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Group 2 Delaware River Watershed Initiative


Upstream Suburban Philadelphia

Five hydrologically separated stream systems run through the Upstream Suburban Philadelphia Cluster of Watersheds.

The Pennypack, Tookany and Wissahickon Creeks flow into the city from the northwest, while the Cobbs and Poquessing define the city limits to the southwest and northeast, respectively. These watersheds encompass 193 square miles, including 61 square miles within the City of Philadelphia, outside the cluster boundary. The cluster includes the upstream suburban portions of these watersheds in Bucks, Delaware and Montgomery Counties, where about 400,000 people reside.

The waterways lie within the nation’s sixth-most-populous metropolitan area and are heavily urbanized. Most of the landscape is developed and has been converted to impervious surfaces—roads, parking lots, buildings—that generally cover from 25 to 50 percent of the landscape but can reach much higher percentages in town centers. The cluster’s streams flow through all or parts of 36 different municipalities including historic boroughs, as well as first- and second-class townships, governed by nearly 300 elected officials.

Almost all of the reaches of the cluster’s waterways are on Pennsylvania’s list of impaired streams due primarily to urban stormwater runoff and secondarily to excessive sediment and nutrient pollution. The region includes an extensive network of streamside parks and greenways that provide significant ecosystem services as well as recreational opportunities. Over 70 miles of walking paths and multiuse trails extend within and along the stream corridors of all five watersheds. Some notable examples are the greenway along the Pennypack and the Green Ribbon Trail along the Wissahickon.

Despite the important parks in the cluster, this area has extremely limited land available for protection, so the Initiative will need to achieve water quality improvements through restoration of degraded areas.

Drinking Water Source 1.7 Million People
Total Area 132 Sq. Mi.
Protected Land 3% Protected

Major Threats

The conversion of open land to impervious cover has increased stormwater runoff, causing high-volume and high-velocity stream flows, flooding, sedimentation and pollutant and nutrient loading. Urbanization has also altered streams, indirectly through excessive stormwater flows and directly through human actions such as the hardening of stream banks and converting streams into underground storm sewers. Natural riparian buffers, associated uplands and connections between streams and their floodplains have been lost.

Deficient Stormwater Infrastructure
Much of the cluster’s stormwater infrastructure pre-dates modern stormwater management methods. Existing components such as culverts and channelized streams are either outdated or undersized, contributing to flooding and poor stormwater management.

Improper WWTP and Sewer Infrastructure
Pollutants and nutrients may be introduced to streams via WWTP and sewer outfalls. These may be caused by leaky pipes and illicit connections to the stormwater system.

Why it’s Important

Urbanization is the greatest stressor to the Upstream Suburban Philadelphia Cluster. Poorly managed and unmanaged stormwater flows are the most severe stressors and are of particular concern given that this cluster comprises the most densely developed landscape in the Delaware River basin. Additionally, effluent from wastewater treatment plants (WWTPs) contributes large portions of base flow in many of the cluster’s stream tributaries and causes nutrient pollution. The furious flush of stormwater across extensive impervious surfaces overwhelms streams and severely restricts groundwater recharge. As the water flows across streets and parking lots, it collects heavy metals, petrochemicals, garbage and other harmful substances and delivers them directly into waterways.

In headwater areas further upstream, public groundwater withdrawals for drinking water deplete streams that are left to be replenished by wastewater treatment plant discharges, resulting in stream flows that are at times predominately treated effluent. The Wissahickon Creek is an example of an effluent dominated stream, which flows into the Schuylkill River just upstream of one of Philadelphia’s drinking water intakes.

The confluences of both Pennypack and Poquessing Creeks with the Delaware River are also near the Baxter Water Treatment Plant, the city’s largest drinking water intake and treatment facility. Philadelphia is home to one of the nation’s most innovative approaches to reduce stormwater pollution and restore water quality with a $2.5 billion plan to install over 10,000 acres of “green” practices, transforming Philadelphia into an “emerald city.” But stormwater issues don’t stop at the city line. Restoration projects in the suburbs upstream of the city could make a major difference in this unprecedented effort to restore waterways degraded by centuries of industrialization and urban development, benefitting both the upstream communities and downstream users.

What We Can Do

Because land in this cluster is largely built out, with limited places for new development or land protection, most opportunities to improve water quality lie in the restoration of urbanized lands through which the five stream systems flow. The cluster organizations plan to complete 28 projects through 2017. To ensure that these investments produce significant impacts that are evidenced by water-quality monitoring and modeling, this plan is concentrating capital investments in the following highly focused “micro-watersheds”:

  • Cobbs Creek tributary East Branch Indian Creek
  • Pennypack Creek headwaters in Horsham Township
  • Tookany Creek portion of the Tookany/Tacony-Frankford mainstem and tributary Jenkintown Creek
  • Wissahickon Creek headwaters in Upper Gwynedd Township
  • Wissahickon Creek tributaries Sandy Run and Rapp Run


To achieve measurable impact in these locations the cluster organizations will implement the following types of projects:

  • Stormwater management: retrofit existing stormwater detention basins that are antiquated or poorly performing and incorporate infiltration and extended detention features; install “green roofs” and rain gardens.
  • Stream-channel restoration: stabilize and restore stream banks, and naturalize stream channels.
  • Protection and restoration of uplands: establish new riparian buffers and increase connectivity of riparian corridors, improve habitat by planting trees and creating meadows, improve stormwater management and secure easements to enhance protection of natural areas.
  • Wastewater treatment plant and sewer infrastructure improvements: replace or repair damaged sewer lines, disconnect illicit connections, and repair and upgrade treatment plants.
  • Education and outreach: coordinate and target public and municipal education and outreach to build support to fund and sustain stormwater best practices; improve municipal stormwater-management practices and policies; empower citizen leaders/constituents to advocate for improved water quality; and increase municipal financial support for green infrastructure.

Monitoring and Measurement

The monitoring for this plan has two goals: to evaluate the effectiveness of stormwater controls and to determine where to install new controls. Each of the five focus areas will have monitoring stations of varying levels of intensity. Cluster organizations will identify additional monitoring points to correspond with new or upgraded stormwater controls. Measurement will include hydrologic and hydraulic modeling that university professionals will conduct on a site and sub-watershed basis.

Along with monitoring, the modeling will seek to accurately predict the effects of stormwater controls and provide an analytical framework for planning and sequencing future controls. University researchers, members of watershed groups and trained citizens will collect the monitoring data.

The project team will develop a suite of tools that will engage citizens in monitoring. For example, a web-based, interactive map will invite direct public input, including pictures, comments and project profiles, and enable the sharing of project information through social media. A smartphone app will allow citizens to submit monitoring data in a standardized form or simply view project information; the app will link with specific monitoring sites by placing a Quick Response (QR) Code on signage in the field. The cluster team will offer a robust training program to recruit volunteers and strengthen their monitoring programs.


Timeline and Investment

As of January 2014, estimated costs to successfully launch the restoration of selected waterways in the cluster totalled $40 million over the next three years, including monitoring ($2.5 million), education and outreach, modeling and technical assistance ($3.5 million). Costs related to restoration of buffers, uplands and streams, and stormwater retrofits total $34 million. The William Penn Foundation has awarded $3.42 million for the work in this cluster with additional support (about $1 million) provided through competitive restoration grants also funded by the William Penn Foundation and managed via the National Fish and Wildlife Foundation.