How is water use managed in an acequia community?

Cities are major water users with growing water needs. Housing developments drain off water from the rivers, but do not return water to the river. As a result, ditches are drying up, water flow is slowed and it is difficult for framers to rely on acequias to meet their water needs. Land values have gone up, so when a farm is sold, it may no longer need the ditches. If the ditch is not maintained, then farms further down may not have enough water.