A modified version of SEAWAT was used in a study by the USGS and the Miami-Dade Water and Sewer Department to simulate effluent injection into the Boulder Zone and groundwater flow and effluent transport in the Floridan aquifer system. The Miami-Dade Water and Sewer Department injects nonhazardous, secondarily treated, domestic wastewater (effluent) into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, in southeastern Florida. Effluent injection into the Boulder Zone began in June 1997 and was first detected outside the Boulder Zone in the overlying Avon Park permeable zone in May 1998. The Department has detected injected effluent outside the Boulder Zone at six locations since May 1998. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20175145).