Birch Run Dam Removed, Conococheague Creek Reborn

Project type: Dam Removal, Stream Restoration, Revegetation 
Location: Michaux State Forest, Franklin PA [open Google map]
Status: Completed, open to public


It was a truly inspirational moment. From the top of that 65-ft mound, peaking between a pair of middle-aged black locusts, I could see the entire one-mile length of the former reservoir—now a lush, green valley with a crystal-clear trout stream bubbling through it.

Just over a decade ago that valley was the muddy bottom of a lake behind a leaky dam wall. Then after the dam's decommission it was merely a sand pit with a drainage ditch, 53 acres of nothing much. Now, with the help of a patchwork of initiatives and organizations, it is revolving back to a forest, a stream, and a functioning ecosystem.

Satellite image, 2003 (Google Earth)

Satellite image, 2007 (Google Earth)

Satellite image, 2012 (Google Earth)
It was my first visit to a large-scale restoration site. I could hardly contain my excitement, scrambling down the blue netting of one wall segment and up the other. A year of books and articles and videos offered less inspiration and understanding that than single afternoon atop the former Birch Run Dam. That moment reaffirmed for me that I was on that right path; that humankind could positively affect biodiversity, nutrient availability, and other criteria for ecosystem health; that there is a science that directly serves Mother Nature: Restoration Ecology.

History
  • 1934 – Birch Run Dam built.  Private contractors completed the 700-ft wide, 65-foot high earthen wall. The resulting Chambersburg Reservoir, named for the nearby town it supplied, could hold up to 337 million gallons from its 14.7 square-mile watershed.
  • 1980's – Structural concerns.  DEP begins monitoring seepage.  Primary concerns were public safety and infrastructure.  By 2002, Birch Run Dam was number one in the PA DEP's list of dams to be removed.
  • 2004 – Reservoir drained.  However, heavy rainfall still filled behind the dam, even with drains open, as was the case with Hurricane Ivan in September of 2004.
  • 2005 – Dam breached.  Contractors (Gleim Environmental) removed the center portion of the dam wall, 77,500 cubic yards of material, or nearly half of the wall's total mass. [1]  100ft of channel stabilized.  Netting laid over remaining wall segments to prevent erosion.  Revegetation and habitat restoration were not major objectives at this stage. [2]
  • 2006 – Revegetation of reservoir's southwestern half
  • 2013 – Revegetation of northeastern half and Stream Restoration

Restoration
I. Erosion Control
  • Water levels drasitically rose and fell during storms and droughts, throughout the reservoir's 70-year lifespan. This "sloshing" caused erosion of the shoreline.
  • Over this peroid, an estimated 189,628 metric tons of silt deposited on the reservoir bed, according to a 2009 study. [3]
  • With the dam breached, this silt (and the remaining wall segments) was in danger of washing downstream and damaging infrastructure. Therefore, a "stable stream" was one of the project's goals. Engineers dredged a 100ft channel, widened it to 16ft, fortified the banks with rocks and sowed grasses


II. Aquatic Habitat Creation

  • During dam removal, habitat was not a primary concern. Aside from stabilizing the stream through the dam breach, the remainder of the nearly mile-long reservoir was left to drain on its own. The result was a uniform flow that lacked variation in depth, obstructions, vegetation cover, and ultimately aquatic habitat
  • Reintroducing native trout to the Conococheague Creek was the objective of a second work phase (2013-2014).
  • Gleim won another contract, this time to build log jams, cross vanes and J-hooks. Twenty-three in total, the mini-waterfalls of these structures help oxigenate water and form deep, cool spots for trout.
  • Streamside trees were also planted to shade waters. Trees also provide habitat for insects, which in turn provide food for trout.



III. Revegetation

  • Closely related to both above objectives is establishing trees.
  • The first phase was in 2006 in the southern half of the reservoir. Areas prone to erosion were priority, namely the reservoir's sloping edges and remaining dam wall segments. Fast-growing, deep-rooting black locust seem to be prevelant here, as well as crown vetch. European Alder dominate the wetlands below the dam. I also identified staghorn sumac, tree of heaven, tulip tree and various willows along the stream, possibly volunteers. According to Roy Brubaker of the DCNR:
The initial planting was kind of thrown together to reveg the most erodible areas after the dam deconstruction and the foresters in charge wanted it to be a woodcock demonstration area. I'm not crazy about their use of the European alder and we hope to at some point begin replacing it with native palustrine alder, willow, dogwood, and viburnum species. We had significant failures in initial plantings, but have recruited some volunteer pine over the same time period, so a lot of what you see is a lot of nature helping itself out, as well as continued persistence on the part of the foresters here. [4]

  • The second phase was in 2013-14, led by local chapters of Trout Unlimited. [5]  The remaining northern half was planted with sycamore, speckled alder and tulip poplar along the stream, and red oaks and white spruce on drier ground.
  • According to the Michaux State Forest auto-tour guide, total plantings were 13,100 trees by a contractor and 16,100 by Bureau of Forestry personnel and volunteers. [6]




Check out these other erosion control projects:
 - Wilkets Creek, Ontario

And reforestation projects:

 - Lehigh Gap, PA

 - Longleaf Pines in Louisiana and Texas



References

[1] Gleim Environmental Group website, "Project Map." [link]
[2] James J. Manuel, "Implementing a Long-term Monitoring System on the Restored Conococheague Creek following Removal of Birch Run Dam," (Masters Thesis, Shippensburg University) 2009. [link]
[3] James J. Manuel, "An Investigation of the Recently Drained Chambersburg Reservoir," Middle States Geographer, 2009, 42: 1-8. [link]
[4] Roy Brubaker, Private Correspondence. July 28, 2015.
[5] Bob Marchio, "Trout Unlimited Chapters to Help with Stream Restoration at Michaux State Forest," The Evening Sun, December 22, 2012 [link]
[6] Pennsylvania DCNR, "Self-Guided Auto Tour; Michaux State Forest." [link]

Robert Kline, "Removal of Large Dams and Site Restoration: Breaching of Birch Run Dam." [link]
(A brief list of the benefits and the lessons learned from the dam removal)

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