Where California's Next One Million Acre-Feet of Water Should Come From

This is a key time for California water: we are coming off of three years of serious drought and growing political conflict over water allocations. The Legislature passed a comprehensive water bill last November. A major water bond was proposed to fund a wide range of interventions, but has now been tabled for at least two years and could be greatly altered or even scrapped altogether. New reviews from around the state are calling for prompt efforts to use infrastructure, markets, and institutional reform to address the state’s water crisis. All parties agree that the state will need a diverse portfolio of solutions for our diverse and complex water problems.

But the argument that we must do everything at once — conservation, new dams, seawater desalination plants, replumbing the Delta, some of this or that — is disingenuous, and wrong. We must do the most critical and effective things first, from a technical, political, and economic perspective.

And the most effective thing, hands down, is improving water-use efficiency. The Pacific Institute has just released a new analysis that recommends a set of specific actions that can annually save a million acre-feet of water quickly and at a lower economic and ecological cost than developing new supplies. These water savings are split 30/70 between the urban and agricultural sectors.

A million acre-feet is a lot of water. A million acre-feet is nearly 12 times the city of San Francisco’s annual water use and 1.6 times LA’s annual water use. It is equivalent to the flow of 890 million gallons of water per day. It is enough water to irrigate all the grain produced in California annually. It is enough water to satisfy the household needs of 6.7 million new Californians (more than the growth that demographers predict will occur within the next 10 years). It would take 18 water desalination plants the size of the proposed Carlsbad plant (which would be the largest in the northern hemisphere) to produce a million acre-feet a year. It is also almost three times the amount of water that would be yielded annually by the two major proposed new dams, Sites and Temperance Flat, combined.

As noted by Heather Cooley, the lead author of the report:

“There is vast untapped potential to reduce our demand for water without affecting the services and benefits that water provides. We identified how the next million acre-feet of water can be conserved in California, with approximately 30% of the savings from the urban sector and 70% from the agricultural sector. Both sectors have savings potential far exceeding this amount, and while we could have identified one million acre-feet of water savings annually in either sector alone, we’re showing how all sectors can benefit from these improvements.”

In the urban sector, the report identifies water savings from replacing old, inefficient water-using devices with high-efficiency models in our homes and businesses, as well as replacing some lawns with low-water-use plants. In the agricultural sector, best water management practices include weather-based irrigation scheduling, regulated deficit irrigation, and switching from gravity or flood irrigation to sprinkler or drip irrigation systems.