Surely the much more nutrient rich (from a plants point of view) toilet water from San Diego can be diverted to these Mexican farm fields to help lessen the impact of the USA correcting a long neglected eviromental problem.
And after all, aren't the burdens (or refuse) of Mexican society, who are sneaking across the same border, helping flush these San Diego toilets? It's only fair Mexico puts this waste to good use, and it will completely negate their concerns over the USA repairing the problem.
I find it ironic as well, that what would normaly be considered an enviromental disaster caused by the "evil USA", is something that some DON'T want fixed!
Just remember to rinse that lettuce very thoroughly, and hope your favorite fast-food place does too!