Urban trees are showing more promise from a storm water perspective than ever before. Trees absorb water from soil and transpire it to the atmosphere, reducing the amount of rainwater that flows untreated into storm sewers and ultimately to local lakes and rivers. In addition, tree canopies intercept rainfall, reducing the amount of energy each raindrop will have to erode soils. Roots break up the soil and aid infiltration. The USGS says that a single large oak tree can transpire 40,000 gallons of water per year. According to a 2005 U.S. Forest Service study designed to quantify the effect of all trees within city limits, trees in Minneapolis save the city over $9 million in storm water control per year.
Recent concerns about increased levels of phosphorus in local waterways as a result of leaves and pollen should not deter you from planting trees in cities or suburban areas. Aggressive street sweeping and/or alternative leaf collection programs may reduce a significant amount of the phosphorus made available by leaves and pollen. Urban trees also offer increased property values, improved air quality, reduced heat island effects, thus lowering maintenance and energy costs. Trees also make a community more attractive to residents and visitors. Storm water trees may be something to consider including in your next infrastructure project.
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About the Author
Ruekert & Mielke, Inc. Staff