Wissahickon Part 2: Forbidden Drive

Bell's Mill Road Bridge, viewed upstream

After Kali and I finished exploring Houston Meadows (previous post), which is located on a high, flat bluff above Wissahickon Creek, we descended the steep valley slope to the stream.  An old carriage road parallels the western bank of the creek for seven miles.  Because vehicles are prohibited from using the old road, it is called Forbidden Drive.  Forbidden Drive is one of the most heavily used recreational amenities in the city, with walkers, runners, equestrians, and bicyclists all mixed together in a generally congenial stew. 

Wissahickon Creek downstream of Bell's Mill Bridge

The land that is now Wissahickon Valley Park was a colonial industrial valley with mills and roads throughout.  The city bought the land in the late 19th century because Wissahickon Creek empties into the Schuylkill River just upstream of the city's drinking water intake, so the city wanted to try to preserve water quality in the Wissahickon and the receiving stream.  Nearly all vestiges of the industrial heritage are gone, but many of the stone ruins and the bridges that bore roads over the creek remain.

Blue wood aster (Aster cordifolius) and Wreath goldenrod (Solidago caesia) on the wooded streambank

Forested slope with denuded understory

White-tailed deer have been very abundant in the park.  As a result, nearly all of the forest understory is gone, and few sapling tress are growing to replace the old trees when they die.  For the last decade, the city has hired sharpshooters from the U.S. Department of Agriculture to cull the herd.  The sharpshooters hunt at night over bait, and the venison is donated to local food banks.  Nevertheless, animal rights group protests are a constant thorn in the city's side over this issue.  The culling has significantly reduced the number of deer, and the forest has begun to recover in places.

Parasitic beech-drops (Epifagus virginiana) in a patch of sunlight

One of the reasons that the Wissahickon is so popular is because it is very scenic.  The creek has cut a deep gorge though very hard rock, so the valley slopes are steep with lots of scenic boulders and bedrock exposed.  Because of the steepness, only one old road crosses the valley directly (Bell's Mill Road, the picture at the head of this post), and few roads penetrate down to Forbidden Drive.  Rex Avenue (image below) is one of those roads that descends from the eastern side of the valley and terminates at Forbidden Drive.

Rex Avenue Bridge

Old park guardhouse along Forbidden Drive

Covered bridge, the only one in Philadelphia

Invasive Japanese angelica-tree (Aralia elata), left, and Japanese knotweed (Fallopia japonica)

Wissahickon Creek rapid

Forbidden Drive

Forbidden Drive is not one of Kali's favorite walks because it is dark and claustrophobic; she much prefers the sun and openness of Houston Meadows.  However, I like the views of the creek and the general sense of community among the users.

StreamWatch

The creek in the county park downstream of my preserve

Our land trust is partnering with the watershed association that champions the environmental quality of the stream that drains the land to our southwest.  Last evening, our two organizations convened a joint training session for prospective stream monitoring volunteers at the county park downstream of my preserve.

Classroom training

About 20 people showed up for the training, which began with a PowerPoint introduction to the monitoring protocol.

Choosing a monitoring site

Then the volunteers split up between the two watersheds to choose their monitoring sites.

Creekside fieldwork.  The prominent outcrop in the background is called Council Rock.

Finally, we moved to the bank of the creek to apply the concepts introduced in the PowerPoint presentation to the "real world."  By then, the sun had started to set.

The volunteers were asked to pledge to monitor their section of the creek once a month - a two-hour commitment.  Everyone who attended was enthusiastic and seemed willing to commit more than two hours each month.

A riffle at sunset