Clean Water Benefits from Healthy Tree Cover

Pennsylvania is lucky to have more than 17 million acres of forests, because more trees equal cleaner streams, rivers, and lakes. Read on to learn more about some of the ways trees work their magic on our waterways.

Trees Reduce Flood Impacts

This June marked 50 years since Hurricane Agnes hit Pennsylvania, causing massive flooding and destruction – the impacts of which can still be seen today. Unfortunately, climate change is making it rain more frequently and more abundantly, leading to greater flood risks. Greg Czarnecki, Director of Applied Climate Science for the Pennsylvania Department of Conservation and Natural Resources (DCNR), said there has been an increase of 70% in heavy rain events in Pennsylvania in recent years, which is defined as storms that would typically occur just 1% of the time.

Stronger rain events and subsequent flooding can have significant environmental and economic impacts, so anything that can be done to reduce its frequency and severity is a good thing. Thankfully, trees play a key role in mitigating the impacts of floods.

According to DCNR, trees protect against flooding by absorbing rainwater with their roots, slowing runoff with their leaves (up to a 60% reduction), and transpiring water, thus drying the soil more quickly. In fact, according to the U.S. Forest Service, the roots from a healthy 100-foot-tall deciduous tree can take up 11,000 gallons of water from the soil and release it through its leaves as oxygen and water vapor each year!

“An incredible amount of water goes up into a mature tree,” said Marci Mowery, President of the Pennsylvania Parks and Forests Foundation (PPFF). “So, that water is not directly flowing into the waterway from a flooding perspective.”

Trees Clean Our Rivers and Stream

While trees absorb all that rainwater, they are also absorbing pollutants in the water, thus keeping it out of our waterways. For instance, studies have shown a reduction of up to 88 percent of nitrate and 76 percent of phosphorus when runoff from farms passed through a forested stream buffer. The same benefits can occur from trees in a residential or commercial setting, where excess lawn fertilizer would otherwise run into storm drains and end up polluting our rivers and streams.

PPFF recently produced a video highlighting the benefits of forests for healthy water quality, including how Pennsylvania’s craft beverage industry (i.e., beer, wine, soda, and more) is reaping those benefits. Better water quality can mean a better local economy! Check out that video, as well as others related to how to plant trees and the health benefits of being outdoors here.

“We developed these videos for a few reasons,” said Mowery. “One is to give the public even more reasons to get outdoors. It’s good for their health! Another reason is to educate people on the importance of forests and other greenspaces for water quality so they will help raise awareness at the legislative level that funding for conservation is critical – it can boost our economy and protect our homes and businesses from flooding!”

How Can You Help Trees?

“Trees play a critical role in not only flood reduction, but in reducing crime, cleaning the air, inspiring art, and improving human health,” said Mowery.

That is one reason PPFF has a statewide tree planting initiative to restore trees damaged in Pennsylvania’s state parks and forests. Plantings have occurred around the state and are ongoing. You can help this effort by volunteering at a state park or forest near you. To learn more, visit their volunteering webpage here.

Or you can plant trees on your own property. The DCNR Climate Adaptation and Mitigation Plan includes a list of which trees will fare better in Pennsylvania under a changing climate. Making sure whichever trees you plant are appropriate for the soil, shade level, and plant hardiness zone (now and 50 years from now) in your location is essential for long-term survival. Download a copy of the report here.

No matter what you do to help enhance tree cover in Pennsylvania, know that the more trees we have in the commonwealth, the better off will be our waterways. That is why RiverStewards Collaborative is highlighting the work of organizations like PPFF and DCNR. Collectively, we can have a significant impact on the natural world.

If your organization is helping improve water quality in the Susquehanna River watershed, we want to hear about it! We are looking for blog posts to share here. Interested? Email a brief description of your work to

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