Trees are a solution to
stormwater runoff

Healthy urban forests are important in decreasing the amount of runoff and pollution in receiving waters. Stormwater runoff results when occasional, short rainstorms leave behind a great amount of water that has no place to go. It therefore goes to waste by puddling in yards and roadways. The water quality suffers when it carries contaminants such as oil, metals or pesticides into streams, wetlands, lakes and marine waters. The presence of trees can prevent this from occurring by absorbing excess water that storms often leave behind.

Studies performed by the Center for Urban Forest Research show that during a rainfall event, precipitation is either intercepted by leaves, branches and the trunk, or it falls directly through the tree to the ground. The intercepted water is briefly stored on leaf and bark surfaces for about 10 minutes before capacity is reached and the water begins to drip and flow from the tree. A medium-sized tree can intercept as much as 2,380 gallons of rainfall per year.

Water is saved and soil erosion reduced when urban forests flourish. Remember these tips when planning an urban forest for the purpose of preventing stormwater runoff:
• Tree species and sizes differ when absorbing water.
• Choose a good location for now and in the future.
• Trees work well in combination with other stormwater controls.
• Maintenance of existing trees will ensure successful interception.
• Plants that can withstand dry seasons and use less water will intercept more water.