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Thurston County Stormwater Utility

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Swales: Go With the Flow

swale in Black Lake neighborhoodIf you’re thinking about filling a ditch or swale near your house, please think twice. There’s a reason why the ditch or swale was designed and approved for your neighborhood.

Ditches and swales convey stormwater runoff from roads, roofs and other hard surfaces. Some are designed to simply convey water from Point A to Point B, for example from a road to a stormwater pond. Others, particularly those lined with grass, are meant to filter and absorb pollutants in the runoff first, and then convey the water.

Either way, ditches and swales near your house are part of a broader neighborhood network for managing stormwater runoff and reducing flooding. If you fill your portion of the swale or ditch with plants, rock, or beauty bark, you might affect a neighbor’s property, damage the neighborhood stormwater pond, or enable more pollutants to enter a nearby water body.

Here’s an example of an innocent mistake made by one homeowner: The homeowner thought the ditch outside his house was unsightly, and decided to beautify it with English ivy. While the natural ditch was designed to convey water away from the road easily, the ivy-filled ditch is actually less capable of transporting water, and the invasive non-native plant encroaches on nearby native plants. Similarly, a ditch or swale filled with beauty bark or undersized gravel can clog drainage pipes and send material into a stormwater pond or stream.

So does this mean you can’t do anything with a swale or ditch? Not necessarily. Just remember that it’s an important part of your neighborhood drainage system and was designed very specifically for your site. Any change needs to be approved by your neighborhood association and comply with county stormwater standards. Your family, neighbors and the environment will all do better when you go with the flow!

Download our brochureswales brochure

Ditches and Swales: Keep them Clean and Clear

Contact Us

 Staff contact: Cathe Linn: (360) 754-4681. E-mail: linnca@co.thurston.wa.us



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