Surface runoff is the stream of water on the ground that is not absorbed by soil—and it can be harmful!
Water runoff can cause flooding, which means property damage and mold formation in damp basements—but that’s not all.
Importantly, water runoff can cause pollution because the stream of water collects various contaminants and brings them to storm drains.
Contaminated water, instead of being naturally absorbed by the soil, eventually makes it back to streams and rivers.
There are two major interconnected consequences of pollution through runoff: it affects people, and it affects the environment.
It affects people: water contaminated by urban surfaces eventually makes it uncleaned to the places from where we take the water we drink.
Vörösmarty et al. (2005) have identified the great impact of runoff as they claimed,
“Runoff from urban systems…generated [close to] densely settled areas, serves nearly three-quarters of the world’s population” (p. 172).
Don’t forget that water runoff may cause damage not only in the form of you drinking water from a contaminated source.
Another major consequence is the damage to the environment.
When contaminants from various urban surfaces get to a natural system, they pollute it, affecting many species of animals and plants.
Such effects are never unnoticed in nature, and the presence of pollutants can result in changes in ecosystems.
It means not only reducing biodiversity (animals and plants die) but also deteriorating natural conditions.
These conditions affect us even though we may have never visited the places we pollute.
Think about it—we all breathe the air that trees make clean for us, and runoff in our cities can pollute the soil from which the trees grow.
So where does water runoff come from?
Cities we live in have so-called impervious surfaces—artificial structures made of impenetrable materials that prevent natural absorption.
Impervious surfaces include roads, sidewalks, parking lots, rooftops, and other surfaces that repulse water.
Unabsorbed, water forms streams and, in properly planned urban systems, does not cause floods but is collected in special channels.
However, after contacting urban surfaces, water becomes polluted—either with human-made materials or natural ones, such as rotten leaves.
Human-made contaminants may include pesticides, petroleum, and various other substances that are not too good for you or the environment.
You may wonder: But should I really worry about it? Shouldn’t the government control all possible pollutants?
Well, you will be surprised to know that the government controls only some pollutants, while many other ones are not regulated.
Out of more than 60,000 chemicals used in the U.S., only 91 are officially regulated by laws on safe drinking water (Duhigg, 2009).
This is not to say that all those 60,000 chemicals are poisonous. But some of the unregulated ones maybe. Consider this case:
In 2009, a reservoir in Los Angeles was covered with plastic balls to prevent the effect of sunlight.
The water there contained chemical substances that were confirmed to produce compounds associated with cancer when contacting sunlight.
People of the area asked why the reservoir was covered with plastic balls if there had been no violation of laws.
Once again: the chemical in the reservoir was proved to be associated with cancer, but it was not regulated by law (Duhigg, 2009).
So what do you think now? Is water runoff still none of your business?
To prevent negative consequences of urban runoff, it is necessary to minimize impervious areas in cities and improve channeling systems.
To mitigate the negative effects of runoff, regulations should be reconsidered to include substances that are known to be dangerous.
References
Duhigg, C. (2009). That tap water is legal but may be unhealthy. The New York Times. Web.
Vörösmarty, C. J., Lévêque, C., Revenga, C., Bos, R., Caudill, C., Chilton, J.,…Reidy, C. A. (2005). Fresh water. Web.