By Becky Wetzel, Guest writer

A growing population of beavers is taking up residence in Upton and Mendon’s streams and ponds, doing what beavers do: cutting down trees with their teeth and building dams and lodges. Besides humans, beavers alter their environment more than any other animal on the planet, which is why they are sometimes perceived as a nuisance, and also why MIT chose "nature's original engineer" as their mascot. 

There are many reasons beavers are good neighbors, and we should welcome them.  Beavers are a “keystone species” because they create habitat that supports countless other species. Beaver ponds create wetlands, which are among the most biologically productive ecosystems in the world. They dramatically increase plant, bird and other wildlife variety, improve water quality, recharge aquifers, protect against flooding and wildfires, and increase salmon and trout populations. Beavers also help mitigate climate change by creating wetlands that turn streams into powerful carbon sinks. 

Beavers are the largest rodents in North America, usually weighing 35 to 65 pounds. They are monogamous, nocturnal, and live up to 24 years in the wild. Hunted to near extinction in the 19th and early 20th centuries, populations are returning to rivers, streams, lakes and ponds all over New England, where they build their dams and lodges from tree branches, vegetation, rocks and mud. They are herbivores, eating tree bark, twigs, leaves, and aquatic plants like water lilies. They do not eat fish. 

Climate change mitigation. Beavers are important in reducing greenhouse gases that contribute the climate change. According to a recent UK study, beaver-engineered wetlands can store carbon at rates up to 10 times higher than similar systems without beaver activity. Over a 13‑year period, a beaver-created wetland stores an estimated 1,300 tons of carbon, compared to 11 tons in non-beaver-populated areas, the study noted. 

Water purification. Beaver dams and ponds trap and strip out pollutants from streams. The algae, plants and sediment in beaver ponds absorb dissolved nutrients, process organic waste, and remove runoff toxins (e.g., heavy metals, pesticides and fertilizers) from the water. Beaver-engineered wetlands serve as the “earth’s kidneys”.

Aquifer and groundwater recharging. Beaver ponds stabilize the water table and replenish aquifers.

Flood prevention. Beaver dams function as natural sponges that store runoff water and slowly release it, thus reducing downstream flooding and erosion.

Drought resilience. Beavers protect against drought by holding water in ponds to better maintain stream flows during droughts. In fact, beavers are being released in drought-stricken areas of US and Great Britain to combat drought conditions. 

Habitat creation. Beaver wetlands increase biodiversity for insects and support many birds, fish, and mammals by providing food, shelter and breeding sites. According to research, beaver-created wetlands averaged 19% more species than other types of wetlands. Species that benefit include otters, mink, muskrats, ducks, bats, herons, frogs, turtles, fish, and countless invertebrates.

Conclusion. Beavers are sometimes regarded as pests, but no other species can better benefit our watershed. Although they can present challenges, managing those challenges will help improve the health of our watershed, control problematic flooding, protect against drought, and reap countless environmental rewards.

The author is one of several people working with the Town of Upton to understand the benefits and challenges of beavers in our watersheds, and to develop sensible and humane ways to manage beaver activity. 

Beaver Activity on Warren Brook in Upton. Photo by Becky Wetzel

RESOURCES:  UK beaver study - https://www.usatoday.com/story/news/weather/2026/03/22/climate-change-study-beavers-have-big-impact/...