Entangle has an area of "plants in a 40-ft.-radius spread" and control water has an area of "water in a volume of 10 ft./level by 10 ft./level by 2 ft./level (S)."
Is this supposed to be like a pseudo target line, in which plants/water in the area are affected by the spell? If so, does it still affect targets in the area that aren't near the plants/water? For example, if a druid attacks a logging convoy on the open road, are they affected by entangle, even though all of the plants aren't in the road, but rather are flanking the road, well away from the loggers?
Or is it more like fireball, where the fire/plants/water expand to fill the area and affect everyone within the spell's radius?
The latter is how our groups have played it, but it leaves room for weird things like someone filling a king's throne room with a torrential flood, even though he started only with a small cup of water. On the other hand, that seems about right for a spell equal in level to other spells that allow you to teleport around the world, disintegrate the king, or create other dramatic effects.
What was the intent of the designers? What do the rules say?