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Discover the Science Behind Shade Balls in LA Reservoir and Their Impact on Water Evaporation, Algae, and Bromate Formation |
Veritasium Info: Understanding the Role of Shade Balls in Water Conservation and Safety
In Los Angeles, a unique solution
has been implemented to address water conservation and safety issues at the LA
Reservoir. These black plastic spheres, known as shade balls, are floating on
the water’s surface in vast numbers. But contrary to popular belief, their
primary purpose is not to reduce evaporation. In this article, we explore the
true function of these shade balls, their effectiveness, and their impact on
water quality.
What
are Shade Balls?
Shade balls are large black plastic
balls that are deployed in water reservoirs. They are made from a material
called high-density polyethylene (HDPE), the same type of plastic used in milk
jugs. These balls are designed to float on the surface of water bodies like the
LA Reservoir, covering large areas and providing shade to the water beneath.
The
Purpose Behind Shade Balls in LA Reservoir
The LA Reservoir serves as a crucial
water source for the city, providing a significant portion of Los Angeles'
water supply. However, the water contains a naturally occurring substance
called bromide, which, when exposed to chlorine and sunlight, forms a
potentially carcinogenic compound known as bromate. To prevent the formation of
bromate, which could endanger public health, a solution was needed to block
sunlight from reaching the water.
The solution came in the form of
shade balls. When scientists at the LADWP (Los Angeles Department of Water and
Power) tested various methods to block sunlight from the reservoir, they found
that shade balls were the most effective and affordable option. These black
plastic balls absorb sunlight, preventing it from reaching the water and
triggering the harmful chemical reaction that forms bromate.
How
Shade Ball Work
Shade balls are designed to cover
the water surface and block sunlight from reaching the water. Their black color
is key to their functionality, as it helps absorb the sunlight, preventing the
water from reacting with chlorine and bromide to form bromate. The material
used to make the shade balls is safe for contact with drinking water and is
stable enough to withstand exposure to sunlight for years.
The
Impact on Water Quality
One of the primary concerns with
open water reservoirs is the growth of algae. In the past, algae outbreaks
would cause discoloration in the water, making it appear slightly green.
However, since the deployment of shade balls, the algae problem has been
significantly reduced. The lack of sunlight has effectively stopped algae from
growing, which has led to improvements in water quality.
Additionally, the shade balls help
reduce the need for chlorine. In the past, high levels of chlorine were added
to the water to control algae growth, but with the shade balls in place, the
water has remained clear with minimal chlorine usage. This not only improves
the taste and quality of the water but also reduces chemical costs for the
city.
Evaporation
Reduction and Water Conservation
One of the most widely discussed
benefits of shade balls is their ability to reduce evaporation. In a city like
Los Angeles, where water is scarce, minimizing water loss through evaporation
is crucial. The shade balls cover approximately 80-90% of the reservoir’s
surface, which significantly reduces the amount of water that evaporates into
the air.
Addressing
Public Concerns
Despite the benefits of shade balls,
some concerns have been raised regarding their use. People have questioned
whether the plastic balls are safe for drinking water and whether they might
leach harmful chemicals into the water over time. However, the shade balls are
made from food-grade plastic and are thoroughly tested to ensure that they do
not pose a risk to public health. The material used in the balls is inert,
meaning it does not react with the water, and it has been proven to be safe for
long-term exposure to sunlight.
Conclusion:
The Science Behind Shade Balls
The shade balls in the LA Reservoir
provide a fascinating example of how science and innovation can be used to
solve real-world problems. By preventing the formation of bromate, reducing
evaporation, and improving water quality, these black plastic balls have proven
to be an effective solution to several water-related challenges in Los Angeles.
While they may appear simple, the science behind shade balls demonstrates the
power of physics and environmental engineering in addressing complex issues
such as water conservation and safety.
With over 96 million shade balls in the LA Reservoir, this project has not only helped to improve water quality but also contributed to the city’s overall water conservation efforts. As more cities face similar challenges related to water supply and quality, the success of shade balls in Los Angeles may serve as a model for other regions looking for innovative solutions to preserve and protect their water resources.