The Sacramento-San Joaquin Delta provides drinking water to over 22 million people in California. Delta islands are used for agricultural purposes and water is pumped off drains on these islands to maintain agricultural production. At times, this drain water contains elevated levels of dissolved organic carbon (DOC) and can exceed the U.S. EPA maximum level for carcinogenic disinfection by-products (DBPs) when chlorinated for drinking water. Coagulation of organic matter with polyvalent metal cations (Al3+ and Fe3+) is commonly used as a water treatment process for the removal of DOC, forming organic flocs through charge neutralization and adsorption. A microcosm experiment with a set of both unfiltered and filtered drain water was set up and dosed with various additions of two commercially available coagulants. DOC removal in a filtered water and unfiltered water sample showed similar trends in the removal of DOC. The coagulation process at optimal dosing, determined as the point of zero charge and measured by a streaming current detector, removed on average 75% of the total DOC. This study further addresses the reactivity of DOC, in terms of DBP formation after coagulation at varied dosings, with the objective of determining at what point the majority of precursor DOC is removed. The composition of DOC remaining following varied coagulant dosings of aluminum and iron coagulants, were examined with XAD/DAD fractionation, a widely used approach to DOC characterization. Of the original drain sample, approximately 60-80% was removed by coagulation at optimal dosing. Of the DOC remaining following coagulation, 40% is hydrophobic in nature. The goal of this research is to understand the nature of the DOC that is implicated in DBP production and to determine the reactivity of the uncoagulated DOC.