In a tiny, moist pocket of Israel's Negev Desert, a few miles from the Sinai Peninsula, there's a spring that bubbles out above a cliff and trickles down into a deep green pool in the Valley of Zin. Israelis call it Ein Afdat (Ain-aff-DAHT), an ancient spring that provided respite to many Arab nomads may have even cooled Moses and the Israelites two thousand years ago. This spring is one of the only natural sources of fresh water in the Negev, which covers more than half of the state of Israel. Yet, today, the Negev Desert is dotted with green. Israel captures the water of the Jordan River, along with aquifers lying beneath Israel and the West Bank, and pipes them into the desert. Israel's control of these waters has long played a part in regional tensions. The founders of modern Israel believed it essential to harness Middle East waters to reconnect the Jewish immigrants with the land. And like the Arab farmers in old Palestine, Israelis now produce citrus and other crops for export. But 50 years later other demands especially from urban Israel may be carving into that Zionist vision.