Construction crews hit water June 30 while tunneling 600-ft below Southern Nevada's drought-racked Lake Mead to create a third straw. The incident required a hasty evacuation, and could delay project progress by months.
A 200-ft-long by 37-ft-high vault breach caused four days of gradual water seepage that eventually made it no longer accessible. Workers were building a 28-ft-dia, 100-ft-long horseshoe-shaped starter tunnel before using a $25 million Herrenknecht 1,500-ton tunnel boring machine when the incident occurred.