LA’s Shade Balls: The ecological costs of plastics in water

black balls hitting the water

From @rrosewarne Twitter feed.

The media has widely reported on the 20,000 black plastic balls tumbling down the slopes of Los Angeles Reservoir last week. Covering a body of water with black plastic balls (aka. “Shade Balls”) when people have been warned against throwing plastic into waterways has sparked a number of questions. Even though there are metal covers for standing water, the city opted for much cheaper plastic. What are the ramifications of this choice for ecological and human health? Luckily, we have a plastics expert at Discard Studies. Dr. Max Liboiron has been studying marine plastics and their chemicals for 8 years. Most of what we know about how plastics behave in water are from studying marine plastic pollution, but the concepts are the same regardless of the body of water and the intent behind the plastic:

  1. Plastics leach chemicals into water. Plastics are polymers. Polymers have long, strong molecular bonds that keep plastics from biodegrading, and are what make plastics strong and flexible. But if you want your plastic to be UV resistant, black, extra flexible, or give it other properties, you add monomers. Monomers are made of shorter molecular chains, and they aren’t chemically bonded to the polymers. Which means they leach and offgas. You’ll see this in everyday plastics; as they get old and lose mononers, they also lose color and get brittle. While the exact composition of the HDPE used in the Shade Balls hasn’t been released, HDPE is a fairly safe plastic. Except we know there are chemicals in the balls that are for UV resistance. Those will leach. The black additive is carbon black, which isn’t supposed to be harmful when it leaches, which is great. Yet even with this precaution, most plastics leach endocrine disrupting chemicals that interfere with animal and human hormone systems (Yang 2011). Some endocrine disruptors, like bisphenol A (BPA), break down in water after a few weeks or months. Some don’t. We don’t know what chemicals are in the Shade Balls, but they will leach, especially because the balls are in the hot sun and are meant to be left in the water over a long period (reports say 10 years). Most water treatment systems don’t take these kinds of chemicals out of the water.
  2. Plastics fragment in the environment. Most plastics found in the marine environment start out as larger objects you would easily recognize, like plastic bags and toothbrushes. Or balls. Over time, they fragment into tiny microplastics. 92% of the 5.25 trillion plastic pieces floating on the surface of oceans (Eriksen 2014) are smaller than a grain of rice because plastics don’t decay into their constituent molecules like organic substances. Instead, they fragment into smaller and smaller bits.

    Plastic fragments found in the North Atlantic. Photo by Annie McBride. 2015.

    Plastic fragments found in the North Atlantic. Photo by Annie McBride. 2015.

  3. Plastic fragments are ingested by marine life.The problem with micoplastics is that the are ingested by a wide variety of marine life. Some are so small they can be eaten by plankton or circulate in the blood of mussels (Browne 2008). Plastics can cause choking, but the bigger concern is that plastics are a way that chemicals move into animal tissues and food chains.
  4. Plastics are magnets for chemicals. Plastics can absorb more than a million times more chemicals than the surrounding water, making them very toxic (Mato 2001). If you’ve ever done dishes after eating leftover spaghetti or curry, you know that orange color that’s so hard to scrub off plastic Tupperware. That is an example of how oily substances are attracted to plastics. Absorbed chemicals include DDT, flame retardants, and other persistent organic pollutants (POPs) (Rochman 2012, Teuten 2009). Scientists nickname ocean plastics “poison pills” because when an animal eats the plastic, the chemicals move into its body as well. These chemicals also become more concentrated as they move up the food chain (biomagnification).
  5. Plastics provide habitat for microbes and other forms of life. Scientists have found that plastics support unique ecosystems, from microbes to fish. They call this the “plastisphere” (Zettler 2013). So while the Shade Balls might block sunlight that encourages algae growth, they are simultaneously providing habitat for other life, including but not limited to algae.
  6. Plastics escape infrastructure. Scientists and governments first became concerned about marine plastics in the 1990s. At the time, they thought that people were dumping garbage straight into the ocean and on beaches. In fact, most marine plastics come from land (Browne 2011). Plastics are very light and durable and they fly, flow, and are carried into new environments all the time. Those Shade Balls will go places they aren’t meant to go, and will continue to leach chemicals, fragment, and be ingested in new environments.
  7. The scale of the problem and the scale of the solution are mismatched. The 300 million gallons of water a year that the shade balls are supposed to capture that would otherwise evaporate is actually a small number when compared to the amount of water being used at industrial scales.* For example, the Washington Post crunched the numbers and argues that if California agriculture increased its water efficiency by only 5%, they would save 500 billion gallons of water in a few months. Fracking uses 2.14 million gallons of fresh water every day. One of the most common problems in environmental solutionism is trying to solve massive problems with tiny solutions. This is one of those cases.
  8. Technological fixes for systemic problems usually lead to more problems. To be fair, California is screwed. There is no water in a populous state. And it’s not going to get better soon. They have to come up with solutions, and fast. Will the shade balls keep 300 million gallons of water from evaporating? Yes. Is the short term gain worth the long term costs? This is the question. Grand technological gestures in the face of massive systemic problems like perpetual drought makes it feel as though action is possible. It’s doing something. But short term technological fixes for long term systemic problems usually lead to their own problematic ripple effects. These are called “wicked problems” and they account for most large scale environmental and urban planning problems. It’s like the woman who swallowed the fly. There are a lot of environmental costs to the Shade Ball fix for relatively little gain, even though little gains might matter in California right now. Yet, as suggested in the point above, there are other solutions that scale better. If we are going to deal with California’s continuing drought, with climate change, with ocean plastics, and the other types of complex, large scale problems characteristic of the 21st century, we need to step away from technical fixes and focus on larger systemic approaches that incorporate the bigger players, like industry.

