10/2 it was closed again and reopened 10/29, only to be closed 12/4. Closed 9/10, it was reopened again on 9/26. Of importance is the number of times Wyckoff Shoal has been closed and reopened over the past 10 weeks. The challenges of timing and testing are easily seen in tracts closed, opened and closed again. Seen above are two of the currently active subtidal tracts in south Puget Sound which are currently closed - Wyckoff Shoal and Fox Island South. Note: For a more current study on sediments and current concerns over increasing "non-point" pollution problems from urban runoff, read " Historical Inputs and Natural Recovery Rates for Heavy Metals and Organic Biomarkers in Puget Sound during the 20th Century". But it is an example of what lies below the surface. Because Manila clams do not burrow as deeply as geoduck it is currently believed these Dioxins will remain in the deeper sediments. However, testing is typically within the upper few centimeters, not deeper where past industrial activities may have resulted in higher discharges than currently taking place and where things may have settled, to be buried over time. In addition to the Arsenic found in the 1997 report to NOAA is what was found in the deeper sediments of Oakland Bay near Shelton. Currently producing the largest amount of Manila clams in the United States, the deeper sediments were found to contain elevated levels of Dioxins. The Department of Ecology generally oversees sediment testing. Who tests the sediments and how deeply are they tested? Oakland Bay's lesson But they did not go away, leaving the highest concentrations remaining in depths of 30 to 50 centimeters, or 1 to 2 feet undisturbed. Rainfall only hastened the deposits. As seen in the graphs above, over time sedimentation buried those deposits. From there the prevailing winds carried the discharge plume north over Puget Sound where the chemicals and metals gradually settled out of the air into the waters of Puget Sound and onto the adjacent lands where they sometimes remained, other times washed into the various bodies of water, both fresh and marine. Since 1997 NOAA has been aware of elevated levels of Arsenic in Puget Sound's sediments, concentrated highest in those sediments north of the old ASARCO plant in Tacoma. Operating for almost 100 years, the once largest smokestack in the United States discharged arsenic, lead, and a variety of other chemicals into the air. Elevated levels of Arsenic in Puget Sound sediments is old news to NOAA
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