Videos and Fact Sheets

Background

The element bromide occurs naturally in drinking water sources. Bromide can be converted to bromate in water treated with ozone. Water treated at the Los Angeles Aqueduct Filtration Plant (LAAFP) is routinely analyzed for bromate because our source waters are known to contain bromide and ozone is used in our treatment process. Bromide is not regulated. However, the U.S. Environmental Protection Agency (US EPA) has set a limit for bromate in drinking water at 10 micrograms/Liter (µg/L). One µg/L is the equivalent of 1 part per billion (ppb). One ppb is the equivalent of one pint in 120 million gallons of water. LAAFP effluent averages less than 5.0 µg/L bromate.

After water is treated at the LAAFP, a secondary disinfectant is required to ensure the safety of the treated water as it travels through the distribution system; reservoirs, tanks, pipelines, and ultimately to your tap. Three chemicals are approved by the US EPA as secondary disinfectants; chlorine, chlorine dioxide, and chloramine. Prior to our 2014 system-wide conversion to chloramine, chlorine was used as our secondary disinfectant.

Before 2009, six of our distribution reservoirs remained uncovered or “open-air” reservoirs. Our uncovered reservoirs contained chlorinated water and were often treated with additional chlorine, but not ozone, to control algae.

In 2007, elevated levels of bromate were detected at three uncovered reservoirs; Elysian, Ivanhoe, and Silver Lake. The bromate levels at these reservoirs were higher than the levels detected in LAAFP effluent and exceeded the limit set by US EPA. Water sent to the three reservoirs typically includes treated groundwater blended with surface water from the LAAFP. Groundwater is known to contain bromide as well; however, because ozone is not used to treat the groundwater, bromate formation was never expected.

Investigation

An investigation was launched to determine how the bromide in the groundwater was being converted to bromate in the absence of ozone. In the interim, operational measures were taken to minimize bromate formation. This required limiting groundwater as a source to the reservoirs, as well as continual monitoring for bromate.

It was suspected that sunlight might be a factor in bromate formation. In our experiments, bottles containing reservoir water (which had bromide and chlorine) were suspended at different depths in Silver Lake Reservoir (an open reservoir). Water in the bottles were then analyzed for bromate. Testing showed that samples closer to the water surface, with more sunlight exposure, formed more bromate. The results also showed that bromate formation did not occur when light transmission was reduced by 80-85%. Sunny and cloudy day in-reservoir sample results were also compared; bromate formation on cloudy days was 15-20% that of sunny days. The conclusion; water with bromide and chlorine formed bromate in the presence of sunlight.

Solution

The solution was clear; shade the reservoirs from sunlight. Unfortunately, design and construction of reservoir covers would take years. A faster alternative was needed because one of our major sources of water; groundwater, was not being fully utilized and bromate levels had to be brought under control.

Shade balls, also known as “bird balls” because they are used to keep birds away from bodies of water near airports runways, were explored as a potential alternative.

The shade balls had to cover the water surface sufficiently to block enough sunlight and they also had to be suitable for use in drinking water. The shade balls that fit the requirements are 4 inches in diameter, made of high density polyethylene plastic, and approved for use in drinking water by the National Sanitation Foundation (NSF) International Standard 61. NSF is an independent, accredited, health and safety organization. Although, other colors were considered, black was chosen because the color was shown to be less susceptible to degradation by ultra-violet radiation (sunlight). Water in contact with the shade balls has consistently tested safe for all uses.

The shade balls have been very effective in reducing light exposure; they block 95% of the sunlight, and prevent bromate formation.

More Shade Ball Benefits

Shade balls now cover our four remaining open reservoirs – Elysian, Ivanhoe, Upper Stone Canyon, and Los Angeles. Silver Lake was removed from service in 2013. Along with being the solution for bromate formation, shade balls have been beneficial in helping us comply with the Stage 2 Disinfectants and Disinfection Byproducts (DBP) Rule. The Stage 2 DBP Rule sets limits on the amount of disinfectant used and requires a reduction in system-wide levels of disinfection byproducts in drinking water. Shade balls help by drastically reducing the amount of chlorine previously used for algae control (algae needs sunlight to grow), resulting in substantial savings in treatment costs and lower levels of disinfection byproducts system-wide.

