This article presents river-water fouling rates at 12 Tennessee Valley Authority (TVA) power plant condensers, nine of which were retubed with a commercially available enhanced tube. Four were located on the Cumberland River, six on the Ohio, and two on the Clinch River. The overall heat transfer coefficients were calculated from logged field data taken over periods extending from 1 to 10 years. The fouling resistances were next calculated with the separate resistance method and with a bundle correction factor to the condensing, single-tube Nusselt prediction. The bundle correction factor was determined for each condenser using the data taken within 1000 hours after each cleaning. With the use of this new bundle factor method, fouling rate data can be obtained even with variable operating conditions.