climateadaptation:

This is a picture of crews working for The Department of Water Protection in Los Angeles, CA pouring 3 million black plastic balls into the Ivanhoe Reservoir on June 10th, 2008. Scientists discovered that when sunlight is combined with the bromides and chlorine that are present in the water, a carcinogen bromate is formed which can be harmful to humans. The Department of Water Protection realized the problem and began construction of a new covered reservoir, but while a new underground facility was being built, they had to determine a way to keep the sunlight out of the water. They explored the possibility of tarps and metal coverings but they were either too expensive or very ugly. They settled on the idea of bird balls which are designed to keep water fowl from landing where they shouldn’t. They are non toxic, and only cost about 34 cents each. The total cost of protecting the Ivanhoe reservoir as well as the Elysian reservoir that was facing the same problem was 2 million dollars. The balls were estimated to remain in the water for five years until the new reservoir is completed.

Via: Supertight