Stream Fragmentation Study


An assessment of 100 randomly-selected road / stream crossings in the entire Driftless Area Ecoregion (WI, IL, IA, MN) were evaluated to estimate the number of stream crossings in the entire Driftless Area that were likely barriers to upstream movement of fish and other aquatic and amphibious animals.


1) Determine the extent that roadway crossings of streams are barriers to aquatic species passage. 2) Determine the frequency of occurrence of different barrier types.


Survey was completed. Findings reported in SWIMS. Finding presented at American Water Resources Association - WI Chapter 2012, presented at the 2012 Society of Freshwater Science conference, presented at Driftless Area Restoration Effort Science Symposium 2013, presented at 2017 dept. Water Quality Biologists meeting.

Study Design

Probabilistic: random sample of 100 randomly-selected stream / road crossings. Sample draw weighted to select equal numbers of crossings by stream sizes and roadway types (e.g. county versus interstate). Results weighted to account for differing numbers of stream sizes (Strahler stream orders) in ecoregion population.

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Statewide Inventory
Reports and Documents
A random sample of 100 stream roadway crossings in the Driftless Area (IA, IL, MN, WI) were surveyed to estimate the proportion of the 8,600 roadway stream crossing in the Driftless Area are likely barriers to aquatic organism passage.