19-08-2015 15:00

California is in its fourth year of a catastrophic drought, so it tries to save as much water as possible.

People released thousands of black balls into a water reservoir in Los Angeles. These balls cost 36 cents each and they float on the surface of water. They protect the water from heat, stop aquatic plants from growing, and keep birds away.

The balls work for 20 years and they will save 1.1 million cubic metres of water every year.

Difficult words: catastrophic (terrible), drought (when it rarely rains), reservoir (a lake used as a water supply), float (to stay on the surface of water).

You can read the original story and watch the video in the Level 3 section.