Directive 2006/113/EC on the Quality Required of Shellfish Waters, also referred to as the Shellfish Waters Directive (SWD) requires the monitoring of, inter alia, certain physicochemical parameters including trace metal contaminants in order to assess and protect the quality of shellfish growing waters and the shellfish harvested from them. The SWD is concerned with the quality of shellfish waters and applied waters designated by the Member States as needing protection or improvement in order to support shellfish (bivalve and gastropod molluscs) life and growth and thus to contribute to the high quality of shellfish products directly edible by man. This report details the Marine Institute’s (MI) monitoring results for physicochemical parameters sampled in seawater and shellfish tissue from designated Shellfish Waters and specifically: Dissolved trace metal concentrations and other physiochemical parameters in seawater sampled from Irish Shellfish Waters in 2016 and trace metal and organohalogen concentrations in shellfish sampled in 2015.