Low-tech offers an elegant solution to water loss and environmental threats
In a drought that seems to have no immediate end in sight, one California municipal water agency literally rolled out a unique solution to protect the valuable commodity in its water storage facilities.
Thousands of black plastic “shade balls,” released Monday, Aug. 10, by the Los Angeles Department of Water and Power (LADWP), are the only things that stand between the water in Sylmar, Calif.'s Van Norman Reservoir and damaging environmental exposures.
Nearly 20,000 four-inch orbs made up the final installment to the 175-acre Los Angeles reservoir, bringing the total number of the polyethylene units to 96 million.
The relatively low-tech solution serves as a sort of “bulletproof vest,” defending the waters below from the constant evaporative barrage of the sun’s ultraviolet rays, as well as other factors, like harmful algae blooms.
“In the midst of California’s historic drought, it takes bold ingenuity to maximize my goals for water conservation,” said Mayor Eric Garcetti in a press release. “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."
While the solution may not be the most technologically advanced in form, its function is expected save an estimated 300 million gallons of water and $250 million each year, according to the municipal agency.
The almost elegant fix to an ongoing problem cost the utility provider around $34.5 million. At 36 cents per orb, the balls were a substantial investment -- but a far cry from a $300 million plan to bisect the reservoir and install floating covers.
“That option would have also required operational adjustments and an additional $100 million reservoir to ensure reliable water service,” said Assistant General Manager Marty Adams.
Several other reservoirs have been treated with the shade balls since 2008. The Van Norman facility serves around 2,700 Southern California homes.
According to Adams, the high-density polyethylene (HDPE) balls are made of the same material used to produce one-gallon milk containers.
“They do not emit or leach any chemicals, but eventually do lose structural integrity and may split in half or fail at the seams," Adams said. "We have previously looked at the effect of the shade balls on temperature both of the water and of the local climate. What we found was there is not effect in either case. It doesn’t warm up the water or the air in any perceptible way."
The agency became the first in California to employ the fix and attributes it largely to retired LADWP biologist Dr. Brian White, who is credited with developing the in-house solution -- and got the idea from the bird deterrents in ponds near airports.
“The idea came to him when he learned about the application of ‘bird balls’ in ponds along airfield runways," Adams said. "The innovative, in-house solution has been used in LADWP’s open-air reservoirs since 2008 to block sunlight, prevent chemical reactions and curtail algae blooms. Currently in place at Upper Stone, Elysian and Ivanhoe reservoirs, the shade balls come with the added benefit of reducing evaporation off the reservoir surfaces by 85 to 90 percent."