Restoring Mill Creek in Lower Merion Township

The Lower Merion Conservancy, in cooperation with Bryn Mawr College, was awarded a Growing Greener Grant to restore approximately 1400 linear feet of stream located in the headwaters of Mill Creek in Lower Merion Township, Montgomery County, Pennsylvania. Mill Creek is a tributary to the Schuylkill River and is the primary drainage network for Lower Merion Township. Data collected by the Lower Merion Conservancy demonstrates that erosion, sedimentation, and thermal pollution are the three main contributors to the reduced macroinvertebrate diversity in the Mill Creek watershed. The project area is a perfect example of these symptoms as much of this reach contains little or no forested buffer to provide bank stabilization and canopy coverage. Previous attempts to stabilize eroding banks in the project area consisted of placing grout bags and gabion baskets along eroding banks and channelizing the stream between rock walls. None of these stabilization techniques took into account natural stream processes and therefore only exacerbated erosion on unprotected banks and caused channel bed scour which has undermined the structures in various locations.