ROBERT SIEGEL, HOST:
California has seen a lot of rain and snow this month, but it's still not enough to pull the state out of its extreme drought. Lauren Sommer reports from member station KQED that that's inspiring some to rethink the way water is stored across the Western U.S.
LAUREN SOMMER, BYLINE: Given how chronically dry California is, there's a rule that's going to sound really weird when you hear it. Reservoirs are not allowed to fill up in the winter, like this one, Folsom Reservoir near Sacramento. Last year, it was just a dry, dusty lakebed.
DREW LESSARD: What reservoir was left was kind of confined to the old river channels before we built the dam.
SOMMER: Drew Lessard helps manage this reservoir for the U.S. Bureau of Reclamation. It's filled up so much, he says, that they're releasing water to empty it out. But this reservoir is only at 60 percent capacity, and it has to stay that way because of federal rules created decades ago.
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UNIDENTIFIED PEOPLE: (Singing) The Spirit of California.
SOMMER: But it's for good reason. Go back to 1986.
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UNIDENTIFIED REPORTER: Word from News 10 reporters throughout the area, more flooding, more evacuations, more levee breaks.
SOMMER: Big winter storms can cause floods in California. When a massive amount of water flows out of the mountains, this reservoir needs to catch it.
LESSARD: And that's why we kind of need to reserve a space during those winter months in case that happens.
SOMMER: Lessard says this is how most reservoirs work in the West, but releasing water is risky if it doesn't rain again, like happened in 1997. The reservoir was lowered.
LESSARD: And it was dry the rest of the year, and we never really rebounded.
SOMMER: Releasing water right now isn't all bad. It helps fish and wildlife downstream, but in a drought year, it's making people anxious, like Shauna Lorance who runs a water district near Sacramento. She says when reservoirs are releasing water, it sends a mixed message.
SHAUNA LORANCE: For me to explain to customers after everything they've done that they need to continue to conserve so it can be spilled is going to be a nightmare.
MARTY RALPH: If you think about it, the rules, the laws that govern water in the West were created in the 19th century, and yet here we live in the 21st century.
SOMMER: Marty Ralph directs the Center for Western Weather and Water Extremes at the University of California, San Diego. He's working on a new way to run reservoirs.
RALPH: Weather predictions have been improving over the last decades.
SOMMER: Forecasts are a lot more accurate, he says, so instead of emptying out a reservoir preemptively just in case a storm comes, managers could keep the reservoir fuller with an eye on the weather. Then if a big storm appears...
RALPH: They'd have three, four, five days lead time, enough to release that extra water, get it out of the way safely.
SOMMER: But if storms don't appear that water would be saved.
GREG KUKAS: We see potential forward. What we're not clear on yet is what the risks associated with that potential might be.
SOMMER: Greg Kukas is with the Army Corps of Engineers, the federal agency that sets flood rules for reservoirs. He says the question is if weather forecasts are accurate enough.
KUKAS: When it comes to forecasting the size of events that we're most concerned about they, you know, are about 20 percent off.
SOMMER: Getting it wrong is not an option. If the dam overflows, it could flood hundreds of thousands of people downstream.
KUKAS: Yeah, the consequences are just - you don't even want to imagine them.
SOMMER: Kukas says they'll decide whether to run Folsom Reservoir using weather forecasts next year. If it works here, it could change the way water is managed across the West. For NPR News, I'm Lauren Sommer in San Francisco.
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