California farmers who hold rights to water that date back as far as the Gold Rush are bracing for their first state-ordered conservation in decades, as a record drought prompts some of the deepest cuts yet in the country’s most productive agricultural state. After telling cities and towns to slash water use by 25 percent and cutting deliveries to some farmers and others, state officials said Wednesday that they would start mandatory cuts this week to the state’s oldest rights holders, who are historically spared from water restrictions.

Regulators said the first orders Friday will affect those holding century-old water rights in the watershed of the San Joaquin River, which runs from the Sierra Nevada mountains to San Francisco Bay and is one of the main water sources for farms and communities. Meanwhile, a second category of senior rights holders are making a surprise effort to stave off those kinds of cuts. Farmers who hold longstanding claims to water because their land lies along the waterways of the Sacramento-San Joaquin river delta offered to voluntarily reduce their water use by a quarter. Officials promised a decision Friday on that offer, which would yield on some of the most iron-clad water rights in California, as they try to chart a path forward for a state locked in its driest four-year period on record. FULL RECORD