With all the Rain, Noticing Anything Unpleasant?

by Oskar Thorvaldsson

While we love what rain does for our natural habitats and gardens, it also carries urban waste into precious ecosystems, not to mention poses a health threat to humans and animals.

An estimate by the National Academies of Science, Engineering and Medicine has the total motor oil runoff entering storm drains at around 1.2 million tons, simply from oil slicks on the streets.

Coastal areas are most affected, with many beaches issuing water quality warnings for a variety of bacteria and contaminants. One study in Southern California found that record-breaking high levels of fecal bacteria in three urban watersheds. The authors report that the contamination appears to originate from repeated external sources, and not produced by regrowth or cross-contamination with other sewer drains (1). In addition to the threat to creeks, rivers, lakes and oceans, the run-off pollution entering storm drains also contributes to groundwater contamination.  One government report by the EPA found that 39% of rivers and streams, as well as 45% of lakes and reservoirs, and 51% of coastal waters, were polluted above water quality standards (2).

The other kinds of pollution that enter storm drains are heavy metals, new chemicals produced by industrial practices, road traffic pollution like carbon monoxide, nitrogen, hydrocarbons, motor oil, lead and sulphur oxides. Other pollutants include fertilizers, coliform, plasticizers, polycyclic aromatic hydrocarbons, paint, plastic litter, detergents used to wash cars, and pesticides. While many of these cannot be easily detected, a high amount of oil in the street or drain clogged with trash, need to be addressed.

What to Do if You Find Pollution in the Street or in a Storm Drain?

Your support is vital for maintaining our water quality. If you notice anything besides rainwater flowing into the curb, gutter, alley, or street, please report it to your local city or county. Many cities have a water pollution hotline or email contact.

Things to report include irrigation runoff, oil, grease, swimming pool water, construction debris (including sediment), landscaping waste, and power washing wastewater. These substances can seriously harm our local waterways.

Remember, only rain should go down the drain. 







1). Sercu, B., Werfhorst, L. C. V. D., Murray, J., & Holden, P. A. (2009). Storm drains are sources of human fecal pollution during dry weather in three urban southern California watersheds. Environmental Science & Technology, 43(2), 293-298.
2). Rădulescu, D., Racovițeanu, G., & Pienaru, A. (2016). Urban storm water runoff pollution–an overview and recent trends. In Conference Proceedings WATER (Vol. 23, No. 25, p. 237).

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