What happened — or didn't — weatherwise during the last two months starkly reminds us of the erratic nature of California's vital water supply.

After months of severe drought, the state saw record-shattering storms in December, creating a hefty mountain snowpack while replenishing seriously depleted reservoirs. But January, historically a month of heavy precipitation, was bone-dry.

With climate change, California's wet periods have become briefer, albeit sometimes more intense, and the dry periods have become longer, making the state's elaborate water storage and conveyance systems less able to cope with precipitation patterns.

The clear need for new approaches, however, collides with California's notoriously byzantine and sloth-like processes for making water policy. It's not unusual for specific issues, such as the construction of a new reservoir or canal, new water quality standards or changes in water diversion rights, to drag on for decades without resolution.

For example, whether to bypass the Sacramento-San Joaquin Delta with tunnels or canals to divert Northern California water into the California Aqueduct for shipment southward has been kicking around for more than six decades, embracing nine governorships.

Something has to give and rather than be forced into short-term emergency actions, we should accept the changing reality and act decisively and proactively. Basically we have three choices, or more realistically, some combination of the three:

—Improving reliability by creating more storage, such as the long-pending Sites Reservoir, to take advantage of the periodic deluges, such as December's storms;

—Increasing water supply by building more desalination plants, such as the one now operating in San Diego County and its twin proposed in Orange County, and more facilities to cleanse and reuse wastewater;

—Shifting more water from agriculture, which now uses about 75% of water allocated for human purposes, to environmental or residential uses.

None of the options is easy, given the many legal, political and procedural hurdles and the huge number of competing interests involved — which is why specific proposals languish and why politicians shy away from confrontation. Instead, they issue bromides, such as exhortations to take shorter showers or water lawns less frequently, that give the illusion of action without material and lasting effects.

Recently, a ballot measure that would have diverted more of the state's budget surplus into traditional storage and conveyance projects popped up, only to be abandoned for lack of unified support. It was aimed at removing some of the pressure on farmers.

Notwithstanding that false start, competing water interests are gearing up for the inevitable day of reckoning. Backers of desalination and storage projects are becoming more vocal and the distribution or redistribution of agricultural water is receiving more attention.

Sensing an opening due to the drought, some environmentalists are pursuing their long-sought goal of reducing agricultural diversions to provide more water for endangered fish species. The Planning and Conservation League has released a new report, drawn up by a team of lawyers, to rewrite California water law and give the state Water Resources Control Board more authority.

It aims to force farmers, even those with water rights dating back more than a century, to justify their diversions or face curtailments, giving teeth to the state constitution's command that "the waste or unreasonable use or unreasonable method of use of water be prevented, and that the conservation of such waters is to be exercised with a view to the reasonable and beneficial use thereof in the interest of the people and for the public welfare."

Challenging water rights would be the mother of all water wars, but it may be inevitable if weather patterns continue to change.