Physical sources of nutrient nitrogen for the Auke Bay, Alaska estuarine ecosystem were investigated. These sources included vertical dispersion, advection, and fresh water sources. Hydrographic circulation patterns for the bay, and a nutrient budget for the surface mixed layer were developed. Measurements of temperature, salinity, currents, wind velocity, rainfall and runoff from the major streams and river influencing Auke Bay were made during the spring and summer of 1971. initial hydrographic and nutrient data (total available nitrogen and nitrate) from early spring were taken during a cruise of R/V Cayuse. Nutrient concentration of nitrate and ammonia in Auke Bay and the fresh water sources entering Auke Bay were measured on a weekly basis from July to September. Vertical mixing rates of 0.42 cubic meters per day were calculated for those times wind mixing did not occur. Mixing rates of 1.2 cubic meters/day were calculated for wind mixed conditions. Vertical dispersion through the pycnocline provided the major source of nutrients for summer phytoplankton production. Fresh water sources provided negligible amounts of nutrients. Average vertical transport of nitrate and ammonia when wind mixing did not occur were 0.5 mg-at/m²/day and 0.3 mg-at/m²/day respectively. During wind mixing, 3.0 mg-at/m²/day for nitrate and 2.0 mg-at/m²/day for ammonia were supplied to the mixed layer. Estimate productivity based on these calculations ranges from an average 100 mgC/m²/day during non wind mixed conditions to 600 mgC/m²/day during wind mixed conditions. / Graduation date: 1973