We are assessing population viability and habitat preferences to develop habitat suitability models for the Illinois state-threatened species, the Eastern Sand Darter and the River Redhorse. Our objective is to evaluate the distribution, abundance, and habitat preferences of these two species in the Embarras and Kankakee Rivers, respectively. We will also identify potential effects of human disturbances and incorporate these data into habitat suitability models for each species within its respective watershed. We will use additional species and GIS-level data to predict the potential distribution throughout the state. We will expand the modeling effort to include two additional darter species and two redhorse species to assess ecological niche partitioning relative to our target species. These models will inform the Illinois Department of Natural Resources on the distribution and population viability of these two state-threatened species, align with the Illinois Wildlife Action Plan goals and efforts through its Streams Campaign, and support conservation planning for Species in Greatest Conservation Need.