Point vs. Non-Point Pollution

Large environmental disasters such as oil spills or waste outlet pipes receive huge amounts of attention in the media and scientific community. These types of “point pollution” -pollution that comes from a single, easily identifiable source- have a large public impact and are relatively easy to clean up or prevent. For example, the Deepwater Horizon oil spill/ disaster sparked a huge cleanup effort in the Gulf Coast. Coastal communities and local fishermen received financial compensation in the millions of dollars for the losses they suffered as a result of the spill. But there’s another threat to our environment that is much less obvious: non point pollution. Non point pollution doesn’t originate from a specific source or event, and can often be much more destructive and difficult to clean up than sources of point pollution. For example, the recent spill of about 100 gallons of oil off of Alki Beach in West Seattle sparked a large cleanup effort by the Department of Energy, but conservative models estimate that over 2 million gallons of oil are spilled into Puget Sound annually from storm water runoff. Unfortunately, oil is one of many sources of non point pollution in Puget Sound.

Non point pollution enters our waterways from many different sources, including wastewater runoff, improperly maintained septic tanks, urban development, pet waste, and agricultural activities. Most of these pollutants enter the groundwater system- water held underground in rock formations and soil- and slowly make their way into Puget Sound. Wastewater runoff, which includes oil, antifreeze, and particulate matter, is prevented from entering the groundwater system by impervious surfaces such as concrete or roofs and flows directly into Puget Sound via storm drains.

Increased development around Washington State has exacerbated many problems with non point pollution. Agricultural runoff, including animal waste and fertilizers, can travel many miles in groundwater and rivers or streams—even areas far away from the ocean can have a large effect on the health of our whole watershed. Increased pesticide and nitrate (fertilizer) concentration in oceans can result in devastating plankton blooms that leave areas of the ocean devoid of oxygen. Logging and road development increase erosion, which changes sediment concentration and makes it harder for fish and other wildlife to see and breathe underwater. Vehicles that do not meet emission standards increase air pollution, vehicles with leaking parts contribute to road runoff, and old brakes shed copper shavings that end up in the ocean.

Luckily, there are a lot of things individuals can do to reduce non point pollution! You can reduce wastewater runoff from roads by washing your car on your lawn (grass acts as a natural filter), fixing leaks in your car system as soon as they’re spotted, turning off your engine if it’s idling for more than 30 seconds, and regularly changing your brakes. At home, consider reusing your roof runoff in a rain barrel, and examine your landscaping to make sure it minimizes erosion and pesticide use. Consider natural pesticide alternatives, such as ladybugs, to eliminate pests in your yard & garden. If you’re hiking or camping, make sure to stay on established trails to prevent erosion, and always pack out your trash.

By working together, we can dramatically reduce the amount of non-point pollution that ends up in our local waterways!

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