Beavers Improving Water Quality
Excess sediment, herbicides, nitrogen, and phosphorous from agricultural fields and urban areas can be dangerous to Iowas ecosystem. These pollutants can have varying consequences downstream in Iowa. This dynamic creates the need to filter out that same sediment, nitrogen, and phosphorous to meet clean drinking water standards.
The water treatment systems often required can be very expensive and time consuming to implement. In addition, excess nitrogen and phosphorous can contribute to harmful algal blooms, which not only can harm wildlife and the environment but also can negatively affect human health.
It's important to consider the beaver as an ally in our battle with water quality in Iowa. While the beavers cannot control water quality alone, they could be an important factor to buffer runoff from agriculture in our state. We are currently seeking funding to support a research project in Iowa between beavers and ag runoff.
A study done at the University of Exeter in the UK did a very compelling study regarding water quality. Click here or click the image below to see the full study. In summary, the researchers measured sediment as well as phosphorous and nitrogen in water flowing into their research site. They compared this data to the water as it ran out of their site after passing through each of the thirteen beaver dams featured in this study. They also collected data on the amount of nitrogen, phosphorus, and sediment trapped by each of the dams.
Their results showed that 100 tons of sediment had been trapped across the 13 dams! 70% of which was soil likely eroded from grassland fields upstream. Thorough testing then revealed that this sediment contained high concentrations of phosphorus and nitrogen, which are the nutrients we must be mindful of when considering water quality and run-off issues.
These results are exciting for Iowans because it could mean beavers provide Iowans with another tool box of ways to assist in watershed management, wetland restoration, and riparian health.
This study at the University of Exeter was led by Richard Brazier, a professor of earth surface processes.
He commented on the results of their research, "it is of serious concern that we observe such high rates of soil loss from agricultural land, which are well in excess of soil formation rates. However, we are heartened to discover that beaver dams can go a long way to mitigate this soil loss and also trap pollutants which lead to the degradation of our water bodies. Were beaver dams to be commonplace in the landscape we would no doubt see these effects delivering multiple benefits across whole ecosystems, as they do elsewhere around the world."
Learn More About Beaver Diets
Beavers in Iowa consume a variety of weedy species and can be potentially be beneficial to stream ecology from a weed control standpoint! While beavers alone are unlikely to control an entire weed population, they are one factor in a larger wetland ecosystem that can thrive because of the engineering beavers provide.
*Cottonwood and Mulberry not listed, among other browse species beavers DO eat in Iowa! This list is not all inclusive.
Benefits of Beavers in Iowa
1. Beavers create critical wetland habitat! Their dams slow the flow rate of the stream, which then often reduces erosion and decreases flood damage downstream. As water sinks into the ground, the water table becomes replenished, and therefore increases riparian vegetation in Iowa for other birds, insects, amphibians, reptiles, and mammals!
2. Beaver ponds, the "Earths Kidneys" cleanse water by filtering out silt, nutrients and other pollutants. This is particularly important in Iowa because of the amount of agricultural chemical run-off.
3. The dams the beavers create to hold ponds can help mitigate the impacts of climate change. Warmer temperatures should cause the streams to dry up earlier in the year. Because the beaver dams hold water and replenish the water table, this could mean the beaver dams keep the water moving downstream all year.
4. While typically wetland restoration is a hefty process, beavers require no special work permits. Considered "ecosystem engineers" beavers supply us with free labor towards the habitats we need in Iowa. Wetland habitat in Iowa is currently just 1.2% of the state.
5. Fish greatly benefit from beaver ponds. Beaver dams, lodges, and resulting ponds create excellent fish habitat and food source, particularly for Iowas trout. Prior to contrary belief, beavers do not eat fish! Beavers are herbivores.
Learn more about the benefits of beavers by exploring the following links.