Modeling nitrate transport in watersheds using travel time distributions Nitrogen-based fertilizers, used in intensive agriculture, and farming are the main causes of nitrate pollution of surface water. Nitrate excess is transported from lands to streams and lakes, leading to eutrophication, and thus to the depletion of water quality and ecosystems. At European level, increasing attention has recently been paid to this issue, as evidenced by the enactment of Nitrate Directive 91/676/EEC in 1991, with the aim of identifying the most endangered areas and implement the necessary countermeasures. Within this framework, new tools are needed, to understand and predict the fate of anthropogenic nitrate released on lands.