200 Years. 200 Stories. Story 107: “Manatawny Creek Dam Removal ”

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Removal of the low head dam on Manatawny Creek near Pottstown, Pennsylvania.

Manatawny Creek Dam Removal

In recent years, concern over degradation of aquatic resources, issues of liability, and maintenance costs has led to the removal of a number of small dams around the United States. Although dam removal has great potential in river restoration, the Pennsylvania Department of Environmental Protection (DEP) wanted to learn more about the ecological consequences of the process. In May 2000, the DEP, through the Growing Greener program, funded a study conducted by the Patrick Center for Environmental Research in collaboration with the Greater Pottstown Watershed Alliance, the Delaware Riverkeeper Network, and the Berks County Conservancy. This two-year multidisciplinary ecosystem study focused on the effects of removing the Manatawny Creek dam near Pottstown, Pennsylvania. Subsequent studies have extended parts of the monitoring through 2010. This project represented one of the first comprehensive studies attempting to document the large-scale physical, chemical, and biological changes in a river system following dam removal.

The team conducted analyses before, during, and after dam removal at the various sites upstream and downstream of the dam to monitor short- and long-term changes to the stream ecosystem. They measured the shape and composition of the channel; monitored water quality; evaluated how changes in water flow affect the movement of sediment and contaminants; investigated how dam removal alters the food web; analyzed levels of algae and organic matter; and considered the effects of dam removal on animals and vegetation. The team reported that storms caused episodic sediment movement that had not occurred immediately following dam removal, yet habitats returned to normal after storms and general creek function improved over time. Removal of the dam has had overall positive effects, improving the migration patterns and health of the creek’s living creatures. However, sediment movement and changes in channel shape and biota will continue in response to storms and other disturbances.

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