TABLE OF CONTENTS

A predictive model for phosphorus in lakes has been developed and verified. The model shows excellent agreement between observed and pre-dicted average phosphorus concentrations for lakes with a wide range of hydraulic detention times (1 to 700 years) and mean depths (14 to 313 meters). At present the model should be applied only to lakes with oxic hypolimnetic waters. The model has been verified for conditions of con-stant nutrient loadings. The model provides an explanation for the effects of mean lake depth on water quality noted by several limnologists. Vertical exchange of phosphorus forms across the thermocline and natural aggregation within the lake are important processes for the transport and deposition of phos-phorus in lakes. The significance of these processes increases with lake depth. Nornographs are presented which summarize model calculations and per