WILLISTOWN CONSERVATION TRUST

DONATE

WCT Receives “Protect Your Drinking Water” Grant

By

By: Kate Etherington & Lauren McGrath

Willistown Conservation Trust (WCT) is thrilled to announce that our Watershed Protection Program has been awarded a $10,000 grant from Aqua Pennsylvania and the Pennsylvania Environmental Council (PEC). At a ceremony held on April 18, 2025, Executive Director Kate Etherington and Director of Watershed Protection Lauren McGrath proudly accepted the award, which will fuel the next phase of our critical work safeguarding the health of our local waterways — and, ultimately, the water you drink.

Since 2017, WCT’s Watershed Protection Program has made significant strides in understanding how land conservation directly impacts the health of small-order streams. Through rigorous, long-term monitoring, our team has gathered a wealth of data illustrating the powerful connection between human activity and water quality. These insights culminated in the 2022 publication of The State of Our Streams — a landmark report that drew on expertise across WCT’s Watershed, Bird Conservation, Agroecology, Land Protection, and Stewardship departments to reveal the intricate web linking land use, wildlife, and water health.

This new grant funding will enable WCT to publish a second edition of The State of Our Streams, incorporating three additional years of water chemistry data along with new findings from benthic macroinvertebrate surveys conducted between 2018 and 2023. Benthic macroinvertebrates — small, spineless creatures visible to the naked eye — play a vital role in freshwater ecosystems and are key indicators of stream health. Their presence (or absence) can tell us a great deal about the overall condition of our watersheds.

In addition to the macroinvertebrate analysis, the updated report will feature expanded chapters on sensitive wildlife species recently documented in our local streams, including freshwater mussels (Unionidae), river otters (Lontra canadensis), American mink (Neogale vision), and American beavers (Castor canadensis).

We are deeply grateful to Aqua PA and PEC for their continued partnership and support, and we are honored to stand alongside the other six grantee organizations working tirelessly to protect and restore the waters that sustain both people and wildlife. You can learn more about the grant and other grantee projects here.

Freeze-thaw Erosion

By

By: Sarah Barker

Rivers and streams are very dynamic, changing physically and chemically with every passing minute. Erosion, the process of sediment wearing away over time, plays an essential role in this endless shaping and reshaping. The movement of sediment in freshwater systems is incredibly important for water quality and habitat health. Soil binds to nutrients and salts, trapping them and preventing them from washing into streams. When severe weather events or abnormal conditions carry away large amounts of sediment these pollutants are freed into the water column, impacting wildlife and drinking water. The rate of erosion is also heavily influenced by the amount of development in the surrounding watershed. As land around a stream is developed, runoff increases and erosion worsens.

Often, erosion is considered as a consequence of storms. However, in humid, temperate climate regions like Southeastern Pennsylvania, the most influential form of erosion actually occurs in the winter, called freeze-thaw erosion. This type of erosion happens in natural cycles when extreme differences in temperature, from below freezing to above freezing, occur over a short period of time. As water freezes in the soil it expands, loosening soil particles, when it warms up suddenly after a cold spell this ice melts, creating space between particles and causing them to wear away more quickly. The impact of freeze-thaw erosion worsens after winter rain as the flow of water over already weakened banks accelerates soil loss. Development near water only makes the issue worse, providing hardened surfaces for runoff to speed into flowing water like a race track, bringing more and more loosened soil down with it. It is projected that these freeze-thaw cycles will only increase as climate change continues to modify normal weather patterns towards extremes.

Erosion on the side of a stream bank in Darby Creek.

There are other factors that can contribute to the severity and frequency of freeze-thaw cycles as well. One of the most important is the presence of vegetation along stream banks. Roots hold soil together, slowing erosion in general, however, the density of plants matter too! A 2006 study found that dense plant cover insulates banks from extreme temperature shifts over the course of a day, protecting soil from more frequent freeze-thaw cycles. Stretches of bank without dense canopy or understory were much more vulnerable to daily changes in temperature and experienced as many as four times the number of freeze-thaw cycles as densely planted sections (Wynn & Mostaghimi, 2006).

