Iowa conservationists restored more than 200 forgotten river bends. Now this endangered fish is returning

Across Iowa's agricultural landscape, old bends in rivers and streams had gradually filled with sediment, leaving behind wetlands that could no longer function as they once did. Over the past 25 years, conservationists and landowners have been digging these forgotten waterways back to life. The effort was designed partly to save a tiny endangered fish, and researchers are now finding the Topeka shiner returning to many of the restored wetlands.

More than 200 oxbows restored saved this endangered species

The waterways are known as oxbows, which are U-shaped wetlands that form when bends split from a river or stream. Since 2001, the US Fish and Wildlife Service's Partners for Fish and Wildlife Program, the Iowa Soybean Association, The Nature Conservancy, and other partners have restored over 200 oxbows in Iowa. The repair often entails removing accumulated silt so that the depressions may once again contain water and reconnect with surrounding streams during floods. The target is simple: a fish measuring only a few inches long.

The Topeka shiner was designated as endangered in 1998 after disappearing from major parts of its native Great Plains range. The Fish and Wildlife Service has identified several risks, including channelised streams, diminishing floodplain habitat, agricultural runoff, and sediment. There are encouraging signs that rebuilding habitat is working.


The Fish and Wildlife Service says Topeka shiners have been documented recolonising many restored Iowa oxbows. Earlier restoration projects produced striking results: the Iowa Natural Heritage Foundation reports that researchers found at least one Topeka shiner in nine of 10 restored oxbows surveyed, with 354 fish recorded in a single oxbow. A similar effort in neighbouring Minnesota offers another indication of what restoration can achieve. Of 130 oxbows restored there over the past decade, about 90% now contain Topeka shiners, according to The Nature Conservancy.

One tiny fish, much bigger benefits

Saving the shiner isn't the only reason to restore these wetlands. The Nature Conservancy says an oxbow can hold up to one million gallons of water per acre, helping capture floodwater before slowly releasing it. Surveys of restored oxbows have recorded 57 fish species and 81 species of migratory birds and waterfowl. Research supported by Iowa State University's Iowa Nutrient Research Centre has also found reconstructed oxbows can reduce nitrogen loads, with reductions ranging from 35% to 76% under certain conditions.

A small comeback, yet a long way to go

The return of the Topeka shiner does not mean the species is fully recovered. Federal officials stress that recovery requires stable, self-sustaining populations across its historical range, not simply sightings in restored habitats. Still, Iowa's experience demonstrates what can happen when seemingly forgotten pieces of a river landscape are restored. More than 200 old waterways have been given another chance — and a tiny endangered fish is increasingly finding its way back home.