Dry Swales or Wet Swales

Wet Swales:

Wet swales are grassed or vegetated open channel capable of temporarily storing water. These swales are usually constructed directly within existing soils and should be designed to store water approximately twenty-four hours. Wet swales have water quality treatment similar to wetlands, which are primarily focused on settling suspended solids, groundwater recharge, and microbial breakdown of pollutants through their use of vegetation. Wet swales may also reduce the velocity of storm water runoff and promote infiltration.

Dry Swales:

Dry swales are a type of open vegetated channel used to treat water quality and storm water runoff. Water runoff from a storm is temporarily held in a pool or series of pools by checkdams or a ditchblock. With dry swales, an underdrain system is installed with permeable gravel incasing a perforated pipe that filters runoff before sending it back into the stormdrain system or a retention pond. Dry swales are a good option in that they discourage long-standing water and make it possible to mow the area even shortly after rainfall.