Shade balls also serve as an interim solution for the Long Term Enhanced Surface Water Treatment (LT2) Rule, while we cover, replace, or provide additional treatment for water in these remaining open reservoirs. Additionally, shade balls have proven to be a great water conservation tool, by drastically reducing evaporation. In fact, at Los Angeles Reservoir alone, we are saving more than 300 million gallons of water annually. Shade balls are a definite win-win for our customers.

For more information on Stage 2 DBP Rule & LT2, please go to Regulations.

For more information on our open reservoirs, please go to Projects and Initiatives.

Frequently Asked Questions

What is the primary purpose of deploying shade balls on the surface of L.A.'s reservoirs?
The small, black plastic balls protect water quality by preventing sunlight-triggered chemical reactions. A cost-effective investment that helps bring the Los Angeles Reservoir into compliance with federal water quality mandates, the shade balls are expected to save $250 million when compared to the number and magnitude of alternate projects and solutions considered to meet that goal. Those alternatives included splitting the reservoir into two with a bisecting dam; and installing two floating covers that would have cost more than $300 million. On the contrary, each shade ball was placed at a cost of 36 cents, making the total cost of the Los Angeles Aqueduct project approximately $34.5 million. The shade balls will also prevent the annual loss to evaporation of about 300 million gallons of water.

Is it safe for shade balls to be in contact with drinking water?
The plastic used to make shade balls is food grade and brings no known issues for health and safety. As a matter of fact, the same plastic is used for water pipes worldwide. The shade ball material and production process have been certified by the National Sanitation Foundation (NSF) International. The balls comply with federal standards and are considered safe to be in contact with drinking water.

When did LADWP first initiate this strategy?
Dr. Brian White, a now-retired LADWP biologist, was the first person to think of using shade balls for water quality. The idea came to him when he learned about the application of “bird balls” in ponds along airfield runways. The innovative, in-house solution has been used in the 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%.

Has this proven effective at other reservoirs? 
The shade balls have effectively controlled the formation of sun-triggered algae and bromates in all deployed reservoirs along with the added benefits of avoided chemical and tactical operational costs. Shade balls were placed on Ivanhoe Reservoir in September 2008, Elysian Reservoir in February 2009 and Upper Stone Canyon Reservoir in April 2012.

Of what materials are the shade balls constructed?
Shade balls are made of high density polyethylene (HDPE) resin with a black colorant that inhibits ultra-violet light degradation. All shade balls have a 4-inch outer diameter. The balls used on the Los Angeles Reservoir weigh 40 grams and are filled with 200 grams of drinking water to give them weight so they are not blown away by wind gusts, as the reservoir is located in a high gust area. Shade balls in place at other Los Angeles Reservoirs - Elysian, Ivanhoe and Upper Stone Canyon - are hollow and not filled with water.

Why are the balls black? Wouldn't lighter colors be better at deflecting heat? 
The balls are black because they have "carbon black" in them as a UV stabilizing agent, which gives them their lifespan. Other colors such as white were considered, but not selected because they contained dyes that could leach into the water. A blue shade that is food grade and not a potential contaminant was considered. However, the manufacturers were not sure the balls would last longer than a year in the sun. The black balls have proven to survive outdoors and are approved for drinking water contact. According to the NSF International, which tested and certified the balls for contact with drinking water, the carbon black does indeed make the plastic more thermally, structurally, and chemically stable and resistant to UV degradation.

Doesn't this exacerbate the heat island effect and/or create a bacteria breeding ground? 
We have found no significant or abnormal heat effects on the water. It is our observation that although the top surface of the shade balls absorb heat, the heat is not well conducted (plastic is a poor conductor of energy) down to the water surface and the air. Rather, the shade balls act as a 4-inch insulation blanket since the 98 million balls cover the surface of the Los Angeles Reservoir. The reservoir itself, a deep pool of relatively cool water, it helps keep itself thermally stable at the surface.

Were balls made in other colors considered?
Yes. LADWP worked with the manufacturers to consider other colors including blue. However, the lack of UV stabilizers and inhibitors in the color resins that were tested did not hold up well to sunlight and the balls would have degraded within one to five years. Other colors would not totally block UV light and would have required dyes, which do leach into the water. The carbon black does not emit or leach any chemicals.

