The minnow U.S. Fish and Wildlife Service ecologists pulled from the shallow moat was a puny thing, with a flare of orange rimming its fins and a dark band of scales running the full length of its inch-and-a-half body. 

“Finally,” thought Kathy Law, as she peered at the little fish. In the summer sun, it glinted metallic.

Topeka shiners once thrived in small and medium streams across the Great Plains. But for several decades, the fish have been hard to find. 

For three summers, Law, a farmer and attorney, had watched expectantly as water, native plants and then wildlife returned to five restored oxbow wetlands on her family farm in Iowa’s Carroll County.

In 2021, the Fish and Wildlife Service and the Iowa Soybean Association excavated the U-shaped ponds on the property, former river meanders cut off from the main channel of Purgatory Creek and filled in with decades of soil erosion. 

The project cost tens of thousands of dollars, paid for by federal, state and private grants. It had all been for the silver minnow she now held.

The expansion of agriculture across the Midwest has blotted out many of the slow-moving, off-channel prairie streams that Topeka shiners favor. In their place, manually drained cropland and artificially straightened rivers have taken over.

In 1998, the U.S. Fish and Wildlife Service listed the Topeka shiner as a federally endangered species, threatened by “habitat destruction, degradation, modification, and fragmentation.” 

But concerted efforts to restore habitats where the endangered minnow might once again thrive have led to the restoration of hundreds of oxbow lakes across Iowa.

A network of federal, state, non-profit, and agricultural trade agencies has teamed up to excavate the former wetlands at little-to-no cost to landowners. Nearly two decades since beginning restoration efforts, they’ve learned that the abandoned river meanders don’t just create habitats for a recovering Topeka shiner population, they also effectively wash out the agricultural pollutants that plague Iowa’s waterways. 

“It really is a success story,” said Karen Wilke, associate director of freshwater at The Nature Conservancy in Iowa. “Now we’re not just doing it for Topeka shiner, but we’re doing it for water quality as well.” 

Over centuries, meandering rivers and streams fold in on themselves like ribbon candy. Insistent currents erode their banks, redrawing riverbeds into ever-tighter sinusoidal waves. 

Chasing the path of least resistance, the current eventually cuts off U-shaped oxbow channels, leaving curving lakes where water flows more slowly, if at all. 

Oxbows are naturally occurring features in the Iowa landscape, but they became more abundant as agriculture brought drastic, manmade transformations to the state’s hydrology, explained Clay Pierce, a former scientist in the U.S. Geological Survey’s Iowa Cooperative Fish and Wildlife Research Unit at Iowa State University. He spent the last decade of his career studying Topeka shiner habitats and recovery efforts.

Before European settlement, wetlands covered approximately 11 percent of Iowa. Their still or slow-moving waters provided habitats for a variety of fish, reptiles and amphibians, including the diminutive, silvery Topeka Shiner. Today, over 95 percent of those wetlands have been drained and converted to farmable land. 

“It’s like one of the wonders of the world, how they changed the Iowa landscape,” said Pierce.

Tile lines, underground drainage systems used to lower the water table in and around fields, transformed the state’s slow-moving wetlands into faster, fuller streams that intensified natural riverbank erosion and the creation of oxbow lakes, Pierce explained.

And as industrialized agriculture rerouted the state’s waters and accelerated oxbow formation, farming practices also exacerbated soil erosion, leading to the drying out of those oxbows.

Tillage, a soil management practice that reached peak popularity in the mid-20th century, left fertile topsoil exposed to the elements and readily carried off fields. Trillions of tons of U.S. topsoil are estimated to have been lost to erosion to date, settling in nearby waterways.

Erosion-mitigating farming strategies, including no-till or low-till agriculture and the planting of cover crops, have become more widely adopted, but many former oxbows in Iowa are still filled with sediment.

The former oxbows look like apostrophe-shaped scars in the earth, said Wilke, at The Nature Conservancy in Iowa. Her team has mapped out tens of thousands of oxbows across the state that are candidates for restoration. 

In rainy years, these patches of land are prone to flooding, as though remembering a past life. Those on farmland are largely unusable—too concave and wet to support a decent yield.

As the slow-moving and standing waters favored by the Topeka shiner all but disappeared from Iowa, so did the fish.

Once common across Minnesota, South Dakota, Iowa, Nebraska, Missouri, and Kansas, documented populations of the fish were reduced to an estimated 20 percent of their original geographic range by the turn of the 21st century, said Pierce. 

Before the onset of industrial agriculture, shiners were found in streams that flowed out of large, slow-moving wetland areas. But those wetland complexes are gone, converted to millions of acres of cropland.

Despite their endangered status, the tiny minnows are shockingly rugged, able to withstand both the broiling summers and frigid winters of the Great Plains, said Pierce. They’re also better equipped to survive in the low-oxygen conditions of shallow waters where few other fish can thrive. That resilience bodes well for their survival in restored wetland habitats.

“We can’t replace all the large, expansive wetland complexes that were here. It wouldn’t be economically or even politically possible to do that. But we can build more oxbows or encourage the ones that are there to function as habitats,” said Pierce.

