Oxbows – To Restore or Not Restore?

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!

Boone River Oxbow. Photo Credit NickWalters, The Nature Conservancy Iowa

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 ejuchems@iastate.edu 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.

Liz Ripley

Wetlands Do Work to Improve Water Quality

Please join us for the Iowa Learning Farms webinar at noon CDT, Wednesday, Oct. 20, featuring  Dr. Sara McMillan, associate professor of agricultural and biological engineering at Purdue University. McMillan will draw on her research on the impacts of agriculture and urbanization on nutrient flow through living systems and their physical environments, to offer insights on ways that wetland ecosystems affect water quality.

In the session, “Ecosystem Function of Wetlands in Midwestern Agricultural Landscapes,” McMillan will utilize the field and laboratory work of her group, as well as others in the Midwest that are studying the roles of wetlands in greater agricultural landscapes, to address the functions of wetlands in improving water quality. Topics will include data-driven modeling of watershed ecosystem effects on downstream environments, and insights into identifying the environmental factors to enable better management of existing wetlands, and inform decisions on construction or restoration of wetlands.

“Wetlands, floodplains and small streams are hot spots that have more positive impacts on water per land area than most other land uses,” said McMillan. “The importance of wetland functions and the vulnerability of these areas to climate and changing land uses can have a disproportional impact on downstream uses, including flood storage, water quality, biodiversity and climate regulation.

Participants in Iowa Learning Farms Conservation Webinars are encouraged to ask questions of the presenters. People from all backgrounds and areas of interest are encouraged to join.

Webinar Access Instructions

To participate in the live webinar, shortly before noon CDT Oct. 20:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

Or go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172

Or join from a dial-in phone line:

Dial: +1 312 626 6799 or +1 646 876 9923

Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

A Certified Crop Adviser board-approved continuing education unit (CEU) has been applied for. Those who participate in the live webinar are eligible. Information about how to apply to receive the credit will be provided at the end of the live webinar.