The Idagon is an invented River. The name comes from a combination of the States of Idaho and Oregon in the Northwest region of the United States. The Idagon was invented to allow you to experiment with different policies on reservoir operation, land development, land fallowing, and the efficiency of irrigation. These policies are of interest to water resource agencies across the West.

The Idagon is simpler than the real river systems in the West, but it is still a challenging system. It is comprised of flows from several tributaries plus the flows in the main stem. The surface flows interact with ground water flows through the Idagon Aquifer. Surface flows are shaped by the operational rules governing the four reservoirs; ground water flows are shaped by hydrological rules.

The various "rules" for the way the river works are translated into mathematical equations. The combination of mathematical equations forms a model of The Idagon. (The model is larger than any of the models in Modeling the Environment, and it uses short names that you are not likely to understand. This makes the model different from all of the other models in the book. You'll learn from experimenting with the model, not from studying its stock-and-flow structure.).

You will experiment with changes in the model to learn if it is possible to improve the simulated performance. Performance will be measured by the river's contribution to the economy and its contribution to wild life. You will choose the relative importance of serving different goals. Your challenge is to learn the combination of policies to allow for the best use of river system. When you are happy with your policies, discuss your approach with the approach favored by your classmates. You may find that you differ on the relative importance of serving economic or wild life goals, but you might discover that you agree on the best policies for managing the river.