This updates the original report by correcting some errors and adding new information. This assessment of the 300 Area was completed to identify any contamination present and determine if it could present a risk to humans and plant and aniimal life. The assessment characterized the radiological and chemical conditions existing in the near-shore environment of the Columbia River at the 300 Area by collecting water, biota, and sediment samples and measuring radiation levels during a time when the effects of riverbank spring discharges and groundwater upwelling into the river was likely to be present.