Presentation given by Steve Sylvester on June 4, 2012 at the Third Annual Choose Clean Water Conference.

1. Legacy Sediment Problems in Pennsylvania
What to do about those dammed eroding
streams?
Pennsylvania
Department of Environmental Protection
Pennsylvania Legacy Sediment Workgroup
Jeffrey Hartranft
Bureau of Waterways Engineering and Wetlands
Division of Wetlands Encroachments and Training

2. Presentation Outline
• Legacy Sediment Examples and Definition
• A New Best Management Practice to Address the Problem
• Big Spring Run Demonstration Project
• Aquatic Resource Restoration Potential

3. Big Beaver Creek – Lancaster County, PA
Photos Courtesy Franklin & Marshall College

4. Conoy Creek – Lancaster County, PA

5. Mountain Creek - Cumberland County, PA

6. Seneca Creek, Maryland
Photo Courtesy Franklin & Marshall College

7. Impact of Water-Powered Mills
on Sediment Storage
New dam
Courtesy Franklin & Marshall College

8. Typical Mill Dam and Valley Cross Section
Riparian Zone
Time 2
Time 1
Upland Upland
Modern Substrate
Soil Soil
Colluvium
Legacy Sediment
Colluvium
Natural Wetland Soils Natural Wetland Soils
Gravel Gravel
r Gr
ate oun
Bedrock oun
dw dw
a te
Bedrock
Gr r
DEPARTMENT OF ENVIRONMENTAL
PROTECTION

9. Typical Valley Cross Section Evolution
Riparian Zone
Time 1
Time 2 - Dam Breached
Time 3 - Dam Breached
Upland Modern Substrates Upland
Soil Legacy Sediment Legacy Sediment Soil
Colluvium
Colluvium
Natural Wetland Soils Natural Wetland Soils
Gravel Gravel
r Gr
ate oun
Bedrock oun
dw dw
a te
Bedrock
Gr r
DEPARTMENT OF ENVIRONMENTAL
PROTECTION

10. Mill density map based on the 1840 US Census and county boundaries.
More than 65,000 waterpowered mills existed along U.S. streams in the year 1840.
The greatest density of mills occurred in the Piedmont and Ridge and Valley
physiographic province.
http://www.depweb.state.pa.us/chesapeake

11. Dam Locations from 1860-1870 Era Atlases
http://www.depweb.state.pa.us/chesapeake

12. Photos Courtesy Franklin & Marshall College

13. http://www.depweb.state.pa.us/chesapeake

14. Natural Streams and the
Legacy of Water-Powered
Mills
January 18, 2008 pp. 299-304
Robert C. Walter and Dorothy J. Merritts
Franklin & Marshall
College
Lancaster, PA

15. Riparian Zones With Incised Channels
Riparian Zone
Rural • Bank Trampling • Stormwater Sub-
& Urban
• Upland Soil Erosion • Impervious surfaces &
Agriculture • Few Trees / Shrubs • Few Trees / Shrubs Urban
• Manure • Wastewater discharges
Flood Flow
Legacy Sediment
Legacy Sediment
Gro
und
w ater ter
dwa
Natural Wetland Soils Base Flow Natural Wetland Soils Gro
un
Gravel Gravel
r Gr
ate oun
dw
Bedrock Gr
o un dw
a te
r
Bedrock
Conventional wisdom DEPARTMENT OF ENVIRONMENTAL
PROTECTION

16. Typical Existing Condition
Flood
Flow
1850 AD (210PB) Existing Root
Zone
Bank-full Flow Legacy Sediment
~300 - ~10,000 BP (14C)
Hydric Paleosol Base Flow Hydric Soils
Gravel
Bedrock Modern, inset bar
• Legacy sediment stored in valley bottoms predominantly was established by the combined
effect of increased sediment supply from uplands and sediment trapping behind ubiquitous
dams in many watersheds of the mid-Atlantic Region. (Walter and Merritts, 2008)
• Conceptual models linking channel condition and sediment yield exclusively with modern
upland landuses are incomplete for valleys impacted by mill dams (Merritts, et al. 2011)
• Streambanks represent a significant sediment and nutrient source in watersheds where
channels have incised through legacy sediment. (Walter, Merritts, Rahnis, 2007; 2010)

17. Big Spring Run - Type Section
Courtesy Franklin & Marshall College

19. Ecological Restoration Guiding Principles
Address ongoing causes of degradation.
• Restoration efforts are likely to fail if the sources
of degradation persist.
• It is essential to correctly identify the causes of
degradation and eliminate or remediate them.
• Understanding a stream’s evolutionary trajectory is
relevant to correctly diagnosing the problem, as well as
to developing restoration approaches that are likely to
be sustainable.
“… understanding the legacy sediment problem is the
first step in proposing a fix.”
Bay Journal, March, 2007. Alliance for the Chesapeake Bay.

20. Natural Floodplain, Stream and Riparian Wetland
Restoration Best Management Practice
Conceptual Design
Typical Existing Conditions Proposed Restoration
Flood
Flow
Existing Root Flood Flow
Zone
Bank-full Flow Legacy Sediment Bank-full Flow
Restored Hydric Paleosol Base Flow Root Zone
Hydric Paleosol Base Flow Hydric Soils
Gravel Gravel
Bedrock Modern, inset bar
Bedrock
Natural Valley Morphology

21. Typical Existing Conditions Restoration
9/13/2011 9/23/2011
Natural Valley
Morphology
Photos Courtesy Franklin & Marshall College

22. Flow Direction

24. 2007 Banta Restoration Site, Lititz Run – Lancaster Co.
Photo Courtesy Franklin & Marshall College

25. 2007 Banta Restoration Site, Lititz Run – Lancaster Co.
Photo Courtesy Franklin & Marshall College

26. 2007 Banta Restoration Site, Lititz Run – Lancaster Co.

27. 2011 Banta Restoration Site, Lititz Run – Lancaster Co.

28. Big Spring Run Natural Floodplain, Stream and
Riparian Wetland Restoration Project
We have assembled a multidisciplinary team of biologists,
ecologists, engineers, geomorphologists, geochemists, landowners,
restoration practitioners, and construction experts (Hartranft et al,

29. USGS 015765195 Big Spring Run near Mylin Corners, PA

33. Funding Partners
PA Department of Environmental Protection
Franklin & Marshall College
US Environmental Protection Agency
US Geological Survey
Joseph V. Sweeney
Chesapeake Bay Commission
Foundation for Pennsylvania Watersheds
PA Fish and Boat Commission
Lancaster Farmland Trust
Big Spring Run ca. 1930
Photo Courtesy Franklin & Marshall College

34. Monitoring and Research Partners
Franklin and Marshall College
US Geological Survey
US Environmental Protection Agency (ORD & Region III)
PA Department of Environmental Protection
PA Fish and Boat Commission
Johns Hopkins University
Elizabethtown College
Penn State University
Big Spring Run ca. 1930
Photo Courtesy Franklin & Marshall College

35. Legacy Sediment Workgroup Collaborator
Organizations and Individuals
PA Department of Environmental Protection
PA Fish and Boat Commission
PA Department of Transportation
US Environmental Protection Agency
US Geological Survey
Chesapeake Bay Commission
Pennsylvania Environmental Council
Franklin and Marshall College
Penn State University
Lafayette College
Landstudies Inc.
Rettew and Associates
CDM
Chesapeake Bay Foundation
PA Farm Bureau
American Rivers
PA State Association of Township Supervisors
Joseph Sweeney