Department of Water and Power workers are emptyingout bales of plastic balls in the Ivanhoe reservoir in Los Angeles onMonday, June 9, 2008. Department of Water and Power released about400,000 black plastic 4-inch balls as the first installment ofapproximately 3 million to form a floating cover over 7 acres of thereservoir to protect the water from sunlight. When sunlight mixes withthe bromide and chlorine in Ivanhoe's water, the carcinogen bromate canform. (Irfan Khan/AP) #