In 2002 , two of the project’s scientists, Drs. Robert Walter and Dorothy Merritts, identified the incised nature of modern streams found throughout the mid-Atlantic region as the product of ubiquitous mill damming activity throughout the 18th-19th centuries. The research team determined that reservoirs upstream of tens of thousands of milldams, built one after the other as uplands were cleared and converted to farmland, had filled with fine sediment by the late 19th century. As water-powered milling became obsolete, milldams fell into disrepair and began to fail during storms.  Others were breached intentionally because low-head dams are safety hazards, barriers to fish passage, and causes of water quality impairment. 

   Red triangles represent the number of mill dams across York, Lancaster and Chester Counties in 1840
Traditional mill dam still intact in _______ filled in with fine sediment

Merritts, Walter, and colleagues identified bank erosion from incised streams upstream of breached milldams as a primary source of fine-grained sediment and nutrients from many tributary streams in the mid-Atlantic region.  


Picture




In addition, scientists determined that many of the valley bottoms now filled with up to 20 feet of millpond mud had formerly consisted of extensive wetland landscapes once dominated by sedges and rushes. Evidence of these original wetland landscapes is pronounced and widespread at BSR and throughout the mid-Atlantic region.  It is found as a dark organic-rich layer of sediment buried beneath historic millpond sediment, the latter of which typically is light brown to red-brown in this region.  Often rich in seeds and other organic matter, the wetland soil is preserved in most places because it was buried almost instantaneously when valley bottoms were flooded behind milldams.
These interpretations represent a paradigm shift that catalyzed the new approach to aquatic resource restoration implemented at Big Spring Run (BSR) in Lancaster County, Pennsylvania.  This approach aims to revive critical ecosystem functions, such as carbon retention and nutrient cycling, that a riparian wetland environment offers. 
In 2011, historic millpond sediment—dubbed “legacy sediment”--was removed from about 1.5 km of valley bottom along the BSR valley bottom, giving the original ecosystem a chance to re-emerge. Today a thriving wetland ecosystem is home to a wide variety of native plant species and wildlife. Ongoing monitoring at BSR indicates that the restored area experiences little to no erosion and traps small amounts of fine sediment delivered from upper, unrestored tributaries.

For more information about the design and engineering at BSR as well as incoming results regarding the success of the restoration, please visit the Methods and Results & Goals pages. 

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Motivation
Research published in the January 2008 issue of Science has reshaped perspectives on the origin and evolution of Mid-Atlantic valley bottom aquatic ecosystems, causing a reassessment of the fluvial geomorphic boundary conditions that influence stream restoration practices in the region.

This website presents ongoing results of a novel, multi-year valley bottom restoration experiment that tests the efficacy and efficiency of this design for improving aquatic and riparian habitats, ecosystem services and functions, water quality improvement, nutrient and sediment load reductions, and stormwater retention, among other objectives. 

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The BSR Restoration
 

In 2002 , two of the project’s scientists, Drs. Robert Walter and Dorothy Merritts, identified the incised nature of modern streams found throughout the mid-Atlantic region as the product of ubiquitous mill damming activity throughout the 18th-19th centuries. The research team determined that reservoirs upstream of tens of thousands of milldams, built one after the other as uplands were cleared and converted to farmland, had filled with fine sediment by the late 19th century. As water-powered milling became obsolete, milldams fell into disrepair and began to fail during storms.  Others were breached intentionally because low-head dams are safety hazards, barriers to fish passage, and causes of water quality impairment. 

   Red triangles represent the number of mill dams across York, Lancaster and Chester Counties in 1840
Traditional mill dam still intact in _______ filled in with fine sediment

Merritts, Walter, and colleagues identified bank erosion from incised streams upstream of breached milldams as a primary source of fine-grained sediment and nutrients from many tributary streams in the mid-Atlantic region.  


Picture




In addition, scientists determined that many of the valley bottoms now filled with up to 20 feet of millpond mud had formerly consisted of extensive wetland landscapes once dominated by sedges and rushes. Evidence of these original wetland landscapes is pronounced and widespread at BSR and throughout the mid-Atlantic region.  It is found as a dark organic-rich layer of sediment buried beneath historic millpond sediment, the latter of which typically is light brown to red-brown in this region.  Often rich in seeds and other organic matter, the wetland soil is preserved in most places because it was buried almost instantaneously when valley bottoms were flooded behind milldams.
These interpretations represent a paradigm shift that catalyzed the new approach to aquatic resource restoration implemented at Big Spring Run (BSR) in Lancaster County, Pennsylvania.  This approach aims to revive critical ecosystem functions, such as carbon retention and nutrient cycling, that a riparian wetland environment offers. 
In 2011, historic millpond sediment—dubbed “legacy sediment”--was removed from about 1.5 km of valley bottom along the BSR valley bottom, giving the original ecosystem a chance to re-emerge. Today a thriving wetland ecosystem is home to a wide variety of native plant species and wildlife. Ongoing monitoring at BSR indicates that the restored area experiences little to no erosion and traps small amounts of fine sediment delivered from upper, unrestored tributaries.

For more information about the design and engineering at BSR as well as incoming results regarding the success of the restoration, please visit the Methods and Results & Goals pages.