Nanofiltration (NF) is an emerging technology for the control of disinfection byproducts (DBPs) from potable water treatment. Numerous NF plants are currently under design or construction or in operation that remove hardness and DBP precursors from shallow ground waters in south Florida. NF plant capacity in Florida is expected to reach 40 million gallons per day by the end of 1993. Likewise, the water industry and regulatory agencies are interested in the use of NF technology for treatment of organic-laden surface waters to meet current and anticipated disinfection and DBP regulations. While limited studies have confirmed NF is also effective for controlling DBPs in surface supplies, they also have demonstrated that membrane fouling is a major constraint in the cost-effective application of this technology. This paper presents the results of a pilot study performed for the City of Chesapeake, Virginia, in which NF was evaluated for its ability to provide potable-quality water from a highly-organic surface supply, the Great Dismal Swamp.