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Insights from Two Years of Community Science Monitoring in Darby Creek

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By Anna Willig, Watershed Conservation Research and Data Specialist

This March, the Darby Creek Community Science Monitoring Program (DCCS) — a collaboration between Willistown Conservation Trust, Darby Creek Valley Association, and Stroud Water Research Center — celebrated its second birthday! We officially launched the DCCS in March 2021 with two stalwart volunteers sampling at two sites in Berwyn. Today, 28 volunteers actively monitor 21 sample sites throughout the watershed, extending past Folcroft (Figure 1). The goals of the DCCS are to learn about the health of Darby Creek and its tributaries and identify key restoration sites through monthly water quality monitoring visits.

Figure 1

Water temperature is a key indicator of stream health. As water warms, it holds less oxygen and becomes inhospitable to aquatic wildlife. Trout fishes are one of the most sensitive groups to high water temperature and are a benchmark for healthy streams. If streams are too warm for trout, they are likely too warm for a host of other aquatic species, including mussels and macroinvertebrates. Water temperatures in Darby Creek are often too warm to support the reproduction and survival of trout species (Figure 2). The removal of trees along a stream, increases in development, and stormwater runoff can all contribute to warming streams. The best way to cool streams down is by reforesting stream banks, planting native plants, and designing stormwater management that allows rain to soak into the soil.

Another indicator of stream health is chloride concentration. Chloride is an ion that reflects the amount of salt in streams. Road salt is the main source of salt in streams and is increasingly recognized as a major pollutant. Chloride concentration varies widely between sites in Darby Creek (Figure 3). Generally, chloride concentrations are below the chronic exposure threshold set by the EPA, but are above levels that researchers have found harmful to aquatic organisms. While road salt is necessary for safe winter travel, limiting use and sweeping salt up after storms can reduce salt pollution in streams.

While temperature and chloride concentration reflect a host of threats to the health of Darby Creek, our volunteers have found good news in Darby Creek. One volunteer found a small population of freshwater mussels — which are uncommon in Darby Creek — at one sample site. Freshwater mussels are one of the most imperiled groups globally, and finding them in Darby Creek is a clear indicator that, despite development and pollution, the creek is still a critical resource deserving of protection. We are working with research groups to document and protect this precious group of mussels.

Figure 2. Water temperature in Darby Creek. Each dot represents a measurement taken by a volunteer. Each site is individually colored. The black line represents the maximum water temperature that supports the reproduction of trout.
Figure 3. Chloride concentration in Darby Creek. Each dot represents a measurement taken by a volunteer. Each site is individually colored.

We are incredibly grateful to all the fantastic volunteers who participate in this program. Through their dedication and enthusiasm, the DCCS has exceeded all expectations! The heart of this program is partnership, and we are thankful for support from Stroud Water Research Center and Darby Creek Valley Association. As the DCCS enters its third year, we are excited to build on partnerships, gain new insights, and leverage our volunteers’ data to improve the health of Darby Creek.

To learn more about the Darby Creek Community Science Monitoring Program, please visit their website or email Lauren McGrath (lbm@wctrust.org).

Introducing WCT’s Strategic Plan

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STRATEGIC PLAN | 2023-2025
Saving, Studying, and Sharing Land, Water, and Habitat


WHERE HAVE WE BEEN?

Land conservation efforts have been underway in the Willistown area for over 40 years. A satellite program of Brandywine Conservancy, formed in 1979, was known as the Willistown Area Conservation Program. With the encouragement of the community and key local conservation leaders, Willistown Conservation Trust (WCT) became an independent, community based land trust in 1996 with a committed and active Board of Trustees.

Using the Crum, Ridley, and Darby Creek watersheds as a boundary guide, WCT’s traditional program area encompasses 28,000 acres in Chester County and portions of Delaware County, and is located approximately 20 miles west of Philadelphia. Despite tremendous growth pressures that have converted many neighboring communities into vast tracts of sprawl development, the WCT program area still remains largely an oasis of green space.

