400 000 black balls at the bottom...

Hundreds of thousands of black balls fell to the bottom of the basin Ivanhoe, which is located in Los Angeles.This was done because of the danger of water for human life.The combination of sunlight and chlorine bromidom As a result, particles that can cause cancer with the use of water.The color balls specifically black - to beat the sun's rays.I wonder whether in such a way to protect water and life.