The George B. Stevenson Dam: Taming the First Fork
The Man Behind the Name
George Bond Stevenson was born in Lock Haven in 1889. He was mayor of the city from 1935 to 1937, which put him in office during the 1936 flood. He then served in the Pennsylvania State Senate from 1939 to 1962, representing a district that included Cameron County, and sat on the State Flood Commission. According to the Senate Library, he stayed committed to flood control for the rest of his career. DCNR credits him with promoting the legislation that authorized the dam. The project was first called the First Fork Dam and was later renamed in his honor.
Engineering a Barrier
The engineering firm Gannett Fleming Corddry and Carpenter designed the dam. In the summer of 1952, Lehigh University's Fritz Laboratory tested a 1:32-scale model of its outlet works. Construction ran from 1953 into the mid-1950s.
The finished dam is a rolled earth-fill embankment:
- 1,918 feet long and 166 feet high
- 940 feet wide at its base
- A 211-foot concrete control tower with two 37-ton sluice gates
- A 16-foot tunnel that carries the First Fork through the dam
How It Works
In normal times, the dam holds a small lake (about 145 acres, per DCNR). In a flood, it can store 75,800 acre-feet of water, about 24.7 billion gallons. At that level, the lake spreads to about 1,470 acres and stretches eight miles up the valley, holding the runoff from 243 square miles of mountains.
One of Four
The dam is part of a four-reservoir plan to protect the West Branch of the Susquehanna. The others are the Alvin R. Bush Dam at Kettle Creek State Park, Curwensville Dam, and the Foster Joseph Sayers Dam at Bald Eagle State Park. Congress authorized the federal part of the plan, including Curwensville Dam, in the Flood Control Act of September 3, 1954, and Pennsylvania agreed to operate its dam in coordination with the Corps dams. Together the four control 1,163 square miles of drainage. During floods, all four follow instructions from the U.S. Army Corps of Engineers' Baltimore District.
A Lake Worth Visiting
Flood control was the reason for the dam, but the lake it created was too good to waste. That lake became Sinnemahoning State Park.
See the dam that tamed the First Fork. Book Resting Eagle Cabin. It's about 25–30 minutes away.
More Sinnemahoning history: The Lumber Era | The Floods | Sinnemahoning State Park
Sources
Pennsylvania Senate Library, George Bond Stevenson biography: https://www.library.pasen.gov/people/member-biography?id=5538
PA DCNR, History of Sinnemahoning State Park: https://www.pa.gov/agencies/dcnr/recreation/where-to-go/state-parks/find-a-park/sinnemahoning-state-park/history
PA DCNR, Sinnemahoning State Park Recreational Guide: https://elibrary.dcnr.pa.gov/PDFProvider.ashx?action=PDFStream&docID=3244697&docName=SINN_GuideText&nativeExt=docx&revision=2
PA DCNR events calendar, "Flood Control in the First Fork": https://events.dcnr.pa.gov/event/flood-control-in-the-first-fork-a-historical-overview-and-film-showing
Lehigh University Fritz Laboratory report, "Tests of a 1:32 model of a proposed outlet structure for First Fork (Sinnemahoning) Dam," June–September 1952: http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=2628&context=engr-civil-environmental-fritz-lab-reports
USACE fact sheets: Curwensville Lake: https://usace.contentdm.oclc.org/digital/api/collection/p16021coll11/id/3549/download ; Alvin R. Bush Dam: https://usace.contentdm.oclc.org/digital/api/collection/p16021coll11/id/3555/download
PA DCNR, Sinnemahoning State Park main page: https://www.pa.gov/agencies/dcnr/recreation/where-to-go/state-parks/find-a-park/sinnemahoning-state-park