Iowa Restores 200 Ponds, Saves Endangered Fish Species

The Topeka shiner, a small silver and orange minnow, almost disappeared from Iowa completely. But saving this tiny fish led to one of the most surprising environmental victories in the Midwest.

Iowa wasn't always covered in cornfields. Before agriculture transformed the landscape, 11% of the state was wetlands, including thousands of oxbow lakes created when rivers changed course during heavy rains. These U-shaped ponds provided perfect homes for the Topeka shiner and countless other species.

Farming erased more than 10,000 of these wetlands, and the shiners vanished with them. By 1998, the fish landed on the Endangered Species List.

In 2000, the US Fish and Wildlife Service partnered with the Nature Conservancy to identify and restore these lost wetlands. They looked for scars left in river bends where oxbow lakes once existed. The plan was simple: bring back the ponds, bring back the fish.

The results exceeded everyone's expectations. The shiners returned to 60% of the restored oxbows. But conservationists noticed something else happening in these wetlands.

Agricultural pollutants washing through streams were settling in the oxbow mud instead of flowing downstream. The restored ponds were acting as natural water filters, tackling Iowa's nutrient runoff problem without expensive infrastructure.

"Now we're not just doing it for Topeka shiner, but we're doing it for water quality as well," said Karen Wilke, associate director of freshwater at the Nature Conservancy in Iowa.

The Ripple Effect

The project transformed from a single-species rescue mission into a full ecosystem revival. Today, over 200 oxbow lakes dot Iowa's landscape again, supporting 57 fish species, 81 bird species, plus mussels, turtles, amphibians, beavers, and river otters.

In 2011, even the Iowa Soybean Association joined the effort, helping restore more wetlands in the Boone River watershed. Private landowners receive funding from state grants, federal programs, and private capital, removing any financial burden.

Each wetland costs tens of thousands of dollars to restore, but the benefits multiply across water quality, biodiversity, and habitat connectivity. On a landscape where 97% of land is privately owned, collaboration made the impossible happen.

The success caught federal attention. A 2021 review recommended moving the Topeka shiner from "endangered" to "threatened" status, marking another win for the Endangered Species Act.

"I think all the species are hungry to have this habitat come back, hungry to have more water on the landscape," Wilke said. Turns out, sometimes the smallest fish can make the biggest waves.