These open, vegetated drainage ways have gradual slopes and collect and slowly move water downstream giving it a chance to soak into the ground before reaching the bayou.  These can replace curb and gutter systems and are especially useful along road ways and parking lots.  Swales can be planted with grass and maintained by mowing, or planted with low growing native wetland vegetation that can withstand both periods of moisture and drought and will not impede flow during large rain storms.