As global freshwater reserves dry up, desalination plants are receiving greater attention as an option for providing both drinking water supplies and agricultural irrigation. But a new study released on Thursday raises several concerns about the environmental impact and cost effectiveness of the widely touted technology to convert seawater to fresh water. Desalination plants pose a risk to marine species when the water is collected from ocean areas, as well as when the salty discharge is deposited into coastal estuaries, according to the report, which was released by the U.S. National Research Council (NRC).