<p>Half a century ago, federal engineers faced a Herculean task. Farmers in the San Joaquin Valley needed more water. There was plenty in far-Northern California's Trinity River, but a 5,000-foot-high mountain range stood in the way.</p>
<p>No problem. In just four years, the U.S. Bureau of Reclamation ripped a pair of tunnels through the mountain, piped most of the Trinity's water into the Sacramento River and let it flow to the Delta. There, it was sucked into giant pumps and delivered to some of the nation's most prosperous farms.</p>