Rain Gardens and Bioswales are examples of green infrastructure, also called Low Impact Design (LID), and use natural functions to capture and filter stormwater.
What is a rain garden?
A rain garden is a garden of native plants that is watered by stormwater. A rain garden accomplishes stormwater filtration by collecting water on low gradients, slowing it, and allowing the water to infiltrate into a porous surface, instead of flowing across asphalt or concrete. When the water is slowed, suspended particles settle out, and pollutants are decomposed by soil microbes, immobilized, or incorporated into plants.
What is a bioswale?
A bioswale looks like a dry creekbed with plants growing inside. The bioswale is engineered with gravelly soil, so stormwater is absorbed quickly and deeply.
After a storm, rain flows over roads and rooftops and carries dirty water with it. Rain gardens and bioswales capture the stormwater and slow it down. This keeps the water from flooding homes and nearby streets, where it can create potholes. Slowing the water also enables it to soak into the ground, and lets dirt and pollutants settle out. Through this process, the rain gardens and bioswales help clean the water before it enters the San Francisco Bay. The native plants in the rain gardens and bioswales also create habitat for birds and butterflies.
Rain gardens and bioswales tackle the issue of pollution in waterways due to urban runoff by absorbing 30% more stormwater into the ground than a conventional lawn and reduce 70% of surface water pollution that originates from stormwater runoff.
With community input and volunteer assistance, The Watershed Project constructs bioswales and rain gardens across Richmond and San Pablo, including a network of 14 bioswales and rain gardens along the Richmond Greenway. Join our dedicated and enthusiastic volunteers every Second Saturday on the Greenway to plant and maintain these projects!