Rain gardens help protect nearby streams, conserve water, & reduce mosquitoes

rgWhat is a rain garden?

A rain garden is a planted depression that allows rainwater runoff from impervious urban areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas, the opportunity to be absorbed.

This reduces rain runoff and pollution by allowing stormwater to soak into the ground reducing rain runoff while improving water quality of nearby creeks and rivers.

Rain gardens can cut down on the amount of pollution reaching creeks and streams by up to 30%

On the surface, a rain garden contains the same wild flowers and other native plants you’d expect to see in any garden or landscaping.  But the difference runs deep.  During a storm or shower, the rain garden soaks up a few inches of water runoff from a roof, driveway, or other paved surface.  That water slowly seeps into the ground instead of heading for the nearest storm drain.

Rain gardens are a great way to make an area aesthetically pleasing while being environmentally friendly.

Why does that matter?


It’s all about runoff.  As our region’s forests, farmland and other green spaces are paved over for highways, housing developments and shopping centers, the amount of impervious surface continues to grow.  This decreases the ground’s natural ability to absorb rainwater.

In many local communities, runoff follows storm drains and surface paths, picking up pollutants that contaminate our nearby creeks & rivers.

Stormwater isn’t free from pollutants.   Though it comes from rain, once on the ground, it gathers pollutants in its path on its way to waterways.   These non-point source pollutants can include fertilizers, oils and E. coli and are difficult to trace.

Rain gardens help rainwater mimic the natural spreading of stormwater.

The city of Austin, Texas, has established rain gardens as an “Innovative Water Quality Control”, per its Environmental Criteria Manual.

524036_456097037766652_2051996746_nA rain garden requires an area where water can collect and infiltrate, and plants to maintain infiltration rates, diverse microbe communities, and water holding capacity. Transpiration by growing plants accelerates soil drying between storms. This includes any plant extending roots to the garden area.

Simply adjusting the landscape so that downspouts and paved surfaces drain into existing gardens may be all that is needed because the soil has been well loosened and plants are well established. However, many plants do not tolerate saturated roots for long and often more water runs off one’s roof than people realize. Often the required location and storage capacity of the garden area must be determined first.

Rain garden plants are then selected to match the situation, not the other way around.

Plant Selection

Native plants are recommended for rain gardens because they generally do not require fertilizer and are more tolerant of one’s local climate, soil, and water conditions, and attract local wildlife such as native birds.


The plants — a selection of wetland edge vegetation, such as wildflowers, hedges, rushes, ferns, shrubs and small trees — take up excess water flowing into the rain garden. Water filters through soil layers before entering the groundwater system. Root systems enhance infiltration, maintain or even augment soil permeability, provide moisture redistribution, and sustain diverse microbial populations involved in biofiltration.  Also, through the process of transpiration, rain garden plants return water vapor to the atmosphere.

Rain water helps plants grow and reduces the need for watering.


Rain gardens are beneficial for many reasons: improve water quality by filtering runoff, provide localized flood control, are aesthetically pleasing, and provide interesting planting opportunities.   They also encourage wildlife and biodiversity, tie together buildings and their surrounding environments in attractive and environmentally advantageous ways, and provide significant partial solutions to important environmental problems that affect us all.

OLYMPUS DIGITAL CAMERAA rain garden provides a way to use and optimize any rain that falls, reducing or avoiding the need for irrigation.   They allow a household or building to deal with excessive rainwater runoff without burdening the public storm water systems.

Rain gardens are easier to maintain and help keep runoff out of stormwater systems.

Rain gardens differ from retention basins, in that the water will infiltrate the ground within a day or two. This creates the advantage that the rain garden does not allow mosquitoes to breed.


Rain gardens come in all shapes and sizes and every little bit helps.

Fact Sheet: Six Easy Steps to Build a Rain Garden