The balls containing the carbon black blocked out sunlight more effectively and resisted degradation longer. The black shade balls had also been certified to be safe to be in contact with drinking water by NSF International.

Are the balls made of recycled content?
No.  Only new high density polyethylene is used.  The balls are completely recyclable.

Are the balls recyclable? What is the City's plan to dispose of/recycle the balls after use?
Yes.  Ideas for reuse or repurposing will be considered before sending them off for recycling once they are no longer needed.

Will the sun and heat degrade the shade balls into micro-plastics that will end up in drinking water?
Since initiating this method in 2008, the LADWP has seen no evidence that shade balls have degraded into "micro-plastics.” Reservoir water is sampled extensively throughout the system and no plastic pieces or chemical leaching from the shade balls have been detected. 

Will the plastic leach endocrine disruptors or cause bacterial contamination in L.A.'s drinking water?
LADWP tests for over 100 compounds and has found no levels of concern among results. Testing began before the shade balls were delivered with certification leach testing by the NSF International to meet its rigorous NSF Standard-61 requirements for any materials in contact with drinking water. This testing has continued with our own regular quarterly testing of the reservoir and distribution water for bacteria and chemical compounds since 2008. If continued testing indicates a problem in the future, the LADWP will be able to detect it and respond immediately. 

LADWP’s daily water quality monitoring and maintenance operations have found neither abnormal thermal effects nor bacterial breeding in the reservoirs as a result of the use of shade balls. To address concerns about possible bacterial reactions, the LADWP implements disinfectants of the water after filtration, and again after it leaves the reservoir. Our water quality monitoring is vigorous and we constantly track for any abnormalities.

The plastic is food grade and brings no known issues for health and safety. As a matter of fact, the LADWP uses the same plastic for water pipes, and they too, are authorized for safe usage by the appropriate nationally recognized authorities. Furthermore, the LADWP has tested the water for this type of plastic for the following endocrine disruptor compounds and chemicals, and none were detected:  

• Alachlor
• Atrazine
• Benzo(a)pyrene
• Benzylbutylphthalate
• Biocide
• Bisphenol-A
• Cadmium
• Chloroform
• Di(2-ethylhexyl)adipate
• Di(2-ethylhexyl)phthalate
• Dibromochloropropane(DBCP)
• Dibromomethane
• Diethylphthalate
• Dimethylphthalate
• Di-n-butylphthalate
• Di-n-octylphthalate
• Disinfection Byproducts [byproducts are present but not due to plastic]
• Fire/Flame retardants
• Gasoline additives
• Heavy Metals
• Mercury
• Molinate
• Organic solvents
• Organics in plastic production
• Organics in production of dyes
• Organics in PVC production
• Pentachlorophenol
• Pesticides
• Phenol
• Refrigerant
• Simazine
• Thiobencarb

What type of water quality issues do shade balls protect against?
Due to the drought, the City is relying on greater quantities of water from the California Aqueduct, which is high in bromide, particularly in dry years. The problem is that a chemical reaction can occur when chlorinated water containing high levels of bromide is exposed to sunlight, creating bromate, a suspected carcinogen. Bromate is a regulated drinking water contaminant that is a known disinfection byproduct of ozonation treatment, but its formation in open bodies of water was not expected. The shade balls significantly reduce sunlight exposure, preventing that chemical reaction and protecting our water supply from contamination.

Uncovered reservoirs, like Los Angeles Reservoir are prone to algae formation due to sunlight exposure, which requires chlorine for treatment. The algae break down over time, turning into organic matter that reacts with chlorine to form disinfection byproducts (DBP) that must be minimized under water quality regulations set by the US EPA and the State Water Resources Control Board, Division of Drinking Water (DDW). The goal at these reservoirs is to reduce sunlight exposure in order to reduce algae and chlorine use and thereby reducing the formation of DBPs.

How do shade balls reduce the amount of chlorine used in treating water?
Chlorine is used to treat algae growth. The use of shade balls greatly reduces the amount of algae growth in reservoirs due to blocked sunlight exposure, thereby reducing the daily chlorine requirement at the Los Angeles Reservoir which have resulted in a savings of nearly $28,000 a month, given current costs of chlorine. More importantly, the reduction in the amount of chlorine deliveries has resulted in improved safety conditions for employees and nearby residents.

