One of the most discussed benefits of trees is their ability to reduce runoff and subsequent water pollution. This has considerable effects in urban and suburban areas, where there are a lot of impervious surfaces that do not absorb water well. When rain falls on an impervious surface, it picks up pollutants, such as pesticides, fertilizers, and oils, which flow into the nearest body of water.

Trees provide canopy cover, which intercepts a percentage of the rainfall that would otherwise flow onto the impervious surfaces. Instead, this water stays on the leaves and is evaporated into the air through a process called evapotranspiration. In addition, trees absorb water from their roots, desaturating the ground around them, allowing for more water to be absorbed instead of turning into runoff. The EPA has found that trees in urban areas can absorb 15-27% of annual rainfall, creating a significant reduction in the amount of water that will carry pollutants into the Chesapeake Bay.

While this process is important anywhere in the world, it is especially important to prevent runoff in Maryland. Maryland is a part of the Chesapeake Bay Watershed, which is the world’s largest land-to-water coastal watershed. Prince George’s County is also included in this watershed, which means we need to take extra care to ensure that harmful runoff into the bay is reduced as much as possible.

The Chesapeake Bay is measured yearly on a letter-grade scale for its concentration of phosphorus and nitrogen, and given a grade based on its contamination levels. In 2024, the bay received a C+, the highest grade in the last 20 years. As conservation efforts across Maryland and other watershed states ramp up, everyone who lives within the Chesapeake Bay Watershed needs to do their part to reduce pollution towards the Chesapeake Bay. Some positive actions would be to eliminate the use of harmful pesticides, plant native plants in your yard, and plant new trees!

GHEP wants to help protect the health of your watershed, ensuring that our natural resources stay healthy and beautiful. If you would like to plant a tree to beautify your home and protect the Chesapeake Bay Watershed, check out our Family Tree Adoption Program! We offer free tree planting services, in hopes that you will enjoy the benefits of a healthy environment!

Sources:
https://www.chesapeakebay.net/discover/watershed
https://www.umces.edu/news/chesapeakebayreportcard-2025
https://www.epa.gov/heatislands/benefits-trees-and-vegetation
https://www.chesapeakebay.net/news/blog/chesapeake-bay-receives-highest-health-grade-in-over-20-years