Description of Work USGS researchers have determined the densities of the eggs as these develop, and how much time the bighead and silver carp require to begin swimming and migrating laterally from flowing water into nursery habitat. This information about egg transport requirements was used to create a Tributary Assessment Tool also referred to as the Fluvial Egg Drift Simulator (FluEgg) model. The development of this tool was a collaborative effort between USGS and the University of Illinois. The tool takes into account the hydraulics of a river (water velocity and dispersion rates) and the water temperature (affects egg and larvae development rates) in order to determine if a river is sufficiently long and the velocities high enough [...]