By Lauren McGrath, Director of Watershed Protection Program, Anna Walsh​,​ Conservation Data and
GIS Specialist and ​Sarah Barker​, Watershed Program Technician

The Darby and Cobbs Creek Community Science Program (DCCCS) was established in 2021 by the Darby Creek Valley Association and Willistown Conservation Trust with technical support from Stroud Water Research Center. While the initial goal of this collaborative project was to supplement the existing water chemistry data set collected by WCT Watershed Protection Program staff in Ridley, Crum, and Darby Creeks, this program has evolved into much more. DCCCS aims to create a network of training and mentoring opportunities to empower the residents and neighbors of Darby and Cobbs Creek watersheds to collect high quality environmental data and become advocates for healthy water in their communities. Detailed monitoring data also helps to identify pollution sources and areas of the landscape that pose a risk to watershed health and integrity.

At the time of publication of this article, the DCCCS program has 37 active sites across the Darby and Cobbs watershed. Each site has a dedicated volunteer who goes out every four weeks to collect data. In a watershed that is home to over half a million people, it is crucial to understand the relationship between human activity on the landscape and the function of these waterways. The data collection efforts of DCCCS volunteers have been making great strides towards aiding that understanding.

The network of DCCCS volunteers has captured the influence of overapplication of road salts and other contaminants on the landscape, as well as the impact of climate-related issues such as the severe drought during the fall of 2024. Additionally, the discovery of sensitive wildlife by volunteers is particularly notable. In 2024, a large bed of breeding freshwater mussels was documented as a result of volunteer sampling and exploration. Over the summer, the Watershed Team, led by Dr. Erik Silldorff of the Delaware RiverKeeper Network, and supported by community volunteers and students, completed a second year of freshwater mussel surveys in the headwaters of Darby Creek. To date, over 1,000 mussels (including two species) have been identified! This incredible community science discovery was shared at the Ecological Society of America conference in Baltimore, MD this past August.

The DCCCS website has also acquired a brand new time-slider tool to visualize the data collected by volunteers. Every month, when volunteers upload their data to the DCCCS portal, it is added to the website, where it is publicly accessible. Now, each site can be observed both in comparison to other sites within the study area, as well as how it changes over time, allowing you to watch how each winter’s salt application ahead of winter storms influences the water chemistry at every site. The relationship between land use type and water quality data is complicated, but several trends have become apparent in the data set: as impervious surfaces increase, so do the negative impacts on water quality. However, as forest cover increases, regardless of impervious surfaces, water quality improves.

These patterns are best reflected in water temperature, conductivity (water’s ability to transmit electricity as a result of dissolving minerals and contaminants from the surrounding environment), and chloride (primarily an indicator of road salt) data. This means that where there is more undeveloped open space, as is found in the northern portions of the watershed, planting more native trees and shrubs along the stream can support healthier waterways. In the sections of Darby and Cobbs Creek closer to Philadelphia, where undeveloped open space is limited, actions like reducing the amount of road salt applied to the landscape and sweeping up road salt after winter storms, may be more impactful. The key to a healthier watershed lies in the collaboration between individuals, organizations, and municipalities across the Darby and Cobbs watershed, from the headwaters all the way to John Heinz National Wildlife Refuge. Visit the website, darbycreekcommunityscience.com, to see the data from the DCCCS program, and check out the new edition of the State of Our Streams Report to learn more about the relationship between land and water!

The critical work of the DCCCS Program volunteers was recognized through a grant from the Pennsylvania Department of Environmental Protection Environmental Education Grants Program. The award will support the continued education and empowerment of the Darby and Cobbs Creek communities, and highlight the data collected by the DCCCS program, what it means, what questions are raised, and actionable steps participants can take to positively affect the health of their local waterways. Three workshops across Chester and Delaware Counties are being scheduled for early spring 2026.

