Published on September 30, 2019

Leave It to Beaver? Not Here!

You may be surprised to learn that, as a result of deforestation and hunting, beavers were virtually eradicated from Massachusetts within about 35 years of the first recorded mill going in at Stony Brook in 1714.

They did not make a return to the Commonwealth until the early 1900s.

Beaver gnawing stick in a pond © Amy Vaughn
Beaver © Amy Vaughn

Successful Reintroduction

By the time the Nature Center at Stony Brook was established in 1964, beavers were well on their way back into their old haunts and moving from the Connecticut River eastward toward the coast. Indeed, there's every reason to believe that the original location for the corn and lumber mills on Stony Brook were discovered first by these industrious creatures.

The Stony Brook watershed, including the wetlands of Bristol Blake State Reservation, have supported beavers and other animals associated with the wetlands for many years now. And since then, thousands of visitors have enjoyed seeing these creatures and the results of their activities. 

But it should come as no surprise that occasionally, decisions by the beavers are at odds with what we are trying to do on the property—maintaining our trails, for instance.

One of the spillways at Stony Brook clogged by beaver debris
Spillway clogged by debris

Trouble Moves to the Neighborhood

During the summer of 2012, a beaver family made the move across the street to Bristol's Pond. They immediately started in on homesteading activities like building a lodge, cutting stumps, girdling trees—and working to stop the flow of water through the adjacent wetlands. 

The beavers dammed up both spillways at Bristol Blake State Reservation, ultimately causing all kinds of problems that we've been working to resolve ever since.

After MA DCR crews removed more than 10 cubic yards of material just from the second spillway, they received permission from the Norfolk Conservation Commission to work with working with a "Beaver contractor" install a beaver pipe (or "beaver deceiver"), a mechanism that allowed the beavers to build their dam while creating a pathway for water to flow underneath their structure, thus keeping all parties satisfied. We were able to maintain the trail and spillway, while the beavers could feel as though they were raising the water level by damming the spillway, even though they actually weren't.

The beaver pipe worked wonderfully—until summer 2016.

Another spillway at Stony Brook clogged by beaver debris
Another clogged spillway


Drought conditions caused the level in the wetlands to drop to a point where the intake of the beaver pipe started making a slurping sound as water flowed through it. Reacting to that sound, the beavers quickly filled the pipe in through the protective grid surrounding it to stop the flow of water. And they were successful.

After that, the beavers busily stopped the flow of water over the two spillways each evening, and a DCR crew, Mass Audubon staff, and volunteers worked to clear the spillways each day. Of course, this led to some interesting conversations among the folks working hard to keep both spillways running!

Further complicating the situation was the fact that the last time the DCR removed the debris clogging the spillways—which had raised the water level about a foot—a rush of water ran over the waterfall and into Stony Brook, temporarily flooding some of the areas downstream.

We can only imagine what the beavers must have thought.

Installing beaver-friendly waterflow device on spillway 750
Installing the waterflow device

A Peaceful Resolution

Finally, in late September 2019, work was completed on a project to install a series of water flow devices into the waterway that will allow the beavers to build and maintain their dams while also allowing the water to continue moving through the watershed. This keeps the habitat healthy, the beavers happy, and allows us to live in harmony with these fantastic wild creatures.

This multi-year "battle" has provided some great teaching moments for all of us. It's also given visitors a perfect opportunity to get a closer look at the impact these industrious and clever creatures can have on their habitat.

Learn more about beavers >