France was amazed to learn of the death of an opponent to the construction of a dam in the forest of Sivens, Tarn (France), during clashes with the police on the night of 25 to 26 October 2014. Such an accident is all exceptional. However, the violence of the means deployed to realize this construction and the determination of opponents, woven in the game of all the actors of this project, foreshadowed the possibility of such a dramatic event. Using the SocLab environment for modeling and simulation of organized action systems, we present a model of this actors’ interplay whose simulation results highlight the overdetermined nature of the emergence of an extremely intensive conflict (Model 1). Variations of this model enable to identify main determinants of this conflict, notably the position of the State, and to consider other possible futures: The existence of alternatives to the extreme conflict (Model 2) and its avoidance (Model 3).