This post is based on a basic literature review of the state of the art of science on marine plastics. If you’re still curious about how plastics behave in water environments, there is a great new open access book, Marine Anthropogenic Litter, that is written by scientists but readable by a public audience that covers the science in greater detail.

*Update 8/19/15: Though LA City Hall told media and public audiences that the Shade Balls were meant to avoid evaporation, increasingly officials have said that the balls are about stopping the creation of bromate, which is formed when naturally occurring amounts of bromide interact with human-injected chlorine under naturally occurring UV radiation. Even with this different intent for the Shade Balls, the science of plastics in water doesn’t change, and the ecological costs are the same.

There are also reports of how the Shade Balls are NSF approved, food safe, and have safer types of additives (carbon black instead of chemical dyes, for example). And it’s quite true that they have done the best possible job they can given that they are dumping plastics in water. However, both NSF (a third party certifier) and the designation of “food safe” allows for levels of endocrine disrupting compounds. For example, the NSF allows for the daily ingestion of 0.05 mg of the endocrine disruptor bisphenol A (BPA) per kg of body weight. The bottom line is that even if you try to control for the escaping monomers (which is difficult because the exact composition of plastics are proprietary, meaning that even the Shade Ball’s manufacturer’s might not know all the additives in the HDPE), you still have the polymer problem (fragmentation, escape, ingestion, etc), not to mention the scale problem. We can debate the exact nature of the excellent bandaid we’ve put on gangrene, but at the end of the day it’s still a bandaid on gangrene.


Bergmann, M., Gutow, L., & Klages, M. (2015). Marine Anthropogenic Litter. Springer. This open-access text is the most comprehensive collection on marine plastics.

Browne, M. A., Dissanayake, A., Galloway, T. S., Lowe, D. M., & Thompson, R. C. (2008). Ingested microscopic plastic translocates to the circulatory system of the mussel, Mytilus edulis (L.). Environmental science & technology, 42(13), 5026-5031.

Browne, M., Crump, P., Niven, S., Teuten, E., Tonklin, A., Galloway, T., Thompson, R. (2011). Accumulation of Microplastic on Shorelines Worldwide: Sources and Sinks, Environ. Sci. Technol., 45 (21), pp 9175–9179

Eriksen M., et al. (2014). Plastic pollution in the world’s oceans: More than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PloS ONE 9(12).

Kang, J. H., Aasi, D., & Katayama, Y. (2007). Bisphenol A in the aquatic environment and its endocrine-disruptive effects on aquatic organisms. Critical reviews in toxicology, 37(7), 607-625.

Mato, Y., Isobe, T., Takada, H., Kanehiro, H., Ohtake, C., Kaminuma, T., (2001).Plastic resin pellets as a transport medium for toxic chemicals in the marine environment. Environmental Science and Technology 35, 318–324.

Rochman, C. M., Hoh, E., Kurobe, T., & Teh, S. J. (2013). Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress. Scientific reports, 3.

Teuten E, Saquing J, Knappe D, Barlaz M, Jonsson S, et al. (2009). Transport and release of chemicals from plastics to the environment and to wildlife. Philos Trans R Soc Lond B Biol Sci 364: 2027-2045.

