During California’s most recent drought, officials went to great lengths to safeguard water supplies, issuing emergency regulations to curb use by thousands of farms, utilities and irrigation districts.It still wasn’t enough to prevent growers in the state’s agricultural heartland from draining dry several miles of a major river for almost four months in 2022, in a previously unreported episode that raises questions about California’s ability to monitor and manage its water amid worsening droughts.It’s not uncommon, during dry spells, for farmers and other water users in California to draw streams down to a trickle in places. But the severity and...