This paper describes a pilot operation that was to confirm possible treatment alternatives and optimize design parameters so that a 290-mgd treatment plant can be designed. The four treatment goals for this project were: removal of disinfection byproduct precursors to Stage 2 D/DBP Rule levels; removal of particulate matter (turbidity) to 0.1 ntu and measured pathogen removal by filtration of >99% (>2-log); maintenance or improvement of the biostability of the New Croton Reservoir water being delivered to New York City; and, operation of a cost effective treatment plant. The pilot plant consisted of three distinct treatment trains: ozone-direct filtration; DAF-Intermediate Ozone-Filtration; and, ozone-biologically active carbon-diatomaceous earth filtration. Only results from the coagualtion trains is presented.