Rain gardens: Managing storm water in your yard

By Bruce Gaudette | May 23, 2012

According to the National Weather Service, Seattle averages 38.6 inches of rain per year. That is a fair amount of water that is inevitably headed to Puget Sound.

So what about all the toxic chemicals that are washed away into our waterways? When rain falls on impervious surfaces, such as concrete or asphalt or roofing, it starts this trip rapidly, flowing to catch basins, culverts and drainage swales collecting all sorts of natural and man-made toxins.

This kind of storm water collection is not natural and does not filter the rainwater. And this, good Beacon readers, is our segue into this month’s title topic: Rain gardens are filters.

Rain gardens are simply natural filters for our storm water. They can be beautiful, and are ecological and naturally functioning systems. When rainwater is diverted to a rain garden, the hardy plants in it, working in combination with the soil, absorb the water and act as a combination mechanical and biological filter for pollutants.

Flooding and pooling of yards can be minimized by rain gardens when placed properly, and the type of plants that thrive in them require so much less care and feeding than the lawn that is displaced.

Immediate savings can be realized in lower fertilizer and watering costs and, of course, substantially reduced grass clippings.

There is a great amount of information “out there” about how to create rain gardens. To do one properly, you should invest Internet research time to learn about calculating just how much rain water your home generates, so that you can size and site your rain garden appropriately.

Given that rain gardens, when properly installed, have a spillway for exceptionally heavy rainfall accumulation that overwhelms them, it is vital for you to plan your project so that the outflow does not create problems for those living downhill from you.

Good sized rain gardens also generally require quite a bit of digging and exportation of our lovely clay cobble soils to create the space for the sandy organic soils required to create them, so that is one more reason to carefully plan the logistics of your project.

If a rain garden is of interest to you, but this is a self-help project that is a little more ambitious than you are ready to undertake, then please give us a call for professional help.

Bruce Gaudette, owner of Land Hoe! Landscape Design and Construction, holds an Associate Degree in Horticulture from Edmonds Community College and industry certifications in paver and permeable paver installation, and was president of the State Landscape Association WALP in 2007.

Land Hoe! has previously worked with Snohomish County on projects to install rain gardens in the Swamp Creek watershed. Land Hoe! is celebrating its 20th year in business in 2012.

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