Williams Prairie State Preserve

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State Preserves

Williams Prairie State Preserve is a 30-acre area featuring a wet prairie. It is located 2.5 miles north of Oxford and 15 miles northwest of Iowa City in western Johnson County. 

In the early 1900s, John Williams bought the area and used it as a hayfield. Botanists from the University of Iowa discovered the area about 1960 and have used it as an outdoor classroom since that time. 

It was deeded to The Nature Conservancy in 1973 and was dedicated as a biological state preserve in 1976. Ownership and management of the preserve transferred to the Johnson County Conservation Board in 2014. 

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About the Land

Located along the edge of the Iowan Surface landform region, the preserve is situated within the broad valley of the Iowa River. 

Most of the preserve consists of shallow lowland that remains wet through the spring and into midsummer. A wet prairie, dominated by dense stands of sedges and bluejoint grass, is located here. 

Some dry knolls are located in the eastern and southern portions of the site, dominated by big bluestem and Kentucky bluegrass. 

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Directions

  1. From the intersection of I-80 and I-380 on the northwest side of Iowa City, take I-80 west for 9 miles to County Road W38 (exit 230). 
  2. Turn north (right) onto W38 (Black Hawk Avenue) and drive 2.5 miles into the town of Oxford. 
  3. On the south edge of Oxford, turn east (right) onto Hawkeye Road (295th Street) and follow it 0.5 mile to Augusta Avenue. 
  4. Turn north (left) and follow Augusta Avenue (which becomes Highway 109) through town for 1.25 miles to Highway 6. Cross Highway 6 and continue north (straight) on W38 1.5 miles to Grabin Road. 
  5. Turn west (left) on Grabin Road and go 1 mile to Black Hawk Avenue NW. Turn north (right) and go 0.25 mile to the preserve on the east side of the road (sign: Williams Prairie). 
  6. Access is through a gate on the southwest corner of the preserve.
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Plants

Over 300 species of vascular plants have been reported in the preserve, including twelve species of sedges and about forty species of grasses. Eight bryophytes (mosses and liverworts) are also found here. 

In the spring, blooms include: 

  • Hoary puccoon
  • Prairie phlox
  • Yellow stargrass
  • Spring cress
  • Golden alexanders
  • Shooting star
  • Marsh marigold
  • Swamp buttercup

Following in the summer are:

  • Swamp milkweed
  • Butterfly weed
  • Michigan lily
  • Marsh vetchling
  • Wild indigo
  • Indigo bush
  • Leadplant
  • Blue flag iris
  • Marsh bellflower
  • Prairie blazing star 

Rare plants found here include Virginia bunch-flower and northern adder’s tongue fern. 

Fall brings: 

  • Swamp lousewort
  • Sneezeweed
  • Panicled aster
  • Nodding bur marigold
  • New England aster
  • Flat-topped aster
  • Canada goldenrod
  • Grassleaf goldenrod
  • Bottle gentian
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Birds & Species

Many nesting birds can be found here, including sedge wren, bobolink, grasshopper sparrow, eastern meadowlark, yellow-throated warbler, and song sparrow. 

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Visitor Information

Botany and zoology classes from the University of Iowa, Cornell College, and local high schools use this preserve for an outdoor classroom. 

Hunting is not permitted. 

Other natural areas in the vicinity include Rock Island, Palisades-Dows, and Hanging Bog State Preserves and Palisades-Kepler State Park.

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