Return the Historic Conditions

What Does “Restoring Historic Conditions” Mean?

When European settlers arrived in Lancaster, they cleared the land for agriculture and built mill dams along the waterways to power colonial industry.  Due to these human activities, large amounts of soil washed down to natural low points – waterways in valley bottoms. Mill dams located every mile or two along those waterways held back these soils and led to significant build-up.

The tall, muddy stream banks that are a common sight around here aren’t the natural condition. They are the result of “legacy sediment” build-up from the past 300 years that didn’t exist for thousands of years before.  These tall banks are also unstable. They are constantly eroding – polluting our waterways – and Lancaster County is losing massive quantities of high quality soil every year as a result.    

A Look Back – And Ahead

What lies beneath all this eroded sediment?  Lost wetland ecosystems!  It’s estimated that Lancaster has lost more than 50% of its original wetlands.  Wetlands are celebrated for their ability to filter and store water, sequester carbon, and support incredible biodiversity.

Rich, dark wetland soils are exactly what scientists found under the legacy sediment, with carbon dating to between 300 – 10,000 years ago.  These wetlands existed as a stable ecosystem for thousands of years – and the soil is full of seeds!  We can identify wetland plant species from the seeds.  This gives us an idea of what the landscape looked like in the past, and how we can help restore historic conditions.
 
History is important. By looking at past and current conditions of a stream segment, we can make informed decisions about how to help.  This work respects the natural and cultural history of the land, creating opportunities for environmental learning, community healing, and long-term sustainability.

How We’re Doing It

By peeling back the “cap” of sediments impairing the stream, we restore the floodplain to its historic condition and expose long lost wetland soils.  The creek is no longer trapped by high eroding banks – it is reconnected to the floodplain.  Water is able to expand, contract, and connect with cool groundwater below.  Natural springs may be daylighted for the first time in centuries! 

The best places to do this are where historical wetlands existed and where stream bank erosion is highest.  Often, erosion “hot spots” are connected to mill damming and sediment build up. 

With a nod to the past, we plant a mosaic of wetlands, meadows, and forest riparian buffers along the stream. The result is “rewilding” – restoring healthy habitats and natural stream flows by letting nature lead the way.  

Human connections are essential.  By understanding our history, we can make informed decisions for the future – where clean water and green spaces abound.

Remove Legacy Sediment
Rewild the Landscape

Uncovering the Past to Restore the Future

Legacy sediment tells the story of how our landscapes were changed — and why they need healing. These images show how sediment is studied, dated, and removed to bring back the natural flow of water, rebuild habitats, and return the land to its original form.

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