Looking for a quick overview of rain gardens? We have a new fact sheet that highlights many aspects of rain gardens!
Rainfall
Clackamas County rainfall map
Imagine your entire property covered in water to the height of an average office desk. That’s how much water falls on us between November and May each year. Higher elevation sites receive even more precipitation.
What is a rain garden?
A rain garden combines plants in a shallow depression to collect, absorb, cool, and filter runoff…before that water reaches local streams. A rain garden often fits into unused space in your home landscape.
Controlling runoff helps streams
Redirecting rainwater into a rain garden helps keep streams clean and cool. Water runs off of surfaces like driveways and houses. Instead of sending that water down the street or into storm drains, use it to water a rain garden!
Benefits
Rain gardens not only improve water quality, but also provide many other benefits, including:
- Reducing flooding in urban areas
- Decreasing erosion in waterways
- Recharging groundwater supplies
- Providing microhabitat for birds, butterflies, and beneficial insects
Designing a rain garden
Rain garden, section view
An infiltration test will determine if your soils drain well enough to install a rain garden. The depth of your rain garden depends partly on the infiltration rate of your soils.
For safety, rain gardens are designed to be shallow depressions. Rain gardens are not deep ponds!
How big should your rain garden be? When properly designed and sited on the right soils, your rain garden should be about ten percent of the impervious surface (like your driveway or roof) that captures the water that drains into the rain garden.
Permits
A permit may be required for your rain garden. Different municipalities have differing requirements.
Download the fact sheet
Download the new rain garden fact sheet for more information!