The dispersion of suspended particles caused by marine works should be controled within a minor influence for the environmental protection.
　The necessity of the turbidity dispersion control is recognized from the viewpoint of regulational background and the influence to marine animals and plants. The fundamental problems are discussed with respect to the definition of turbidity, the generation rate of turbidity, settling rate of suspended particles, and the measuring method of turbidity.
　The major attention is focused on such problems as assumptions, properties, and application procedures of models on the prediction of the fate of suspended particles, and also the applictaion to the environmental control.
　As the result of the investigation, the following items are clarified. The fate of suspended particles can be mathematically treated throught the temporal and spatial averages of particle distributions, even though they are still under strong influence of the ambient current. The three-dimensional model has the widest application, among the analytical, semi-analytical and all other models. The three-dimensional model has also high possibility to play important roles in the turbidity control, when more field data are accumulated and the applicability of the model is proved by comparing the predicted values to the field data.