Restored oxbows reduce nutrient runoff and improve fish habitat

Abstract

A n oxbow is a remnant meander of a river or stream that has been cut off from present flow as the stream channel has migrated within its floodplain. The remaining depression is often connected to the water table, leaving pools of standing water throughout the year. Regular flooding and land use practices cause sediment and organic material to be deposited in the depression over time. The deposited material reduces the depth of the historic oxbow, limiting its potential for flood storage, nutrient cycling, and off-channel fish habitat. In recognition of the important ecosystem services that they provide, the US Fish and Wildlife Service (USFWS) has been restoring oxbows in the Raccoon River Watershed in Iowa since 2002 (Betts 2014). The USFWS, the Nature Conservancy (TNC), Iowa Department of Natural Resources (IDNR), Iowa Soybean Association (ISA), Sand County Foundation (SCF), USDA Natural Resources Conservation Service (NRCS), and other partners have contributed to additional oxbow restorations as an innovative fish habitat improvement and tile line nitrate (NO3) treatment practice. Partners have worked with area producers through a voluntary conservation program to restore a series of oxbows that collect water from tile lines. The practice is intriguing to landowners since water quality and…