The nearly 2,000 mile-long border between Mexico and the United States is hot and dry. Few rivers cross this arid expanse. Yet, despite the lack of visible, life-sustaining water, the region is growing – the combined border population, currently around 14.4 million, is expected to increase 40% by 2020. The reason for this remarkable growth is ground water, more specifically, transboundary aquifers. As many as twenty aquifers straddle the Mexico-U.S. border, many of which serve as the primary or sole source of fresh water for the border’s communities and unique ecosystems …