A historic drought across the U.S. West is taking a heavy toll on California. State authorities told some farmers in one of the country’s most important agricultural regions to stop taking water out of major rivers and streams because the drought is threatening the drinking water supply for 25 million people.

A nearly empty Lake Oroville is seen from above in Oroville, California, U.S., Sept. 5, 2021.

A swing installation is seen in the Salton Sea, California's largest inland lake, where the state's worst drought since 1977 has exacerbated an area already in decline, in Bombay Beach, California, U.S., July 4, 2021.

Houseboats sit in a narrow section of water in a depleted Lake Oroville in Oroville, California, U.S., Sept. 5, 2021.

An aerial view shows an almost evaporated canal, with toxic residues, as California faces its worst drought since 1977, in Salton City, California, U.S., July 4, 2021.

Houseboats sit in a narrow section of water in a depleted Lake Oroville in Oroville, California, U.S., Sept. 5, 2021.

A former boat launch is seen on a Salton Sea’s beach, with the water much further away, as California faces its worst drought since 1977, in Salton City, California, U.S., July 4, 2021.

A burned property is seen over a depleted Lake Oroville in Oroville, California, U.S., Sept. 5, 2021.

An aerial view shows tourists visiting Salvation Mountain, as California faces its worst drought since 1977, in Slab City, California, U.S., July 4, 2021.

An aerial view shows the Salton Sea, California's largest inland lake, where the state's worst drought since 1977 has exacerbated an area already in decline, in Salton, California, U.S., July 4, 2021.

A dried buoy sits along a dry portion of the Lake Oroville lakebed in Oroville, California, U.S., Sept. 5, 2021.

The Salton Sea is pictured, California's largest inland lake, where the state's worst drought since 1977 has exacerbated an area already in decline, in Bombay Beach, California, U.S., July 4, 2021.

A marooned boat sits along a dry portion of the Lake Oroville lakebed in Oroville, California, U.S., Sept. 5, 2021.

A car drives along the Enterprise Bridge while passing over Lake Oroville in Oroville, California, U.S., Sept. 5, 2021.

An art installation is seen on the beach at Salton Sea, California's largest inland lake, where the state's worst drought since 1977 has exacerbated an area already in decline, in Bombay Beach, California, U.S., July 4, 2021.

Low water levels are visible at Lake Oroville, which is the second largest reservoir in California and according to daily reports of the state's Department of Water Resources is near 35% capacity, near Oroville, California, U.S., June 16, 2021.

An aerial view shows the dry ground on a beach at Salton Sea, California's largest inland lake, where the state's worst drought since 1977 has exacerbated an area already in decline, in Salton City, California, U.S., July 4, 2021.