The local geology and predominant soil type of a region also significantly influence the impact of freeze-thaw erosion. Fine sediment types like clay, silt, or loam tend to be much more susceptible to this process than coarser varieties. In addition, the Piedmont region of Southeastern Pennsylvania is more heavily impacted compared to other kinds of regional geology, like the Atlantic Plain (Inamdar et al., 2018). At Rushton Woods Preserve, an ongoing erosion study documenting the progressive changes within an erosion feature called a headcut may show just how severe freeze-thaw cycles can be when these factors combine. 

Starting in June 2024, 40 pieces of  rebar, called erosion pins, were hammered into the sides of a headcut at Rushton Woods Preserve to measure the rate of soil movement due to erosion. The study area is mostly fine sediment under a canopy of beech trees, but there is sparse understory to help secure soil. Several recent freeze-thaw erosion events were documented this winter where freezing nights were followed by winter rainfall, leading to rapid movement of soil. Some erosion pins were completely buried in frozen sediment, so that they could not be measured until the next warm day. Data is still being collected, but these winter freeze-thaw measurements are already significant to the study!

Erosion is a complicated natural process, and scientists are still untangling the many mechanisms that may play a role in its impacts. However, there are some things that are very clear. Planting dense vegetation along stream banks combats severe and frequent freeze-thaw cycles. In addition, proper stormwater runoff management is vital for keeping soils stable as winter rainfalls increase in frequency. Freeze-thaw cycles themselves are normal for this area, but it is important to make sure that the rate of erosion doesn’t outpace what local streams can handle. Protecting the land around waterways is essential for healthy habitat and clean water!

References:

Inamdar, S., Johnson, E., Rowland, R., Warner, D., Walter, R., & Merritts, D. (2017). Freeze–thaw processes and intense rainfall: The one-two punch for high sediment and nutrient loads from mid-atlantic watersheds. Biogeochemistry, 141(3), 333–349. https://doi.org/10.1007/s10533-017-0417-7 

Luffman, I., & Nandi, A. (2019). Freeze-thaw induced gully erosion: A long-term high-resolution analysis. Agronomy, 9(9), 549. https://doi.org/10.3390/agronomy9090549 

Wynn, T. M., & Mostaghimi, S. (2006). Effects of riparian vegetation on stream bank subaerial processes in southwestern Virginia, USA. Earth Surface Processes and Landforms, 31(4), 399–413. https://doi.org/10.1002/esp.1252 

Choose Native Plants: Our New Responsibility Made Easy by a Local Techie

By

By Blake Goll, Education Programs Manager at Willistown Conservation Trust

Hummingbird clearwing moth on wild bergamot. Photo by Aaron Coolman

Do you remember excitedly chasing the glow of fireflies through your yard on summer evenings, as they traced those distinctive J-shapes in the sky? Do you have fond memories from your youth of a cheery robin’s song waking you from your slumber each morning? Maybe you recall spending hours in the garden, courageously catching bumblebees in your little bug box and marveling over those gorgeous monarch butterflies sporting their striking Halloween colors of orange and black. Did you flip rocks in the woods and delight over the prehistoric-looking salamanders you found peering back at you? Did your grandmother show you which berries you could pick from the brambles at the edge of the yard and pop in your mouth for a juicy snack? Children nowadays stand to lose these eminent memories from their identities, and in fact, many already have.


