Nutrient enrichment experiments indicated that Kane'ohe Bay, O'ahu, Hawaiian Islands is now distinctly nitrogen-limited. The water column appears more oligotrophic now than in 1978-1979 (the year immediately following diversion of two sewer outfalls). Inorganic nitrogen and phosphate concentrations now border on the limit of detection by colorimetric methods. Chl a concentrations have declined by 35-40% and Secchi depths have increased by 15-35% since 1978-1979. About 40% of the phytoplankton chl a is accounted for by picoplankton.