LOS ANGELES — For more than a century, California has been the state where people flocked for a better life — 164,000 square miles of mountains, farmland and coastline, shimmering with ambition and dreams, money and beauty. It was the cutting-edge symbol of possibility: Hollywood, Silicon Valley, aerospace, agriculture and vineyards.

But now a punishing drought — and the unprecedented measures the state announced last week to compel people to reduce water consumption — is forcing a reconsideration of whether the aspiration of untrammeled growth that has for so long been this state’s driving engine has run against the limits of nature.

The 25 percent cut in water consumption ordered by Gov. Jerry Brown raises fundamental questions about what life in California will be like in the years ahead, and even whether this state faces the prospect of people leaving for wetter climates — assuming, as Mr. Brown and other state leaders do, that this marks a permanent change in the climate, rather than a particularly severe cyclical drought.

This state has survived many a catastrophe before — and defied the doomsayers who have regularly proclaimed the death of the California dream — as it emerged, often stronger, from the challenges of earthquakes, an energy crisis and, most recently, a budgetary collapse that forced years of devastating cuts in spending. These days, the economy is thriving, the population is growing, the state budget is in surplus, and development is exploding from Silicon Valley to San Diego; the evidence of it can be seen in the construction cranes dotting the skylines of Los Angeles and San Francisco.