While the weather prevented us from being at an oxbow restoration in progress, the indoor field day offered a great opportunity to discuss whether every oxbow needs to be restored to be able to provide benefits to water quality and wildlife.
Did you know? Iowa has over 40,000 acres of oxbows!
Oxbows were meanders that were cut off when the river or creek path changed, either naturally or through channel straightening. They provide critical habitat for fish, including the federally endangered Topeka Shiner, birds, frogs and other amphibians, as well as insects, mammals and microorganisms. Oxbows can also provide floodwater storage and improve water quality through denitrification. Monitoring of oxbows in the Boone River Watershed has shown a 42% reduction in nitrate concentration in the water that is routed through them.
So what does it take to determine if an oxbow should be restored?
According to presenter Darrick Weissenfluh, private lands fish and wildlife biologist for the U.S. Fish and Wildlife Service, the decision to restore relies on the answers to the questions below.
- What are your goals?
- Is the oxbow degraded?
- Is restoration feasible?
Determining goals for the oxbow is a critical first step in the process. Is the aim to improve wildlife habitat, provide a drinking water source for livestock out of the neighboring water body, store floodwater or treat tile drainage water to reduce nutrient loss? All of the above? The goals will guide what, if any, actions need to be taken to meet the intended target.
Secondly, visitng the oxbow throughout the year can help determine if the site is degraded based on observed plant communities. In some cases, the oxbow does not need to be excavated if the tree canopy around the area is opened to increase the sunlight in the area and decrease the contribution of leaf plant materials to the system. In other situations, improving the connection channels to the neighboring water body will in turn improve the oxbow function.
Lastly, it is important to consider the feasibly of restoration both financially and the impact of the excavation equipment on the surrounding area. Restoration can cost up to $25,000, depending on the volume of soil excavated and how far that soil needs to be transported. There are many funding assistance programs available to offset some or all of the costs. If you are interested in possible oxbow restoration on your land, email firstname.lastname@example.org and I will connect you with the staff at the Iowa Department of Agriculture and Land Stewardship.
So why not just restore all the oxbows?
Without in-field practices like cover crops and no-till, the restored oxbows can refill with sediment over time and decrease their benefits. It takes both in-field and edge-of-field practices, working together to improve water quality, reduce flooding and ensure wildlife habitat for now and years to come.