estuarine bay on the northern Oregon Coast of the U.S. state of Oregon, located about 5 miles (8.0 km) southwest of Tillamook. The unincorporated community of Netarts is located on the north end of the bay and Netarts Bay Shellfish Preserve, managed by Oregon Department of Fish and Wildlife, is located on the south side of the bay. The sand spit on the west side of Netarts bay is part of Cape Lookout State Park.
The bay is approximately 5 by 1.5 miles (8.0 by 2.4 km) and totals 2,325 acres (9.41 km2) in area, making it Oregon's seventh largest bay. Of that, 812 acres (3.29 km2) are permanently submerged—the balance of 1,513 acres (6.12 km2) is intertidal land. It experiences a maximum tidal range of 9 feet (3 m).
The bay is part of a watershed of 13 square miles (34 km2) that is fed by at least 16 small creeks. From north to south, there is Fall Creek, Hodgdon Creek, O'Hara Creek, Rice Creek, two unnamed creeks, Yager Creek, three unnamed creeks, Whiskey Creek, an unnamed creek, Austin Creek, two unnamed creeks, and Jackson Creek.
Like other estuaries along the Oregon Coast, Netarts Bay experiences semi-diurnal tides (two high tides and two low tides per day). At mean low low water (the lower low tide), the bay contains approximately 113 million cubic ft of water. Contrasting that with that a mean higher high tide volume of approximately 450 million cubic feet, the bay's tidal prism is about 33 million cubic feet. The tidal range varies between 1.5 and 3 meters(5 – 9 feet), which can vary the amount of water (40–90%) flushed out of the estuary during each tidal cycle. With a mean tidal period of 745 minutes, bay waters turn over, on average, twice a day. Mixing within the estuary is dependent on local winds and tides. Horizontal mixing is limited, although vertical mixing is strong. Little to no vertical variations in temperature and salinity prevent density-driven current velocities, indicating that Netarts Bay is a well-mixed estuary. This has been further corroborated by water quality and dye studies.
Rates of sedimentation average to the bay average nearly 2500 tons annually. An observed 10% decrease in mean high water volume between 1957 and 1969 in conjunction with high sedimentation rates suggests that the bay is gradually filling with sediment over time. LIDAR data have shown the strong erosional response of the Netarts Littoral Cell (a 14-km long stretch of beach tucked between the neighboring Cape Meares and Cape Lookout Headlands) to ENSO (El Niño Southern Oscillation) forcing. During strong El Niño events (e.g. 1997–98), as much as 70,000 cubic meters of sand can be transported. Waves propagating from the southwest erode the southern portion of the spit and transport sediment northward, resulting in northward movement of the bay inlet. This erosion-deposition pattern is amplified by rip currents that create erosional "hot spots" along the spit. Cape Lookout State Park, situated within one of these hotspots, is subject to this intense erosional forcing.
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