SESOIL is a user-friendly mathematical soil compartment model designed for long-term environmental hydrologic, sediment, and pollutant fate simulations. It can describe: water transport (quality and quantity); sediment transport (quality and quantity); pollutant transport and transformation: soil quality; pollutant migration to groundwater; and other processes. Simulations are performed for a user specified soil column extending between the ground surface and the lower part of the unsaturated soil zone of a region. The simulations are based upon a three-cycle rationale, each cycle being associated with a number of processes. The three cycles are the: (1) hydrologic cycle which takes account of rainfall, soil moisture, infiltration, exfiltration, surface runoff, evapotranspiration, groundwater runoff, (2) sediment cycle which takes account of sediment washload (from storms) and sediment resuspension (due to wind), and (3) pollutant fate cycle which takes account of advection, diffusion/volatilization, adsorption and desorption, chemical degradation or decay, biological transformation, hydrolysis, photolysis (not operational), oxidation (not operational), complexation of metals by organic ligands, cation exchange, fixation (not operational) and other processes. The program is written in the FORTRAN programming language for implementation on a DEC VAX 11/780 computer using the VMS 4.1 operating system. 256K bytes of core storage are required to operate the model.