Historical Ecology of Philadelphia

The Philadelphia area was built upon tidal marshes of the Delaware River estuary. Roughly half of all tidal marshland in the Delaware Estuary was historically impounded for the development of agricultural or urban land. As early as the 1680s, arable tidal marshland was diked by European colonists for farmland, until many of the dikes (embankments to prevent inundation of land) were abandoned or neglected in the 19th Century as many farmers left the East Coast for farmland in other regions of the US. Following long periods of impoundment and impoundment breaching, tidal freshwater marshes frequently transform into tidal saltwater marshes as ocean water is introduced to the system, while other former wetlands fall in sea level, converting to open water.

While there are few active diked farms on the East Coast, Philadelphia is one of a few cities which are the result of impoundment of wetlands. By the 19th Century, Philadelphia’s tidal estuary system was utilized for industry. Ships and barges were soon replaced by rail yards, slaughterhouses, and trash yards. The Delaware and Schuylkill Rivers were used for all varieties of transportation, but were especially instrumental in the city’s waste management and sanitation economy.

River Ecology and Pollution

Lower Schuylkill River, 19th Century

On January 17, 1924, John Frederick Lewis delivered an address to the City Parks Association of Philadelphia at the Historical Society of Pennsylvania at 1300 Locust Street. Lewis was employed in various positions in urban and park planning throughout his career, and was introduced by Eli Kirk Price to speak on “The Redemption of the Lower Schuylkill.” Lewis describes in detail the idyllic and verdant banks of the Schuylkill, and quotes the poet Thomas Moore, who in 1824 wrote:

“Alone by the Schuylkill a wanderer rov’d. 
And bright were its flowery banks to the eye…

The stranger is gone—but he will not forget
When at home he shall talk of the toils he has known,
To tell with a sigh what endearments he met
As he strayed by the waves of the Schuylkill alone.”

Illustration accompanying Lewis’ address

Lewis then describes the “river as it is”: “To our left, without even turning around, we see at our feet immediately below the double decked bridge at Callowhill Street, an enormous dump heap, to which ashes, waste paper, tin cans, old bottles, and domestic waste, are carted across this magnificent Parkway, between the Art Gallery at the west and the Cathedral at the east, and then loaded into barges to be hauled downstream and dumped upon the banks of the river, less the dust and waste paper which blows off on the journey and can be seen floating upon the surface.”

Lewis writes that the domestic and industrial waste of nearly 1,000,000 people clogged the river, lamenting waste from sewage, slaughter houses, oil refineries, chemical factories, and paint works.

Thomann, “River Ecology and Man” (1972)

A 1972 report on the Delaware estuary explains that water quality becomes progressively poorer moving from Trenton to Philadelphia, with lower saturation of oxygen and greater values of nitrogen and phosphorus. The report notes: “The cost of improving our environment must be squarely recognized and such costs must compete on a priority basis with other social demands made on the economy of a region… The lack of specific environmental goals for a particular river system is probably one of the most difficult problems to deal with in water quality management.”

Air Pollution: Regulation and Enforcement

By the 1940s, Philadelphia’s air quality was poor from the burning of coal for electric power generation, the concentration of polluting industries in the city, and emissions from automobiles. In 1948, the Philadelphia Department of Public Health founded a Division of Environmental Health, which included Air Pollution Control. Though Air Pollution Control conducted air quality tests in the interest of surveying harmful particles from soot and burning materials, air quality was not uniform across the city. Overall, the tests confirmed that unhealthy amounts of these particles existed in Philadelphia’s air, with some areas being more greatly impacted. 

Under pressure from the National Air Pollution Control Administration and Pennsylvania’s Air Pollution Commission, in 1969, Philadelphia adopted a new Air Management Code, lauded as “the toughest air control bill in the nation.” The Code allowed the city to establish air quality objectives and enforce them by exercising its land use restrictions, and by banning some enterprises in the city entirely.  In his 1972 analysis of the first three years of the Code, James D. Keeney found that several of the “Top 15” air polluters in Philadelphia that were dependent on consumer marketing could be threatened with publicity. However, he also found that virtually all public polluters retained immunity to local enforcement tools, and that it was difficult to secure compliance from image-indifferent corporations.

Solid Waste: Management Strategies

South Philadelphia Incinerator, 1950s

In the 1950s, Philadelphia exchanged open dumping for sanitary landfills. While an improvement on open dumping which fostered populations of vermin, sanitary landfills still tended to contaminate groundwater and generated flammable methane gas. In 1956, the city government drafted a set of regulations for private dumps and landfills. In addition to dumps and landfills, the city opened four new waste incinerators. While incinerators had existed in Philadelphia since the late 19th Century, they were more costly to maintain than dumps or landfills, and produced noxious smoke. A combination of new, privately-owned dumps, landfills, and incinerators comprised a new waste management system in Philadelphia in the 20th Century.


Pollution, 1970: Who, What, Where?

