This applet is designed to show how the population growth drives the demand for power which in turn requires more power generation capacity, which in turn has an environmental consequence.

In this case, our community Salmonville relies on hydroelectric power. Due to its pollution free nature and high degree of renewability, many other people are attracted to Salmonville and the community begins to enjoy economic prosperity and full employment. Of course, the fish don't like this too much.

This simulation shows the relation between population growth, energy consumption and fish decimation. Note that many people in Salmonville own fish restauraunts where Salmon is the main course, so even without dams, the Salmon population is threatened by fish eaters.

The inputs which the user controls in this simulation are the following:

• The exponential rate of population increase. The default value is set at 5% per year.

• The Technology factor - this controls the power consumption per person as time increases. If you want to promote energy conservation - set this value equal less than 1. If you think people consume more energy as civilization advances, set this to a value greater than 1. The default is 1

• The fish kill factor - this controls the percentage of incoming fish that are killed by a single dam. The default is 10%. Note, if you set this to 0%, the dams have no effect and its only the Salmon restuarants in Salmonville that are a threat to the Salmon.

• Dams modifier - this factor takes into account any non-linearity that might be present. Most of the complexity of the simulation is in this number. For instance, the default is 1, which means that 2 dams on the river kill twice as many fish as one dam. If you think the dam multiplier is greater than 1, then set it greater than one. If you think its less than 1, then set it less than one. The default is 1.

Your task is to construct different scenarios to see the length of time it takes to decimate the initial population of 1 billion fish, starting from an initial population of 20,000 people and one dam. Can you construct a scenario that preserves the fish for 1000 years?