BOULDER CITY, Nev. (AP) — Just six miles from where the Hoover Dam holds back the largest reservoir in the nation, workers are struggling against solid rock, geologic faults and seeping water to construct an intake tunnel to keep drinking water flowing from shrinking Lake Mead to thirsty Las Vegas.

Their work in a hot, humid cavern some 600 feet below ground goes largely unnoticed by local residents and tourists enjoying icy drinks in glittery Sin City casinos and nightspots.