This paper presents calculational methods for estimating the river flux of materials when continuous flow records and little concentration data are available. These methods are especially applicable to materials whose concentration is a function of flow rate (most substances). They are applied to total phosphorus and suspended sediment in the rivers of the Lake Erie Basin and compared with previous methods of estimation. Total phosphorus is an important pollutant to Lake Erie because much of this particulate material can be converted to a soluble form and utilized by the algae in the lake. Thus, the estimation methods were applied extensively to Lake Erie river basins. The calculated total phosphorus effluxes were compared between river basins on a unit area basis. The results indicate a large variability of unit area loadings, even for river basins that are very similar.