By Lauren McGrath Director of Watershed Protection Program, Anna Walsh​,​ Conservation Data and
GIS Specialist and ​Sarah Barker​, Watershed Program Technician

Aquatic ecosystems, like the headwaters of Ridley, Crum, and Darby Creeks studied in the State of Our Streams (S.O.S.) report, are facing a devastating reality: if human activity continues unchecked, it will result in the destruction of this invaluable resource. Studies around the world have shown that climate change and human development have had disproportionate impacts on aquatic systems, causing as high as an 85% decline of all aquatic habitat.¹ As this ecosystem declines and species are lost, it becomes weaker in the face of future disturbances. At the state level, the Pennsylvania Department of Environmental Protection’s Integrated Water Quality Report published in 2024 shows that across Pennsylvania, 34% of stream miles are considered impaired for one or more uses, an increase over the 2022 report. More locally, 79% of stream miles in Chester County and 95% of stream miles in Delaware County are considered impaired.²

Since 2018, WCT’s Watershed Protection Program has monitored water quality at ten sites in the headwaters of Ridley, Crum, and Darby Creeks, visiting these sites once every four weeks to collect data. The goal of the program is to understand local trends in water quality and how water quality relates to land use. To provide a biological context to water quality data, we have also conducted surveys of stream insects, freshwater mussel, and diatoms. The updated S.O.S. report contains findings from all of this data, as well as data from the Darby and Cobbs Creek Community Science Program and observations of local wildlife.

In the study area covered in the 2025 edition of the S.O.S., Ridley, Crum, and Darby Creeks are considered impaired for their designated aquatic life uses, meaning water quality is not high enough to support the full diversity of fish and other organisms that should live in the stream. The data presented in the S.O.S. showcases the intricate relationship between activity on the landscape and the reaction of the waterway. From the compelling complexities of water chemistry, to the biology of stream insects and diatoms, similar patterns are emerging from the data: the region’s streams have warm waters, high chloride levels (from the application of road salt before winter storms), and elevated nutrients. However, there is a relationship between concentrated land protection and restoration efforts: where there is more development, water temperatures rise, as does the impact of road salt and nutrients. Where there is more protected open space and, importantly, more forest cover, these impacts are reduced (Figure 1).

Over the last seven years, Watershed Protection Program staff have witnessed the increasing instability of these systems first hand. Extreme flooding, like that of 2021’s Hurricane Ida, has caused substantial erosion and contamination. The historic drought of the fall of 2024, where no rain fell in the month of October, led to dangerously low flows and elevated chloride levels – an indication of salt build up in the soils and groundwater. It is difficult to overstate the impact that events like these have had on the wildlife that call this region home. Predictions are that climate change-driven instability will continue to be a significant hurdle for aquatic ecosystems to clear as we move into the future.

Alongside the observed realities of climate change, Watershed staff could have never predicted that we would document so many unexpected new wildlife species in these watersheds over the last seven years. Despite the combined pressures of human expansion and increasing climate instability, this region retains an incredible ability to recover and support sensitive and declining populations – from freshwater mussels, one of the most at risk groups of organisms on the planet, to the American river otter, which had been driven almost to extinction in Pennsylvania due to poor water quality.

Our hope is that this report will help community members throughout the region understand the science behind the stream research and offer tangible suggestions for ways to improve watershed health. We know that we can improve the health of our streams when we work together. Life depends on it.



References:
World Wide Fund for Nature. (2024). Living Planet Report 2024 [Online report]. WWF. Retrieved [July 15, 2025], from Living Planet Report website.
Pennsylvania Department of Environmental Protection. (2024). Pennsylvania integrated water quality report 2024 [Interactive report]. Commonwealth of Pennsylvania. Retrieved [July 15, 2025], from Pennsylvania DEP website.

Funding for the S.O.S. publication was awarded through the “Protect Your Drinking Water” grant program, administered by the Pennsylvania Environmental Council with funding from Aqua, an Essential Utilities Company.

By: DeJenae Smith

Living in a densely populated city, the sight of a stray chip bag near a drain or illegally dumped trash is like finding a pebble in cobblestone. But what if there was pollution happening that we couldn’t easily perceive?

Water is one of the world’s largest and most valuable resources, and yet our society’s current structure has a strong reliance on a supply that actively pollutes water bodies – plastics. Just over twenty years ago, the term ‘microplastics’ was first used in a scientific publication and since then, an entire branch of research has since blossomed and exploded. Scientists have researched and found the presence of microplastics in the air, water, soil, and many aquatic and terrestrial organisms – including humans.

