Not only are we trying to do more with an already finite resource, but that finite resource is trending backwards. We are getting less and less of it every year. Eventually the treaty is going to get so heavily loaded with water debt as to become effectively meaningless. Theres gonna be fuck-all to give to Texas. I grew up pretty close to Falcon Lake, which is downstream of Laredo, which is downstream of La Boquilla, where the Rio Grande is on the Mexican side of the Tex/Mex border. This is about my home area. I live somewhere else in south Texas now, but it is close to another reservoir that is experiencing the same fate; too many things taxing the reservoir before it can recharge along with extreme drought. South Texas is fucking parched.
The farmers that were diverting the entire river are sorta pissing on everyone downstream of them, but they are trying to do less with whats there. They are downstream of a reservoir that is running dry and so has less to discharge downstream. The reservoir has less to recharge with because man has made the climate shit the bed and too many people taxing a finite supply is bad for recharging reservoirs. So how tf does it get handled? It is a zero sum game, isnt it?