What type of governmental water quality regulations do the shade balls fulfill?
For Los Angeles Reservoir, shade balls in concert with UV treatment and operational modifications to the water distribution system will allow the LADWP to comply with state and federal water quality regulations from the State Water Resources Control Board, Division of Drinking Water (DDW) and the US Environmental Protection Agency (US EPA). These regulations include the Safe Drinking Water Act (SDWA) and the US EPA’s Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBP Rule).

Is the LADWP the first to use shade balls?
No. Plastic balls have been around for many decades and have had a variety of applications in other fields. Most notably they have been used at or near airports to minimize bird strikes and in the mining industry to control evaporative water loss. However, the LADWP is the first utility to use shade balls to mitigate water quality issues in drinking water.

What is the life span of the shade balls?
The balls have a service life of at least 10 years. The shade balls will eventually lose structural integrity and may split in half or fail at the seams after a decade at which point they will be removed and fully recycled. 

Will the balls allow a location for additional bacteria to grow and enter the water supply?
LADWP provides disinfection of the water before and again after it leaves the reservoir. Our water quality monitoring is vigorous and we constantly test the water at each step of the treatment process and during distribution for abnormalities. Today, L.A.’s drinking water consistently meets or is better than all drinking water standards for water quality. 

Do shade balls help conserve water that would otherwise be lost to evaporation? If so, how much?
Shade balls contribute to reducing the effects of evaporation by reducing the water surface area exposed to the sun, and by reducing the flow of wind above the water surface. It is estimated that up to 90% of water that would be lost due to evaporation could be saved when the reservoir is fully covered with shade balls.

What else is the LADWP doing to conserve water?
The City of Los Angeles is a leader in water conservation efforts. Over the past 40 years, Los Angeles’ per capita water usage has remained flat – despite a population increase of over 1 million people.

This year alone, Los Angeles has led the charge and already cut our city’s water usage by 13%. Thanks to an executive directive from Mayor Garcetti, the LADWP is on track to make further reductions to usage that will allow us to reduce purchased water imports by 50% by 2025.

Why are the balls water-filled?
Shade balls at the Los Angeles Reservoir are partially water-filled to weigh them down to counteract the force of the winds that tends to push aside the shade balls and expose the surface to sunlight.

Are the shade balls permanent?
At Elysian, Ivanhoe and Upper Stone Canyon Reservoirs, the shade balls are temporary. At Ivanhoe, the shade balls will be removed when Headworks Reservoir East is complete and fully operational. Shade balls on Elysian and Upper Stone Canyon Reservoirs will be removed as floating covers are installed. At Los Angeles Reservoir, the shade ball solution is permanent. They will be removed, recycled and replaced every 10 years.

How many balls are needed at the Los Angeles Reservoir?
Three million air-filled balls were deployed at both Ivanhoe and Elysian Reservoirs. At Upper Stone Canyon, 6.4 million air-filled balls were deployed. At Los Angeles Reservoir, 96 million water-filled balls were deployed.

Did the LADWP consider alternatives to shade balls in Los Angeles Reservoir?
Shade balls were an alternative to the original solution planned at Los Angeles Reservoir to meet federal water quality requirements. The original plan was a multi-faceted solution that included splitting the existing reservoir in two by building a division dam, constructing new inlet and outlet works, and installing two of the world’s largest floating covers over each half. LADWP also would have had to construct a new reservoir to handle the operational needs while the Los Angeles Reservoir was out of service. This project would have been a major undertaking and very expensive. Early estimates of such a project were at least $300 million.

In conjunction with the shade ball effort, the LADWP will build a second, $100 million ultra-violet treatment facility to further treat Los Angeles Reservoir water, allowing the Department to meet its regulatory timeline for compliance with the Long Term 2 Enhanced Surface Water Treatment Rules, save more than $250 million in capital improvement costs, and reduce water losses.

What company fabricates the shade balls?
Two vendors provided shade balls for the Los Angeles Reservoir. The primary vendor was Artisan Screen Printing, a small minority-owned blow-molding business based in Azusa. They provided 89.6 million balls. The second vendor was XavierC, a small woman-owned broker out of Glendora providing balls manufactured by Microdyne Plastics out of Colton. They provided 6.4 million balls.