The North Western Sahara Aquifer System (NWSAS) is a very large aquifer system extending on a 1 million Km2 surface, under the national territories of Algeria, Libya and Tunisia. Due to the lack of fresh surface water availability in these desert and semi-arid regions, its importance is today strategic for the above mentioned countries economic and social development, As a consequence of it, in the last decades, its exploitation has increased exponentially, causing serious hydrogeological problems and worries for the future. Supported by the scientific community, many national and international organizations, the Observatoire du Sahara Sud (OSS) above all, have recently raised the debate on the compatibility between the Algeria, Tunisia and Libya withdraws and the very little groundwater resource renewal rate. The apparent, but difficult, upcoming solution is a shared management of the whole aquifer system by the three involved countries. In this context, some results of a hydrogeological study carried on the tunisian NWSAS region are presented, focused on the actual exploitation state of the art definition and to estimate the different withdrawal scenarios consequences at medium-long period on the aquifer system at local and regional scale.