The Arroyo Seco Confluence is mostly concrete where the 5 and 110 Freeways intersect. There are red-legged stilts on the concrete and swallows nest under the bridge. Downtown Los Angeles is where it is because of this confluence – ditches or “zanja” were dug from the River to supply water to the Pueblo.
Located under the Pasadena Freeway is the Confluence of the Arroyo Seco and the Los Angeles River. In 1769, the Portola expedition’s Father Juan Crespi described this area as “very well lined with large trees, sycamores, willows, cottonwoods, and very large live oaks.” This concrete-lined site is just downstream from the natural-bottomed Glendale Narrows. You’ll see red-legged stilts in the shallow water and swallows flying overhead – you can find their mud nests under the bridge.