Little drops of stormwater could add up

A homeowner waters plants from a rain barrel in Los Angeles, which could become a model for stormwater collection.
A homeowner waters plants from a rain barrel in Los Angeles, which could become a model for stormwater collection. Los Angeles Times

The freak storm that deluged Southern California last weekend didn’t make much of a dent in the drought. But it did highlight the latest talk of the town in water conservation – capturing stormwater for later use.

It may not be the grandest of ideas, like a new dam, or the most futuristic, like desalination. But Los Angeles County’s Department of Public Works, just to name one example, collected enough rain from that one storm to supply 6,000 residents with water for a year, nearly 245 million gallons.

And that’s a drop in the bucket compared with the rain grab envisioned by California water officials. With the state’s existing water supplies spoken for (and then some), raindrops and runoff are among the few water sources with untapped potential.

By some estimates, hanging onto more stormwater—as opposed to just cleaning it so it doesn’t wash pollutants into rivers, aquifers and the ocean—could supply a city such as Los Angeles with a third to half of the water it needs annually – and reduce demand for water from up here.

That’s why the State Water Resources Control Board has targeted L.A. County as a potential state model for stormwater conservation. And that’s why the city’s Department of Water and Power has unveiled an aggressive initiative to more than quintuple its stormwater collection, via projects from small rain gardens to permeable pavement and large spreading fields.

Not every part of California is right for a big build-out of stormwater infrastructure. In Sacramento, the tight, silty soil – so perfect for farming – isn’t porous enough in most places for the large-scale filtration and capture systems that show such promise in places such as L.A., Bakersfield and Fresno. Regional water officials here are right to prioritize more obvious goals, such as making the existing network of surface reservoirs and groundwater supplies more efficient.

But even in this drought, Sacramento gets substantially more rain than Southern California, and letting stormwater go to waste can’t be an option. A couple of pilot projects are underway in the foothills and other areas where the geology might be more conducive, and low-impact design standards should make a difference over time if we enforce them. But we can do more.

San Diego offers rebates to property owners who install cisterns that hold 1,000 or more gallons. Why not set aside a modest sum here for a similar program? Even rain barrel subsidies can be improved upon, to encourage wider use and more attractive designs.

Thinking big is the obvious first choice, but little drops of water are famous for adding up, too. An inch of rain on a 1,000-square-foot span of roof generates 600 gallons of water that might be put to good use, with the right equipment. Wouldn’t that be welcome on Sacramento’s dry lawns?