Amogh Shetty, Kevin Zhang, Nihar Cheruku
Is water pollution still a problem in Illinois?
Amogh Shetty, Kevin Zhang, Nihar Cheruku
When we think of water pollution, the first image that comes to most people's minds is a pipe sticking out of a factory dumping a disgusting brown gush of sewage and "chemicals" into the water.
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That was true for the most part in the 20th century in Illinois, but after the Clean Water Act was passed in 1972, industrial facilities gradually adopted more modern ways of disposing of waste, and many waste water treatment plants were built to clean sewage water.
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However, that does not mean water pollution is still not a problem. Now days, the largest sources of pollution is non-point pollution, or in other words runoff.
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What is Runoff?
The leftover water after a rainy day.
Imagine the path a raindrop takes from its formation in a cloud to the time it reaches a river.
When the raindrop falls to the ground, it collects fertilizer, pesticide, dust, grease, and other waste.
If the raindrop enters a storm drain, the raindrop collects even more dirt and this time human waste.
Finally, the raindrop's journey ends up at a river or in groundwater, the same source that may supply your water.
Now one raindrop may not seem like enough, but now say this cycle repeated billions, if not a trillion times, in a single storm. This is why water pollution is still such a large problem.
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Image Credit: Pixabay
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What's different about Nonpoint Source Pollution?
Nonpoint source pollution is difficult to limit because we do not know the exact point where it may come from. Point source pollution is easier to reduce because we know exactly where it comes from, and thus we can pass regulations and procedures for the facilities causing the pollution to follow.
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An example showing another reason why it is more difficult to reduce nonpoint source pollution is this analogy. We know where a factory may be dumping highly polluted water into a lake, but it is nearly impossible to know all the different paths a dirty raindrop may take to enter a river.
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With point source pollution it is easy to target and "clean" the water before it enters a body of water, but because runoff doesn't have one converging location, reducing runoff isn't so easy.
What are some common sources of Non-point pollution?
Much has been done to limit water pollution in Illinois during the past decades. For instance, during the later half of the 20th century, many wastewater treatment plants were built to limit the amount of sewage water entering our waterways.
However, that did not stop sewage water from entering waterways through storm drains. Much of Illinois's storm drains are connected via a combined storm drain. In other words, water entering storm drains during a storm leads to the same pipes that sewage flows through.
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When storm drains overflow, sewage water can come to surface, eventually moving its way into our waterways.
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You can see below how concentrations of orthophosphates, nitrates, and nitrites, chemicals that are commonly found in sewage, are higher in urban areas with older sewage systems and larger quantities of sewage.
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Image Citation: sfbetterstreets
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Excess Orthophosphate and Nitrates
Orthophosphates are phosphate molecules that are present in sewage and decaying material. When it seeps into water through runoff, algae blooms become more common, which can disrupt the environment. In the image above we can see that the highest concentrations of orthophosphate are near populated areas which highlights the lack of proper sewage treatment in urbanized areas, especially those in the North East, where sewage systems tend to be older.
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Sources for data: National Water Information System (Note that all data is from the year of 2019), USA 2010 Census
Why does pollution from sewage matter?
Pollution from sewage is called nutrient pollution. Excess nutrients in our waterways can lead to a process called eutrophication, which is where algal organisms are more likely to grow and spread. The excess amount of algae decreases resources in the water, such as dissolved oxygen, and blocks sunlight from reaching other plants. Ultimately, the excess amount of nutrients in the water decreases the ability of other plants and animals that inhabit the waterways to gain resources.
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What are some former sources of point pollution?
Until recently, another form of pollution came from powerplants.
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Powerplants used river water to cool machinery. While nothing is added to the water, the temperature of the surrounding water increases.
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Higher water temperatures limit the ability of streams and river to hold dissolved oxygen. As a result, water life in surrounding areas is negatively impacted.
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To the right, one can see a picture of a a powerplant flushing hot water into a water way.
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While this form of pollution was prevalent for most of the 20th century, powerplants have started to shift away from directly dumping hot water into local water sources. This was to avoid thermal water pollution and also due to benefits of alternative cooling methods, such as circulating water through cooling towers.
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Image source: Stanford University
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Temperature and Dissolved Oxygen
In the past, many power plants used water from rivers to cool down machinery. However, this would increase the temperatures of waterways. As a result of increasing temperature, the levels of dissolved oxygen would lower leading to harmful effects on the environment. This is an example point-based pollution.
Point-based pollution has decreased in recent days. As a result dissolved oxygen levels are at relatively healthy levels.
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Sources for data: National Water Information System (Note that all data is from the year of 2019), USA Energy Information Administration
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Dissolved Oxygen Over Time
The right is a graph portraying the amount of dissolved oxygen in the Des Plaines river over time. The Des Plaines river is located in the northeastern region of Illinois, which is hope to a significant number of powerplants. As one can, dissolved oxygen levels at the Des Plaines river have been increasing from 2015 to 2020.
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Data source: National Water Information System
Needed Solution
Lack of proper processing of sewage is one of the largest sources of pollution in Illinois. While many wastewater treatment plants have been built in Illinois, the prevalence of connected sewer systems can make waterways vulnerable to pollution from sewage water. In order to decrease water pollution in Illinois, cities and counties must take a larger to stance to replace connected sewer systems with newer separated sewer systems.
Citations
https://www.enr.gov.nt.ca/sites/enr/files/dissolved_oxygen.pdf
http://osse.ssec.wisc.edu/curriculum/earth/Minifact2_Phosphorus.pdf
https://extension.usu.edu/waterquality/files-ou/Agriculture-and-Water-Quality/riskwater/NR_WQ_2005-23.pdf
https://waterdata.usgs.gov/il/nwis/qw
https://www.eia.gov/state/?sid=IL#tabs-4
http://www.usa.com/rank/illinois-state--population-density--county-rank.htm
https://mwrd.org/understanding-your-sewer-0
https://www.sfbetterstreets.org/find-project-types/greening-and-stormwater-management/stormwater-overview/
https://blogs.illinois.edu/view/789/423237#:~:text=The%20main%20source%20of%20thermal,of%20surface%20water%20in%20Illinois.