SACRAMENTO — California’s largest water suppliers will have to report their monthly use and conservation efforts under a measure approved Tuesday by state regulators.

More than 400 urban systems that supply 90% of the state’s population will have to make monthly reports to the State Water Resources Control Board under a vote that makes the voluntary program mandatory. After passing a legal review, it would take effect in October.

The last time such reports were required was from 2015 to 2017 when the board enacted an emergency water conservation regulation in the midst of a five-year statewide drought.

“Since the drought, Californians continue to use on average 20% less water than what was used in 2013, the pre-drought baseline. More than 75% of water systems have continued to voluntarily report this data since mandatory reporting ended,” the board said in a statement.

California’s Snowpack — a Chief Source of Water — Remains Below Normal

While a wet spring replenished Southern California’s rainfall total after a dry winter, Northern and central California have dry conditions heading into the warmest months. Nearly half of the state currently is abnormally dry or has moderate or severe drought, according to the National Oceanic and Atmospheric Administration’s National Integrated Drought Information System.

Despite the spring storms and full reservoirs, California’s snowpack — a chief source of water — remains below normal. State authorities have urged people to use water wisely, saying the climate continues to show extreme unpredictability.

“As we continue to see, the quality, timeliness, and gathering of data are critical to managing California’s water in the 21st century,” State Water Board Chair E. Joaquin Esquivel said in the statement. “Urban monthly water use data have driven enduring, widespread, public awareness and understanding of water use, conservation and efficiency in our state.”

“As Californians have come to know, efficiency is a way of life when the next drought is always around the corner,” he said.