美抗旱奇招：水库投"遮阳球"

The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality.
为了保护水质，洛杉矶市向露天水库投放了9600万个“遮阳球”，这些球浮在水面上，水库表面已被遮盖。目前该项目已全部完成。

City officials this week dumped the last 20,000 of 96 million black balls into the Los Angeles Reservoir in Sylmar, 25 miles northwest of downtown. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir.
本周，洛杉矶市官员将最后2万个黑色塑料球投放到洛杉矶水库，该水库位于西尔马，距离洛杉矶市中心西北部25英里。这些塑料球直径为4英寸，覆盖了水库175英亩（约71公顷）的水面，使其避免太阳光照射。

That prevents chemical reactions that can cause algae blooms and other problems, allowing the Department of Water and Power (DWP) to meet U.S. Environmental Protection Agency water-quality requirements.
这也可以避免发生化学反应，而化学反应可能导致水藻滋生等其它问题。此举使得洛杉矶水电局达到美国国家环境保护局的水质标准。

They have the added perk of aiding with the ravages of the drought, and are expected to keep about 300 million gallons annually from evaporating.
此举已经缓解了干旱所带来的破坏，预计每年可以减少3亿加仑的蒸发量。

"In the midst of California's historic drought, it takes bold ingenuity to maximize my goals for water conservation," Mayor Eric Garcetti said in a statement, noting that the effort is "emblematic of the kind of the creative thinking we need to meet those challenges."
洛杉矶市长埃里克•贾西提在一次声明中说道：“面对加州史上少有的干旱，我们需要有相当大胆的创造力来帮助我们最大化地实现节水，”市长还强调，此举“体现出我们迎接挑战所需要的创造性思维”。

The 36-cent balls also will help prevent evaporation of 300 million gallons of water annually from the 3.3 billion-gallon reservoir, the DWP said.
水电局工作人员称，洛杉矶水库的储水量为33亿加仑，每个遮阳球的成本为36美分，每年可帮助该水库减少3亿加仑的蒸发量。

The city began using shade balls in 2008.
洛杉矶市自2008年开始使用遮阳球。

Vocabulary
algae: 水藻
perk: 额外津贴
evaporate: 蒸发
emblematic: 象征