Once irrigated and lush but now barren, the Mesopotamian plain circling the ruins of Gilgamesh’s Uruk makes present day calls for food security via vast new irrigation projects appear shortsighted. Irrigation today suffers the same problems as in ancient times -- salt buildup in the soil, collapsing dams, irrigation channels narrowed and blocked by silt buildup -- plus some new ones, such as pesticide runoff. But irrigation planners figure they have learned a few things since Gilgamesh’s time. We can expect Egypt, Iraq, Saudi Arabia and others to go on building new, expensive irrigation projects until they finally reach the limits of their water supplies. Reaching these limits should take only two or three more decades.