Most Californians, on some occasions, realize that their vast, populous state is largely desert - desert made to bloom and boom by ingenious transfers of water, usually from out of state.
The state's arid geography comes to the forefront during periodic droughts. Then a few calculations might be made about how much more water could be drained from the relatively wet northern counties or wrung from the Colorado River.
Some forward-looking people have even thought of making development of housing tracts, which now carpet the state's hillsides, contingent on the proven availability of water. But that idea runs counter to a tradition of limitless growth, and has faced high political hurdles.
Until this year, anyway.
California's legislature just passed, and Gov. Gray Davis just signed, bills that require builders to show that adequate water is available to serve subdivisions of more than 500 units - and require counties and cities to consult with water agencies early in their planning processes.
These logical moves were impelled by the state's rough experience recently with electricity - another commodity sometimes taken for granted - and by a realization that the options for getting more water had narrowed considerably.
The new legislation should force California's planners to track more carefully the supply and use of the state's most precious natural resource. It's an overdue step, and one that other fast-growing Western states should watch closely.