Successful land conservation and stewardship paved the way for major growth within the organization. Since its founding, WCT has grown to include a suite of activities focused on science, stewardship, education, and community engagement. In addition to Land Conservation and Land Stewardship, these core activities include Bird Conservation, Community Farm, Watershed Protection, and Outreach and Education. This holistic approach to conservation explores the connections among land, birds, habitat, agriculture, and water, and educates the public on these connections.

Our land protection and stewardship efforts have been focused on the Willistown area; however, our work has a regional and national impact on conservation.

WHERE ARE WE GOING?

Over the next three years, as our land protection efforts thrive and new opportunities in our traditional program area diminish, we anticipate a growing emphasis on habitat conservation and restoration, education and community outreach. Within these conserved lands, we will use our growing body of research in bird, water, and agro-ecology to inform best practices and engage with the community to educate and inspire an ethos of conservation and care of our land, waters, and habitat where wildlife thrives. In addition, we will identify and consider land protection and conservation opportunities outside of our traditional program area that fulfill service gaps in surrounding communities and meet vital conservation needs, as we interact and collaborate with new communities and organizations.

We will continue to be a robust organization that is well established, broadly supported, and attracts leaders at the forefront of the conservation field. Our science-based programs will contribute research to inform conservation priorities and best practices on a regional, national and international scale. We will attract a diverse group of staff, Trustees, and volunteers who are deeply committed to the mission of WCT and bring a variety of perspectives, skills, and experiences to our work. We will offer robust community and educational programs that attract a wide swath of participants. We will use our established expertise and connections for the conservation benefit of communities outside our traditional area of focus.

To read our Strategic Plan in full, click the cover below:

Watershed Holiday Gift Guide

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Check out some of our favorite watershed-themed gifts by clicking the photos to shop!

And don’t forget to shop local! Use this store locator to order these books from a bookshop near you.

Books for Kids & Adults

1. Over and Under the Pond by Kate Messner


2. Song of the Water Boatman & Other Pond Poems by Joyce Sidman


3. Eager: The Surprising, Secret Life of Beavers and Why They Matter by Ben Goldfarb


4. Beaver Land by Leila Philip


5. The Book of Eels by Patrik Svensson


Activities, Clothing, and Jewelry

1. Mayfly T-Shirts


2. Aquatic Insects Activity


3. Caddisfly Jewlery


4. Mayfly Onesies

Help Keep our Drinking Water Clean by Reducing Salt Pollution

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By WCT Conservation Research and Data Specialist Anna Willig
Cover Photo by Jennifer Mathes

Salt levels, often measured as chloride concentration, have increased dramatically in U.S. streams since the 1940s, when it became common practice in the U.S. to salt roads during winter storms. The Pennsylvania Department of Transportation applies over 800,000 tons of road salt per year to state roads in addition to a similar amount applied by municipalities and private citizens. These numbers add up to over 1.5 million tons of road salt applied per year in Pennsylvania alone, all of which eventually ends up in waterways. Though salt is naturally present in streams at trace concentrations due to the weathering of rocks and soils, the insects, fish, mussels, and amphibians that live in local waterways cannot tolerate the spikes in salt concentration that occur in winter.

Road salts threaten streams in two ways. During and after a winter storm, salt concentrations in streams can skyrocket as salty meltwater rushes in, creating conditions that are acutely toxic for fish and other stream creatures. Salts also build up in soils and in groundwater, slowly entering streams throughout the year and resulting in chronically elevated salt concentrations. Many stream organisms, particularly freshwater mussels, cannot tolerate these long-term increases in salt concentration and gradually disappear from streams.  

In the streams in the Willistown region, we have seen both acute spikes in salt concentration and evidence of chronic build-up through our monthly water quality monitoring program  in the headwaters of Ridley, Crum, and Darby Creeks. Chloride concentration, an indicator of salt pollution, is typically highest in winter months, with a notable spike occurring in February 2021. The spike in February 2021 was caused by snowmelt actively washing road salts into the streams. Chloride concentrations remain elevated throughout the year, often exceeding 50 mg/L, the maximum salt threshold that the most sensitive stream organisms can tolerate. 

