Monday, July 18, 2022

Tropical Storm Agnes in the Allegheny River Valley

If you have been following our series on the effects of Tropical Storm Agnes in the various river drainages of Pennsylvania, you may have noticed a pattern of devastating damage followed by the resilient recovery of the people and properties affected.  In many cases recovery included construction of reservoirs and other flood control projects to protect against future flooding events.  As part of the planning and construction of these facilities, archaeology was often required to mitigate damage to possible archaeological sites.  As a result, many new sites were discovered and both new and previously known sites were more thoroughly excavated than would have been possible without the flood control initiative. 

 The Allegheny River Valley was positioned differently than the other river basins previously featured in this series.  The St. Patrick’s Day flood of 1936 caused devastation throughout the region and hit Pittsburgh particularly hard.  More than 63 inches of snow received over the course of the winter began to melt and combined with the increased rain on March 16 led to a major flooding event.  Described here by the U.S.Geological Survey’s Water Supply Paper 799:

“During the period March 9-22,1936 there occurred in close succession over the northeastern United States . . . two extraordinarily heavy rainstorms. The depths of rainfall mark this period as one of the greatest concentrations of precipitation, in respect to time and magnitude of area covered, of which there is record in this country. At the time of the rain there were also accumulations of snow on the ground over much of the region that were large for the season. The comparatively warm temperatures associated with the storms melted the snow and added materially to the quantities of water to be disposed of by drainage into the waterways . . . the total quantity that had to be disposed of . . . ranged between 10 to 30 inches.”

The Allegheny and Monongahela Rivers converge at the point in Pittsburgh to form the Ohio River.  The water crested more than 20 feet over flood stage to 46 feet which left much of downtown Pittsburgh underwater, and millions of dollars of damage in its wake.  It also left 62 dead, more than 500 injured and approximately 135,000 people homeless throughout the region.  This was the impetus for Congress to pass the Copeland Act in 1938 allotting the funds for the construction of levees and reservoirs in the Allegheny and surrounding drainages. 

Area of the Kinzua Dam Project

The Kinzua Dam and Allegheny Reservoir were a product of this construction and are credited with significantly lessening the impact of Agnes on Pittsburgh thus fulfilling its promised function. The lessened impact still created considerable damage to Pittsburgh with the rivers cresting at 35.8 feet.  The Pennsylvania Historical and Museum Commission had recently opened the Fort Pitt Museum in 1969 on Pittsburgh’s “Golden Point”.  It was inundated with 45 inches of water damaging the structure as well as the artifacts and exhibits causing it to close for almost two years for repairs.  Other towns and cities throughout the region were severely impacted by Agnes.  The town of Freeport in Armstrong County is situated between the Allegheny River and Buffalo Creek and had what one resident, PaulWhite, described as “double flooding”.  

Unfortunately, the construction of the Kinzua Dam also had a significant downside.  It caused the displacement of Pennsylvania’s last group of Indigenous people.  The Seneca that occupied approximately 10,000 acres of their Allegheny Territory had been deeded this land as part of the Treatyof Canandaigua, signed by President George Washington in 1794. The Allegheny River was known as the “Beautiful River” or “Good River” in Seneca language Ohi:yo’.  It was the source of food, plants, and medicines for thousands of years and culturally significant to the Seneca Nation peoples living in the Allegheny Territory and those living on the Cornplanter Grant.    After many years and many legal battles, the government eventually used the right of eminent domain to claim the land and removed the approximately 600 Tribal members living there to the Allegheny Reservation in Salamanca, New York

The Seneca Nation Onödowá'ga:' (oh-non-doh-wah!-gawh!), which means "People of the Great Hill” have created an exhibit that relays their story of this event to educate others at their museum (

Soon after the passage of the Copeland Act the Pennsylvania Historical Commission(PHC) examined areas that would be impacted by construction of the dam.  In 1941 a Civilian Conservation Corp (CCC) project was conducted on the Pearl Smith farm located two miles north of Kinzua, Warren County.  The investigation led to the recovery of materials representing activities from the Middle Woodland period  (1000- 2400 years ago).  Additional archaeological investigations were conducted in 1942 in a midden area associated with the village component of the Sugar Run site (36WA0002). Unfortunately, this work was halted due to the outbreak of WWII and call to duty of the excavators.  This multi- component site has been linked to similar sites in New York and Ohio, demonstrating complex social networks.

