Freshwater has spatial and temporal constraints, affecting possibilities to generate electricity. Previous studies approached this from a water perspective quantifying water consumption of electricity to optimize water use, or from an electricity perspective using modeling methods to optimize electricity output. However, power plants consume different water volumes per unit of electricity, depending on the applied technology, and supply systems often include a mix of different technologies with a different water footprint (WF), an indicator of water consumption, per unit of electricity. When water availability varies in time, probably the contribution of different electricity generating technologies also varies in time, resulting in WF fluctuations. Focusing on electricity generation from the water perspective, we assessed how water availability affects an electricity mix's dynamics and its blue WF using Ecuador as a case study. We studied the Amazon and Pacific basins, which have different temporal and spatial water availability fluctuations, assessing monthly water availability, electricity production, and blue WFs per plant. The Amazon basin has smaller temporal and spatial availability fluctuations than the Pacific. The difference between the largest and smallest water availability in the Amazon basin is two-fold, in the Pacific four-fold. Hydropower generation in the Amazon basin contributes more than 60\% to the electricity mix. However, hydropower is directly affected by water availability, and its production decreases in water-limited periods. For biomass plants, limited water availability affects the fuel source, sugarcane bagasse. As water availability decreases, other technologies in the mix take over, causing WF variation (from 4.8 to 8.6 10(3) m(3) per month). Usually, less water-availability means more water-efficiency, implying fossil-fueled plants in the Pacific take over from hydropower in the Amazon. It is relevant to assess the water-electricity nexus in countries with electricity mixes dominated by hydropower because energy planning needs to consider water availability and electricity mix dynamics. (C) 2019 Elsevier B.V. All rights reserved.