Figure 1. Chloride concentration, an indicator of salt contamination, in the headwaters of Ridley, Crum, and Darby Creeks. All the red points indicate sample sites in Ridley Creek, the green points indicate sample sites in Crum Creek, and the blue points indicate a sample site in Darby Creek. 

Salt contamination in streams also harms human health and infrastructure. Road salt can end up in drinking water wells and water supplies and often is not removed by water treatments facilities. As salts move through the environment, they can pick up other pollutants along the way, further contaminating streams and drinking water. Salts also speed up the corrosion of metal pipes and concrete, shortening the lifespan of infrastructure. Similarly, overuse of salt rusts and corrodes cars, leading to expensive repairs. 

While road salt is necessary for safety, here are some ways to reduce salt pollution:

  • Shovel before applying salt. Even on cold days, the sun can still melt a thin layer of snow and may take care of the problem for you.
  • Do not use more than the recommended amount of salt. Only 1 mug full of salt, or 12 oz., is required to melt a 20-foot-long driveway. Read the instructions on your bag to see how much you need. 
  • If you feel crunching when you walk, you applied too much! Salt only works when it dissolves, so all the crystals that you feel crunching underfoot are not actually melting snow and ice. 
  • After the snow and ice have melted, sweep up any remaining salt! Save it and apply it during the next storm. 
  • Report large piles of salt on roads to your local municipality.
  • Share information about road salt and encourage your neighbors to use less!

To learn more about how to reduce salt pollution, check out these resources: 

Capturing a Snapshot of Darby Creek

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By WCT Conservation Research and Data Specialist Anna Willig 

At the beginning of November, the Watershed Protection Program at Willistown Conservation Trust (WCT) partnered with the Darby Creek Valley Watershed Association (DCVA) and, together, enlisted four volunteers to conduct a sampling “blitz” in the Darby Creek Watershed. With the help of our determined volunteers, we collected samples from 19 previously unstudied sites in two hours (Map 1). Once the volunteers collected the samples, everyone met at the Upper Main Line YMCA’s Artisan Village to analyze water quality and discuss the results. 

Our Team (from left to right): Charlie Coulter (volunteer), Anna Willig (WCT, author), Lauren McGrath, Michelle Lampley (UMLY), Deirdre Gordon (volunteer), Lloyd Cole (volunteer), Dale Weaver (volunteer), and Aurora Dizel (DCVA).

Darby Creek originates in small tributaries along the Route 30 corridor from Easttown to Ardmore which flow together as the stream makes its way towards John Heinz National Wildlife Refuge where it meets the Delaware River. Throughout its length, Darby Creek flows through many highly developed areas, picking up road salts, fertilizers, and other pollutants from lawns, parking lots, and roadways. 

Despite these threats to the health of the stream, few community science studies have been completed to understand the health of Darby Creek and all of its tributaries. To shed some light on the water quality in the Darby Creek Watershed, the Darby Creek Community Science Monitoring Program was launched in 2021 in partnership with DCVA and under the scientific guidance of Stroud Water Research Center. To date, volunteers have been trained to collect high quality water chemistry data at 15 sites throughout the entire watershed every four weeks. 

The sampling blitz, which covered 19 sites in the headwaters of Darby Creek, allowed us to gain even more information on water quality while controlling for weather conditions. Rain, heat, and other weather conditions can impact water quality measurements. By sampling at a single point in time, we can capture differences in water quality between sample sites rather than changes caused by time. Many of the sampling sites were located on small tributaries, allowing us to study how fine-scale differences in land use upstream of the sample site can impact water quality. 

One of the goals of the sampling blitz was to understand salt pollution in the headwaters of Darby Creek. Road salts applied in the winter end up in streams as snow and ice melt and flow into the nearest waterway. Salts can build up in groundwater and soils, resulting in long-term increases in salt concentration in streams, a phenomenon known as freshwater salinization. Freshwater salinization is occurring across North America, and increases in salt concentration threaten the fish, insects, mussels, and other organisms living in streams. By measuring salt concentration in November, before winter road salts are applied, we capture baseline concentrations that reflect long-term buildup of salts in soils and groundwater. 

