Drinking water providers now have an array of tools for addressing the control of disinfection by-product (DBP) formation and allied biodegradable compounds through enhanced removal of precursors, better process sequencing to minimize formation, use of alternative disinfectants to reduce the formation of chlorine-based DBPs, and distribution system management to minimize dead ends. This research examines the relationship between DOC and dissolved DBP precursors in surface waters, and extends this information to the modeling of natural organic matter (NOM) and precursor organics in drinking water catchments. In addition, substudies cover the highly biodegradable components of NOM and long-term trends in bulk NOM concentrations.