IT WAS OFFICIALLY called an "initiative" - Californians certainly seized it. By nearly 2 to 1, they turned a far-reaching tax-cut proposition into a hard fact of fiscal life for the state and local governments. And so now Gov. Jerry Brown - who started a political brush fire with his no-frills style of government and then saw it rage into an inferno - has to figure out what to do next. it will be up to him and the state legislature to deal with the loss of an estimated $7 billion in property-tax revenues - money that had been going to the local governments. The whole episode can hardly have enhanced Mr.Brown's political standing for any greater run that he may contemplate - but already he's sprinting to get to the head of the line of mutious taxpayers.

Step One, of course, was to make a forthright announcement of the patently obvious - namely, that he would not try to increase state taxes. Step Two, after a thoughtful election-night assessment of the returns, was to reach the starting conclusions that the vote "comes from liberals, conservatives, moderates, PRepublicans and Democrats". The third move - is to turn back the state's $4-billion to $5-billion surplus from income taxes. It is this paceling out of relief money to communities, schools and other special districts, along with a good-faith reduction of some magnitude in the state budget, that is bound to create intraste friction and political fallout.

But like or not, opponents of proposition 13 should resist any temptations to retaliate with insanely risky cuts, in, say, school services or police forces. In any event, it is curious that one offshoot of this decision by the voters to take tax matters into their own hands will be a weakening of their local governments; what money there will be- will rest primarily with the State.

In the meantime, there will no doubt be legal and constitutional challenges that could delay things. But the cutting must begin anyway, for the tax problem in California is real. Inflation and runaway real-estate assessments clearly put too much of a burden on the property tax while creating a surplus from income taxes - an imbalance that must be corrected. Moreover, the extreme circumstances in California do not mean that rest of America is in for the same kind of drastic rebellion. But in varying degrees, the feeling is certainly growing that the billfor government's services is going to need adjustments.