Performance of Some Empirical Phosphorus Models

Applicability of four empirical phosphorus models to 22 western lakes is investigated. The models by Jones and Bachman, and Walker show significant agreement with observed phosphorus concentrations as indicated by the Spearman correlation of 0.809 and 0.812 respectively. The values calculated by the other two models by Dillon and Kirchner, show poor correlation with observed data. Vollenweider type classification charts are also derived for the four models. Although all the models show some degree of disagreement with the EPA National Eutrophication Survey trophic classifications, the models by Walker, and Jones and Bachman can be used for predicting a first cut estimate of total phosphorus for lakes low in nutrients.