Microplastics are defined to be between one and five millimeters in size and are derived from a wide variety of sources. Primary microplastics enter the environment micro-sized, like tire dust or microbeads found in personal care products. Secondary microplastics are from larger plastics being broken down into smaller particles. Both plastic types can easily find their way into our streams and rivers: from directly polluting water with non-biodegradable waste to washing synthetic materials down our drains and sinks through everyday activities. Beyond the direct harm of ingesting microplastics, these materials can also carry harmful chemicals with them, leading to unknown complications for organisms’ wellbeing.

Since April of this year, I have been working alongside Willistown Conservation Trust (WCT) and PolyGone Systems to better understand the contamination of microplastics in our waters and further the advancement of technology for microplastic removal and recovery. After months of planning and development, PolyGone and WCT officially deployed a microplastic-collecting device (affectionately referred to as the ‘Plastic Hunter’) this July in Ridley Creek at WCT’s Ashbridge Preserve. I have been conducting a 9-week study of the microplastics collected over time, along with testing the Plastic Hunter’s performance.

Working with PolyGone, I have gained a lot of experience on the technical component of science, along with developing the skills necessary for an independent researcher. Through their diverse and specialized teams, I have better learned how to better communicate with other scientists, as well as through interdisciplinary channels.

Experimental results that are easily digestible to me may not be the same for an engineer, or even my lab partner – and learning how to translate such information to other people has been a great experience about perspective and its importance of having diversity. As our team worked on the completion of a prototype, it quickly became clear to me how valuable having others present to critique and discuss was, and that aspect played a strong role in the visualization and creation of this year’s Plastic Hunter (Figure 1).

Alongside soft skills, I have also developed significantly as an independent researcher and lab technician.

In comparison to my research experiences in a college-setting, I have had much more autonomy and played an important role in the designing of my research project and collection of data. As the current Plastic Hunter has gone through design changes from previous years, I encountered many new challenges, often having to find creative solutions and work-arounds (Figure 2).

While working on a separate project, I was also considered a valued lab member and thus became very familiar with the space and how to conduct key tasks and operate equipment. After the departure of my fellow interns for the school year, I now frequently manage the lab space on my own as I complete the day’s given experiments or sample processing (Figure 3, Figure 4, Figure 5).

While I work on my technical skills in the lab with PolyGone, it is with WCT that I am able to effectively apply and adapt my approach in the environment, which has undoubtedly been the best part of my co-op experience. Where one may precisely model and predict results in the lab, I enjoy having each of those expectations wiped-out by the inconsistencies and unpredictably inherent to the natural world.

Being mentored by Lauren McGrath, Anna Willig, and Sarah Barker of the Watershed Team, alongside the wonderful individuals in other WCT departments, I have started to comprehend the true multidimensionality that is our environment. Alongside conducting water chemistry and analysis, I have learned much about Pennsylvania’s and the world’s natural history, from environmental justice to case studies in wetland ecology. As I approach the end of my co-op and enter my junior year, this internship has truly been a transformative experience for me. Before, I used to focus solely on the analytical component to science and research, but my internship with PolyGone and WCT has drastically changed that view for me. As I continue my education and grow as a professional, I now aspire to become a naturalist alongside a scientist. Instead of taking from the environment for the sake of my research, I wish to connect deeper with natural landscapes and use my results in pursuit of palpable change to conserve and improve the state of our water, air, and biota (Figure 6).

