I grew up in a town along the Mississippi River. It's "ass to glass" all the way from Minnesota to Louisiana. Basically every city, town, and village on both banks treats its drinking water and its wastewater, then releases its treated wastewater downstream.
Are the farmers paying so much less for treated, potable tap water delivered through municipal water mains? I think you'll find the cost of the water itself is pretty small. You may find that treating it, transporting it, and distributing it pretreated to all those people are the real economic costs even during most stages of a drought.
The farmers are consuming the majority of the water and there is no way to even get them to pay for their usage. Many have grandfathered old school water rights. Meanwhile, they pass idiotic laws like the ban on unsolicited table water in restaurants to pretend like they are doing something.
Funny thing is, most waste water treatment plants I've seen - the water coming out of the waste treatment plant is cleaner than the water removed from the river for drinking (which is then treated).
Wait until people learn that they air they breathe has likely already been breathed by someone else...
Are the farmers paying so much less for treated, potable tap water delivered through municipal water mains? I think you'll find the cost of the water itself is pretty small. You may find that treating it, transporting it, and distributing it pretreated to all those people are the real economic costs even during most stages of a drought.