Streamflow, water quality, and precipitation data collected during the 1980 and 1981 water years are reported. The purpose was to document changes in total phosphorus loads resulting from a change in agricultural waste management practices in the Johnson Brook watershed in Maine. Streamflow data include mean-daily discharges for the period May 12, 1980, through September 30, 1981, and instantaneous discharges determined during water quality sampling. Water quality data for the period March 1980 to September 1981 include total phosphorus concentrations determined from samples collected using cross-sectional depth-integrating sampling techniques and from samples collected using a pumping sampler. Suspended sediment concentrations, and water temperature and specific conductance values are also included. The precipitation data are daily totals for the period October 1980 through September 1981. (Lantz-PTT)