The Merced River in California river dried up below Yosemite. The reason was a mystery — until now

In 2022, the third year of a severe drought, state regulators had enacted emergency “curtailments” on water rights holders because of the river’s already diminished flows, which prevented some from pumping. However, those who were allowed to continue pumping, according to the analysis, still took enough for the river to empty.

Foresman, with the state water board, explained that regulators weren’t able to curtail all of the water right holders because of the seniority of their rights. For example, riparian rights, under California law, give property owners along a river, notably farmers, the ability to essentially take all they want under certain conditions, including not storing the water or moving it off-site.