Aquatic Disposal Field Investigations Columbia River Disposal Site, Oregon. Evaluative Summary.
Final rept. Aug 74-Jun 76,
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
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A multidisciplinary study was conducted offshore of the mouth of the Columbia River to characterize the baseline physical, chemical, and biological aspects of the nearshore zone and to investigate the effects of open-water disposal on the study area. Physical data analyzed during the study indicate that dredged material deposited in the nearshore zone off the mouth of the Columbia River maintains its identity relative to surrounding sediments for periods of years and that such material migrates towards the north at a rate of approximately 0.6 kilo-metre per year. Chemical data suggest that the release of dredged material at the experimental disposal area has no measurable effect on either ambient water quality or quality of the sediments. Dredged material removed from the Columbia River entrance channel can be characterized as fine to medium sand with insignificant levels of pollutants. Bottom sediments examined from the tidal delta in the region of disposal site B consistently showed higher levels of nutrients and metals than sediments from adjacent sampling sites. Biological studies indicate that the disposal of dredged material had a measurable effect on both the benthic macroinvertebrates and the demersal finfish at the experimental disposal area.
- Water Pollution and Control