What does dam removal look like?

May 6, 2012 by shannon

Friends of Glen Providence Park, after carefully doing research and weighing the evidence, has decided to fully support dam removal and stream restoration as the most promising option for the resolution of the 3rd Street Project. But the question on everyone’s mind seems to be:

What would Broomall’s Lake look like if it became Broomall’s Run again?

Look upstream, look downstream. You see a babbling brook, a creek, surrounded by woods and rocks. There are some wetlands, which are precious birthing grounds for turtles, frogs and fish. You see trees such as Sycamore, Tulip Poplar, American Beech, Oaks and Maples. You see shrubs like Witch Hazel and Spicebush. (Yes, there are some invasives…more on that later.) Some experts think that there are some natural waterfalls, undoubtedly smaller than the man-made one, because of the significant drop at the dam. Apparently, pre-dam, the same area was where people forded the creek, hinting that there may be bedrock beneath the dam somewhere.

Contrary to common belief, dam removal and stream restoration does not ultimately result in horrible mud flats and mosquitos. Nature finds equilibrium and sediment runs downstream while plants get seeded. With some help from restoration experts, some tree planting and perhaps some earth moving, things return to a “new normal.” In fact, it’s more like the “old normal,” before the dam was built.

Going with nature, by removing the dam and restoring the stream, will save a great deal of money and effort. When humans go against nature, it’s always costly. Right now, Broomall’s Lake needs expensive dredging because it is filling up with sediment. Why is it filling up with sediment? Because there is not supposed to be a lake or dam.

And what about that sediment? According to American Rivers regional experts, sediment in Pennsylvania’s old dams is rarely dangerously toxic, though it’s not spa-worthy mud.

And the State of Pennsylvania and American Rivers both know a thing or two about dam removal, stream restoration and management of sediments. Pennsylvania is the country’s leader in dam removal, probably because we are a large old state with a lot of old, old dams. American Rivers has been assisting public and private entities to clean up their waterways across the country. If you think Broomall’s Dam is a big project, look at the recent removal of Elwha Dam.

Here’s an example of before and after photographs, courtesy of American Rivers:

 

 

 

 

 

 

 

 

 

Finally, the Pennsylvania Department of Environmental Protection has a compelling slide show about Pennsylvania dam safety, with some great before/after comparisons.