Darby-Cobbs Watershed

The Darby-Cobbs Watershed drains approximately 77 square miles, including portions of Chester, Delaware, Montgomery, and Philadelphia counties. The headwaters of the Cobbs Creek sub-watershed begin in three distinct places: East Branch Indian Creek, which springs up in a small residential neighborhood in Narberth Borough; West Branch Indian Creek in Lower Merion Township in Montgomery County; and Cobbs Creek in Haverford Township, Delaware County.

Image of trees, rocks and a shallow creek or other body of water, with two people in the foreground

In total, Cobbs Creek weaves its way through 10 municipalities until it meets with the mainstream Darby Creek in Colwyn Borough, where it then dashes down to the John Heinz Wildlife Refuge in Tinicum.

The watershed is often subdivided into the Cobbs Creek, Darby Creek, and Tinicum subwatersheds for planning purposes.

The Cobbs Creek Watershed has something for everyone to discover. In addition to many historical and diverse neighborhoods, active and passive recreational activities can be found along the Cobbs Creek and in the surrounding area, connecting you with your watershed neighbors.

Watershed Fast Facts


The entire watershed drains approximately 77 square miles; the Cobbs Creek subwatershed is approximately 22 square miles.

Stream Miles

The Darby Cobbs watershed contains approximately 135 linear miles of streams, about 33 miles of which are in the Cobbs Creek subwatershed.


The watershed as a whole is home to about 460,000 residents, but population density is much higher in and near the City of Philadelphia. About 230,000 people, or half of the watershed’s residents, live in the Cobbs Creek subwatershed.

Impervious Cover

Impervious cover is estimated at 45 percent.


The watershed encompasses areas of Chester, Delaware, Montgomery, and Philadelphia counties, with all or parts of 31 municipalities, including Easttown, Tredyffin, Aldan, Clifton Heights, Collingdale, Colwyn, Darby, East Lansdowne, Folcroft, Glenolden, Haverford, Lansdowne, Marple, Milbourne, Morton, Newtown, Norwood, Prospect Park, Radnor, Ridley Park, Ridley, Rutledge, Sharon Hill, Springfield, Tinicum, Upper Darby, Yeadon, Lower Merion, and Narberth.

Help protect your watershed!

Aquatic wildlife markers are an easy way to remind your neighborhood to keep trash and chemicals out of drains.

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