Down the Drain

THE WATERSHED

The watershed of a stream is all the land that sheds water to that stream when it rains or when snow melts. There has always been an inseparable connection between people and water. Personally, we need to drink water to keep us healthy. We also need it to keep ourselves clean, to cook with, and to carry our waste away. Collectively, we use water to keep our streets clean, and to keep our homes and businesses safe from damaging fires. We enjoy the beauty of our waterways for fishing, boating, and picnicking. In earlier times, we depended on our waterways to transport vital (and luxury) goods and to power our mills. Water was an integral part of the industrial age, used in the manufacture of everything from clothing and blankets to beer and locomotives. Philadelphia has always looked to the Delaware and the Schuylkill Rivers and their tributaries to supply its citizens with drinking water and to carry its wastewater away.

Originally, settlers could rely on nature to take care of keeping that supply clean. Now nature needs help from the Philadelphia Water Department because as the population grew, so did pollution, and the city became more and more dependent on a government or municipal entity to keep things healthy.

Ironically, the rapid growth and development of the city in the industrial age both helped its citizens prosper and posed a grave threat to their health as the very source of healthy drinking water became contaminated with industrial waste. By looking at the watershed during this time period, students will see how the land use changed from a predominantly agricultural use, with scattered farms and small water-powered mills along the creek to residential use, with densely packed neighborhoods of row houses as we see it today. They will discuss what impact the land use changes had on the health of the creek.  As in many urban areas, most of Philadelphia’s surface streams, encompassing many square miles of watershed, were systematically obliterated over the course of the city’s development.

Local streams and creeks that ran throughout the city landscape were used by people and industry for drainage to carry away wastewater. Eventually, too polluted to bear, the stream system was converted to sewer infrastructure. The wastewater was encapsulated in pipes and the valleys that were once cut through with natural waterways, were leveled by fill to accommodate a grid of streets and row houses.  These streams have become part the city’s 3,000-mile sewer drainage system. In about 60% of Philadelphia (the oldest parts), these pipes carry human wastewater and stormwater from runoff in the same pipe, and are called a combined sewer. In newer parts of the city, raw sewage and stormwater runoff are separated.

Use of urban streams for sewage disposal and, ultimately, as the beds of actual sewers, was standard practice for 19th and 20th century engineers. Initially, stream pollution and its deleterious effect on human health was the main reason for undertaking such drastic measures. For example, when a section of the Cohocksink Creek in Philadelphia was  enclosed in a tunnel in 1860, the Board of Health applauded the project as “one of the most valuable sanitary improvements ever to be undertaken by the corporate authorities.”

However, by the second half of the 19th century, as epidemic diseases (in particular typhoid fever) killed thousands of Philadelphians, the provision of proper sewerage and drainage became a subject of great concern, and city engineers began planning the culverting of creeks in advance of development. As early as 1853, city surveyor Samuel H. Kneass acknowledged that natural watersheds would have to be utilized to provide proper drainage for the city. In the 1880s, when the city engineers drew up their preliminary drainage maps for Philadelphia’s 129 square miles, converting many of the city’s smaller streams into sewers was an integral part of the plan.
For much more detailed history of Philadelphia’s Sewer System, check out Water History PHL