Water quality assessment using satellite-derived chlorophyll-a within the European directives, in the southeastern Bay of Biscay

► Implementation of European Directives requires an intensification of water quality monitoring. ► We aimed to assess the ecological status of Basque coastal water bodies using satellite imagery. ► Sea surface satellite-derived chl-a algorithms were compared against in situ measurements. ► The OC5 algorithm corresponded most accurately with in situ measurements performed in the area. ► A chlorophyll-a map was created with this algorithm to apply the classification scheme.