On the one hand, if water bottlenecks are well managed and the change of resource availability is well anticipated, all the options available to limit the effect of water scarcity will be implemented in a cost effective way. In that case, the cost of adjusting to the bottleneck is quite low for the electricity system. On the other hand, if disruptions in the electric sector cannot be avoided, they can be very costly. Therefore one needs to take into account the cost of investments to hedge energy systems against the risk of disruption, for instance by providing more back-up generation capacity.