Woods not Lawns for Water Quality

Penn State Forest Stewards series article – written by Jim Finley, Professor Emeritus, Forest Resources Management, Center for Private Forests at Penn State.

It’s January and perhaps your thoughts are already turning toward summer activities. For many Pennsylvanians, mowing and maintaining lawns is either a larger or small part of their summer routine. Lawns, as we know them, are part of American culture and history(1). An Internet search on lawn maintenance suggests creating the perfect lawn is a major industry very dependent on labor and chemical inputs.

Annually we spread millions of tons of insecticides, herbicides, fungicides, and fertilizer around our homes to have the envy of the neighborhood – a perfectly green lawn(2). Interestingly, as interest in organic foods increases, there is a disconnect about using despised chemicals where our children and pets spend quality time. At the same time, water quality suffers as excess nutrients from lawns and agricultural fields are one of the largest sources of non-point pollutants impacting water quality in our streams, rivers, lakes, and the Chesapeake Bay.

Penn State’s Center for Turfgrass Science estimates that Pennsylvanians maintain about 2 million acres of grass (about 7% of the state’s surface area), and 1.4 million acres of this are home lawns (about 5% of the state). About two-thirds of Pennsylvania is in the Chesapeake Bay watershed and contains an estimated one million acres of lawns. 

Pennsylvania has set a goal of converting 10,000 acres of these lawns to woodlands or meadows. This seems like a small target and maybe you can help by learning how to convert lawns to woodlands and meadows by participating in a Penn State Extension Winter Workshop series entitled “The Woods in Your Backyard: Learning to Create and Enhance Natural Areas Around Your Home.” This webinar-based education program will use a full-color, 108-page publication by the same title to guide you through the process of developing and implementing projects to enhance your land’s natural resources. Register by Saturday, 18 January 2020 via the link above, or call 877-345-0691.

A principle focus of the workshop series is to learn about what happens to the rain and snow that falls on your land. There is a very strong link between land use and our water resources. Buildings, pavement, lawns, fields – human changes to the landscape – have affected natural water movement and water cycles Water now moves across the land and into streams in different ways and carries with it nutrients and pollutants.

Interestingly, most lawns are very poor at absorbing water – in fact, they are only a little better than pavement! Your lawn, because of grass root structure and soil compaction, can only absorb about 2 inches of water per hour compared to a forest that can handle 14 inches or more in the same time frame. In the ideal scenario, water does not move across the land – instead, it should move into the soil.

You may know that, among all our land uses, forests are best at managing water quantity and quality. That rain or snow falling on forested lands is more likely to percolate through the soil and in the process augment aquifers and control water flow into streams. As well, through this process, forest soils remove soil sediments and other pollutions. That about 56% of Pennsylvania is forested is a real benefit to our water resources.

Interestingly, tree cover in our urban landscapes is important to protecting and improving water quality as well. Individual tree crowns have the potential to intercept 10% to 40% of rainfall from an individual storm event depending upon season and tree species. This captured water then evaporates from leaves, twigs, branches, and stems, preventing it from entering storm water drains. The next time it rains, watch how much rain it takes to have water run down at tree bole. Sometimes it takes nearly a half-inch to wet the bole to the point that water flows to the ground. Trees are important to maintaining the functionality of a healthy water cycle.

If you have a lawn and an interest in reducing its impact on water quality, consider participating in the Woods in Your Backyard webinar series. If you do convert lawn to a meadow or woods, especially if you live in the Chesapeake Bay watershed, let your DCNR Bureau of Forestry Service Forester know, so your contribution counts toward the 10,000-acre goal.

  1. K. O’Costa. 2017. The American Obsession with Lawns. https://blogs.scientificamerican.com/anthropology-in-practice/the-american-obsession-with-lawns/
  2. Pesticides Industry Sales and Usage 2008 – 2012 Market. https://www.epa.gov/pesticides/pesticides-industry-sales-and-usage-2008-2012-market-estimates


The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management. For a list of free publications, call 800 235 9473 (toll free), send an email to RNRext@psu.edu, or write to Forest Stewardship Program, The Pennsylvania State University, 416 Forest Resources Building, University Park, PA 16802. The Pennsylvania DCNR Bureau of Forestry, USDA Forest Service, Penn State Extension, and the Center for Private Forests at Penn State, in Partnership through Penn State’s Department of Ecosystem Science and Management, sponsor the Forest Stewardship Program in Pennsylvania.