The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality.
為了保護(hù)水質(zhì)，洛杉磯市向露天水庫投放了9600萬個“遮陽球”，這些球浮在水面上，水庫表面已被遮蓋。目前該項目已全部完成。

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，洛杉磯市官員將最后2萬個黑色塑料球投放到洛杉磯水庫，該水庫位于西爾馬，距離洛杉磯市中心西北部25英里。這些塑料球直徑為4英寸，覆蓋了水庫175英畝（約71公頃）的水面，使其避免太陽光照射。

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.
這也可以避免發(fā)生化學(xué)反應(yīng)，而化學(xué)反應(yīng)可能導(dǎo)致水藻滋生等其它問題。此舉使得洛杉磯水電局達(dá)到美國國家環(huán)境保護(hù)局的水質(zhì)標(biāo)準(zhǔn)。

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.
此舉已經(jīng)緩解了干旱所帶來的破壞，預(yù)計每年可以減少3億加侖的蒸發(fā)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."
洛杉磯市長埃里克?賈西提在一次聲明中說道：“面對加州史上少有的干旱，我們需要有相當(dāng)大膽的創(chuàng)造力來幫助我們最大化地實現(xiàn)節(jié)水，”市長還強調(diào)，此舉“體現(xiàn)出我們迎接挑戰(zhàn)所需要的創(chuàng)造性思維”。

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.
水電局工作人員稱，洛杉磯水庫的儲水量為33億加侖，每個遮陽球的成本為36美分，每年可幫助該水庫減少3億加侖的蒸發(fā)量。

The city began using shade balls in 2008.
洛杉磯市自2008年開始使用遮陽球。

Vocabulary
algae: 水藻
perk: 額外津貼
evaporate: 蒸發(fā)
emblematic: 象征

英文來源：美聯(lián)社
譯者：實習(xí)生馮佳佳
審校&編輯：許晶晶