This paper describes model development of solute mass transfer in an integrated membrane system (Hydranautics LFC1). The data was generated from the St. Johns River Water Management District (SJRWMD) Water Treatment Project. A wide spectrum of constituents in source waters is known to contribute to fouling. Membrane foulants are classified roughly into dissolved organic substances, colloidal or particulate matter, insoluble inorganic compounds, and biological matter such as bacteria. In order to control organic and colloidal fouling, ferric sulfate coagulation using Super Pulsator (SP) blanket clarifier followed by dual media gravity filtration and Zenon (Z) immersed ultrafiltration were used. Monochloramine was used to prevent biofouling, while antiscalants were added to membrane feed water for scaling control. In this study, the effects of these pretreatment processes are evaluated by monitoring membrane productivity change over operating time. Furthermore, pretreatment water qualities are correlated to membrane performance through mass loading and/or resistance modeling. Includes 29 references, tables, figures.