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Scientist: We Should Just Let the LA River Flood Sometimes

The soon-to-be-revitalized Los Angeles River is the concrete flood control channel that it is today because in the early days of the city it flooded frequently and disastrously, often enough and with devastating enough consequences that the Army Corps of Engineers and the city felt it needed to be constrained. But what if letting at least part of the river flood again could really help Los Angeles meet more of its water needs locally (instead of having to ship in water)? After more than four years of scarily little rainfall, that proposition is starting to sound less nuts these days, says TakePart. "Natural waterways allow more water to percolate down into underlying aquifers," and so allowing the river to overflow could possibly help boost LA's groundwater resources.

"If you let the river flood, which it historically did on a regular basis, there is a potential to accomplish a lot of recharge for the groundwater," says a hydrogeologist from UC Davis who has cowritten a study about moving back levees from irrigation channels in order to allow flooding and replenish groundwater in the parched Central Valley.

A "dream team" of local firms has in fact already created a plan that would allow parts of the Piggyback Yard site in Lincoln Heights—currently in use as a rail yard—to flood a few days out of the year, while serving primarily as a park. (Putting parks to use for flood control in Los Angeles dates back to the Olmsted Brothers' unimplemented plan for a glorious citywide networks of parks in Los Angeles.) That plan, says TakePart, "would allow for up to 60 percent of the 125-acre property to be inundated with storm water when the river bursts its banks (which used to happen every five to 20 years)." The water would be sucked into the ground through a network of wetlands and islands that would "replace" the concrete part of the river, while inflatable dams would divert and contain the water in a safe way.

However, an engineer with the consulting firm that worked on the Piggyback Yard proposal point out that there are many Downtown buildings with foundations that "reach into the water table, and their basements are regularly pumped to avoid flooding." The flooding plan, the engineer worried, would exacerbate the existing situation and "potentially creat[e] some very unhappy, very rich neighbors." (Furthermore, Piggyback Yard's owners, Union Pacific, don't seem to want to sell the property, not even for the good of the 2024 Olympics.) But with 51 miles of river between the Valley and Long Beach, and parks planned all along the way, there might be a lot of potentially suitable segments for flooding.

LA's already got big plans to recharge the groundwater via a combination of large- and small-scale projects in the Valley and across the city that seek to collect rainwater and put it back into the ground without letting the river flood.
· L.A. Remembers It Has a River [TakePart]
· Los Angeles's Plan to Start Harvesting Its Rainwater [Curbed LA]
· Dream Team Assembled For LA River Piggyback Yard Project [Curbed LA]
· 25 Photos of the Los Angeles River Before It Was Paved in 1938 [Curbed LA]