Water quality modeling for environmental management: lessons from the policy sciences

Models are used in many policy arenas to predict the future consequences of current decisions. A model is typically viewed as a rational, objective means of processing complex information to predict future conditions. With respect to socioeconomic modeling, policy scientists have found that models frequently do not live up to these promises - they often incorporate the modelers' biases, are difficult for decision makers to use, and do a poor job of point predictions. While awareness of these characteristics of socioeconomic models has increased, less attention has been paid to such factors in environmental modeling. This paper explores the implications of policy scientists' observations about socioeconomic models for the use of water quality models in environmental decision making. For example, the relatively simple task of modeling for an estuarine waste load allocation decision incorporates judgment in model choice, calibration, and use. More complex watershed models involve even more choices that have implications for decision making. Thus, environmental models are not strictly technical inputs to the policy process. Model users, regulators, and the public should be aware of the judgments and uncertainties involved in surface water quality modeling so that model results are used appropriately in the decision-making process.