The lurid scene we’ve fostered over the past human lifetime is a monotonous patchwork of largely lifeless manicured lawn—nonnative Kentucky bluegrass—dotted with whatever ornamental trees and shrubs we randomly chose from the nearest nursery. We dump more diabolic chemicals—pesticides, herbicides, fertilizers—onto our yards than some agricultural areas do, and we fearfully say “yes” to any mosquito busting Joe Schmoe who vows to eliminate the pesky critters from our sacred domains. We oblige to mowing our yards weekly so as not to be cast out of our neighborhood tribe. Meanwhile, monarch butterflies are on track to be listed under the Endangered Species Act, insect populations as a whole have suffered 80% declines in the past few decades, and birds have disappeared by almost 30% in the past 50 years. Myriad factors contribute to these harrowing losses of biodiversity, from agricultural intensification to pesticides, but the underlying element is pervasive loss and degradation of habitat.

Monarch butterfly on purple coneflower. Photo by Blake Goll


Fortunately, our yards hold the keys to restoring some of this lost habitat and with it, those precious childhood memories. Every one of us, whether you have just an apartment balcony or a full 4-acre lawn, can contribute significantly toward this new responsibility of reviving our shared ecosystem. It’s a simple formula that starts with the plants. Native plants. Zach Leahan, local Malvern resident and a Director at PwC, recognized this five years ago. He was growing disgruntled about following the traditional lawn care path and superficially choosing plants based only on aesthetics. Something didn’t feel right. Soon he happened upon the Willistown Conservation Trust’s homeowner habitat initiative, which provided him with resources on the importance of native plants, including shortlists of beneficial plants. He began viewing his property in a new light, with the intricate connections between plants, insects, birds, and ourselves at the forefront of his mind.


Native plants, because they evolved with local wildlife over millennia, are the pillars of a finespun web of life—attracting and supporting our native pollinators and other insects that in turn support the birds and the rest of the food chain. (Invasive plants, on the other hand, can wreak havoc on our ecosystems because they often outcompete natives once they’re free from the diseases and insects that keep them under control in their countries of origin.) As Zach delved deeper into the benefits of native plants and started analyzing their ecological attributes, he was determined to honor those childhood memories of chasing fireflies and picking raspberries. In addition to incorporating native plants into his own yard, he used his background in technology to make the native plant journey more accessible to everyone.

Song sparrow on native goldenrod. Photo by Aaron Coolman


He founded ChooseNativePlants.com, a mobile-friendly web application that helps PA residents find native plants that fit the needs of their home. Complete with intelligent search options from plant color to pollinators attracted, the website features beautiful images of Pennsylvania natives and acts like a “knowledgeable neighbor” ready with the perfect plant. While there are now many native plant lists and resources, this app’s standout feature is that it bridges the gap between native plant discovery and purchase, listing over twenty all-native nurseries in Pennsylvania. Zach envisions a community where we all plant with purpose.


Replacing mowed lawn areas with native wildflowers and grasses—and embracing the buzz they attract is a great step toward restoring the balance to our environment. Landscaping with native trees and shrubs in well-planted beds where leaves are allowed to rest is paramount as well. (90% of caterpillars that develop on trees drop to the ground below for part of their life cycle.) Native plants are the answer. The insects they attract are the proof. If we simply continue as we have, we stand to lose nature. If we lose nature, we lose ourselves. Choose native plants.

Visit choosenativeplants.com to find which native shrubs, plants and flowers from Pennsylvania have the right conditions to flourish in your garden. ChooseNativePlants.com is an open-source project with a volunteer team. This team is preparing for the next major update in the spring. If you have interest in supporting the project, sign up for a “Code for Philly” account to join the project’s Slack channel.

Zach Leahan, Director at PwC and founder of ChooseNativePlants.com.


Willistown Conservation Trust is an accredited nonprofit land trust that focuses on 28,000 acres in Chester and Delaware Counties. It has permanently conserved 7,500 acres since 1996 and offers six renowned programs for public engagement and research: Bird Conservation, Community Farm, Education and Outreach, Land Protection, Stewardship and Watershed Protection. For more habitat at home resources and inspiration, visit WCTrust.org and follow @WCTrust.