Spatial-temporal changes in the physico-chemical characteristics of the Agura river (Basque Country and Cantabrian region, Spain) were studied over six months, a period that included a long period of unusual drought and the return to more normal hydrological conditions. The chemical composition of the water was affected by water flow. It was influenced either directly through the drainage characteristics at the level of different parts of the surrounding basin, or indirectly through the action of biotic communities on their environment. From these results, some spatial and/or temporal models have been developed for the dynamics of the different variables in this study.