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.
On Lake Mead, the white line is where the water used to be. CBS News. Lake Mead was created by the Hoover Dam in 1935. It provides water for 20 million people in southern Nevada, southern California and Arizona. Since 2000, the lake has lost 4 trillion gallons of water.ithout Lake Mead, there would be no Las Vegas.. Pat Mulroy of the Southern Nevada Water Authority. CBS News. All of us are in it together, and all of us are either going to survive this or all of us are going to feel the consequences, Mulroy said.