Save. Jupiterimages/Photos.com/Getty Images. It's easy to mistake lichens as the cause of tree or branch death because they tend to grow on sick trees. In fact, the reason they turn up is because a sick tree has a thin canopy and lets in the sun that makes lichens grow.ave. Jupiterimages/Photos.com/Getty Images. It's easy to mistake lichens as the cause of tree or branch death because they tend to grow on sick trees. In fact, the reason they turn up is because a sick tree has a thin canopy and lets in the sun that makes lichens grow.
4 Hoover Dam. Hoover Dam is one of the world's great engineering marvels. This massive structure, completed in 1935, crosses the Colorado River, linking Arizona and Nevada. It is 726 feet high and 1,244 feet long. Lake Mead, held back by the Hoover Dam, is the largest artificial lake in the United States. It is 110 miles long, and holds the equivalent of two years of flow of the Colorado River.
The before images were taken when the lake level was 1,111 feet above sea level. Lake Mead hasnât been officially fullâ1,221 feet above sea levelâsince 1983. The massive intake towers on the Hoover Dam in Lake Mead straddle the Nevada/Arizona border, in this 2007/2014 before-and-after. Should the current drought continue, the Hoover Dam could lose the ability to generate electricity. Image: Ethan Miller/Getty Images. Thanks to an ongoing mega-drought, Lake Meadâs water level will continue to fall for the indefinite future.