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LA is saving storm water instead of getting rid of it




LA DWP is working to capture more rain in roadway medians and parkways.
LA DWP is working to capture more rain in roadway medians and parkways.
lastormwater.org

The first major storm of the season dumped about two inches of water, but rain in Southern California is a mixed blessing. Prompting mudslides and debris flows, this week's rains have claimed at least 15 lives, swept away homes and closed major roadways.

Still, there's no denying: our drought-prone region needs the water. Marty Adams is director of water operations for the LA Department of Water and Power, and he joined Take Two to talk about how the city is working to capture the rain so we can use it later.

The LA Department of Water and Power is increasing the capacity of its Tujunga Spreading Grounds to capture more rainfall.
The LA Department of Water and Power is increasing the capacity of its Tujunga Spreading Grounds to capture more rainfall.
scpr.org

How much water LA captured during this week's storm

Two inches of rainfall is billions of gallons of water that comes down, and we were able to capture about 1.5 billion gallons, between the water that infiltrates naturally through lawns and open space and parks and water we intentionally diverted out of storm channels to try to get it back into the groundwater basin.

The challenges of catching rain

One of our big challenges is to capture as much as we can. It's hard when the storms are really heavy as we saw. Not only does it cause problems with mudslides, but we have such a steep drainage that it's hard to capture the water because it's coming down so fast. It's hard in a big, dense, urban setting to have enough open space.

Rain barrels are used by many L.A. residents to catch rain at their homes.
Rain barrels are used by many L.A. residents to catch rain at their homes.
scpr.org

Large-scale and neighborhood-scale projects

There's a number of large spreading basins, these open areas that look like dirt fields, almost. And they're next to the large storm channels, so water is diverted out of the channels and it percolates to the ground and it's cleaned as it goes through the ground and joins our local groundwater.

The neighborhood projects are becoming much more important because we really can't find new open space of that magnitude, so we have to look for space in parkways and medians and centers of streets and green street projects and dry wells, along the curb, where the water infiltrates in instead of running down. Once water gets in the storm drain system, it's on its way to the ocean as fast as possible. We need to try to stop it before it gets there.

How many households can be supplied with captured rainwater

Last year we had a lot of water. We captured over 10% of the whole city's water demand by the local storms. And so ultimately we want to have 25% of our water supply come from the local groundwater basin, so that's one million people living off our local water supply. This last storm alone, the last couple days, was enough water for between 10,000 and 15,000 families.

LA DWP encourages homeowners to capture rainwater so it can infiltrate on their properties and replenish the groundwater supply instead of draining to the ocean.
LA DWP encourages homeowners to capture rainwater so it can infiltrate on their properties and replenish the groundwater supply instead of draining to the ocean.
lastormwater.org

Public parks and private property will be used to capture 100% of the rain that falls

That's the goal, but it's difficult because as flat as we think things are around here, the L.A. River actually falls more feet vertically in 52 miles than the entire Mississippi River in 1,000 miles. The challenge is the terrain is so steep. For us, we want to catch the water as close to where it falls as possible to try to get back into the ground. We're going to have to use more public property, Recreation and Parks property, Water and Power property, to try to find places where there's open space and ultimately go onto private property and ask people to do things to try and capture water on their property.

L.A.'s traditional water sources are becoming unreliable

Historically our water has come from the L.A. Aqueduct from the Eastern Sierra. Because we've lost a lot of that supply due to different negotiations and settlements and environmental concerns, probably the biggest portion comes from the Metropolitan Water District, which is the state water project coming out of the Sacramento Delta. We know that's a very environmentally sensitive area, with a lot of concerns about reliability, so our goal is within the next five to seven years to have 25% of the water we drink generated locally, so coming out of the groundwater basins, and by 2040 to have half or more of all the water we drink generated locally.

LA's attitude shift to capture storm water instead of discard it

The aggressive move to capture more water really happened about ten years ago, and Mayor Garcetti really issued a challenge for us to accelerate how fast we capture that storm water. Storm water can be a problem. There's a lot of dangers and issues with debris flow, but at the same time, it's a valuable resource.