Cleantech
LA Has Found a Creative, Low-Cost Way to Conserve 300M Gallons of Water a Year

In a creative attempt to protect California’s waning water supply, Los Angeles mayor Eric Garcetti yesterday announced the release of 20,000 “shade balls” into the LA Reservoir. The deployment marks the final phase of a program to safeguard the 175-acre, 3.3 billion gallon reservoir by releasing 96 million of the balls onto its surface.

The Los Angeles Department of Water and Power (LADWP) is managing the dispersal of the shade balls. It will be the first utility company to use this technology for water quality protection, highlighting the city’s leadership in addressing sustainability challenges.

According to the LADWP website, the shade balls are made of high-density polyethylene (HDPE), the same material as one-gallon milk cartons, and are approved for contact with drinking water by the National Science Foundation. The carbon black is an added layer of UV protection from the sun that does not emit or leach any chemicals; to have used other colors would have required dyes, which would eventually leach into the water. The shade balls do eventually lose structural integrity and may split in half or fail at the seams after 10 years at which point they will be removed and fully recycled.

LADWP had previously looked at the effect of the shade balls on temperature both on the water and the local climate, and we found no effect in either case. The shade balls don't warm up the water or the air in any perceptible way; rather, they provide a 4-inch layer of thermal protection that keeps the water cool.

The shade balls are touted as a cost-effective investment for the city that will save $250 million compared to other reservoir conservation methods. Costing just $0.36 each, the shade balls require no construction, parts, labor or maintenance aside from occasional rotation.

“As the drought continues, it has never been more important to focus on innovative ways to maintain the highest-quality drinking water for our 4 million residents,” councilmember Mitchell Englander said at the announcement event Monday. “In addition to cutting back on the need to chemically treat our water to prevent natural occurrences like algae, these shade balls are a cost-effective way to reduce evaporation each year by nearly 300 million gallons, enough to provide drinking water for 8,100 people for a full year.”

Mayor Garcetti commended the LADWP’s effort to innovative and implement water conservation tools as the state’s drought intensifies. “In the midst of California’s historic drought, it takes bold ingenuity to maximize my goals for water conservation,” he said. “This effort by LADWP is emblematic of the kind of the creative thinking we need to meet those challenges. Together, we’ve led the charge to cut our city’s water usage by 13 percent, and today we complete an infrastructure investment that saves our ratepayers millions and protects a vital source of drinking water for years to come."

The idea to use shade balls as a method of water quality protection came from retired LADWP biologist Dr. Brian White. He says he was inspired by the application of “bird balls” in ponds along airfield runways. Since White’s innovation in 2008, the LADWP has employed shade balls on open-air reservoirs to block sunlight, prevent chemical reactions and curtail algae blooms.

“Shade balls are a great example of how engineering meets common sense,” Marcie Edwards, LADWP General Manager, said. “Our water system has significantly changed since William Mulholland built it more than 100 years ago. As we make updates, we are mindful to be wise and practical with our investments. Shade balls are an affordable and effective way to comply with regulations, and helps us continue to deliver the best drinking water to our customers.”

LADWP’s use of shade balls adds to the growing number of creative solutions being developed to mitigate California’s devastating, multi-year drought. Scientists are exploring genetically engineered drought-resistant plants, companies such as Nexus eWater are developing household water recyclers, and technology startups are partnering with big brands to more efficiently manage their water use.