Ecological Modelling, 72(1994) 1-20

The usefulness of water quality simulation models for environmental management is explored with a focus on prediction uncertainty. Ecological risk and environmental analysis often involve scientific assessments that are highly uncertain. Still, environmental management decisions are being made, often with the support of a mathematical simulation model. In the area of pollutant transport and fate in surface waters, few of the extant simulation models have been rigorously evaluated. Limited observational data and limited scientific knowledge are often incompatible with the highly-detailed model structures of the large pollutant transport and fate models. Two examples are presented to illustrate data and knowledge weaknesses that are likely to undermine these large models for decision support. An alternative to comprehensive structured simulation models is proposed as a flexible approach to introduce science into the environmental risk assessment and decision making process.