Trees aren’t just for shade; they are highly effective and natural stormwater managers, as well. Urban trees can reduce annual stormwater run off by 2-7 percent. In forests, they help reduce stormwater run off by 85 percent.
Releaf Michigan endeavors to plant urban trees while educating communities on exactly how trees manage stormwater run off. By planting large trees (six feet or taller) Releaf helps Michigan communities invest in this low impact development by planting large trees (six feet or taller), which work to manage stormwater on-site.
Trees act as stormwater managers by first physically intercepting rainfall. Droplets collect on the leaves and bark before eventually evaporating. The soil surrounding the tree soaks up more falling rain, while the tree roots absorb water that then transpires into the atmosphere. During large storms, a mature tree can store up to 100 gallons of water.
Managing stormwater is especially crucial for Grand Rapids since stormwater run off is the leading source of water pollution in the area. Stormwater runs off impermeable surfaces, like roofs and sidewalks, and then flows directly into streams, lakes and rivers. Along the way, it picks up all sorts of debris; trash, pesticides, chemicals and oil. Then, the run off gushes, untreated, into the water. In Grand Rapids, it only takes 15 to 30 minutes for stormwater run off to reach the Grand River.