Blades made of Flint Ridge Chert from the Sugar Run Village Site (36WA0002), from the collections of The Pennsylvania State Museum.

Corner-Notched Points made of Onondaga Chert from the Sugar Run Village Site (36WA0002), from the collections of The State Museum of Pennsylvania.

The construction of the levees and reservoirs that resulted from the Copeland Act predate the enactment of The National Historic Preservation Act of 1966 which required (and continues to require) the consideration of impact on archaeological and historic resources from federally funded construction projects.  Hence, there was no legal requirement for archaeological investigations prior to implementation of the flood control projects.  Fortunately, in 1950 the Carnegie Museum initiated the Upper Ohio Valley Archaeological Survey.  Its purpose was to create “a basic framework of information covering all of man’s time in the area” (Mayer-Oakes, 1955).  This comprehensive survey laid the groundwork for our understanding of the precontact and historic occupations of the area.   

Kinzua Phase Pot found in Cold Spring, New York and curated by the Seneca Iroquois

National Museum Salamanca, New York. (Myers, 2019)

The National Park Service sponsored survey and testing in the area that would be inundated by the Allegheny Reservoir in September and October of 1958 by William A. Ritchie (New York State Museum) and Don W. Dragoo (Carnegie Museum).  Most of the initial survey was confined to surface testing because the land was still privately owned and much of it was being actively farmed.  After the land   was purchased by the U.S. Government, a more thorough investigation could be conducted.  One site of particular interest was the Kinzua site (36WA0053).  Only a few chert flakes (debitage) had been found at this location during the initial surface survey.

Stanley Lantz of the Carnegie revisited the site in 1965, as the dam was nearing completion.  A large portion of the site had already eroded away by the lapping waters of the rising reservoir, revealing pottery sherds associated with the Allegheny Erie Tradition (A.D.1100-1300) (Lantz 2020).  Full scale excavations commenced in 1965 with the mechanical removal of topsoil exposing the precontact indigenous occupation.  The remaining portion of the site, approximately 1,200 m2, was excavated and found to be a stockaded village complete with houses, hearths, storage pits and artifacts attributed to a community whose economy was based on agriculture, hunting, and fishing.  The Kinzua site, like many other sites within the Allegheny Reservoir  impoundment area are now under water.  Thankfully a few of them were thoroughly excavated with National Park service funds providing a window into Pennsylvania’s past. 

Tropical Storm Agnes’s effects in western Pennsylvania were devastating but they were less severe than they might have been due to construction of flood control projects following the deadly St. Patrick’s Day flood 36 years earlier. The construction of similar flood control projects in central and eastern  Pennsylvania were not implemented, for the most part,  until after those communities suffered the wrath of Agnes.

If you missed our Learn at Lunch program on the impact of Agnes on cultural resources,  the link is provided here to watch the recorded program.


Dragoo, Don W.

1965       Archeological Investigations in the Kinzua Area of the Allegheny Basin of Western Pennsylvania During 1965, Manuscript on file, The Pennsylvania State Museum Section of Archaeology, Harrisburg, Pennsylvania.

Lantz, Stanley W.

2020       The Allegheny Erie Tradition. In The Archaeology of Native Americans in Pennsylvania Volume 2 edited by Kurt W. Carr, Christopher A. Bergman, Christina B. Rieth, Bernard K. Means, and Roger W. Moeller, pp. 465 – 482, University of Pennsylvania Press.

Mayer-Oakes, William J.

1955       Prehistory of the Upper Ohio Valley; An Introductory Archeological Study. Carnegie Museum Anthropological Papers, No. 2. Pittsburgh, Pennsylvania.

McConaughy, Mark A. and Janet R. Johnson

2003       Sugar Run Mound (36Wa359) and Village (36Wa2): Hopewell/Middle Woodland in Warren County, Pennsylvania. Foragers and Farmers of the Early and Middle Woodland Periods in Pennsylvania, Recent Research in Pennsylvania Archaeology, No.3, PHMC, Harrisburg, Pennsylvania.

Myers, Andrew J.

2019       The Cold Spring Pot: An Allegheny Erie Tradition Vessel Found in the Upper Allegheny Drainage. In Pennsylvania Archaeologist 89(1):25 – 44.

Making History: The Heinz History Center Blog


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For more information, visit or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .

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