The City of Fargo Water Treatment Plant (WTP) recently piloted GE submerged ZeeWeed 1000, Siemens encased MemCor L20N, and Pall encased UNA-620A membranes for its new 15 million gallons per day (mgd) membrane WTP. The source water Sheyenne River quality is challenging for membrane treatment: elevated total dissolved salts, high total organic content, and long cold season (34-35 øF (1.1-1.7 øC ) for 4-6 month annually). The goal of the pilot study was to determine flux and other conditions to yield stable, repeatable performance, especially clean permeability. Results and conclusions are discussed herein.