The chemical status of a coastal water body (coastal water or transition water) is determined by the most declassing of the defined states for heavy metals, pesticides, industrial pollutants and other pollutants taken into account by the WFD . The assessment is done once per management plan (once every six years). The most recent assessment of the state of the chemical state is presented in the DCE Loire-Bretagne atlas. Earlier reports are available in annual archives.

The analysis concerns the assessment of the overall state of the coastal and transitional waters of the Western Channel and the Bay of Biscay. It results from the combination of the ecological status and the chemical status of each water body according to the rules of the European Water Framework Directive (WFD). The most recent assessment of the state is presented in the DCE Loire-Bretagne atlas. Earlier reports are available in annual archives.

The analysis focuses on monitoring the ecological status of the coastal and transitional waters of the Western Channel and the Bay of Biscay. The ecological status of a coastal water body within the meaning of the European Water Framework Directive (WFD) is determined by the biological state, physicochemical state and hydromorphological state of the water mass, water. The statement is determined according to the rules described in the decree of 25 January 2010.