The National Association of Local Government Environmental Professionals, Trust for Public Land, and ERG put out a study in 2003 to help communities address the water quality impacts of sprawl. Their findings reinforce the value of trees and links between urban forestry and stormwater management.
Like water, trees are an excellent indicator of environmental health. As land is developed, trees are removed to make way for impervious surfaces such as homes and roads.
However, trees are a cost effective way to reduce stormwater- exactly what is necessary with increased imperviousness. Community forests function as nonstructural stormwater management facilities. In addition to slowing stormwater flow, trees increase soil permeability, thus facilitating groundwater recharge. Reduced stormwater flow decreases the amount of pollutants that wash into waterbodies since pollutants can be absorbed naturally into the soil and vegetation.
In addition, an analysis conducted by American Forests found that the existing tree canopy in the Washington, DC metropolitan area has reduced the need for additional stormwater retention structures by 949 million cubic feet. Indeed, Washington's trees have saved the region $4.74 billion in gray infrastructure costs per 30-year construction cycle.
Other case studies cited in this resource include:
* Arkansas Forestry Commission/City of Fayetteville, Arkansas
* TreePeople/City of Los Angeles
* City of Charlotte, North Carolina
As a conclusion, the guide lists the top 10 actions for advancing SmartGrowth for clean water in your community. Step 5 of 10 is: Expand Urban and Community Forestry.
SmartGrowth for Clean Water (PDF)
National Association of Local Government Environmental Professionals
Trust for Public Land
L.A. Million Trees Initiative
Arkansas Forestry Commission