Wissahickon Watershed - Act 167

Wissahickon Watershed  - Act 167 Plan

2013

The CSC has completed a $1.2 million, 30-month study to assess, model, and map flooding problems in the Wissahickon Creek Watershed in Montgomery and Philadelphia counties. The study included the creation of a Digital Elevation Model for the watershed; an evaluation and field verification of flood elevations and stream obstructions; hydrologic/hydraulic modeling; the preparation of new 100- and 500-year floodplain maps and floodways; and the development of an enhanced stormwater management plan for the watershed.

Photo - Jeff Featherstone looking at a map

Our goal was to prepare new and accurate flood hazard maps to meet and exceed FEMA (Federal Emergency Management Agency) specifications.

The Wissahickon Creek Watershed encompasses 15 municipalities in Montgomery County and the City of Philadelphia. Municipalities include: Abington Township, Ambler Borough, Cheltenham Township, Horsham Township, Lansdale Borough, Lower Gwynedd Township, Montgomery Township, North Wales Borough, Springfield Township, Upper Dublin Township, Upper Gwynedd Township, Upper Moreland Township, Whitemarsh Township, Whitpain Township, Worcester Township, and the City of Philadelphia. 

The major tributary to the Wissahickon Creek is the Sandy Run creek, which drains an area of 12.6 square miles. That subwatershed was extensively studied by the CSC as part of the Fort Washington Flooding and Transportation Improvement Study, which was completed in 2008.

As part of the comprehensive study, researchers created new flood hazard maps, computer simulations depicting water flow and flooding in different flood events, and they identified specific stormwater improvements — running models that examined the potential reduction of flooding and pollution and the potential costs.

Center researchers prepared an “Act 167” Stormwater Management Plan for the watershed, evaluating the condition and performance of existing stormwater facilities and outlining strategies to improve their performance, including retrofit and alternative stormwater Best Management Practices (BMPs).