Thirty sampling stations were surveyed each season during the period 2013-2015 in the objective to determine the water quality in the coastal areas between Saidia and Cala Iris. The CPA Analysis shows 5 groups associated following the water quality of 12 components. Only the sites close to the agglomerations bordering the lagoon of Nador and Al Hoceima show high values of BOD5, Nitrites and PO4. This deterioration of the water quality observed in some coastal sites explains in large part their low richness of the biodiversity of the algae