OCTOBER 8, 2011
Ivanhoe Reservoir, Los Angeles
Photograph by Gerd Ludwig, National Geographic
This Month in Photo of the Day: Photos From New National Geographic Books
In 2007, high levels of bromate—a carcinogen formed when bromide and chlorine react with sunlight—were found in Los Angeles’s Ivanhoe Reservoir. Today three million black plastic balls help deflect UV rays.
(From the upcoming National Geographic book Visions of Earth)