John Whitehead of Environmental Economics points out the folly of asking people to use less water in the midst of a water shortage, making an argument for spot pricing. Key quote:
Command and control regulatees usually can find a way around restrictions. If commercial fishermen are told to reduce the number of fishing trips then they get bigger boats so that they can catch more fish on each trip. In the same way, if households are asked to water their lawns on a limited number of days, then they’ll increase the amount of water they put on their lawn that day.