There is a body of water at the back of the city, a lake that has shrunken due to the drought. The river that feeds it is running low, and at the other end stands a dam that impedes outflow.
This source of water is most precious to the inhabitants and it is what they intend to protect and preserve at all costs. So we conclude after observing the comings and goings of the local militia all day, and in particular their concentration in the vicinity of the dam.
Over on that side of the city Tomas was a witness to their opposition to some tanker trucks he recognized.
Though they retreated we are sure they will return in force.