A Tuolumne County judge has thrown out a lawsuit seeking to drain San Francisco’s Hetch Hetchy Reservoir, the linchpin of a system that supplies drinking water to 2.5 million people in the Bay Area.

In a ruling delivered Thursday, Superior Court Judge Kevin Seibert sided with San Francisco officials who have objected to emptying the reservoir, situated in Yosemite National Park, and restoring the valley it now occupies. Restore Hetch Hetchy, the group that sued to shut down Hetch Hetchy, had argued that the dam and reservoir violate Article X, Section 2 of the California Constitution.