Lake Mono at sunset. This lake in California, USA, is an important habitat for species of bird. In the mid-20th century the lake's tributaries were diverted to support the growth of Los Angeles. This led to a significant drop in the lake's water level, exposing nesting sites to predation. It also exposed the previously submerged tufa formations seen at centre. Since the mid-1990s a campaign to protect the lake has resulted in an increase in its water level.