References

How Do Microplastics Enter The Environment?. (2022, January 28). Ocean Diagnostics. Retrieved August 15, 2025, from https://oceandiagnostics.com/ocean-diagnostics-blog/post/how-do-microplastics-enter-the-environment

Issac, M. N., Kandasubramanian, B. (2021, March 2). Effect of microplastics in water and aquatic systems. Environ Sci Pollut Res, 28(16), 19544 – 19562. https://doi.org/10.1007/s11356-021-13184-2

Kye, H., Kim, J., Ju, S., Lee, J., Lim, C., Yoon, Y. (2023, March). Microplastics in the water systems: A review of their impacts on the environment and their potential hazards. Heliyon, 9(3). https://doi.org/10.1016/j.heliyon.2023.e14359

Lai, C. (2022, July 20). Microplastics in Water: Threats and Solutions. Earth.org. https://earth.org/microplastics-in-water/

Microplastic Contamination: Sources, Effects, and Solutions. (2025, August 1). Biology Insights. Retrieved August 15, 2025, from https://biologyinsights.com/microplastic-contamination-sources-effects-and-solutions/

Savchuk, K. (2025, January 29). Microplastics and our health: What the science says. https://med.stanford.edu/news/insights/2025/01/microplastics-in-body-polluted-tiny-plastic-fragments.html

Targhan, H., Evans, P., Bahrami, K. (2021, December 25). A review of the role of hydrogen peroxide in organic transformations. Journal of Industrial and Engineering Chemistry, 104, 295-332. https://doi.org/10.1016/j.jiec.2021.08.024

Thompson, R.C., Courtene-Jones, W., Boucher, J., Pahl, S., Raubenheimer, K., Koelmans, A.A. (2024 September 19). Twenty years of microplastic pollution research – what have we learned?. Science, 386(6720). doi: 10.1126/science.adl2746

Types of Pollution. (n.d.). Science Facts. Retrieved August 14, 2025, from https://www.sciencefacts.net/types-of-pollution.html

Water Quality and the Global Microplastic Crisis. (n.d.). Safe Piping Matters. Retrieved August 14, 2025, from https://safepipingmatters.org/2019/03/20/water-quality-and-the-global-microplastic-crisis/

Yale Experts Explain Microplastics. (2020, December 1). Yale Sustainability. Retrieved August 13, 2025, from https://sustainability.yale.edu/explainers/yale-experts-explain-microplastics

Yee, M.S., Hii, LW., Looi, C.K., Lim, WM., Wong, SF., Kok, YY., Tan, BK., Wong, CY., Leong, CO. (2021 February 16). Impact of Microplastics and Nanoplastics on Human Health.  Nanomaterials, 11(2), 496. https://doi.org/10.3390/nano11020496

By: Lauren McGrath

American river otters (Lontra canadensis) are a highly sensitive and beautiful stream resident. Known for their charismatic personality and cartoonishly adorable faces, these adorable predators play an important role in managing aquatic ecosystems as well as showcasing ecosystem health.

River otters range from about 2.5 to 5 feet in length, and can reach weights up to 33 pounds. In the weasel family, (scientifically known as the mustelid family), otters have a long, muscular body, streamlined for swimming, with short legs and webbed feet and are apex predators in stream ecosystems. With a rapid metabolism, river otters need to eat frequently and their small, square skull is heavily muscled, allowing them to rapidly snap their jaws around their fast moving prey while underwater.

River otters are highly sensitive to changes in water chemistry, making it a valuable indicator species for aquatic ecosystem health. As a top predator in freshwater environments, river otters depend on clean, well-oxygenated water to support their diverse diet, which includes fish, mussels, clams, crayfish, crabs, frogs, birds’ eggs, birds and reptiles such as turtles. Changes in pH, dissolved oxygen, and nutrient levels can affect prey availability and disrupt the delicate balance of the aquatic ecosystems otters inhabit. Additionally, pollutants, such as heavy metals, pesticides, and industrial runoff, can bioaccumulate in their bodies through the food chain, leading to health issues including reproductive problems and organ damage leading to population declines. Because of their dependence on high-quality water, even subtle chemical shifts can impact otter populations, highlighting the importance of restoring and maintaining clean waterways for their survival. 

In addition to being indicators of healthy ecosystems, river otters play an important role in the environment. River otters are a keystone species in aquatic ecosystems: as a predator, they regulate prey populations, their foraging and den building behaviors modify habitat structure for other wildlife, and their presence in the ecosystem influences community dynamics. Most importantly, they serve as indicators of ecosystem health, and contribute to overall biodiversity and ecosystem resilience. Protecting and conserving otter populations and their habitats is essential for maintaining the ecological balance and functioning of freshwater ecosystems.

