text: PCLake is designed to study the effects of eutrophication on shallow lakes and ponds. On one hand, the model is used by scientists to study the general behavior of these ecosystems. For example, PCLake is used to understand the phenomena of alternative stable states and hysteresis, and in that light, the relative importance of lake features such as water depth or fetch length. Also the potential effects of climate warming for shallow lakes have been studied. On the other hand, PCLake is applied by lake water resource managers that consider the turbid state as undesirable. They can use the model to define the critical loadings for their specific lakes and evaluate the effectiveness of restoration measures. For this purpose also a meta-model has been developed. The meta-model can be used by water managers to derive an estimate of the critical loading values for a certain lake based on only a few important parameters, without the need of running the full dynamical model.