Dear Gil, I have to say about my experience living in Mexico-USA border, since 1995, NAFTA recently signed, the volume of cargo trucks in the border increased so high. To 1999, was developed the first and only Air Quality Plan of Mexicali, Baja California (INE-SEMARNAT) among other border cities. Since then, was diagnosed a huge pollution caused by cars, made it possible those imports and trades. To check volumes of northbound and southbound traffic, please see transportation plans of San Diego area by SANDAG.

Later in 2001, two bigger energy companies (SEMPRA and SHELL-INTERGEN) arrived to the border due to a national mexican concession by CFE. Foreseeing later energy crisis of California, those companies installed a gas and residual water process (combinated cicle) to generate 1000 MVA of electricity from Mexico to California. Plants comply mexican environmental regulations, but no EPA regulations. NAFTA never planned the fact that border issues involve shared basins, nor only through pipelines, desalination plants, regasification plants, installed in Mexico border in late 2000-2010.

I think those examples represents some issues in environment, thanks to NAFTA trading. Hope this help to your research.

Best regards,