In northwestern Mexico, where rainfall is scarce and aquifers cannot keep up with demand, desalination has become a central part of the water strategy. Baja California, Baja California Sur and Sonora already operate or are building plants that turn seawater into fresh water. However, the technology faces questions about its cost, its energy consumption and its impact on fragile ecosystems such as the Gulf of California. … The greatest environmental risk is brine. Most processes generate about 1.5 liters of brine for every liter of drinking water, which can raise the salinity, temperature and turbidity of seawater and damage seagrass beds, reefs and seafloor communities. Water intakes can also trap plankton, fish eggs and larvae. The risk is greater in the northern Gulf of California, which UNESCO added to its List of World Heritage in Danger in 2009.