CORVALLIS, Ore. – A new guide on building sunken-bed rain gardens to collect and filter runoff water can help Northwest homeowners learn how to redesign home landscapes to help protect rivers and streams.
Rain gardens can help restore the natural water cycle, according to Rob Emanuel and Derek Godwin of Oregon State University Extension and Oregon Sea Grant Extension.
"As our landscapes became developed, rain falling on hard surfaces was directed to pipes, ditches and storm drains that route to streams or into stormwater sewer systems," Emanuel said. "The result is too much water arriving in a short amount of time and carrying pollutants."
Rain gardens work like a native forest, meadow or prairie.
"They capture and redirect stormwater from hard surfaces such as roof tops, driveways, parking lots and streets," Godwin said. "Rain gardens help keep watersheds healthy by filtering out toxins before they pollute streams and lakes, and they can actually recharge aquifers by encouraging water to soak into the ground."
The new 44-page illustrated guide, "Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams," was written by Emanuel, Godwin and Candace Stoughton, who works for the East Multnomah Soil and Water Conservation District. It can be found online or ordered by calling OSU Sea Grant Communications at 541-737-4849. Copies are $4.95 each, plus shipping & handling.
This how-to publication provides information specific to Oregon's conditions. No stormwater, garden or landscape expertise is necessary to use it. The step-by-step approach teaches how to determine where water flows across a homeowner's property and the best place to put a rain garden to manage water flow across impervious areas.
The guide points out what local regulations need to be followed and how to determine slope, drainage rates and texture of the soil. Size of the rain garden and volume of water it can hold also are discussed, as are how to excavate, grade and build berms. The guide also recommends native perennials that can withstand both frequent wet and dry cycles.
The guidebook is a joint project of the OSU Extension Service and Oregon Sea Grant, East Multnomah Soil and Water Conservation District, Jackson Soil and Water Conservation District, and the Oregon Environmental Council. Partial funding for the guide was provided by a grant from Oregon Department of Environmental Quality.