Beavers are doing a fantastic job at purifying rivers, especially in the western United States where it’s getting hotter and drier due to climate change. When beavers construct dams in rivers, they create miniature reservoirs upstream. These reservoirs act as natural filtration systems, capturing sediment, excess nutrients, and contaminants before they can flow downstream. Beavers are ecosystem engineers: their dams purify water in rivers.
Beaver building a dam. (Robert McGouey, 2017).
Water quality refers to how safe and clean water is for a certain purpose, such as drinking or irrigation. The activity of beavers is especially important for preserving water quality with environmental changes from a warming climate. During droughts, water quality declines. Beaver dams can effectively preserve water quality in these conditions by trapping sediment and filtering out pollutants. So, these dams act as protective barriers for water quality. When streams dry out, pollution levels increase because there is not enough water flowing to flush out contaminants. Researchers from Stanford University studied how pollutants move through the environment by taking measurements and using computer models.
It is also important to understand how ecosystems function in response to climate change. Excess nitrogen can promote algae overgrowth, which can block sunlight necessary for photosynthesis. The researchers found that beaver dams played a role in reducing nitrate, a harmful form of nitrogen. This reduction happened because the dams created a sudden drop in water levels, which helped filter out the nitrate from the water.
Comparison of stream health with (left) and without (right) beaver dams. (Shanthanu Bhardwaj, 2024).
While the study specifically focused on rivers in the western United States, these findings have broader implications that could relate to Vermont. Vermont, like many other areas, is experiencing the effects of climate change, including alterations in precipitation patterns and increased instances of extreme weather events.
In Vermont, beavers play a role in shaping local ecosystems. The dams built by beavers in Vermont’s rivers and streams could potentially contribute to water quality improvement by acting as natural filters. This could be especially important during periods of drought or heavy rainfall when water quality may be compromised. Climate change is creating an increase in heavy rainfall and extreme weather events, which can affect water quality and stream habitats.
Understanding the impact of beaver activity on water quality is relevant for Vermont’s ecosystem management and conservation efforts. By recognizing the beneficial role of beavers in maintaining river health, policymakers, conservationists, and local communities in Vermont can consider incorporating beaver management strategies into their plans for mitigating the effects of climate change and preserving water quality.
Beaver dam in a montane stream. (GSA, 2023).
References
Bhardwaj, Shanthanu. Water quality in Chicago’s rivers improving, but still needs work. 2017. Photograph.
Brazier, Richard E., Allen Puttock, Hugh A Graham, Roger E Auster, Kye H Davies. and Chryssa M.L. Brown. 2020. “Beavers: Nature’s Ecosystem Engineers.” WIREs Water 8(1). https://doi.org/https://doi.org/10.1002%2Fwat2.1494.
Dunn, Sarah. EEAGER – The Search for Beavers. March 15, 2023. Photograph.
McGouey, Robert. Beaver Building a Dam. 2017. Photograph.