Rio Hondo Meets the L.A. River

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The Rio Hondo Converges with the Los Angeles River

The concrete channnel of the Rio Hondo River (on the right) enters the Los Angeles River (on the left). This intersection also marks an interesting geological feature in Los Angeles. At this point the sand, silt, and clay sediments in the Los Angeles basin are at their deepest. . . over 30,000 ft. You could fit Mt. Everest in this pit! Commercial airliners cruise at this height (depth?).

Los Angeles is sitting on top of a deep bowl of sediment. This foundation of loose fill tends to shake more during earthquakes. The walls of this pit are formed by the Palos Verdes pennisula, and the mountains of San Gabriel, Santa Monica, and Santa Ana. The earth's moving crustal plates created this bowl which was eventually filled in with sediments brought by ocean currents, and (ironically) from sediments deposited by previous ancient rivers. Now an urban drainage system lies atop these ancestral rivers, lined with millions of tons of concrete in an effort to speed the sporadic winter flood waters to the sea. 6
Rio Hondo channel facing down river. Proposed wall area.

This view south at the Rio Hondo convergence (right) shows the area that the U.S. Army Corps of Engineers in planning on spending $400 million to line the channel with a wall on both sides down to Long Beach. More than half the length of the wall will be 2 ft. high, but it will 8 ft. in places. FoLAR has challenged the plan and has suggested that there might be other ways to spend public funds that might enhance part of the river, replenish the ground water supplies, and provide for public safety. The Corps' philosophy is to get the flood waters to the ocean as quickly as possible. They state that the price of real estate in L.A. County is so high, that even a minor breach of the present channel walls would cause millions of dollars in damage to nearby residential and commercial property. D.J. Waldie in this Buzz magazine article supports this view. For communities along the lower river, such as Lakewood, the issues of flood control and flood insurance remain very hot topics.

FoLAR has published a flood control plan and claims that the experience with the floods of 1994 shows that the present channel is safe, and can be made safer with less expensive measures. The Corps maintains that the floods of 1994 and 1992 are portends of future disasters. During one rain in 1992 the flood waters reached within inches of the top of the channel. New studies will be commissioned to study alternatives to building the wall.

Continue the tour here. So batten down your hard drives and cover your keyboards. The adventures of the urban river awaits you. Good Luck and remember, don't drink the water!

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