<p>The European Water Directives (WDs, 2000/60/EC; 2006/118/EC) force Member States to proceed to the characterization of groundwater bodies in order to define their quantitative and chemical status and their environmental objectives. Since the earlier years of this century, the Department of Water Resources Management of the Apulia Region implemented the WDs by setting a wide groundwater monitoring network, delineating regional groundwater bodies and characterizing their status. The groundwater bodies characterization showed that the risk of not achieving a good status was generally related to salt contamination and the exceedance of the threshold values or the quality standards for some parameters (e.g., NO<sub>3</sub>, Fe, Mn), as expected for regions with a predominantly agricultural vocation and characterized by extensive coastal development. The main regional aquifers reside in the carbonate bedrock characterized by intense fracturing and karstification.</p><p>The groundwater Directive 2006/118/EC allows the evaluation of Natural Background Levels (NBLs) to be taken into account when establishing the relevant threshold values.</p><p>During the last years, the IRSA-CNR collaborated with the National Environmental Protection Agency (ISPRA) in defining scientifically based guidelines for the NBLs assessment and clarifying some methodological aspects. These guidelines suggest excluding water samples characterised by high levels of specific markers clearly indicating anthropogenic inputs.</p><p>The project "VIOLA - Natural background levels for the groundwater bodies of Apulia Region ", has been funded by the Department of Water Resources Management of the Apulia Region for carrying out the application and validation of the above mentioned methodologies and to develop and test methodologies better tailored for coastal aquifers. In particular, isotopic techniques will be used to discriminate between the anthropogenic and natural origin of the salinization and historical data of groundwater salinization will be processed in order to study its evolution in time. . Finally, the investigation of innovative microbiological techniques is envisaged to evaluate how changes in groundwater quality will affect the resident microbial community properties involved in C-flux.</p><p>The VIOLA project will last three years during which the IRSA-CNR will:</p><ul><li>collect and order all the background knowledge relating to the hydro-geo-chemical characteristics of the Apulian groundwater bodies,</li>
<li>define adequate groundwater sampling procedures and assessment protocols for the NBLs,</li>
<li>carry out field activities, aimed at sampling groundwater at a specific monitoring network and measuring values of main physico-chemical and microbiological parameters, in the study area of the coastal Murgia groundwater body, and</li>
<li>produce tools to support the planning and management of groundwater resources integrated in a GIS environment.</li>
</ul><p>This contribution aims at providing an overview at the ongoing activities at the regional scale, illustrating the groundwater bodies setting, the main pressures and the preliminary derivation of NBL using the historical data.</p>
eNaBLe, an On-Line Tool to Evaluate Natural Background Levels in Groundwater Bodies
