There is growing concern about nutrient enrichment of lakes, streams, and rivers as a result of nonpoint source pollution from a number of land management practices. Examples include runoff from fertilized cropland, pastures, golf courses, lawns, and forests. The quality of streamwater in forests typically exceeds the quality of water in other land use areas. Streams draining agricultural lands average almost ten-times greater concentrations of nitrate and phosphate than streams draining forested areas. However, if forest fertilization causes large increases in streamwater nutrient concentrations, then unacceptable degradation of water quality could result. This bulletin summarizes information from studies of forest fertilization around the world, and evaluates the responses of streamwater chemistry. The results of these studies are tabulated and plotted as histograms that show the frequency of large increases in nutrient concentrations among the studies. In general, peak concentrations of nitrate-N in streamwater increase after forest fertilization, but these increases remain within acceptable limits for drinking water quality. Increases in average concentrations of nitrate are much less than increases in the peak values. Relatively high concentrations of streamwater nitrate-N tend to occur with repeated fertilization, use of ammonium nitrate (rather than urea), and fertilization of N-saturated hardwood forests. No evidence has been reported of detectable effects of forest fertilization on the composition or productivity of stream communities, but more detailed studies may be warranted (especially in relation to P fertilization). Major limitations in current knowledge include the effects of repeated fertilization in short-rotation plantations, and the effects of fertilization on streamwater chemistry in tropical plantations.