Iowa’s biggest prairie has 200 free-roaming bison and land found nowhere else

It’s 17 miles north of Sioux City

Broken Kettle Grasslands Preserve sits in Plymouth County, Iowa, and it holds the largest stretch of native prairie left in the state. The Nature Conservancy manages the land and keeps it open to the public every day.

You drive in and the tallgrass rolls out to the horizon in every direction, cut by rugged ridgelines and wooded valleys. More than 200 bison graze the hills.

Two hundred bird species nest and migrate through. And the ground you walk on exists in only one other place on Earth.

The road north from Sioux City takes about 20 minutes, and what waits at the end of it goes back 25,000 years.

Wind and ice built these hills from river dust

The preserve sits inside Iowa’s Loess Hills, a narrow ribbon of bluffs running along the state’s western edge.

Glaciers started retreating about 25,000 years ago, and strong winds picked up fine silt from the Missouri River valley and piled it here for thousands of years. Those deposits run up to 200 feet deep in places.

The only comparable loess formations on the planet sit in Shaanxi, China.

Walk the ridgelines and you can see the sharp slopes and stair-like “cat-step” terraces where the soil shifts and slides under its own weight.

Watch 200 bison graze hills they once ruled

The Nature Conservancy brought the first 28 bison to Broken Kettle in the fall of 2008. That original stock traced back to Wind Cave National Park in South Dakota and carried genetically pure bloodlines.

The herd now numbers more than 200 and roams freely across the grasslands. Their grazing does real work, too.

Bison create a patchwork of tall and short grass that supports a wider mix of plant species. The herd has done so well that extra bison have gone to tribal nations through the Intertribal Buffalo Council.

Prairie rattlesnakes and desert toads call this home

In 1999, The Nature Conservancy found prairie rattlesnakes at Broken Kettle, a species so rare in Iowa that almost nobody knew it lived here.

The Great Plains toad and plains spadefoot toad also turn up on the preserve, both species you would expect in western deserts, not Iowa grassland. Badgers, coyotes and deer move across the open hills.

Several rare prairie butterflies breed here too, including the regal fritillary, the Ottoe skipper and the Pawnee skipper.

Golden eagles ride the thermals off Butcher Road

Around 200 bird species use the preserve, and the mix of open ridgetops and wooded valleys pulls them in from across the Great Plains. Upland sandpipers, bobolinks and western kingbirds all nest here.

If you park along Butcher Road on the south side, you can watch migrant raptors pass through, including golden eagles and Swainson’s hawks.

The nearby 234th Street dead-end road is one of the best spots for finding American woodcock and northern bobwhite calling from the brush.

Wildflowers bloom from spring through first frost

The tallgrass prairie puts on a different show every month. Pasque flowers push up first in spring, breaking through before most other plants wake up.

By summer, purple coneflower, dotted blazing star and scarlet gaura fill the hillsides. Big bluestem and little bluestem grasses grow taller than you by midsummer and turn bronze and gold when fall hits.

Scattered between them, you will find lead plant, ground plum, snow-on-the-mountain, yucca and buffalo berry working their way through the grass.

Drive the ridge road loop for wide-open views

One of the easiest ways to take in the preserve is from your car along Butcher Road and the Ridge Road loop. The gravel roads follow the tops of loess ridges, and the views open up in every direction.

You might spot bison grazing on a distant hilltop without ever stepping out of the car.

This drive runs along the northern stretch of the Loess Hills National Scenic Byway, the same corridor that Lewis and Clark described as a “sea of grass” when they passed through western Iowa in 1804.

Ten miles of trails connect prairie to deep woods

About 10 miles of trails link Broken Kettle with neighboring Camp Joy Hollow and Five Ridge Prairie. Camp Joy Hollow, a former Girl Scout camp added to the preserve in Dec. 2022, takes you through rich woodland on shaded paths.

Five Ridge Prairie covers 964 acres next door, with marked trails winding through oak-filled valleys and open ridgetops.

The terrain gets steep and rugged in places, but the overlooks of the Big Sioux River make the climb worth it. You can cross from deep forest into open grassland in a single hike.

Catch sunrise from a ridgetop bench on Butcher Road

The high ridgelines at Broken Kettle look west over the Missouri River valley and east across rolling prairie.

Sunrise and sunset turn the grasses bronze and gold, and the light stretches across miles of open land with nothing blocking it. No development crowds the view.

No light pollution washes out the sky at night.

Benches along Butcher Road give you a place to sit and let the quiet settle in while you watch birds work the thermals above the bluffs.

Bison and fire keep 6,000 acres from disappearing

Without grazing and fire, trees and invasive plants would swallow this grassland whole. The Nature Conservancy runs controlled burns to mimic the natural fires that once swept the prairie clean.

Bison do the rest. Their grazing creates patchy zones of tall and short grass, which gives different plants, insects and birds the varied ground they need.

Bison wallows, the shallow dirt pits where they roll, open up bare soil for species that can not survive in thick grass. Fire and grazing together keep Broken Kettle working the way it did hundreds of years ago.

From 1992 to 7,500 protected acres and counting

The Nature Conservancy started buying land at Broken Kettle in 1992. The preserve has expanded more than 20 times since then.

In 2022, TNC purchased the 356-acre Camp Joy Hollow property from the Girl Scouts of Greater Iowa for $1.4 million, adding a block of woodland habitat to the prairie.

Together with partners, TNC has now protected more than 6,000 acres in the northern Loess Hills.

The connected conservation land totals roughly 7,500 acres, giving bison, birds and everything else an unbroken range to roam.

Pack water and wear sturdy shoes for the hills

The preserve sits off Butcher Road near Westfield, Iowa, and it opens every day from 7 a.m. to 7 p.m.

You will not find restrooms, a visitor center or any developed facilities on the land. Camping, campfires and seed collecting are all off limits.

The terrain climbs and drops sharply in places, so bring solid footwear and plenty of water.

Some sections close from time to time for grazing management or Girl Scout activities at Camp Joy Hollow, so check conditions before you go.

Visit Broken Kettle Grasslands Preserve in Iowa

You can see bison, wildflowers and some of the rarest land in North America without paying a dime.

Broken Kettle Grasslands Preserve is located off Butcher Road near Westfield in Plymouth County, about 17 miles north of Sioux City. The Nature Conservancy manages the site, and it is free and open daily from 7 a.m. to 7 p.m.

Take Highway 12 north to Butcher Road for the scenic ridge drive, or head to neighboring Five Ridge Prairie for marked hiking trails. Check the official website for current conditions before you head out.

This article was created with AI assistance and human editing.

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