I'm sure the mexicans using the groundwater plume would prefer that.
Water flows from Mexico into California's lake the Salton Sea, from the New River delta, a river which originates 20 miles inside Mexico and consists entirely of wastewater discharged by a million inhabitants of the Mexicali Valley. Maybe they could divert it.
http://www.sci.sdsu.edu/salton/NewRiverTrailOfPoison.html