what is its nutrient cycle?
Both natural and anthropogenic processes are involved in the cycling of nutrients in it.
Columbia River
Both natural and anthropogenic processes are involved in the cycling of nutrients in the Columbia River basin. 
what is hanford site? A decommissioned nuclear production complex. where is it located? On the Columbia River in Benton County. where is this river's course? It flows northwest and then south into the US state of Washington. what are the dams of this river? Grand Coulee Dam.
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Columbia River [SEP] Nutrient cycle
Both natural and anthropogenic processes are involved in the cycling of nutrients in the Columbia River basin. Natural processes in the system include estuarine mixing of fresh and ocean waters, and climate variability patterns such as the Pacific Decadal Oscillation and the El Nino Southern Oscillation (both climatic cycles that affect the amount of regional snowpack and river discharge). Natural sources of nutrients in the Columbia River include weathering, leaf litter, salmon carcasses, runoff from its tributaries, and ocean estuary exchange. Major anthropogenic impacts to nutrients in the basin are due to fertilizers from agriculture, sewage systems, logging, and the construction of dams.