The results of the sampling blitz indicate that salt pollution (as measured by chloride concentration) varied widely across the headwaters of Darby Creek. Chloride concentration ranged from 34 ppm to 230 ppm (Map 1). The lowest chloride concentration was measured at Site 19, a site located on Camp Run, a small tributary to Darby Creek. The area that drains into Camp Run is predominantly agricultural land, with some sections of limited residential development and forest. By contrast, chloride concentration was highest at Site 2, a site on an unnamed tributary. The land that drains into Site 2 is similar to the size of the Camp Run watershed, but is much more developed. The tributary originates near a SEPTA train station and flows under Route 30, picking up salt and contamination from residential and commercial developments. Identifying pollution hotspots, such as Site 2, can help determine areas that should be targeted for future restoration. 

Map 1. Sample sites in the headwaters of Darby Creek. Each point represents the approximate location of a sample site and is colored by the chloride concentration at that site. Low chloride concentrations are represented by pale yellow, with high chloride concentrations represented by a dark red. The red box indicates the sample area.

Another indicator of water quality that volunteers measured was specific conductivity, which reflects how well electricity can move through water. Pure water is a poor conductor and has a low conductivity. As more ions are added to the water — from pollutants such as salts, fertilizers, and heavy metals — conductivity increases. Conductivity also varied greatly between sites, ranging from 325 to 967 μS/cm. While a higher conductivity indicates a higher concentration of pollutants, it does not indicate the type of pollutant. When chloride (which is an ion that increases conductivity) is compared to conductivity at each site, we found that there is a strong relationship between the two measurements (shown by the trendline), indicating that salt pollution is the biggest driver of conductivity in the headwaters of Darby Creek (Figure 1). However, there are two sites, Site 1 and Site 9, that do not quite follow the relationship. Further research is needed to understand what is driving conductivity at these sites. To learn more about conductivity, check out the State of Our Streams Report. 

Figure 1. The relationship between chloride concentration and specific conductivity in the headwaters of Darby Creek. Each point represents a chloride concentration and specific conductivity measurement taken at a sample site. Points are colored by site. 

The results of the snapshot survey indicate that water quality is highly variable in the headwaters of Darby Creek. Sites that drain the highly-developed Route 30 corridor, such as Site 2 and Site 5, have relatively poor water quality, while sites that drain areas with more open space, such as Site 18 and Site 19, have much better water quality. The variability in water quality within a small section of the Darby Creek Watershed highlights the deep connection between local land use and stream health. Protecting areas of open space, especially in small tributaries, is crucial to maintaining and improving water quality throughout the entire watershed. 

Additionally, increasing awareness of threats to water quality, such as winter road salt application, can help to reduce the impact on local streams. To reduce road salt contamination in streams, avoid over applying salt and sweep up any salt that remains after snow and ice have melted. The salt can be reused for the next winter storm, saving money and helping improve water quality! 

This snapshot survey was a pilot for a larger survey WCT, DCVA, and Stroud Water Research Center are hoping to conduct in the spring. We are deeply grateful to the Upper Main Line YMCA for hosting this event and to our fantastic volunteers who were willing and eager to explore new sections of stream to collect this data. The snapshot survey would not have been possible without our partnerships with DCVA and Stroud Water Research Center. If you are interested in joining our community science program, please contact Lauren McGrath at lbm@wctrust.org. 

OUR NATURE PRESERVES

Our nature preserves are open to the public 365 days per year from sunrise to sunset, providing natural places that offer peace and respite for all. Willistown Conservation Trust owns and manages three nature preserves in the Willistown area - Ashbridge, Kirkwood and Rushton Woods Preserve. We maintain these lands for the … Learn more about our nature preserves.

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HELP US SAVE, STUDY, AND SHARE OTHER WAYS TO GIVE If you would like to make a gift of securities, such as stocks, bonds, or mutual fund shares, please contact us at 610-353-2562 for instructions. For more information on ways to give, please contact us at development@wctrust.org  … Donate Today

WHERE WE WORK

The work of the Willistown Conservation Trust is concentrated on 28,000 acres of Willistown Township … read more