The socio-ecological system of the Jujuy Model Forest territory is analyzed within the framework of conceptual models, constructed using the participatory method PARDI (Problem, Actors, Resources, Dynamics, Interactions). Two principal models focus on water quality and availability in two areas: an upstream Catchment zone and a downstream Irrigation zone. Socio-ecological dynamics there are linked to diverse processes: social (population increase, immigration and urbanization), ecological (state of the upper basin and land use downstream) and economic (development models, prices and market fluctuations). Four complementary sub-models account for: pollution, erosion, sedimentation and deforestation, highlighting the central role of these processes for water quality and availability in the future. In the Catchment zone, water is first of all affected by the state of its sources (Rio Grande and Perico rivers, rainfall). The demand for drinking water to supply the municipalities and agricultural activities in the downstream zone put pressure on its availability. The water from the catchment basins also plays a central role in fishing, tourism, agriculture and livestock activities located nearby. In the Irrigation zone, water serves two main uses: as drinking (domestic) water for residents and as irrigation water, mainly in tobacco and sugarcane production. In both areas, water quality is decreasing because of pollution, classified as either solid (garbage), biological (sewage, animal waste) or chemical (agricultural inputs and industrial chemicals). In the long term, current dynamics can have strong impacts on public health, the desirability of the area for tourism and its economy. Local responses include: improvements to the efficiency of the irrigation system and other hydro-infrastructure, environmental awareness, and alternative development models adapted to a sustainable management. With a view to future planning, we identify decision rules that modify local actors’ practices in the context of climate change.