Yang, C. Z., Yaniger, S. I., Jordan, V., Klein, D. J., & Bittner, G. D. (2011). Most plastic products release estrogenic chemicals: a potential health problem that can be solved. Environmental Health Perspectives, 119(7), 989-996.

Zettler, E., Mincer, T., Amaral-Zettler, L., (2013). Life in the “Plastisphere”: Microbial communities on plastic marine debris. Environmental Science and Technology 47, 7137-7146.

Dr. Max Liboiron is an Assistant Professor of culture and technology at the Memorial University of Newfoundland. Liboiron’s dissertation, Redefining Pollution: Plastics in the Wild looks at how the science of pollution around plastics is changing the face of science and activism. Liboiron now directs the Civic Laboratory for Environmental Action Research (CLEAR), which creates citizen science tools for environmental monitoring in extreme environments with a specialization in marine plastics.  

19 thoughts on “LA’s Shade Balls: The ecological costs of plastics in water

  1. So, this makes it sound like a no-brainer to instead use water more efficiently. Is this a case of political will and short term thinking? I mean, like, what the hell? Don’t any of these decision-makers have children?

    • There is already a mandatory reduction in consumer water use that’s saved millions of gallons of water. That was the low hanging fruit. Looks like the fruit is getting higher, and asking industry to reduce is still more political friction than solutions that operationalize known environmental harm.

  2. Excellent survey, thank you! I will be following your blog, and including this post at my next report for Extinction Radio, Dispatch From The Endocene.

  3. Perhaps the biggest problem with using low grade PVC is much of it is coming from plants that use a chloralkali process to produce the chlorine need to make PVC. Chloralkali is a mercury cell process, PVC can be loaded with residual mercury. China uses almost 1000 metric tons of mercury a year in making pvc.

    • Thanks for your comment. The shade balls are HDPE, not PVC. You’re right; PVC is one of the worst plastics out there, all the way along its lifecycle. HDPE is better than PVC in terms of what it leaches, but plastics are still plastics. They’ve done a good job of using the least worst materials they can (in terms of plastic, that is). We can talk all day about the materials and quality of the bandaid we’ve put on gangrene, but at the end of the day, it’s still a bandaid on gangrene.

  4. Very well-done review of the key issues! I have sent it far and wide.

  5. From what I’ve read it has nothing to do with evaporation or water conservation. The shade balls may in fact increase evaporation. Their function is to prevent the formation of bromate in the treated reservoirs

    • Thanks for your comment. There are conflicting reports on this. Several years ago, the EPA did use shade balls to prevent the chemical reactions in the water (the bromate formation you mention). But LA City Hall says these balls are for evaporation and to prevent algae blooms. In both cases, the science of putting plastic in water and the problem of scale is the same.

      • Yeah, wow, since the initial flurry of “look how the mayor is helping us save water!” I have been seeing more and more “explainers” telling us it’s not about water conservation, but about protecting us from bromate, which is formed when naturally occurring amounts of bromide interact with not-so-naturally occurring amounts of chlorine under naturally occurring UV radiation.

        Any way you look at it this was a massive scientific communication fail. Here is the mayor’s press release:

        It refers vaguely to “water quality,” and “chemical reactions” but talks about preventing the loss of “more than 300 million gallons of water” right in the photo caption, and the only quote from Garcetti himself is about the conservation angle. It’s clear they were trying to get the press to pick up on the “city is doing SOMETHING about the drought” story.

        There must have been an opportunity sometime in the last few years (see this article from 2008, which doesn’t mention evaporation at all: ) to have a debate about whether putting a bunch of plastic into the water is the best way to prevent bromate contamination. Indeed, right in the mayor’s press release, a plan to partition the reservoir in two is mentioned, but dismissed as being too expensive.

        If only the reservoir-dividing-in-half lobby were as strong as the putting plastic balls in water lobby!

        On the bright side, most of our reservoirs are underground, and I think the plan is to move away from above-ground reservoirs entirely, maybe even before we run out of water.

  6. Solar panels over reserviors is be coming a very effective way to provide shade to reduce evaporation, keep out dirt, insects and contaminants while producing electricity which can be used to pump water during the day when it is most needed. Some water districts are doing this already, India is beginning to cover all their desert water canals with PV. The southwest with thousands of miles of canals could produce 100s of megawatts if they did this.
    Water plants like duck weed and water hyacinth shade water, remove nitrates and other contaminants and produce biomass that can produce energy and compost.

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