WRA ACHIEVEMENT AWARD Presented to
Transforming the Manayunk Canal into a thriving aquatic ecosystem connected to the Schuylkill River, and creating a welcome place for wildlife and the community.
In spring 2025, the Philadelphia Water Department (PWD) completed the Flat Rock Dam project, a rehabilitation of the intake structure to the Manayunk Canal. This project reconnects the canal – closed since the 1940s – to the fresh water flow of the Schuylkill River. The project achieved its two primary goals: addressing structural integrity concerns at the Flat Rock Dam feeder gate house and channel wall; and improving water quality and ecology in the canal that runs for two miles along the Schuylkill River Trail and Manayunk’s Main Street.
The Philadelphia Water Department (PWD) is honored to receive this year’s Achievement Award for the Flat Rock Dam Project. Thanks to a $21 million PENNVEST loan from the Commonwealth of Pennsylvania, PWD was able to construct a new intake system near the dam and invigorate the once-stagnant Manayunk Canal. By reconnecting the canal to the freshwater flow of the Schuylkill River, we have seen immediate improvements to water quality and aquatic habitat. We look forward to celebrating this rejuvenated space for all, including Manayunk neighbors, business community, and users of the Schuylkill River Trail.
~ Benjamin Jewell, Commissioner for the Philadelphia Water Department
The Flat Rock Dam project was made possible by a $21 million PENNVEST loan and nearly 3 years of active construction work. PWD began planning for this project nearly two decades ago. Over the years PWD engaged with the Manayunk neighborhood and community through public meetings and collaborated with or received input from the Manayunk Development Corporation, the Philadelphia Canoe Club, Philadelphia Parks & Recreation, Schuylkill River Greenways, and other stakeholders.
A new intake system controls flow into the once-stagnant canal. The site also features educational signage, the preservation of historic iron gearboxes, and green infrastructure to manage stormwater. Freshwater mussels were deployed in the canal and are thriving, acting as natural filters in the water column. In order to design this project, PWD monitored existing water quality conditions and created a model using the EPA’s Water Quality Analysis Simulation Program (WASP) to determine optimal flows to achieve the desired dissolved oxygen levels in the canal. These predictive measures informed the project design and gate operations, making it possible for the canal to meet state water quality criteria.
Water quality benefits in the Manayunk Canal have been immediate and noticeable. Fish and other aquatic life have returned, dissolved oxygen levels now meet state water quality criteria, and algal blooms have diminished. The canal is more aesthetically pleasing for those who fish, birdwatch, and recreate along the Schuylkill River Trail. PWD will continue to monitor water quality in the canal to assess benefits to the Queen Lane drinking water treatment plant, whose intake is located approximately 1.5 miles downstream of the canal.