“Pollution” has fallen out of common parlance in discussion of climate change and ecology, but in April of 1970, Earth Day organizers cited “pollution” as a main reason for protest. Nebulous and ill-defined, “pollution” referred to air pollution, water pollution, and solid waste. As a catch-all term for anthropogenic environmental degradation, mobilizing rhetoric about “pollution” did not require activists to make direct or pointed claims at individual actors or parties; rather, “polluters” at large were accused. Despite Thomann’s 1972 report and assertion that ecological goals would need to be considered along with economic and social factors, activists and legislators alike decried “pollution.” In January 1970, the Pennsylvania Governor’s Office released a statement which declared that all pollution from State buildings, facilities, and activities would be ended by September of that year. Earth Week activists condemned all pollution, and sought to draw attention to air pollution, water pollution, and solid waste, particularly litter.

In order to highlight air and water pollution in Philadelphia, Penn Earth Week activists organized an Ecology Bus Tour to “see, smell Top 10 Air Polluters in Action.” The bus tour was rated “R” because of the “visually obscene nature” of the tour. The bus tour visited ten of the city’s “Top 15” polluters, in an homage to the tour of Philadelphia’s historic “Liberty Trail.” 




In addition to the dramatic Ecology Bus Tour, Earth Week participants across the country organized litter pick-ups. High school students and younger children joined the mass clean-up and held their own protests. High schoolers in Joliet, Illinois wore masks to protest air quality in their town, and Philadelphia residents hiked through Fairmount Park to protest pollution from automobiles.

While Earth Day speeches tended to focus on chemical pollution, grassroots activists and local participants proved that solid waste posed a significant threat to local ecology. These demonstrations illustrated the primacy of trash and garbage within the umbrella category of “pollution.” Equipped with brooms and trash bags, schoolchildren in Pennsylvania and elsewhere set about to clean up their environments.

Students from Bethel Park. Pittsburgh Post-Gazette, April 23, 1970

Trash that Kills: A Century of Pollution

Just as Earth Day activists did not pin-down or concretely define the unwieldy topic of “pollution,” Earth Day activities neglected to shed light on who exactly was affected by pollution. The Ecology Bus Tour, like an urban safari, safely transported students and participants to the neighborhoods most affected by pollution, in order to gawk at the environmental contamination there before returning home. In 1970, the “Top 15” polluters in Philadelphia, refineries, plants, and smelting companies, were mostly located near poor black neighborhoods, and a disproportionate number of waste disposal facilities were located in South and Southwest Philadelphia, home to African American and immigrant Philadelphians.

Explosion at the PES Refinery. Source: Philadelphia Inquirer

On June 21, 2019, a fire and several subsequent explosions at the Philadelphia Energy Solutions refinery, located on the Schuylkill River in the Grays Ferry neighborhood of Philadelphia, caused thousands of pounds of hydrofluoric acid to be released into the atmosphere. If not for the swiftness of the emergency response team, the sheer quantity of HFL that was kept on site could have generated the greatest industrial accident in US history. The refinery has since been shut down to be used as a mixed-use industrial site, but PES had posed lethal harm to the community for decades prior.

Sylvia Bennett, 76, who has lived in the neighborhood for most of her life and is a member of environmental activism group Philly Thrive, told the Philadelphia Inquirer in February 2020 that two of her daughters have cancer, a granddaughter has asthma, and that she believes that this was due to living in close proximity to the refinery. In 2012 the Public Health Management Corporation’s Community Health Data Base estimated that 19.4% of adults in Philadelphia had asthma, more than twice the 7.0% national prevalence.

For Philadelphia residents, neighborhoods near refineries, landfills, and waste management facilities are home, not stops on the Ecology Bus Tour. These Philadelphians can’t escape pollution on a bus, but live with it all their lives, and watch it affect generations of friends and family. While Earth Day activists in 1970 did not address Philadelphia’s blatant and systemic environmental racism, activists today do not make the same oversight. On this Earth Day in 2020, Philadelphia activists celebrate the shut down of the PES refinery, fight for their communities, and organize for more victories to come.


Smith, Joseph A. M., Steven F. Hafner., and Lawrence J. Niles. “The Impact of Past Management Practices on Tidal Marsh Resilience to Sea Level Rise in the Delaware River Estuary.” Ocean and Coastal Management 149 (2017): 33-41.

Barendregt, Aat, Dennis Whigham, and Andrew Baldwin. Tidal Freshwater Wetlands. Weikersheim: Margraf Publishers, 2009.

Sicotte, Diane. From Workshop to Waste Magnet: Environmental Inequality in the Philadelphia Region. New Brunswick: Rutgers University Press, 2016.

Thomann, Robert V. “The Delaware River: A Study in Water Quality Management,” in River Ecology and Man, ed. Oglesby et al. New York: Academic Press, 1972.

Delaware River Basin Commission, 1966 Annual Report.

Keeney, James D. “Enforcement of Philadelphia’s 1969 Air Management Code: The First Three Years,” Villanova Law Review 18 (1972).

Silverman, Ellie. “South Philadelphia Refinery Sale to Hilco Has Neighbors Hopeful about PES Site.” Philadelphia Inquirer, February 14, 2020. https://www.inquirer.com/business/energy/south-philadelphia-oil-refinery-explosion-sale-pes-hilco-pollution-environment-20200214.html.

“South Philadelphia.” Center of Excellence in Environmental Toxicology. Perelman School of Medicine, n.d. http://ceet.upenn.edu/target-communities/south-philadelphia/.