From the 2019 NACD Summer Conservation Forum and Tour. Learn about how the Roosevelt Soil and Water Conservation District is using an innovative product to address water evaporation from stock tanks in New Mexico's semiarid climate. From the 2019 NACD Summer Conservation Forum and Tour. Learn about how the Roosevelt Soil and Water Conservation District is using an innovative product to address water evaporation from stock tanks in New Mexico's semiarid climate. By Anqi Zhang July 19, 2019 As you may know or not, the Los Angeles Department of Water and Power (LADWP) deployed around 400,000 balls in the Ivanhoe reservoir since 2008 for the environmental reasons. Later in 2015, 96 million shade balls were dumped into the Los Angeles Reservoir to improve water quality and save water. (See picture above- Image credit: AP/Damian Dovarganes). Shade balls are small plastic spheres made of high-density polyethylene (HDPE) with carbon black additive floated on top of a reservoir for environmental reasons. They are about 4 inches (10 cm) in diameter, and are partially filled with water to avoid being blown by wind. The main objectives of dumping the shade balls into reservoir is preventing the formation of a carcinogenic chemical, bromate, which forms when naturally occurring bromine reacts with chlorine in the presence of sunlight. Other environmental benefits include slow evaporation, prevent algae growth and prevent birds from landing on bodies of water. According to the Los Angeles Department of Water and Power (LADWP), shade balls could keep contaminants out of the water and reduce the evaporation of the reservoir by 85 to 90 percent during a drought. However, there is a debate saying that even though the balls saved 1.7 million cubic metres of water from evaporating during their deployment from August 2015 to March 2017, they required 2.9 million cubic metres of water in their manufacture. In other words, the amount of water needed to produce the shade balls appears to be greater than the amount of water saved by preventing evaporation. On the economic side, the LA Weekly report criticized that the savings of shade balls do not match the cost.(Maddaus 2015)1 More specifically, it takes $34.5 million to manufacture the shade balls, but save only $2 million per year. What’s more, the shade balls need to be replaced every ten years. That’s $20 million of water savings for every $34.5 million of balls. Therefore, it is of great importance to understand the whole life cycle of the shade balls before dumping them into the open reservoir to save our water. Instead, learning from the mistake, quick technological solutions to water management, such as shade balls, need integrated sustainability analyses to reduce the environmental and economic risks. Bản dịchVí dụ về đơn ngữThe colour varies from shades of brown, grey and green. The fragrant flowers are white or shades of purple. Her choice of color, shades of white and black, evoke a range of associations. At that time, the common belief was that only chorus girls, actresses and other women of ill-repute altered their natural shade. Rope dyeing is considered the best yarn-dyeing method, as it eliminates shading across the fabric width. The trick when using these correctors is to blend the shades into the skin with a buffing foundation or concealer brush. More fifty shades of greys, than grey to be honest. For his fifth collection, he has focused on shades of deep and olive greens. If one is writing in these dark times then shades of the ongoing turbulence does creep in... more than creep in. A double casement window on the west has horizontal folding shades.
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California's water problem is severe. Despite 2016 seeing a distinct improvement in precipitation over previous years, to almost average levels in many areas, much of the state is in extreme drought. As well as ordering mandatory water reductions, the state has also been looking to other solutions. "Shade balls," the 4-inch wide black plastic balls pictured above blanketing Los Angeles Reservoir, have been touted as one of those solutions. But they're not. The primary purpose of the release, which went viral last year, was to obey Federal rules on covering drinking water. The Los Angeles Department of Water and Power (LADWP) had previously used the balls in smaller reservoirs, and in the case of the Los Angeles Reservoir, says the balls helped the department save more than $250 million over installing a more permanent cover. Although they were released to headlines like Shade Balls in Los Angeles Reservoir to Save 300 Million Gallons of Water Annually, the main benefit of the balls is to prevent sunlight from reacting with the chlorine-treated water and naturally occurring bromide to create the possible carcinogen bromate. The shade balls aren't a complete solution, and there are accusations that they may deteriorate and release dangerous chemicals into the water. The water in the Los Angeles Reservoir, however, goes through a UV treatment process before it makes its way to citizens. So why the headlines? Well, the shade balls also discourage algae growth and, as a side-benefit, prevent evaporation to an extent. But the "300 million gallons saved" claim represents less than a day's water use for the LADWP. According to LA Weekly, 300 million gallons of water was worth around $2 million at the time the balls were deployed, or roughly $32 million less than the cost of the balls themselves. Evaporation reduction is a fringe benefit, then, and tying the shade balls to drought (which the LADWP absolutely did with its press release) wasn't the brightest idea. According to the LADWP, though, shade balls have been a successful alternative to the extensive construction work required to install a cover. They'll remain in place at Los Angeles Reservoir, but they've been, or are being, removed from all the other reservoirs under LADWP's jurisdiction. One such site was scheduled for closure, while the others will get permanent floating covers. Whether this decision was taken for financial reasons, or because those sites lack the Los Angeles Reservoir's backup UV treatment process, is unclear. Despite their lack of drought-busting guile, shade balls nonetheless make for a fantastic photo opportunity, and have inspired some fascinating stories. Silica Magazine's cover story on the subject is recommended reading, while National Geographic photographer Gerd Ludwig has a photo series that's simply stunning. As for California's water issues, there's always cloud seeding, although that comes with its own conspiracy theories. The Big Picture is a recurring feature highlighting beautiful images that tell big stories. We explore topics as large as our planet, or as small as a single life, as affected by or seen through the lens of technology. All products recommended by Engadget are selected by our editorial team, independent of our parent company. Some of our stories include affiliate links. If you buy something through one of these links, we may earn an affiliate commission. All prices are correct at the time of publishing. |
