Contaminants in water, sediment, and biota from the Bill Williams River National Wildlife Refuge, Arizona

Abstract

One hundred sixty two composite samples were analyzed for organochlorine compound residues and 19 trace elements and heavy metals. There was no evidence that flushing of washes in times of flood increases contaminant levels in the Bill Williams River, or that historical mining operations currently contributed to the element load. There was evidence that Colorado River water increased selenium levels in biota in the delta; one hundred percent of fish collected from the confluence of the Bill Williams River and the Colorado River contained elevated selenium concentration (geometric mean = 9.98, range 2.80-17.56 μg/g dry weight). These levels exceed standards set for the protection of predatory species of fish and wildlife.