Several bench-scale studies were conducted to evaluate the effectiveness of enchanced coagulation for controlling chlorination byproducts and to assess the impact of coagulation pH preadjustment on total organic carbon (TOC) removal and plant operating costs. Tests were conducted on a variety of surface water sources with TOC values ranging from 2 to 11 mg/L. An iron-based coagulant, such as ferric chloride, was consistently more effective than alum in removing natural organic matter (NOM). Coagulation pH appeared to be a determining factor for maximum NOM removal when ferric chloride was used as a primary coagulant. Typically, preadjustment of pH at a value of 6.0 plus or minus 0.2 increased NOM overall removal to as much as 65 percent and reduced the coagulant dose by as much as 60 percent. Enhanced coagulation led to higher overall operating costs, but preadjustment of pH with sulfuric acid reduced costs by lowering the coagulant dosage as well as sludge production. Includes 13 references, tables, figures.