Williams Prairie State Preserve is located in the Iowan Surface landform region and contains a wet prairie with more than 300 plant species are found here, including 12 sedges, 40 grasses and 8 bryophytes. Springtime sees flowers like hoary puccoon and yellow stargrass, followed by butterfly weed and indigo bush in the summer. The preserve is also home to rare plants like Virginia bunch-flower and norther adder's tongue fern. Numerous nesting bird species are found here as well such as sedge wren and bobolink.

In 1973, John Williams deeded the area to The Nature Conservancy and it became a biological state preserve in 1976.

Fees, permits, and reservations may apply.