Twin Cities WRS Seminar

Nutrient Load Reduction in Restored River Oxbows


Keith Schilling
University of Iowa

October 2, 2020


Nutrient export from the agricultural Midwest is an ongoing challenge that threatens local waterbodies and contributes to the development of hypoxia in the Gulf of Mexico. Oxbows are natural waterbodies formed when a river cuts off a meander loop as it migrates within its floodplain. Restoration of former oxbows can potentially reduce export of nitrate from agricultural land as well as provide important habitat for many species, including the endangered Topeka Shiner. Recent studies of nitrate export reduction by oxbows in Iowa are encouraging, demonstrating a 45% reduction in nitrate export of water entering oxbows from subsurface tiles compared with water discharged to the adjacent stream. Oxbow restorations are as effective as several other nutrient reduction practices, are relatively inexpensive to build, and can provide significant ecosystem services. We recently added multi-purpose oxbows as a new BMP in the Iowa Nutrient Reduction Strategy for reducing nitrate export from agricultural lands.

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Meeting ID: 943 2193 2246
Passcode: 3x787i