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Water, water, everywhere. Reservoirs are overflowing, utilities are beaming and skiers are ecstatic. The City and County of San Francisco is experiencing the wettest year-to-date on record, and we are only half way through January.

Ironically, we are also seeing the highest levels of water conservation and lowest water use in decades. Combined averages of wholesale and retail sales in San Francisco, which have historically hovered around 250 Million Gallons per Day (MGD) are down to a low of 215 MGD and water use is down almost 4 percent from last year.

Why, you may ask, is water use so low when water supply is so plentiful? Good question, and one that municipalities across the state are grappling with. Most agree that it is one of three reasons. First is good-old fashioned conservation. Poll after poll has shown how much we love our environment here in California, we continue to invest in and promote a variety of water efficiency measures. Surprisingly, one of the few benefits of our weakened economy is more office vacancies, which means fewer toilets flushed, which in turn means more water saved. And in this economic climate, people are ever more price sensitive, tightening their belts and saving wherever they can. If lower water use means a lower water bill, darned right I am going to use less water. And then there is the rainy weather. More rain means less watering -- landscape use accounts for 15% of San Francisco's water use.

Whatever the reason, we have not seem this kind of drop in demand since times of drought. Hallejulah is what I say, and may the rain continue. But woe is he who is lulled into a false sense of security or protracted state of complacency. Climate change, dry spells and water scarcity are getting worse, and fast. How easy we forget California's long periods of drought, when we are awash in rain.

2006-'07 was a dry winter for California -- the Sierra snowpack was the lowest in nearly 20 years, while Southern California logged its driest year on record. The situation was further complicated that year by a judicial decision to reduce water deliveries from the state's two largest water delivery systems, the State Water Project (SWP) and Central Valley Project (CVP), in order to protect an endangered fish species, the Delta smelt. The combined effect of these factors created the equivalent of a multi-year drought for the State.

Then we have The National Climate Data Center of the National Oceanic and Atmospheric Administration's recent announcement that 2010 was the hottest year on record worldwide (tied with 2005), that seven of the eight warmest years on record have occurred since 2001, that all 10 of the warmest years have occurred since 1995. Global Trends predicts that nearly half of the world will live in water-stressed countries by 2015 and Noah Knowles from the Scripps Institute of Oceanography predicts that by 2090, 20% of California's water supply will be lost as a result of melting snowpack caused by global warming. "Just a few degrees' rise in temperature could mean less snow in the mountains, depriving the state of badly needed water in the spring and summer" says Knowles. "By 2060, we see a loss of about a third of the state's snowpack. And by 2090, we see a loss of about half of the [state of California's] snowpack. And that's about 20 percent of the state's water supply."

Water experts don't think that California's water roller coaster is a temporary ride. Changing precipitation patterns and drought, diminishing snowpack, decreases in river flows, severe declines in populations of fish species like salmon and the Delta smelt, and rising sea levels in the San Francisco Bay are just a few of the challenges before us. Water agencies face the added conundrum of lost revenue as people conserve and sales decrease.

What are we going to do? Well let's start with the agricultural sector in California, which uses the vast majority of our state's water supply at 80% of the 44.3 million acre-feet of water used in the year 2000. The agricultural sector needs to transition to the more efficient water systems possible, as soon as possible. No more flood irrigation, bring in the drip systems.

Then there is the rest of us. The remaining 20% of our state's water goes to residential, commercial, institutional, and industrial uses. Flushed toilets account for most residential water use (29%), followed by washing machines (22%), shower/bath (17%), kitchen/bath faucets (16%), leaks and drips (14%) and dishwashers (2%). That means, if you have not yet invested in a high efficiency toilet or washing machine, now is the time to do so. For you San Franciscans, the SFPUC is offering $200 rebates on high efficiency toilets through June. It will be one of the best investments you can make -- for your pocketbook and for the planet.

Cities and countries need to implement a "no-regret" water conservation and efficiency strategy immediately. We need to diversify our water supply so that we are not so dependent on diminishing upstream water sources. We need to get off the rivers and reduce river diversions, in order to protect threatened fish populations and our ecosystems. We need to continue to invest in emerging and innovative technologies, including recycled water plants, conjunctive use projects, water efficiency measures, low impact design, grey water systems and rainwater catchment. We need more conservation education from water agencies, in schools and from ourselves. Tell your neighbor what you know about how to save water.

We live in a time and land of plenty. The future is shaping up to be a time of scarcity. The time to conserve is now.