Following the Topeka shiner’s federal endangerment listing, the U.S. Fish and Wildlife Service (USFWS) focused its efforts on preserving remnant populations in the North Raccoon River watershed, which runs through intensely cultivated cropland in western Iowa.

Though the Service initially attempted to engineer habitats within creeks, diverting currents with boulders and excavating deeper pools, they more often than not found shiners in oxbow lakes set back from the main channel and occupying private property. 

Oxbow lakes became, and remain, central to the Topeka shiner recovery plan.

In the early 2000s, USFWS worked with The Nature Conservancy of Iowa, which served as “boots on the ground,” finding funding sources, connecting with landowners, and overseeing the restorations, said Wilke. By 2008, the agencies had restored nearly twenty former oxbows in the Racoon River watershed.

The impact of restorations on local wildlife populations was immediately evident, said Wilke. Topeka shiners began returning to the landscape, but so did countless other species.

Research conducted by The Nature Conservancy documented 57 fish species and 81 bird species using the newly restored oxbow habitats. “Turtles, mussels, frogs, river otters, beavers, you name it,” said Wilke. “I think all the species are hungry to have this habitat come back, hungry to have more water on the landscape.”

In 2011, the Iowa Soybean Association came on board, joining forces to restore more oxbows in the Boone River watershed in north-central Iowa. With its connections to farmers across Iowa, the trade association for soybean producers brought new momentum to the project, said Wilkes.

Unlike other states with vast swaths of public land, over 97 percent of Iowa’s land is privately owned. This means that the majority of former oxbows are on private land where restoration hinges on buy-in from the owners. The Iowa Soybean Association held powerful sway with those property owners.

The organizations collaborating with the U.S. Fish and Wildlife Service make up the Iowa Topeka Shiner Recovery Partnership and provide both technical support and a diverse array of private funding, in addition to the suite of state and federal grants used to cover restoration costs. 

Though each acre of wetland costs approximately $20,000 to excavate, not a single cent comes from landowners, said Wilke.

For Kathy Law, that was a huge selling point in her decision to restore the five oxbows on her family farm. “We didn’t have to spend any money on it. And they took care of everything,” she said. “I think that’s the neat part of it. It shows we can do things that don’t cost us any money, and try to make a difference.”

To date, more than 200 oxbows have been restored in the state of Iowa. Though far from a complete comeback, Topeka shiner populations seem to be on the rise.

In 2016 and 2017, Pierce and his students at Iowa State University collected the endangered minnows in 60 percent of the Iowa watersheds they’d historically inhabited, a significant rebound from only 32 percent in 2010 and 2011.

In 2019, Pierce published an article documenting the status of Topeka shiners in Iowa.

“I think the picture is brighter, and I firmly believe that oxbows are part of that story,” said Pierce. “It’s an ‘if you build it, they will come’ sort of thing.”

Sampling by the Nature Conservancy in Iowa has also turned up Topeka shiners in the majority of restored oxbows. 

In fact, the minnows may not be classified as “endangered” for much longer. In the 5-year status review for the Topeka shiner, completed by USFWS in 2021, federal wildlife officials recommended that the fish be downlisted to “threatened.”

The surge in oxbow restorations hasn’t only served the Topeka shiner, participants in the recovery partnership are quick to point out.

The restored wetlands are also powerful water-quality tools, helping remove nitrogen runoff from tile lines that drain much of Iowa’s farmland before it can pollute major waterways.

“We’re able to intercept that tile into these wetlands before that water gets into the river, and we’re finding that it removes 62 percent, on average, of the farm chemicals, the nitrate, that comes in from that tile,” said Wilke.

Based on those findings, Iowa’s Nutrient Reduction Strategy added oxbow restorations as a nutrient-reducing practice in 2019. Introduced in 2014 to address the high volume of agricultural nutrients exiting Iowa’s waterways, the strategy promotes voluntary conservation measures for farmers looking to minimize nutrient loss from their fields and allocates state funds to those practices.

The Iowa Department of Agriculture and Land Stewardship now covers 100 percent of the costs of oxbow restorations that will receive water from a tile line.

Unlike other nutrient-reduction practices the state funds, such as saturated buffers and bio-reactors, oxbows are both natural and long-lasting, said Wilke. “You do it, and it’s done. And then you just let nature take over and do its thing.”

The water quality benefits of oxbow restorations have brought a new group of landowners on board, said Grace Yi, habitat systems manager at Practical Farmers of Iowa, the most recent member of the Iowa Topeka Shiner Recovery Partnership.

“That’s what makes oxbows really great. They have a lot of different benefits and angles that you can approach farmers and landowners with,” said Yi.

Some of those benefits, “you can’t really put a price tag on,” like a more beautiful property or, as one farmer told Yi, time spent catching frogs with his grandson.

For Kathy Law, oxbow restorations have returned her family’s farm to a state she remembers from her early days there.

Mallards now paddle through the still waters. Off the muddy banks, fat tadpoles whip their golf-ball-sized bodies beneath fallen leaves. 

If Law encountered the Topeka shiner during childhood fishing expeditions on the farm, she doesn’t remember it. But the oxbows stir at something in her memory.

“I remember there were little creeks, little streams going through here. We hadn’t had those for forever.”