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California is getting drenched. So why can't it save water for the drought?

Drivers barrel into standing water on Interstate 101 in San Francisco on January 4.
Josh Edelson
AFP via Getty Images
Drivers barrel into standing water on Interstate 101 in San Francisco on January 4.

A bomb cyclone hit California this week, knocking out power, downing trees, and dumping massive amounts of water.

Some California residents are watching this precious H20 wash away and wondering, why can't we save the water for times when we desperately need it?

The state grapples with drought, but it's not as simple as putting out a big bucket, says hydrogeologist and professor at UC Santa Cruz, Andrew Fisher.

Professor Fisher spoke with NPR about the challenges facing the state, and where the water goes when it's not being captured.

This interview has been lighted edited for length and clarity.

Interview highlights

On how much water can be stored for later and where

Some of it can be captured for later, but the short answer is it falls so quickly that we lack the ability to take that water and set it aside quickly enough in a place where we can store it for later. The primary forms of storage for water in California are the snowpack, that typically accumulates annually, and then reservoirs behind dams, and then groundwater aquifers.

And the challenge is that when we get a lot of rainfall like this, it's not forming snowpack in lower areas. And reservoirs tend to fill up rather quickly. Then we have aquifers, and they have space, but it's hard to get water where it needs to be so it can infiltrate into the ground. And even then, it's hard to get it in fast enough.

On the different challenges with capturing rainwater

Because the water falls at a very fast rate and it creates a hazard, we do tend to treat stormwater as a nuisance and try to get it off the landscape as quickly as possible.

So, when we have the option to hold that water back a little bit and let it percolate into the ground, this is a tremendous opportunity. However, sometimes that water is not suitable for drinking. That's an additional bottleneck because you can't treat the water as quickly as it's falling or as quickly as it's running off. And, of course, the level of treatment you need might vary from place to place, and it does create quite a logistical challenge in order to deal with that water.

The Golden Gate Bridge is seen through a mix of rain and splashing bay water in Sausalito on January 5.
Josh Edelson / AFP via Getty Images
AFP via Getty Images
The Golden Gate Bridge is seen through a mix of rain and splashing bay water in Sausalito on January 5.

On where the stormwater flows when it's not being captured

It's going to a variety of places. A lot of it will end up rolling out to the ocean. Some of it is being diverted and we're collecting some of this stormwater and directing it towards infiltration basins where it can percolate into the ground.

There are other folks around the state and around the western United States who run similar projects. So people are trying to collect as much of this stormwater as we can when we have this opportunity. It turns out, a lot of water is falling, a lot of water is running off, so a large part of that does end up flowing out to the ocean.

On the current storm with more rain coming

I've got a student group that's out right now, sampling from some of our systems. And we dashed out here between the storms, because it's an opportunity when it's safe to go collect water samples and see how water quality looks. I'll just note that we have to get more water in the ground. We simply have no choice.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Mary Louise Kelly is a co-host of All Things Considered, NPR's award-winning afternoon newsmagazine.
Erika Ryan
Erika Ryan is a producer for All Things Considered. She joined NPR after spending 4 years at CNN, where she worked for various shows and CNN.com in Atlanta and Washington, D.C. Ryan began her career in journalism as a print reporter covering arts and culture. She's a graduate of the University of South Carolina, and currently lives in Washington, D.C., with her dog, Millie.