Tree Canopy and Water Quality

tree canopy

How Trees Impact Water Quality

When we think of the benefits we gain from having trees in our landscapes we often forget about the role they play in improving water quality.  Trees work in a number of ways to help reduce the amount of pollutants and sediment that ends up in our streams and lakes after storm events.

Trees intercept, or catch, rainfall which helps slow and/or reduce the amount of water that reaches the ground, which can reduce the amount of water runoff.

Tree roots draw large amounts of water from soil and release it into the atmosphere as water vapor in a process called transpiration.  This process is essentially a way to store stormwater runoff.

Trees take up harmful chemicals from the soil and transform some of them into less harmful substances which they can either store in their tissues or use as nutrients in a process called phytoremediation

As tree roots grow, expand, die and decay they create soil conditions that are less compacted and more able to absorb rainfall.

These benefits are extremely important when we think about what happens to stormwater when it hits the ground.  Excess water runoff picks up chemicals, sediment, bacteria and pollutants from paved or hard surfaces and, unless it is captured by the soil or other holding areas, ends up in our streams and waterways.  Trees help reduce the chances that these pollutants will end up in our waterways.

Click here for more information on how the City manages stormwater.

What You Can Do To Help

Helping to improve water quality can be as simple as planting a tree.  Having trees in our yards, along our streets, in our parks and around our streams has a direct impact on our watersheds. If you are interested in donating a tree, click here for more information about the City’s Adopt-A-Tree Program.

If you own property with a stream or other waterway, establish a buffer, or strip of land on all sides which is planted with permanent vegetation, to help filter and slow stormwater runoff.  The City of Winchester Code Section 9-80 through 9-85 requires all land new land development adjacent to Abrams Creek, Town Run, Hogue Run, Buffalo Lick Run and Redbud Run to contain a thirty-five foot wide buffer on each side of the stream.  For more information, refer to the Winchester City Code sections mentioned above.

Installing a rain garden on your property is another great way to collect and filter rainwater from paved surfaces or roofs into a depressed area which contains trees, grasses and other vegetation.  Excess water flows from the surrounding area and is allowed to soak into the soil where it can then be taken up by the vegetation and/or filtered through the soil.

Our greatest stormwater benefits from trees come from large, mature trees in our landscapes, but not every location can provide the rooting and overhead space that a large tree requires.  For more information on selecting the right tree for your location, please review the City’s Recommended Tree List

What is the City of Winchester Doing To Help

Since 2014 the City of Winchester has received funding through the Virginia Trees for Clean Water (VTCW) Grant through the Virginia Department of Forestry.  The VTCW program is aimed at improving water quality in the Chesapeake Bay by planting trees in cities across the state.  The objectives of the grant are to: (from the DOF Website)

  • Plant trees to restore and improve the waters of the Chesapeake Bay for the benefit of current and future citizens of the Commonwealth
  • Achieve long-term improvements in water quality through long-lived tree cover and increased public involvement
  • To raise public awareness about the benefits of planting trees for the health of our streams and rivers.

Since 2014 the City has planted 116 trees within the downtown area and the median strip on W Jubal Early Dr along Abrams Wetland Preserve with the assistance of VTCW grant funds.  In the fall of 2017 the City will be installing 31 trees in the median area of East Jubal Early Dr to restore a dwindling tree canopy. These areas, when fully planted, will be a significant source of rainwater interception and filtration of stormwater runoff.

Additional Resources