Few people have played a greater role in determining how the reservoir’s coveted and contested water supply has been used than Mulroy. Much of it has gone to nourish the Southwest’s booming cities, and for 26 years, Mulroy was the chief arbiter of water for the fastest-growing city of them all, Las Vegas. As the head of the Las Vegas Valley Water District, she handled the day-to-day approval of water for new housing developments, emerald golf courses and towering casinos. As the general manager of the Southern Nevada Water Authority — a second job she held starting in 1993 — she also budgeted water for Las Vegas’ future, helping to decide its limits. As the Water Authority’s general director, Mulroy stretched her enormous influence over state bounds, shaping how Nevada negotiated with the six other states sharing Colorado River water.