These incredible animals were present in most waterways across North America prior to the arrival of European settlers. As a result of trapping for their valuable pelts, habitat destruction, and widespread declines in healthy ecosystems due to human development, river otters disappeared from waterways across most of Pennsylvania by the early 1900’s, however focused reintroduction efforts in the 1980s led to a population rebound in northern Pennsylvania. Currently, river otters are protected in Pennsylvania.

In 2023, river otters were documented in the headwaters of Ridley Creek in southeastern Chester County. It was the first time they had been documented in this waterway in over 100 years. There are known populations further west in Chester County, notably in the Brandywine watershed. The arrival of these highly sensitive animals is an indication that the work of Willistown Conservation Trust and other local conservation and watershed organizations throughout the region has provided space for sensitive wildlife, such as otters, to return. Continued monitoring of water quality will ensure that we maintain the high standards that these incredible animals need to thrive!

Funding for this project was awarded through the “Protect Your Drinking Water” grant program, administered by the Pennsylvania Environmental Council with funding from Aqua, an Essential Utilities company.

By: Lauren Carroll

Hello and happy Creek Week! My name is Lauren Carroll, and I am a senior at Conestoga High School. During May of our senior year, we are given the opportunity to intern at an external non-profit or company in a field of interest/our major in college. I am lucky enough to be doing my internship with the Watershed Department here at the Willistown Conservation Trust! During this month I have learned so much about work after graduating high school, as well as our earth. I have been able to learn so much so fast, partially because of how much time we spend out in the field. 

For example, I, along with a fellow intern, Clare, and our supervisor, Anna, performed a mini-stream study on the upstream Ashbridge sensor area. This study was conducted in hopes of finding out why the sensor station located in Ridley Creek was reading high levels of conductivity. Conductivity is the measure of how easily electricity can move through water. To begin the mini-study, we first made a map (Map 1) and chose 13 sites of interest to sample. We made sure to choose sites in the mainstream of Ridley Creek, in the outflow of the wastewater tributary, where these waterways meet, downstream, and on the various parts of the left and right stream banks. At each of these sites we collected 125 mL bottles of water and also recorded the temperature of the water, the time we took the sample and the conductivity of the water in that specific location. 

Later, in the lab, we tested chloride levels, which relate to conductivity, as well as nutrient levels such as nitrates and nitrites at select sites.  This is because there is a wastewater treatment plant that deposits water into this stream from a tributary, and we know wastewater typically contains high levels of nutrients and has higher conductivity as well. These nutrients are harmful to the overall health of our streams in abundance.  The word nutrients may sound positive, but it actually is not. They cause, in excess, an event called eutrophication, which is extreme plant growth, most often algae. This causes dissolved oxygen levels to decrease, which harms aquatic life. Mass fish die-offs can occur because they are suffocated. Interestingly, while we were in the creek taking samples, we could see the difference between the right bank and the left bank’s algae growth due to the nutrients carried by the wastewater tributary. The right bank was brown, and the left bank was a vibrant green which shows this difference in algae growth. 

Learning how to take water samples properly, measure conductivity in the field, record data, perform tests for chloride and nutrients in the lab and interpret the data has been such a beneficial experience. Throughout my internship, I have also been able to learn about other fascinating things going on in our waterways that are less chemistry-focused, such as taking a look at our Freshwater Mussel population and seeing their effect on water quality as well as their use as an indicator species. Another animal that can be used as an indicator species is the River Otter. When you see freshwater mussels and otters in a stream, you know it is happy and healthy! 

Overall, I have loved looking at our waterways through all the different lenses, from things as small as a molecule of NO3 to as large as an Otter! I have learned so much about how everything interacts and balances each other out, as well as how to help our waterways to be healthier and happier. I hope you learn just as much this week as I have and can help us keep our waterways healthy and happy!

Funding for this project was awarded through the “Protect Your Drinking Water” grant program, administered by the Pennsylvania Environmental Council with funding from Aqua, an Essential Utilities company.