Read the case studies
- Pollutant reduction: Beaver dams significantly reduce downstream sediment, nitrogen, and phosphorus levels in water from intensively managed grasslands
- Water filtration: Dams slow and filter water, causing sediment and nutrients to settle in ponds
- Sediment impact in storms: During storms, water leaving the beaver-modified site had three times less sediment than water entering it
- Sediment storage: 13 ponds held over 100 tons of sediment, including 15 tons of carbon and 1 ton of nitrogen
- Agricultural benefits: Beaver ponds may help mitigate diffuse pollution from agriculture, trapping eroded sediment and improving downstream water quality (External link)
- Water storage: Beaver dams create wetlands that store significant amounts of water. Research shows that beaver wetlands in Devon can store over 24 million litres of water, equivalent to around 10 Olympic-sized swimming pools(External link)
- Drought alleviation: During droughts, the water stored in beaver wetlands is released slowly, maintaining river and stream flows. This creates “green oases” that support wildlife even in dry conditions
- Ecosystem resilience: Beavers’ activities help create more resilient landscapes by maintaining base flows during dry periods and reducing the impacts of drought
- Flow attenuation: Beaver dams significantly reduce peak flow levels during storm events shows that peak flows can reduce lows by on average ca. 30 % and up to ca. 60%. Read the study.(External link)(External link).
- Water storage: Beaver-created ponds store large volumes of water, which helps to moderate stream flow and maintain base flows during dry periods.
- Lag time increase: The presence of beaver dams increases the lag time between peak rainfall and peak flow, reducing the risk of flash flooding.
- Hydrological stability: Beavers contribute to more stable hydrological regimes by creating wetlands that buffer against both floods and droughts.
The River Otter Beaver Trial
The River Otter
(Picture credit Krzysztof Dabrowsk)
In 2015 Devon Wildlife Trust secured a five-year licence from Natural England to conduct a formal wild beaver re-introduction project to monitor the impacts of beavers within the catchment. We, the EA, were an important partner in the study ensuring the trial provided valuable data on how beavers can influence hydrology and river ecosystems.
Devon Wildlife Trust
Outcomes:
The trial demonstrated that beavers can enhance water storage, reduce flood risks, and improve water quality by filtering pollutants. The success of the trial has informed future reintroduction projects and conservation strategies.
Benefits of beavers for water quality
Location: Enclosed beaver project, Tamar catchment, UK
(Picture credit Krzysztof Dabrowsk)
Monitoring:
Conducted by the University of Exeter and Devon Wildlife Trust
Key findings:
Implications:
Beavers can play an important role in enhancing water quality by filtering pollutants and holding sediment, making them valuable for improving the overall health of our rivers. It is important to note that there is still a need to focus on catchment management to remove and reduce inputs at source.
Benefits of beavers in drought conditions
Location: River Otter, Devon, UK
Monitoring:
Conducted by the University of Exeter and Devon Wildlife Trust
Key findings:
Implications:
Beavers play a crucial role in mitigating drought effects by enhancing water storage and maintaining stream flows, which supports both ecosystems and human communities.
Effects of beavers on hydrology
Location: River Otter, Devon, UK (and three other sites nationally)
Monitoring:
Conducted by the University of Exeter and Devon Wildlife Trust
Key findings:
Implications:
Beavers play a crucial role in natural flood management and hydrological stability. Their dam-building activities help to mitigate the impacts of extreme weather events, making landscapes more resilient to both floods and droughts.