Another credit system involves trees credited for a runoff volume reduction based on retention value individual trees. In some areas, greater volume reduction credit is awarded for preserved trees over planted trees (20 ft^3 for preserved trees, 10 ft^3 for planted trees)[7] while in other areas credits can instead be determined based on size with trees (10 gal/inch for trees under 12” DBH, 20 gal/inch for trees over 12” DBH)[8] (for example, Washington DC, GA, VT). Additional factors that can affect the amount of credit awarded are soil volume and tree canopy to assess stormwater benefits.[3]