Plant a tree! Just one tree can reduce rainwater runoff by 4,000 gallons each year? Tree canopies and roots absorb and filter rainwater, helping to reduce flooding and erosion, and protect water quality. Trees also add curb appeal - it's estimated that one tree in the front yard can increase a home's sale price by one percent!
(Sources: Alliance for Community Trees. "The Value of Trees!" http://actrees.org/files/Resources/ValueOfTrees_FactSheet.pdf; Natural Resources Conservation Service, Backyard Conservation Tip Sheet: Tree Planting. http://www.nrcs.usda.gov/feature/backyard/treeptg.html; National Gardening Association, www.garden.org)