With a third year of drought shrinking the creeks that cascade down the eastern Sierra Nevada, the level of Mono Lake has fallen so low it has triggered a 72% reduction in the amount of water Los Angeles can divert from area streams this year.

On April 1, Mono Lake’s level measured just under 6,380 feet above sea level — about 1 inch below a threshold set in the Los Angeles Department of Water and Power’s licenses for diverting alpine runoff from streams that feed the lake east of Yosemite National Park.