1. What would a decision tree of the farmers' problem look like?

2. What are their best choices and expected costs?

Newisham has a population of about 30,000. It traditionally got its water supply from the nearby River Feltham but increasing quantities of water were being extracted from the river by industry upstream. When the flow reaching the Newisham water treatment works became too small to supply the town's needs, the council decided to build a reservoir by damming the Feltham and diverting tributaries. This work was finished in 2002 and gave a guaranteed supply of water to the town.