On Monday afternoon, the 20,000 black plastic balls tumbled down the slopes of Los Angeles Reservoir, joining 95,980,000 of their brethren already covering the surface of the water.
The final deployment of these shade balls was the last step in a $34.5 million water quality protection project aimed at preventing evaporation and algae growth in the reservoir.
On Monday afternoon, the 20,000 black plastic balls tumbled down the slopes of Los Angeles Reservoir, joining 95,980,000 of their brethren already covering the surface of the water.
The final deployment of these shade balls was the last step in a $34.5 million water quality protection project aimed at preventing evaporation and algae growth in the reservoir.
The EPA mandates that all reservoirs be covered, but because tarps can be expensive and metal coverings can take too long to install, shade balls — at least in Los Angeles — are becoming a preferred method.
According to a 2008 Los Angeles Times article, the LA Department of Water and Power used the plastic shade balls in 2008 to cover the Ivanhoe Reservoir. In that case, the balls were installed not to block evaporation and algae but to prevent a harmful chemical reaction from taking place in the water.
"The water needs to be shaded because when sunlight mixes with the bromide and chlorine in Ivanhoe's water, the carcinogen bromate forms, said Pankaj Parekh, DWP's director for water quality compliance. Bromide is naturally present in groundwater and chlorine is used to kill bacteria, he said, but sunlight is the final ingredient in the potentially harmful mix."
Photo credit: www.microdyneplastics.com
Read more at NPR.
