The L.A. River was paved before WW2. https://www.latimes.com/california/story/2022-03-01/why-we-turned-the-la-river-into-a-freeway-for-water https://www.latime

The L.A. River was paved before WW2. https://www.latimes.com/california/story/2022-03-01/why-we-turned-the-la-river-into-a-freeway-for-water https://www.latimes.com/california/story/2022-03-01/why-we-t... For some time now, Los Angeles and Orange County have been in the process of adding soil and plants to the bottoms of the concrete channels. Here’s the website for the L.A. river revitalization. https://lariver.org/ https://lariver.org/