Grass Swale

A grass swale is a long, narrow grassy channel used to convey stormwater to a downstream green infrastructure practice or storm drain. Grass is typically kept to a height of about three to six inches to slow down the runoff and allow any debris or sediment to settle out without interfering with the direction of flow. Depending on site conditions, additional features such as check dams and underdrains may be required to comply with New Jersey Soil Erosion and Sediment Control Standards.

Grass Swale Diagram
Image Credit: NJ BMP Manual, 2018

Considerations: The stability of grass swales needs to be considered during the design process. High velocities and steep slopes can lead to erosion issues.

Cost: Grass swales are typically more affordable than traditional piping. Maintenance costs are relatively low.

Maintenance: Grass swales are easily maintained through regular mowing and debris removal.