Today we left the Guanacaste province and spent most of the day traveling southeast to Montéverde. On the way we stopped at the Planta Hidroeléectrica De Arenal. We had a guided tour of the facility and learned about the process of generating hydroelectric power. The facility we toured is the first of three dams in series from Lake Arenal. They produce 160Mw, 180Mw, and 32Mw respectively. Enough energy to power over 600,000 homes, roughly 30-40% of the entire energy demand of Costa Rica! (According to Wikipedia and a 2011 census there are about 1,300,000 homes in Costa Rica). The first and second dams operate via gravity and the gradient of the hillside, while the third operates by pressure from volume in a reservoir, which is why it only produces 32 megawatts. The second station has the steepest slope and produces the most power. Water is diverted from Lake Arenal at 110 cubic meters per-second and flows through three turbines connected to three generators. This plant came online in 1979 and the turbines must be replaced every thirty years. Maintenance is required annually, but has not occurred for two years due to energy priorities. Our tour guide stated that the water is potable throughout the entire system and that there is no significant temperature increase after generation. However I am somewhat skeptical about the later statement. Additionally there were some major externalities of this operation. Most significantly, two entire villages/small towns had to be relocated for the implementation of the artificial Lake Arenal reservoir. Also a large portion of water was diverted away from the San Juan River to the North. The ICE power company had to compensate each citizen of the towns by buying them an equivalent area of land and providing their power at no cost. Lake Arenal is fed by water that originated in the high mountains of the continental divide, which includes the Children’s Eternal Rainforest private biological reserve. The reservation not only protects the wildlife and ecosystem, it also protects the hydrologic cycle that inevitably powers the country, an extremely important relationship between humans, nature and society.