This component of the resource and ecological assessment of Panguil Bay is conducted for a ten-month period (February -December 1991). It aims to determine the extent of pesticide contamination in Panguil Bay and to identify the tributaries that serve as waterways of pesticide residues. Water samples, sediment samples and bivalve samples are tested only for the presence of organophosphate and organochlorine insecticides using methods prescribed by the US Environmental Protection Agency.