The 10% Solution : Bradley shows the way to avoid making the water shortage worse.

Anyone who doubts the significance of Southern California’s 1990 water shortage should go take a look at the Sierra Nevada snowpack that normally serves as the state’s biggest water reservoir. At Tamarack Flat in the Sierra above Sacramento this week, snowpack moisture amounted to only two-tenths of 1 inch. Normal is 20 inches. Some areas were bare for only the eighth time in nearly 40 years.

The story is just as bleak in the eastern Sierra watersheds that supply Los Angeles’ aqueduct system. Historically, Los Angeles has called on the Metropolitan Water District of Southern California for less than 10% of its needs. This year, it’s more than 50%.

This is only the tip of Southern California’s water problems. Both Ventura and Santa Barbara have launched stringent water-rationing programs to cope with their emergencies. About half of the agencies belonging to the San Diego County Water Authority have adopted mandatory conservation programs. The rest are expected to do so this month.

The situation is not so bleak in Orange County because of its vast underground aquifer system. Still, a conservation task force is at work on some innovative proposals that are to go to the Board of Supervisors in June.

This gets us to the point of Los Angeles Mayor Tom Bradley’s decision Wednesday to propose a 10% mandatory water savings in the city. There was grumbling from some City Council members and neighboring communities that such stringent measures are premature; that the crisis is not all that bad. Even if they were correct, the mayor’s action can be justified as the right symbolic step. Southern Californians use more water than they need to, even in normal times. And the mandatory plan would only make citizens do what they are supposed to be doing already. The present approach requires Angelenos to save 10% voluntarily, in part by observing a ban on the hosing off of sidewalks and patios.

For the new plan to work, though, the Department of Water and Power must develop a measurement and enforcement program that is accurate, flexible and fair. The admission by DWP officials last week that they weren’t sure they could compare present use with previous years’ water consumption did not inspire confidence. Residents who already have achieved their share of savings should not be penalized by being told to save more.

There still will be some doubters. The mayor and other local leaders should conduct a vigorous public education program that will shame the naysayers into silence. How about taking them up into the Sierra to see the snowpack that isn’t there this year?