General limnological and trophic conditions of 55 lakes and ponds in north and central Florida were established over an extensive one year sampling period. Florida lakes are typically shallow and in a sandy terrain. Most of the lakes have soft water, and high organic color is a common but variable property. Trophic conditions range from ultraoligotrophy in the sand-hill lakes of the Trail Ridge region to hypereutrophy in some large drainage lakes in Alachua County and in the Oklawaha River Basin. Trophic data were analyzed by multivariate techniques, and logical trophic groups derived by cluster analysis. A quantitative index of trophic state (TSI) was derived using 7 trophic indicators, and the TSI values were used to establish quantitative relationships between lake trophic conditions and watershed characteristics. Nitrogen and phosphorus budgets were calculated for the lakes based on land use and population patterns in the watersheds, and critical loading rates were estimated from the budgets and the trophic conditions. (Author)