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Group 2 Delaware River Watershed Initiative


Beavers, the newest water quality, climate, and flooding solution?

Before European colonization, hundreds of millions of beavers roamed what’s now known as North America, building dams and supporting people and the land. But centuries of unregulated trapping resulting in the elimination of most beavers and their dams. Without beaver dams to slow, sink and store stream water, waterways were degraded and many of our streams became badly eroded, incised, and damaged.

With a void of beavers in their natural landscape, erosion started to cut stream channels deeper and deeper into the ground, which resulted in the surrounding water table also lowering around it. In many areas, particularly in the western half of the United States, the water table dropped low enough where the roots of nearby plants could not reach an adequate water supply, resulting in the lush native vegetation dying off. Instead of lush wetlands, a barren and arid landscape with a lack of biodiversity was all that remained. Without beaver dams, a lowland teeming with life can become a desolate dust bowl and a fire risk.

While extreme droughts such as those in the American West may not be in the cards for areas such as the Delaware River Watershed, beaver dams do keep enough water in the landscape and ground to help with whatever droughts may occur in our changing climate. Their stream restoration qualities may perhaps be of greater significance, however. As beaver dams slow water velocity, suspended particles to are allowed to settle. As sediment accumulates, the stream bottom rises resulting in corresponding elevations of the surrounding water table. As the water table rises and streambeds rise, what was once a running stream with a defined channel becomes a vast wetland, bringing numerous benefits to the landscape such as the aforementioned biodiversity and water storage.

A major benefit that an increasing number of studies have found has been an increase in water quality downstream of beaver dams. When pollutants flow into streams, they start to run uninterrupted into the rivers and onwards to the oceans. When beaver dams slow the water flow in streams, they start to act as a natural filter by mostly stopping the surface water from flowing, whilst allowing cleaner ground water to runoff into the streams and continue the downstream water flow. The higher water table pushes this groundwater through the soil, filtering out many pollutants within it. A resulting higher water quality can help aquatic populations everywhere from the streams themselves to the river estuaries.

For more in depth information on the benefits of beavers on the landscape, please go to the online library at There you can find studies, articles, videos and more that will help you better understand how beavers affect the environment around us.

– The Beaver Institute

Check out this 45-minute webinar providing an overview of our organization, the tools and resources available, and a primer on certain issues we can help address in your restoration work. We are incredibly grateful for the support and vision of the William Penn Foundation who have made this opportunity possible.