The US Army Corps of Engineers lists more than 90,000 dams in its National Inventory of Dams, making them a common feature of our waterways. These structures have been built for a variety of beneficial uses — including irrigation, water supply, power generation, flood control, and even recreation — but sometimes, there’s good reason to remove them.
Broadly speaking, a dam is a structure that restricts or diverts the flow of water. A low-head dam fully extends across a waterway and raises the water level upstream. You often see this type of dam being used to control water flow for the outlet of a lake, pond, or reservoir.
Here, we’ll discuss several ways that removing a low-head dam is beneficial for the environment, animals, and even people!
1. Water Quality
Removing a top-flowing dam restores the natural flow of a waterway. This raises the oxygen levels in the water, which is vital for the survival of fish and other organisms.
Dam removal also drops water temperature. When sitting behind a dam, water is warmed significantly by sunlight. Water flowing through a natural stream channel is much cooler by comparison. When you remove a dam from a stream classified as a warmwater fishery, the water is able to return to its natural cool or cold temperature — allowing native fish that could not tolerate warm water to return.
2. Fish Passage
And speaking of fish, dam removal also helps them re-establish passage routes. This allows native fish species to reach spawning areas that had been cut off by dams, sometimes for hundreds of years.
3. Sediment Removal
Over the course of its life, “legacy sediment” builds up behind a dam — sometimes thousands of cubic yards of it. Sediment can increase flood hazards, pollute water, and bury floodplains and wetlands.
Removal of sediment is generally addressed with dam removal projects. To encourage this, MS4 (municipal separate storm sewer system) credits are available for sediment removal from floodplains, part of the ongoing efforts to clean up the Chesapeake Bay.
4. Reduced Liability
Some dams were constructed 100 years ago (or more), at a time when construction methods varied greatly and regulation was not what it is today. Many of these are now failing structurally — making them a liability for property owners.
5. Public Safety
Low-head dams are a natural place for people to gather for swimming, kayaking, and other recreation, but they can be dangerous. This type of dam creates turbulent, unpredictable currents. People who go over the dam can become trapped underwater, leading to injury or even drowning.
Expert Dam Removal
Removing any type of dam is a complex project, so it’s important to call in an expert. Flyway Excavating has completed approximately 75 dam removal projects out of the 400 total removed in Pennsylvania during the last 25 years. From project management and field staff to equipment and techniques, we have the tools and expertise to do the job right. If you’d like to discuss your dam removal project, contact us today!