Karl W. Behrens Memorial Ponds and Woodland is a 29-acre preserve featuring a series of sandy ponds inhabited by the blue-spotted salamander, a rare species in Iowa. It is located 6 miles northwest of Cedar Rapids and 1.5 miles northwest of Toddville in Linn County. The property was deeded to The Nature Conservancy by Karl W. Behrens in 1977 and was dedicated as a biological state preserve in 1982.
Located on the Iowan Surface landform region, the natural features of this preserve are tied to the glacial history of the area. As the immense Wisconsinan glacier melted some 12,000 years ago, a variety of sediments were deposited in the nearby Cedar River valley. Sand from these alluvial deposits was later blown onto adjacent uplands to form gently rolling sand dunes. Today, the sandy soil found in the preserve provides a variety of habitats, including oak woodland, thickets, prairie openings, marshes, and several natural ponds.