Water is not a commercial product like all others but a heritage that must be protected and treated appropriatelyThe implementation of the European Water Framework Directive 200060EC WFD or as internationally stated WFD is a necessary condition for the sustainable management of water resources in the country Monitoring the quality of all surface waters ensures the correct early assessment of the problems of water resources to take clearly defined management measuresAccording to the WFD for each type of water body in Europe the undisturbed structure and function of aquatic biocommunities are described as type-specific or reference conditions Depending on the deviation of each water body from these conditions its ecological status is classified as high good moderately deficient or bad The WFD set the target in 2015 for all water bodies of the European Union to have good ecological status In each Member State the determination of water bodies is the basis of the application of the WFD as in each water body sampling points are defined that are defined. The Hellenic Centre for Marine Research (HCMR) implemented Phase A and Phase B of the Monitoring of the Ecological Quality of river coastal and transitional waters in Greece 20122015 and 20182023 The monitoring network provided for in this project was formed on the basis of the network of Phase B Monitoring and taking into account the changes resulting from this, changes in the number of monitoring frequency and location stations.