The Fluvial Egg Drift Simulator (FluEgg) estimates bighead, silver, and grass carp egg and larval drift in rivers using species-specific egg developmental data combined with user-supplied hydraulic inputs (Garcia and others, 2013, Domanski, 2020). This data release contains results from 240 FluEgg 4.1.0 simulations of bighead carp eggs in the Illinois River under steady flow conditions. The data release also contains the hydraulic inputs used in the FluEgg simulations and a KML file of the centerline that represents the model domain. FluEgg simulations were run for all combinations of four spawning locations, six water temperatures, and ten steady flow conditions. Each simulation included 5,000 bighead carp eggs, which develop and eventually hatch into larvae. The simulations end when the larvae reach the gas bladder inflation stage. The four spawning locations were just downstream of the lock and dam structures at Marseilles, Starved Rock, Peoria, and LaGrange. For each of these spawning locations, the eggs were assumed to have been spawned at the water surface and at the midpoint of the channel. The six water temperatures were 18, 20, 22, 24, 26, and 28 degrees Celsius. The ten steady flow conditions ranged from half the annual mean flow to the 500-year peak flow and are discussed in more detail below. Note that in the streamwise coordinate system used by FluEgg, the streamwise coordinate of the Mississippi River confluence is 396,639 meters. Any drift distances greater than this value should be excluded from any further analysis of this data. The hydraulic inputs for the FluEgg simulations were generated using a one-dimensional steady Hydrologic Engineering Center-River Analysis System (HEC-RAS) 5.0.7 model for the Illinois River between Marseilles Lock and Dam and the Mississippi River confluence near Grafton, Illinois (HEC-RAS, 2019). The HEC-RAS model was developed by combining four individual HEC-RAS models obtained from the U.S. Army Corps of Engineers Rock Island District (U.S. Army Corps of Engineers Rock Island District, 2003). The model was run for the following ten flow profiles: half the annual mean flow, annual mean flow, annual mean flood, 2-year peak flow, 5-year peak flow, 10-year peak flow, 25-year peak flow, 50-year peak flow, 100-year peak flow, and 500-year peak flow. The flow rates for each of the profiles were obtained for the following U.S. Geological survey (USGS) streamgaging stations from USGS StreamStats: 5543500 Illinois River at Marseilles, Illinois, 5558300 Illinois River at Henry, Illinois, 5560000 Illinois River at Peoria, Illinois, 5568500 Illinois River at Kingston Mines, Illinois, 5570500 Illinois River near Havana, Illinois, 5585500 Illinois River at Meredosia, Illinois, 5586100 Illinois River at Valley City, Illinois (Soong and others, 2004; Granato and others, 2017). Garcia, T., Jackson, P.R., Murphy, E.A., Valocchi, A.J., Garcia, M.H., 2013. Development of a Fluvial Egg Drift Simulator to evaluate the transport and dispersion of Asian carp eggs in rivers. Ecol. Model. 263, 211–222, https://doi.org/10.1016/j.ecolmodel.2013.05.005. Granato G.E., Ries, K.G., III, and Steeves, P.A., 2017, Compilation of streamflow statistics calculated from daily mean streamflow data collected during water years 1901–2015 for selected U.S. Geological Survey streamgages: U.S. Geological Survey Open-File Report 2017–1108, 17 p., https://doi.org/10.3133/ofr20171108. Domanski, M.M., Berutti, M.C., 2020, FluEgg, U.S. Geological Survey software release, https://doi.org/10.5066/P93UCQR2. Hydrologic Engineering Center-River Analysis System (HEC-RAS), 2019, accessed August 20, 2020, at http://www.hec.usace.army.mil/software/hec-ras/. Soong, D.T., Ishii, A.L., Sharpe, J.B., and Avery, C.F., 2004, Estimating flood-peak discharge magnitudes and frequencies for rural streams in Illinois: U.S. Geological Survey Scientific Investigations Report 2004–5103, 147 p., https://doi.org/10.3133/sir20045103. U.S. Army Corps of Engineers Rock Island District, 2004, Upper Mississippi River System Flow Frequency Study, Hydrology and Hydraulics, Appendix C, Illinois River, accessed August 20, 2020, at https://www.mvr.usace.army.mil/Portals/48/docs/FRM/UpperMissFlowFreq/App.%20C%20Rock%20Island%20Dist.%20Illinois%20River%20Hydrology_Hydraulics.pdf.